Heavy and toxic metals removal from wastewater has never been easy and becoming a major concern for environmental and societal health. Among these heavy metals, lead ion (Pb (II)) is highly toxic and can cause great environmental pollution and health effects. Removal of the Pb (II) from aqueous solutions can be performed by utilizing composite materials. In this work, we established composites from kaolinite (K), CoFe2O4 (CF), and graphene oxide (GO) for adsorption of the lead ion (Pb (II)).
Long-term sulfuric and hydrochloric acid resistance of silica fume and colema...Publ 2022
Yurdakul Aygörmez (Main and Corresponding Author)
Yildiz Technical University, Department of Civil Engineering Davutpasa Campus 34220, Esenler, Istanbul (Turkey)
aygormez@yildiz.edu.tr
https://orcid.org/0000-0001-7405-2450
Orhan Canpolat
Yildiz Technical University, Department of Civil Engineering Davutpasa Campus 34220, Esenler, Istanbul (Turkey)
canpolat@yildiz.edu.tr
https://orcid.org/0000-0003-2744-7876
ABSTRACT
For this paper, silica fume (SF), slag (S), and colemanite waste (C) were added to metakaolin (MK)-based geopolymer composites and exposed to 10% (by volume) hydrochloric acid (HCl) and sulfuric acid (H2SO4) solutions for up to 12 months. Geopolymer composites were examined in terms of weight loss, compressive strength, and flexural strength at 3, 6, and 12 months in solutions. Furthermore, Scanning Electron Microscopy (SEM), Microcomputed Tomography (micro-CT), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) analyses were carried out to examine the microstructure before and after acid attacks. An important decrease in flexural and compressive strengths was seen when geopolymer mortars were subjected to sulfuric and hydrochloric acid attacks. The main cause of this situation is the deterioration of the oxy-aluminum bridge (-Al-Si-O) when exposed to sulfuric and hydrochloric acid. The oxy-aluminum bridge (-Al-Si-O), the primary factor in the geopolymer matrix, plays a significant role in consolidating the gel and enhancing the bond formed between the matrix components. Despite this, geopolymer mortar samples maintain the aluminosilicate structure. Compared to hydrochloric acid, sulfuric acid is a stronger solution, resulting in a greater loss of compressive and flexural strengths.
Water pollution due to several factors such as industrial
and agricultural waste, deforestation, volcanic eruption,
mining, oil spills, radioactive waste, etc., has become a
very critical issue for the human race as the human body
contains water as the main portion of its constitution and
very important to maintain a healthy human race. Global
warming has led to an increase in the sea levels resulting
in an increase in the volume of salted water. As per the
WHO report, around 765 million people across the world
lack basic drinking water, of which around 144 million
depend upon surface water and around 2 billion people
use contaminated water. It leads to several epidemic diseases
like diarrhea, typhoid, cholera, etc. which result in
around 500,000 deaths every year. This estimate clearly
shows the importance of improving water quality for
decreasing diarrheal disease burdens. Apart from the thirst
crisis, there could be a food crisis due to water pollution.
Wastewater contain heavy metal ions and azo dyes as the
most common toxic materials is a huge concern for the
human health and the conservation of our ecosystem
(Pru¨ss et al., 2002; Pru¨ss-Ustu¨n et al., 2014; Molinari
et al., 2004; Al-Degs et al., 2006; Sadegh et al., 2015;
Babel and Kurniawan, 2003; Karimi and Zohoori, 2013;
Islam et al., 2017; Abdulla et al., 2020; Abdulla et al.,
2019; Fatima et al., 2019a; Fatima et al., 2019b; Rathi
et al., 2020; Rathi et al., 2018). Furthermore, heavy
metals pass into food through irrigation and thereby enter
the human body and lead to fatal diseases like liver or
kidney damage and cancer (Cui et al., 2015; Siddiqui and
Chaudhry, 2017a,b,c,d; Siddiqui et al., 2017; Siddiqui
et al., 2020). Therefore, it is essential to individual, government,
as well as the scientific communities to have a
sense of responsibility towards humanity for providing
the basic necessity of safe water to all individuals. The
traditional techniques employed in water treatment have
proven to be less efficient owing to high energy utilization
and production of secondary pollutants. It is crucial
to develop innovative technologies with high efficiency
and low energy consumption. In recent years, nanotechnology
has appeared as a promising technique where it
utilizes novel functional nanomaterials for water treatment
(Siddiqui et al., 2018a,b,c,d; Siddiqui and Chaudhry,
2018a,b; Siddiqui et al., 2019a,b,c,d; Siddiqui and
Chaudhry, 2019; Tara et al., 2020a,b,c; Zaidi et al.,
2019). Carbon-based 2-D materials like graphene, GO
(graphene oxide) and rGO (reduced graphene oxide) have
exhibited great potential for water treatment, especially
for drinking water because of their remarkable properties,
for example good anti-fouling property, chemical stability,
high mechanical strength, and easy membrane accessibility
(Nausad, 2019; Yin et al., 2016).
Effects of alternative ecological fillers on the mechanical, durability, and ...Publ 2022
In this research, the performance of fly ash/GGBS geopolymer mortars made with different quarry waste powder as filler materials by substituted the river sand fine aggregate with different ratios was evaluated based on the mechanical, physical, durability properties and microstructural analysis. Limestone waste, marble waste and basalt waste powder were used as filler materials developing eco-friendly and economical geopolymer from industrial waste as a promising sustainable area of research. A series of tests were conducted such as on strength properties, ultrasonic pulse vel-ocity (UPV), physical properties, abrasion resistance test, splitting tensile strength and microstructure analysis (SEM). The samples were elevated at the high-temperatures of 200 C, 400 C, 600 C and 800 C. Results conducted that the use of limestone waste powder and marble waste powder up to 50% ratio improved the geopolymer composite’s strength. The three filler geopolymer composites positively affected water absorption, strength properties and abrasion ratio results. The current article’s finding has indicated a potential solution, presenting another geopolymer class followed by the successful use of fly ash and quarry waste as significant asset materials. The output of this study is commercially expected to be effective intercession for waste recycled and friendly environmental management conclusions.
The document summarizes a final year project presentation on the effect of fiber on geopolymer concrete. The presentation was given by four civil engineering students to their final year project committee and external examiners. The project investigated the effect of polypropylene fibers on the compressive strength of fly ash-based geopolymer concrete cured at ambient temperatures. Testing was conducted on the materials properties and concrete mixes were designed with varying alkaline activator solutions. Results showed that compressive strength increased with higher alkaline activator concentrations and curing temperatures.
Dry Grinding - Carbonated Ultrasound-Assisted Water Leaching of Carbothermall...brianmaks
The document presents a dry grinding and carbonated ultrasound-assisted water leaching (CUAWL) process for recycling spent lithium-ion battery black mass containing anode and cathode materials. The process aims to enhance selective lithium carbonate recovery and reduce energy requirements for crystallization while maximizing recovery of high-value metals like nickel, manganese, and cobalt. Key steps include carbothermic reduction roasting of the black mass, followed by dry grinding and CUAWL. Optimization studies examined factors affecting metal leaching efficiency. The optimized method achieved up to 92.25% selective lithium recovery for a mixture of multiple cathode materials.
Mortar strength of Low calcium Flyashbased GeopolymerIOSRJEEE
Development of an alternative to conventional cement binder has become the essential need in the construction industries. Production of the conventional constituents of concrete particularly Portland cement exploits significant amount of natural resources and emits equivalent amountof carbon dioxide to the atmosphere. Research made on making binder without cement has come to a viable level of developing geopolymers.Industrial wastes and by products that are pozzolanic in nature are being used as source material and activated using alkaline solutions to use as binder. Considerable research has been carried out to study about the performance of geopolymer concrete with steam curing or hot curing which are feasible for precast concrete and practically not viable for conventional construction activities. However, there is not much data available on themortar strength.Abasic study on the strength characteristicsof low calcium flyash based geopolymer with 8-16M molar concentration of Sodium hydroxide and 1.5-3.0 liquid ratios of sodium silicate to sodium hydroxide. Both hot oven curingat 65oC and ambient curing at room temperature aremade. The results are compared and the optimum molarity for maximum strength is reported.
Long-term sulfuric and hydrochloric acid resistance of silica fume and colema...Publ 2022
Yurdakul Aygörmez (Main and Corresponding Author)
Yildiz Technical University, Department of Civil Engineering Davutpasa Campus 34220, Esenler, Istanbul (Turkey)
aygormez@yildiz.edu.tr
https://orcid.org/0000-0001-7405-2450
Orhan Canpolat
Yildiz Technical University, Department of Civil Engineering Davutpasa Campus 34220, Esenler, Istanbul (Turkey)
canpolat@yildiz.edu.tr
https://orcid.org/0000-0003-2744-7876
ABSTRACT
For this paper, silica fume (SF), slag (S), and colemanite waste (C) were added to metakaolin (MK)-based geopolymer composites and exposed to 10% (by volume) hydrochloric acid (HCl) and sulfuric acid (H2SO4) solutions for up to 12 months. Geopolymer composites were examined in terms of weight loss, compressive strength, and flexural strength at 3, 6, and 12 months in solutions. Furthermore, Scanning Electron Microscopy (SEM), Microcomputed Tomography (micro-CT), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) analyses were carried out to examine the microstructure before and after acid attacks. An important decrease in flexural and compressive strengths was seen when geopolymer mortars were subjected to sulfuric and hydrochloric acid attacks. The main cause of this situation is the deterioration of the oxy-aluminum bridge (-Al-Si-O) when exposed to sulfuric and hydrochloric acid. The oxy-aluminum bridge (-Al-Si-O), the primary factor in the geopolymer matrix, plays a significant role in consolidating the gel and enhancing the bond formed between the matrix components. Despite this, geopolymer mortar samples maintain the aluminosilicate structure. Compared to hydrochloric acid, sulfuric acid is a stronger solution, resulting in a greater loss of compressive and flexural strengths.
Water pollution due to several factors such as industrial
and agricultural waste, deforestation, volcanic eruption,
mining, oil spills, radioactive waste, etc., has become a
very critical issue for the human race as the human body
contains water as the main portion of its constitution and
very important to maintain a healthy human race. Global
warming has led to an increase in the sea levels resulting
in an increase in the volume of salted water. As per the
WHO report, around 765 million people across the world
lack basic drinking water, of which around 144 million
depend upon surface water and around 2 billion people
use contaminated water. It leads to several epidemic diseases
like diarrhea, typhoid, cholera, etc. which result in
around 500,000 deaths every year. This estimate clearly
shows the importance of improving water quality for
decreasing diarrheal disease burdens. Apart from the thirst
crisis, there could be a food crisis due to water pollution.
Wastewater contain heavy metal ions and azo dyes as the
most common toxic materials is a huge concern for the
human health and the conservation of our ecosystem
(Pru¨ss et al., 2002; Pru¨ss-Ustu¨n et al., 2014; Molinari
et al., 2004; Al-Degs et al., 2006; Sadegh et al., 2015;
Babel and Kurniawan, 2003; Karimi and Zohoori, 2013;
Islam et al., 2017; Abdulla et al., 2020; Abdulla et al.,
2019; Fatima et al., 2019a; Fatima et al., 2019b; Rathi
et al., 2020; Rathi et al., 2018). Furthermore, heavy
metals pass into food through irrigation and thereby enter
the human body and lead to fatal diseases like liver or
kidney damage and cancer (Cui et al., 2015; Siddiqui and
Chaudhry, 2017a,b,c,d; Siddiqui et al., 2017; Siddiqui
et al., 2020). Therefore, it is essential to individual, government,
as well as the scientific communities to have a
sense of responsibility towards humanity for providing
the basic necessity of safe water to all individuals. The
traditional techniques employed in water treatment have
proven to be less efficient owing to high energy utilization
and production of secondary pollutants. It is crucial
to develop innovative technologies with high efficiency
and low energy consumption. In recent years, nanotechnology
has appeared as a promising technique where it
utilizes novel functional nanomaterials for water treatment
(Siddiqui et al., 2018a,b,c,d; Siddiqui and Chaudhry,
2018a,b; Siddiqui et al., 2019a,b,c,d; Siddiqui and
Chaudhry, 2019; Tara et al., 2020a,b,c; Zaidi et al.,
2019). Carbon-based 2-D materials like graphene, GO
(graphene oxide) and rGO (reduced graphene oxide) have
exhibited great potential for water treatment, especially
for drinking water because of their remarkable properties,
for example good anti-fouling property, chemical stability,
high mechanical strength, and easy membrane accessibility
(Nausad, 2019; Yin et al., 2016).
Effects of alternative ecological fillers on the mechanical, durability, and ...Publ 2022
In this research, the performance of fly ash/GGBS geopolymer mortars made with different quarry waste powder as filler materials by substituted the river sand fine aggregate with different ratios was evaluated based on the mechanical, physical, durability properties and microstructural analysis. Limestone waste, marble waste and basalt waste powder were used as filler materials developing eco-friendly and economical geopolymer from industrial waste as a promising sustainable area of research. A series of tests were conducted such as on strength properties, ultrasonic pulse vel-ocity (UPV), physical properties, abrasion resistance test, splitting tensile strength and microstructure analysis (SEM). The samples were elevated at the high-temperatures of 200 C, 400 C, 600 C and 800 C. Results conducted that the use of limestone waste powder and marble waste powder up to 50% ratio improved the geopolymer composite’s strength. The three filler geopolymer composites positively affected water absorption, strength properties and abrasion ratio results. The current article’s finding has indicated a potential solution, presenting another geopolymer class followed by the successful use of fly ash and quarry waste as significant asset materials. The output of this study is commercially expected to be effective intercession for waste recycled and friendly environmental management conclusions.
The document summarizes a final year project presentation on the effect of fiber on geopolymer concrete. The presentation was given by four civil engineering students to their final year project committee and external examiners. The project investigated the effect of polypropylene fibers on the compressive strength of fly ash-based geopolymer concrete cured at ambient temperatures. Testing was conducted on the materials properties and concrete mixes were designed with varying alkaline activator solutions. Results showed that compressive strength increased with higher alkaline activator concentrations and curing temperatures.
Dry Grinding - Carbonated Ultrasound-Assisted Water Leaching of Carbothermall...brianmaks
The document presents a dry grinding and carbonated ultrasound-assisted water leaching (CUAWL) process for recycling spent lithium-ion battery black mass containing anode and cathode materials. The process aims to enhance selective lithium carbonate recovery and reduce energy requirements for crystallization while maximizing recovery of high-value metals like nickel, manganese, and cobalt. Key steps include carbothermic reduction roasting of the black mass, followed by dry grinding and CUAWL. Optimization studies examined factors affecting metal leaching efficiency. The optimized method achieved up to 92.25% selective lithium recovery for a mixture of multiple cathode materials.
Mortar strength of Low calcium Flyashbased GeopolymerIOSRJEEE
Development of an alternative to conventional cement binder has become the essential need in the construction industries. Production of the conventional constituents of concrete particularly Portland cement exploits significant amount of natural resources and emits equivalent amountof carbon dioxide to the atmosphere. Research made on making binder without cement has come to a viable level of developing geopolymers.Industrial wastes and by products that are pozzolanic in nature are being used as source material and activated using alkaline solutions to use as binder. Considerable research has been carried out to study about the performance of geopolymer concrete with steam curing or hot curing which are feasible for precast concrete and practically not viable for conventional construction activities. However, there is not much data available on themortar strength.Abasic study on the strength characteristicsof low calcium flyash based geopolymer with 8-16M molar concentration of Sodium hydroxide and 1.5-3.0 liquid ratios of sodium silicate to sodium hydroxide. Both hot oven curingat 65oC and ambient curing at room temperature aremade. The results are compared and the optimum molarity for maximum strength is reported.
metal organic framework-carbon capture and sequestrationVasiUddin Siddiqui
MOF is a porous crystal like a spunge having an enormous surface area and provide much more rooms for storage the gases preferentially hydrogen and carbon dioxide and work as storage for next generation fuel.
This document discusses the effect of various parameters on the compressive strength of ground bottom ash geopolymer mortar. It examines the effect of molar ratio of SiO2/Na2O, ratio of Na2SiO3/NaOH, and curing mode (ambient vs steam). Test results found that a Na2SiO3/NaOH ratio of 2 with a SiO2/Na2O molar ratio of 1 achieved the highest compressive strength under both ambient and steam curing. The document provides background on geopolymers and discusses parameters that influence geopolymer strength such as alkaline liquid to binder ratio and curing conditions.
Recovery of silver from x ray film processing effluents by hydrogen peroxide ...Muhammad Adeel Shakoor
This document summarizes a study on recovering silver from X-ray film processing effluents using hydrogen peroxide precipitation. Key findings include:
- Hydrogen peroxide treatment is highly exothermic and rapidly precipitates over 95% of silver from effluents containing 1.1 g/L silver and 113 g/L thiosulfate when at least 37.6 g/L hydrogen peroxide is used.
- Increasing pH and adding ethylene glycol enhances silver recovery, likely by stabilizing hydrogen peroxide.
- Characterization of precipitates found silver is mainly present as fine silver sulfide.
- Hydrogen peroxide consumption oxidizes thiosulfate, increasing sulfate
This document summarizes a study on using coagulation-flocculation with micro sand to treat stabilized landfill leachate. The study examined different particle sizes of micro sand in combination with PAC, alum, or ferric chloride coagulants. The highest removal efficiencies for SS, color, COD, and ammoniacal nitrogen were achieved using PAC and cationic polymer with micro sand sizes of 75-90μm or 181-212μm. Removal rates of over 90% were achieved for SS and color, while COD and ammoniacal nitrogen removal rates were over 60% and 50% respectively. Micro sand provided improved removal compared to micro zeolite, though efficiencies were slightly lower
Global Journal of Environmental Science and Management (GJESM)
Application of amorphous zirconium (hydr)oxide/MgFe layered double hydroxides composite in fixed-bed column for phosphate removal from water.
Hexamolybdenum clusters supported on graphene oxide: Visible-light induced ph...Pawan Kumar
Hexamolybdenum (Mo6) cluster-based compounds namely Cs2Mo6Bri
8Bra6
and
(TBA)2Mo6Bri
8Bra
6 (TBA = tetrabutylammonium) were immobilized on graphene oxide (GO)
nanosheets by taking advantage of the high lability of the apical bromide ions with
oxygen-functionalities of GO nanosheets. The loading of Mo6 clusters on GO nanosheets
was probed by Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron
spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) and elemental
mapping analyses. The developed GO-Cs2Mo6Bri
8Bra
x and GO-(TBA)2Mo6Bri
8Bra
x
composites were then used as heterogeneous photocatalysts for the reduction of CO2 under
visible light irradiation. After 24 h visible light illumination, the yield of methanol was
found to be 1644 and 1294 lmol g1 cat for GO-Cs2Mo6Bri
8Bra
x and GO-(TBA)2Mo6Bri
8Bra
x,
respectively. The quantum yields of methanol by using GO-Cs2Mo6Bri
8Bra
x and
GO-(TBA)2Mo6Bri
8Bra
x as catalysts with reference to Mo6 cluster units presented in 0.1 g
amount of catalyst were found to be 0.015 and 0.011, respectively. The role of immobilized
Mo6 clusters-based compounds on GO nanosheets is discussed to understand the
photocatalytic mechanism of CO2 reduction into methanol.
Hexamolybdenum clusters supported on graphene oxide: Visible-light induced ph...Pawan Kumar
This document summarizes a study on immobilizing hexamolybdenum clusters on graphene oxide nanosheets for photocatalytic reduction of carbon dioxide into methanol. Specifically, Cs2Mo6Bri8Bra6 and (TBA)2Mo6Bri8Bra6 clusters were immobilized on graphene oxide through replacement of apical bromide ions with oxygen functional groups on the graphene oxide surface. The developed GO-Cs2Mo6Bri8Brax and GO-(TBA)2Mo6Bri8Brax composites were then used as heterogeneous photocatalysts for CO2 reduction under visible light, producing methanol yields of 1644 and 1294 μmol g−1cat, respectively
This document summarizes a study on producing eco-friendly mortar mixes using geopolymer as a binder and recycled fine aggregate (RFA) partially, and evaluating their resistance to aggressive environments. Fly ash, ground granulated blast furnace slag (GGBS), and an alkaline solution of sodium silicate and sodium hydroxide were used to make geopolymer binder. Mortar mixes with 0%, 25% RFA and alkaline liquid to binder ratios of 0.4 and 0.6 were tested for acid resistance, sulfate resistance, and rapid chloride permeability. Results showed strength reduction with RFA, but mixes with a 0.6 ratio performed better durability-wise than a 0.4 ratio. The
This document summarizes a study that examined using micro zeolite combined with coagulants and coagulant aids to treat stabilized landfill leachate. The study tested different dosages of polyaluminum chloride (PAC), alum, and ferric chloride combined with micro zeolite and a polymer. The micro zeolite was tested at different particle sizes. The combination of PAC and micro zeolite achieved the highest removal rates for suspended solids (99.7%), color (96%), chemical oxygen demand (76%), and ammoniacal nitrogen (68%) with a settling time of 30 minutes.
Cobalt Phthalocyanine Immobilized on Graphene Oxide: An Efficient Visible-Act...Pawan Kumar
New graphene oxide (GO)-tethered–CoII phthalocyanine
complex [CoPc–GO] was synthesized by a stepwise
procedure and demonstrated to be an efficient, cost-effective
and recyclable photocatalyst for the reduction of carbon
dioxide to produce methanol as the main product. The developed
GO-immobilized CoPc was characterized by X-ray
diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/
Vis spectroscopy, inductively coupled plasma atomic emission
spectroscopy (ICP-AES), thermogravimetric analysis
(TGA), Brunauer–Emmett–Teller (BET), scanning electron microscopy
(SEM), and transmission electron microscopy (TEM).
FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental
analysis data showed that CoII–Pc complex was successfully
grafted on GO. The prepared catalyst was used for the photocatalytic
reduction of carbon dioxide by using water as
a solvent and triethylamine as the sacrificial donor. Methanol
was obtained as the major reaction product along with the
formation of minor amount of CO (0.82 %). It was found that
GO-grafted CoPc exhibited higher photocatalytic activity
than homogeneous CoPc, as well as GO, and showed good
recoverability without significant leaching during the reaction.
Quantitative determination of methanol was done by
GC flame-ionization detector (FID), and verification of product
was done by NMR spectroscopy. The yield of methanol
after 48 h of reaction by using GO–CoPc catalyst in the presence
of sacrificial donor triethylamine was found to be
3781.8881 mmolg1 cat., and the conversion rate was found
to be 78.7893 mmolg1cat.h1. After the photoreduction experiment,
the catalyst was easily recovered by filtration and
reused for the subsequent recycling experiment without significant
change in the catalytic efficiency
Cobalt Phthalocyanine Immobilized on Graphene Oxide: An Efficient Visible-Act...Pawan Kumar
Abstract: New graphene oxide (GO)-tethered–CoII phthalocyanine
complex [CoPc–GO] was synthesized by a stepwise
procedure and demonstrated to be an efficient, cost-effective
and recyclable photocatalyst for the reduction of carbon
dioxide to produce methanol as the main product. The developed
GO-immobilized CoPc was characterized by X-ray
diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/
Vis spectroscopy, inductively coupled plasma atomic emission
spectroscopy (ICP-AES), thermogravimetric analysis
(TGA), Brunauer–Emmett–Teller (BET), scanning electron microscopy
(SEM), and transmission electron microscopy (TEM).
FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental
analysis data showed that CoII–Pc complex was successfully
grafted on GO. The prepared catalyst was used for the photocatalytic
reduction of carbon dioxide by using water as
a solvent and triethylamine as the sacrificial donor. Methanol
was obtained as the major reaction product along with the
formation of minor amount of CO (0.82 %). It was found that
GO-grafted CoPc exhibited higher photocatalytic activity
than homogeneous CoPc, as well as GO, and showed good
recoverability without significant leaching during the reaction.
Quantitative determination of methanol was done by
GC flame-ionization detector (FID), and verification of product
was done by NMR spectroscopy. The yield of methanol
after 48 h of reaction by using GO–CoPc catalyst in the presence
of sacrificial donor triethylamine was found to be
3781.8881 mmolg1 cat., and the conversion rate was found
to be 78.7893 mmolg1cat.h1. After the photoreduction experiment,
the catalyst was easily recovered by filtration and
reused for the subsequent recycling experiment without significant
change in the catalytic efficiency.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
Reduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
tReduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Synthesis of novel and tunable Micro Mesoporous carbon nitrides for Ultra Hig...farnaztabarkhoon
Carbon nitride (CN) materials with intrinsic high nitrogen content are potential candidates for acidic gas
adsorption. However, these nanomaterials should be further treated to achieve tunable textural properties for
ultra-high gas adsorption. Herein, we synthesized dual-pore carbon nitride materials (DP-CN) with a series of
ethylenediamine to carbon tetrachloride ratios with different amounts of potassium hydroxide (KOH) as a
chemical activator using nanosilica (SiO2) as a hard template to tune the physicochemical properties of the
materials. The prepared DP-CN adsorbents had a large surface area (up to 2036.9 m2/g), great pore volume (up
to 1.15 cm3/g), and high nitrogen content (10.6 to 15.1 wt%). The best DP-CN displayed ultra-high CO2 and H2S
adsorption capacity at 1 bar (8.3 and 13.8 mmol/g, respectively), 10 bar (16.9 and 23.1 mmol/g, respectively),
and 30 bar (22.9 mmol/g for CO2) at 25 ◦C, which was significantly higher than those of other pure mesoporous
carbon nitrides (M-CN) and carbon-based adsorbents. Moreover, the best adsorbent exhibited good CO2/N2,
CO2/CH4, H2S/N2, and H2S/CH4 selectivity, suitable heat of adsorption, and excellent cyclic stability. According
to density functional theory calculations, H2S adsorbs more strongly than CO2 on carbon nitride surfaces, and the
adsorption energies of CO2 and H2S are related to charge-transfer values from the surface to the adsorbed species.
The results revealed that the exceptional textural properties and high nitrogen content of the materials could play
the main role in the superior adsorption of CO2 and H2S. This generation of CN materials is expected to be
practical for a various range of separation processes, catalysis, capacitors, and energy storage.
- The document discusses the resistance of fly ash-based and slag-based geopolymer concrete to sulfate and acid attack.
- Specimens of both geopolymer concretes and ordinary Portland cement concrete were subjected to 5% sodium sulfate and 5% sulfuric acid solutions.
- Test results found that both types of geopolymer concrete underwent very little change in compressive strength under acid and sulfate attack, suggesting their durability is much superior to ordinary cement concrete in these environments.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
This document describes the synthesis and characterization of a core-shell structured reduced graphene oxide wrapped magnetically separable rGO@CuZnO@Fe3O4 microspheres photocatalyst and its use for the photoreduction of carbon dioxide to methanol under visible light irradiation. The photocatalyst takes advantage of the high photocatalytic efficiency of zinc oxide, the high surface area and charge carrier mobility of reduced graphene oxide, and the magnetic properties of an iron oxide core. Experimental results showed the rGO@CuZnO@Fe3O4 photocatalyst had higher catalytic activity than other possible combinations, with a methanol yield of 2656 μmol/gcat under visible light, and could be readily recovered and
Nanostructured composite materials for CO2 activationPawan Kumar
This document summarizes the challenges of rising CO2 levels and discusses nanostructured composite materials for CO2 activation. It notes that CO2 levels are the highest in 800,000 years due to fossil fuel use. While CO2 storage is possible, conversion to chemicals is promising. Semiconductors can photocatalytically reduce CO2 but require visible light absorption and charge separation to be efficient. The document reviews the thermodynamics of CO2 reduction and discusses producing hydrogen from water splitting to enable CO2 conversion to hydrocarbons like methanol.
This document summarizes a research article that reviewed the utilization of fly ash waste from coal combustion in the cement industry and its environmental impacts. Fly ash is a byproduct of burning coal in power plants and contains various metal oxides. The research finds that while fly ash utilization helps absorb waste, it also contributes to air pollution if not managed properly. However, technologies exist to reduce environmental impacts, such as using fly ash as a raw material in concrete or other building materials. The full article provides background on fly ash properties and production, details the methodology of a literature review, and analyzes fly ash use in cement manufacturing and its effects on air quality.
Final report on Behaviour of Geopolymer Concretechetansingh999
This document is a thesis submitted by Chetan Singh Pundeer to fulfill the requirements for a B.Tech degree in Civil Engineering from Lingaya's University. It involves a study of the behavior of geopolymer concrete. Chetan declares that the work is original and was carried out under the supervision of Utkarsh Yadav. The thesis acknowledges the guidance of Nazim Ali and assistance of Utkarsh Yadav. The abstract indicates that the study focuses on developing environmentally friendly geopolymer concrete using fly ash as a cement replacement and studying its durability when exposed to acids, sulfates and chlorides.
metal organic framework-carbon capture and sequestrationVasiUddin Siddiqui
MOF is a porous crystal like a spunge having an enormous surface area and provide much more rooms for storage the gases preferentially hydrogen and carbon dioxide and work as storage for next generation fuel.
This document discusses the effect of various parameters on the compressive strength of ground bottom ash geopolymer mortar. It examines the effect of molar ratio of SiO2/Na2O, ratio of Na2SiO3/NaOH, and curing mode (ambient vs steam). Test results found that a Na2SiO3/NaOH ratio of 2 with a SiO2/Na2O molar ratio of 1 achieved the highest compressive strength under both ambient and steam curing. The document provides background on geopolymers and discusses parameters that influence geopolymer strength such as alkaline liquid to binder ratio and curing conditions.
Recovery of silver from x ray film processing effluents by hydrogen peroxide ...Muhammad Adeel Shakoor
This document summarizes a study on recovering silver from X-ray film processing effluents using hydrogen peroxide precipitation. Key findings include:
- Hydrogen peroxide treatment is highly exothermic and rapidly precipitates over 95% of silver from effluents containing 1.1 g/L silver and 113 g/L thiosulfate when at least 37.6 g/L hydrogen peroxide is used.
- Increasing pH and adding ethylene glycol enhances silver recovery, likely by stabilizing hydrogen peroxide.
- Characterization of precipitates found silver is mainly present as fine silver sulfide.
- Hydrogen peroxide consumption oxidizes thiosulfate, increasing sulfate
This document summarizes a study on using coagulation-flocculation with micro sand to treat stabilized landfill leachate. The study examined different particle sizes of micro sand in combination with PAC, alum, or ferric chloride coagulants. The highest removal efficiencies for SS, color, COD, and ammoniacal nitrogen were achieved using PAC and cationic polymer with micro sand sizes of 75-90μm or 181-212μm. Removal rates of over 90% were achieved for SS and color, while COD and ammoniacal nitrogen removal rates were over 60% and 50% respectively. Micro sand provided improved removal compared to micro zeolite, though efficiencies were slightly lower
Global Journal of Environmental Science and Management (GJESM)
Application of amorphous zirconium (hydr)oxide/MgFe layered double hydroxides composite in fixed-bed column for phosphate removal from water.
Hexamolybdenum clusters supported on graphene oxide: Visible-light induced ph...Pawan Kumar
Hexamolybdenum (Mo6) cluster-based compounds namely Cs2Mo6Bri
8Bra6
and
(TBA)2Mo6Bri
8Bra
6 (TBA = tetrabutylammonium) were immobilized on graphene oxide (GO)
nanosheets by taking advantage of the high lability of the apical bromide ions with
oxygen-functionalities of GO nanosheets. The loading of Mo6 clusters on GO nanosheets
was probed by Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron
spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) and elemental
mapping analyses. The developed GO-Cs2Mo6Bri
8Bra
x and GO-(TBA)2Mo6Bri
8Bra
x
composites were then used as heterogeneous photocatalysts for the reduction of CO2 under
visible light irradiation. After 24 h visible light illumination, the yield of methanol was
found to be 1644 and 1294 lmol g1 cat for GO-Cs2Mo6Bri
8Bra
x and GO-(TBA)2Mo6Bri
8Bra
x,
respectively. The quantum yields of methanol by using GO-Cs2Mo6Bri
8Bra
x and
GO-(TBA)2Mo6Bri
8Bra
x as catalysts with reference to Mo6 cluster units presented in 0.1 g
amount of catalyst were found to be 0.015 and 0.011, respectively. The role of immobilized
Mo6 clusters-based compounds on GO nanosheets is discussed to understand the
photocatalytic mechanism of CO2 reduction into methanol.
Hexamolybdenum clusters supported on graphene oxide: Visible-light induced ph...Pawan Kumar
This document summarizes a study on immobilizing hexamolybdenum clusters on graphene oxide nanosheets for photocatalytic reduction of carbon dioxide into methanol. Specifically, Cs2Mo6Bri8Bra6 and (TBA)2Mo6Bri8Bra6 clusters were immobilized on graphene oxide through replacement of apical bromide ions with oxygen functional groups on the graphene oxide surface. The developed GO-Cs2Mo6Bri8Brax and GO-(TBA)2Mo6Bri8Brax composites were then used as heterogeneous photocatalysts for CO2 reduction under visible light, producing methanol yields of 1644 and 1294 μmol g−1cat, respectively
This document summarizes a study on producing eco-friendly mortar mixes using geopolymer as a binder and recycled fine aggregate (RFA) partially, and evaluating their resistance to aggressive environments. Fly ash, ground granulated blast furnace slag (GGBS), and an alkaline solution of sodium silicate and sodium hydroxide were used to make geopolymer binder. Mortar mixes with 0%, 25% RFA and alkaline liquid to binder ratios of 0.4 and 0.6 were tested for acid resistance, sulfate resistance, and rapid chloride permeability. Results showed strength reduction with RFA, but mixes with a 0.6 ratio performed better durability-wise than a 0.4 ratio. The
This document summarizes a study that examined using micro zeolite combined with coagulants and coagulant aids to treat stabilized landfill leachate. The study tested different dosages of polyaluminum chloride (PAC), alum, and ferric chloride combined with micro zeolite and a polymer. The micro zeolite was tested at different particle sizes. The combination of PAC and micro zeolite achieved the highest removal rates for suspended solids (99.7%), color (96%), chemical oxygen demand (76%), and ammoniacal nitrogen (68%) with a settling time of 30 minutes.
Cobalt Phthalocyanine Immobilized on Graphene Oxide: An Efficient Visible-Act...Pawan Kumar
New graphene oxide (GO)-tethered–CoII phthalocyanine
complex [CoPc–GO] was synthesized by a stepwise
procedure and demonstrated to be an efficient, cost-effective
and recyclable photocatalyst for the reduction of carbon
dioxide to produce methanol as the main product. The developed
GO-immobilized CoPc was characterized by X-ray
diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/
Vis spectroscopy, inductively coupled plasma atomic emission
spectroscopy (ICP-AES), thermogravimetric analysis
(TGA), Brunauer–Emmett–Teller (BET), scanning electron microscopy
(SEM), and transmission electron microscopy (TEM).
FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental
analysis data showed that CoII–Pc complex was successfully
grafted on GO. The prepared catalyst was used for the photocatalytic
reduction of carbon dioxide by using water as
a solvent and triethylamine as the sacrificial donor. Methanol
was obtained as the major reaction product along with the
formation of minor amount of CO (0.82 %). It was found that
GO-grafted CoPc exhibited higher photocatalytic activity
than homogeneous CoPc, as well as GO, and showed good
recoverability without significant leaching during the reaction.
Quantitative determination of methanol was done by
GC flame-ionization detector (FID), and verification of product
was done by NMR spectroscopy. The yield of methanol
after 48 h of reaction by using GO–CoPc catalyst in the presence
of sacrificial donor triethylamine was found to be
3781.8881 mmolg1 cat., and the conversion rate was found
to be 78.7893 mmolg1cat.h1. After the photoreduction experiment,
the catalyst was easily recovered by filtration and
reused for the subsequent recycling experiment without significant
change in the catalytic efficiency
Cobalt Phthalocyanine Immobilized on Graphene Oxide: An Efficient Visible-Act...Pawan Kumar
Abstract: New graphene oxide (GO)-tethered–CoII phthalocyanine
complex [CoPc–GO] was synthesized by a stepwise
procedure and demonstrated to be an efficient, cost-effective
and recyclable photocatalyst for the reduction of carbon
dioxide to produce methanol as the main product. The developed
GO-immobilized CoPc was characterized by X-ray
diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/
Vis spectroscopy, inductively coupled plasma atomic emission
spectroscopy (ICP-AES), thermogravimetric analysis
(TGA), Brunauer–Emmett–Teller (BET), scanning electron microscopy
(SEM), and transmission electron microscopy (TEM).
FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental
analysis data showed that CoII–Pc complex was successfully
grafted on GO. The prepared catalyst was used for the photocatalytic
reduction of carbon dioxide by using water as
a solvent and triethylamine as the sacrificial donor. Methanol
was obtained as the major reaction product along with the
formation of minor amount of CO (0.82 %). It was found that
GO-grafted CoPc exhibited higher photocatalytic activity
than homogeneous CoPc, as well as GO, and showed good
recoverability without significant leaching during the reaction.
Quantitative determination of methanol was done by
GC flame-ionization detector (FID), and verification of product
was done by NMR spectroscopy. The yield of methanol
after 48 h of reaction by using GO–CoPc catalyst in the presence
of sacrificial donor triethylamine was found to be
3781.8881 mmolg1 cat., and the conversion rate was found
to be 78.7893 mmolg1cat.h1. After the photoreduction experiment,
the catalyst was easily recovered by filtration and
reused for the subsequent recycling experiment without significant
change in the catalytic efficiency.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
Reduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
tReduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Synthesis of novel and tunable Micro Mesoporous carbon nitrides for Ultra Hig...farnaztabarkhoon
Carbon nitride (CN) materials with intrinsic high nitrogen content are potential candidates for acidic gas
adsorption. However, these nanomaterials should be further treated to achieve tunable textural properties for
ultra-high gas adsorption. Herein, we synthesized dual-pore carbon nitride materials (DP-CN) with a series of
ethylenediamine to carbon tetrachloride ratios with different amounts of potassium hydroxide (KOH) as a
chemical activator using nanosilica (SiO2) as a hard template to tune the physicochemical properties of the
materials. The prepared DP-CN adsorbents had a large surface area (up to 2036.9 m2/g), great pore volume (up
to 1.15 cm3/g), and high nitrogen content (10.6 to 15.1 wt%). The best DP-CN displayed ultra-high CO2 and H2S
adsorption capacity at 1 bar (8.3 and 13.8 mmol/g, respectively), 10 bar (16.9 and 23.1 mmol/g, respectively),
and 30 bar (22.9 mmol/g for CO2) at 25 ◦C, which was significantly higher than those of other pure mesoporous
carbon nitrides (M-CN) and carbon-based adsorbents. Moreover, the best adsorbent exhibited good CO2/N2,
CO2/CH4, H2S/N2, and H2S/CH4 selectivity, suitable heat of adsorption, and excellent cyclic stability. According
to density functional theory calculations, H2S adsorbs more strongly than CO2 on carbon nitride surfaces, and the
adsorption energies of CO2 and H2S are related to charge-transfer values from the surface to the adsorbed species.
The results revealed that the exceptional textural properties and high nitrogen content of the materials could play
the main role in the superior adsorption of CO2 and H2S. This generation of CN materials is expected to be
practical for a various range of separation processes, catalysis, capacitors, and energy storage.
- The document discusses the resistance of fly ash-based and slag-based geopolymer concrete to sulfate and acid attack.
- Specimens of both geopolymer concretes and ordinary Portland cement concrete were subjected to 5% sodium sulfate and 5% sulfuric acid solutions.
- Test results found that both types of geopolymer concrete underwent very little change in compressive strength under acid and sulfate attack, suggesting their durability is much superior to ordinary cement concrete in these environments.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
This document describes the synthesis and characterization of a core-shell structured reduced graphene oxide wrapped magnetically separable rGO@CuZnO@Fe3O4 microspheres photocatalyst and its use for the photoreduction of carbon dioxide to methanol under visible light irradiation. The photocatalyst takes advantage of the high photocatalytic efficiency of zinc oxide, the high surface area and charge carrier mobility of reduced graphene oxide, and the magnetic properties of an iron oxide core. Experimental results showed the rGO@CuZnO@Fe3O4 photocatalyst had higher catalytic activity than other possible combinations, with a methanol yield of 2656 μmol/gcat under visible light, and could be readily recovered and
Nanostructured composite materials for CO2 activationPawan Kumar
This document summarizes the challenges of rising CO2 levels and discusses nanostructured composite materials for CO2 activation. It notes that CO2 levels are the highest in 800,000 years due to fossil fuel use. While CO2 storage is possible, conversion to chemicals is promising. Semiconductors can photocatalytically reduce CO2 but require visible light absorption and charge separation to be efficient. The document reviews the thermodynamics of CO2 reduction and discusses producing hydrogen from water splitting to enable CO2 conversion to hydrocarbons like methanol.
This document summarizes a research article that reviewed the utilization of fly ash waste from coal combustion in the cement industry and its environmental impacts. Fly ash is a byproduct of burning coal in power plants and contains various metal oxides. The research finds that while fly ash utilization helps absorb waste, it also contributes to air pollution if not managed properly. However, technologies exist to reduce environmental impacts, such as using fly ash as a raw material in concrete or other building materials. The full article provides background on fly ash properties and production, details the methodology of a literature review, and analyzes fly ash use in cement manufacturing and its effects on air quality.
Final report on Behaviour of Geopolymer Concretechetansingh999
This document is a thesis submitted by Chetan Singh Pundeer to fulfill the requirements for a B.Tech degree in Civil Engineering from Lingaya's University. It involves a study of the behavior of geopolymer concrete. Chetan declares that the work is original and was carried out under the supervision of Utkarsh Yadav. The thesis acknowledges the guidance of Nazim Ali and assistance of Utkarsh Yadav. The abstract indicates that the study focuses on developing environmentally friendly geopolymer concrete using fly ash as a cement replacement and studying its durability when exposed to acids, sulfates and chlorides.
Similar to cofe2o4/graphene oxide for adsorption of heavy metal ions (20)
Climate Change All over the World .pptxsairaanwer024
Climate change refers to significant and lasting changes in the average weather patterns over periods ranging from decades to millions of years. It encompasses both global warming driven by human emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. While climate change is a natural phenomenon, human activities, particularly since the Industrial Revolution, have accelerated its pace and intensity
Microbial characterisation and identification, and potability of River Kuywa ...Open Access Research Paper
Water contamination is one of the major causes of water borne diseases worldwide. In Kenya, approximately 43% of people lack access to potable water due to human contamination. River Kuywa water is currently experiencing contamination due to human activities. Its water is widely used for domestic, agricultural, industrial and recreational purposes. This study aimed at characterizing bacteria and fungi in river Kuywa water. Water samples were randomly collected from four sites of the river: site A (Matisi), site B (Ngwelo), site C (Nzoia water pump) and site D (Chalicha), during the dry season (January-March 2018) and wet season (April-July 2018) and were transported to Maseno University Microbiology and plant pathology laboratory for analysis. The characterization and identification of bacteria and fungi were carried out using standard microbiological techniques. Nine bacterial genera and three fungi were identified from Kuywa river water. Clostridium spp., Staphylococcus spp., Enterobacter spp., Streptococcus spp., E. coli, Klebsiella spp., Shigella spp., Proteus spp. and Salmonella spp. Fungi were Fusarium oxysporum, Aspergillus flavus complex and Penicillium species. Wet season recorded highest bacterial and fungal counts (6.61-7.66 and 3.83-6.75cfu/ml) respectively. The results indicated that the river Kuywa water is polluted and therefore unsafe for human consumption before treatment. It is therefore recommended that the communities to ensure that they boil water especially for drinking.
Presented by The Global Peatlands Assessment: Mapping, Policy, and Action at GLF Peatlands 2024 - The Global Peatlands Assessment: Mapping, Policy, and Action
Optimizing Post Remediation Groundwater Performance with Enhanced Microbiolog...Joshua Orris
Results of geophysics and pneumatic injection pilot tests during 2003 – 2007 yielded significant positive results for injection delivery design and contaminant mass treatment, resulting in permanent shut-down of an existing groundwater Pump & Treat system.
Accessible source areas were subsequently removed (2011) by soil excavation and treated with the placement of Emulsified Vegetable Oil EVO and zero-valent iron ZVI to accelerate treatment of impacted groundwater in overburden and weathered fractured bedrock. Post pilot test and post remediation groundwater monitoring has included analyses of CVOCs, organic fatty acids, dissolved gases and QuantArray® -Chlor to quantify key microorganisms (e.g., Dehalococcoides, Dehalobacter, etc.) and functional genes (e.g., vinyl chloride reductase, methane monooxygenase, etc.) to assess potential for reductive dechlorination and aerobic cometabolism of CVOCs.
In 2022, the first commercial application of MetaArray™ was performed at the site. MetaArray™ utilizes statistical analysis, such as principal component analysis and multivariate analysis to provide evidence that reductive dechlorination is active or even that it is slowing. This creates actionable data allowing users to save money by making important site management decisions earlier.
The results of the MetaArray™ analysis’ support vector machine (SVM) identified groundwater monitoring wells with a 80% confidence that were characterized as either Limited for Reductive Decholorination or had a High Reductive Reduction Dechlorination potential. The results of MetaArray™ will be used to further optimize the site’s post remediation monitoring program for monitored natural attenuation.
Improving the viability of probiotics by encapsulation methods for developmen...Open Access Research Paper
The popularity of functional foods among scientists and common people has been increasing day by day. Awareness and modernization make the consumer think better regarding food and nutrition. Now a day’s individual knows very well about the relation between food consumption and disease prevalence. Humans have a diversity of microbes in the gut that together form the gut microflora. Probiotics are the health-promoting live microbial cells improve host health through gut and brain connection and fighting against harmful bacteria. Bifidobacterium and Lactobacillus are the two bacterial genera which are considered to be probiotic. These good bacteria are facing challenges of viability. There are so many factors such as sensitivity to heat, pH, acidity, osmotic effect, mechanical shear, chemical components, freezing and storage time as well which affects the viability of probiotics in the dairy food matrix as well as in the gut. Multiple efforts have been done in the past and ongoing in present for these beneficial microbial population stability until their destination in the gut. One of a useful technique known as microencapsulation makes the probiotic effective in the diversified conditions and maintain these microbe’s community to the optimum level for achieving targeted benefits. Dairy products are found to be an ideal vehicle for probiotic incorporation. It has been seen that the encapsulated microbial cells show higher viability than the free cells in different processing and storage conditions as well as against bile salts in the gut. They make the food functional when incorporated, without affecting the product sensory characteristics.
Evolving Lifecycles with High Resolution Site Characterization (HRSC) and 3-D...Joshua Orris
The incorporation of a 3DCSM and completion of HRSC provided a tool for enhanced, data-driven, decisions to support a change in remediation closure strategies. Currently, an approved pilot study has been obtained to shut-down the remediation systems (ISCO, P&T) and conduct a hydraulic study under non-pumping conditions. A separate micro-biological bench scale treatability study was competed that yielded positive results for an emerging innovative technology. As a result, a field pilot study has commenced with results expected in nine-twelve months. With the results of the hydraulic study, field pilot studies and an updated risk assessment leading site monitoring optimization cost lifecycle savings upwards of $15MM towards an alternatively evolved best available technology remediation closure strategy.
Kinetic studies on malachite green dye adsorption from aqueous solutions by A...Open Access Research Paper
Water polluted by dyestuffs compounds is a global threat to health and the environment; accordingly, we prepared a green novel sorbent chemical and Physical system from an algae, chitosan and chitosan nanoparticle and impregnated with algae with chitosan nanocomposite for the sorption of Malachite green dye from water. The algae with chitosan nanocomposite by a simple method and used as a recyclable and effective adsorbent for the removal of malachite green dye from aqueous solutions. Algae, chitosan, chitosan nanoparticle and algae with chitosan nanocomposite were characterized using different physicochemical methods. The functional groups and chemical compounds found in algae, chitosan, chitosan algae, chitosan nanoparticle, and chitosan nanoparticle with algae were identified using FTIR, SEM, and TGADTA/DTG techniques. The optimal adsorption conditions, different dosages, pH and Temperature the amount of algae with chitosan nanocomposite were determined. At optimized conditions and the batch equilibrium studies more than 99% of the dye was removed. The adsorption process data matched well kinetics showed that the reaction order for dye varied with pseudo-first order and pseudo-second order. Furthermore, the maximum adsorption capacity of the algae with chitosan nanocomposite toward malachite green dye reached as high as 15.5mg/g, respectively. Finally, multiple times reusing of algae with chitosan nanocomposite and removing dye from a real wastewater has made it a promising and attractive option for further practical applications.
ENVIRONMENT~ Renewable Energy Sources and their future prospects.tiwarimanvi3129
This presentation is for us to know that how our Environment need Attention for protection of our natural resources which are depleted day by day that's why we need to take time and shift our attention to renewable energy sources instead of non-renewable sources which are better and Eco-friendly for our environment. these renewable energy sources are so helpful for our planet and for every living organism which depends on environment.
2. GRAPHICAL ABSTRACT
1 Introduction
Water is the most essential substance for human beings’
survival although its pollution by different pollutants or
contaminants brings severe threats to the health of the
environment and the societies (Asadi et al., 2020). These
contaminants may be released from different sources into
water bodies. The growth of civilization, population, and
industrialization have led to a steady worsening in the purity
of available water resources (Fiyadh et al., 2019).
Processing industries are the main sources of these pollutants
(Obayomi and Auta, 2019), which include toxic heavy metal ions,
organic dyes, particulate matter, and so on. Heavy metal ions such as
Lead (Pb), Cadmium (Cd), Mercury (Hg), Tin (Sn), Iron (Fe),
Manganese (Mn), Copper (Cu), Zinc (Zn), Chromium (Cr),
Cobalt (Co), Arsenic (As), and Nickel (Ni) can be released from
different processing industries such as mineral mining, metallurgical
plating, batteries, and fertilizer plants (Yadav et al., 2019a; Es-
sahbany et al., 2019). Among these different heavy and toxic
metal ions Pb, Cd, Hg, and As are highly carcinogenic (Obasi
and Akudinobi, 2020).
Pb (II) is an extremely toxic metal and can cause large-scale
environmental pollution and health effects in many parts of the
world (Monear and Xhabija, 2020). Generally, human vulnerability
to lead is due to drinking water. The Environmental Protection
Agency (EPA) has established zero as the ultimate pollutants level
goal for lead in tap water because lead can impair human health even
at low levels of exposure (Triantafyllidou and Lambrinidou, 2009).
Thus, to live in a clean environment and healthy life, the removal of
Lead from water is crucial.
There are several techniques to eliminate or minimize the level
of these heavy metals such as ion exchange, chemical precipitation,
electrolysis, membrane separation, solvent extraction, and
adsorption (Mnasri-Ghnimi and Frini-Srasra, 2019). Among
these methods, adsorption is considered the most effective due to
its easy operation, low cost, available adsorption materials, and high
efficiency (Zheng et al., 2021).
For the adsorption process, different adsorbent materials can be
utilized. The adsorption materials include: carbon nanotubes
(CNTs) (Yadav and Srivastava, 2017; Hayati et al., 2018; Fiyadh
et al., 2019; Verma and Balomajumder, 2020), activated carbon
(Kobya et al., 2005; Lo et al., 2012; Deliyanni et al., 2015;
Nejadshafiee and Islami, 2019), clay minerals with good
adsorbing and ion exchangeability (Yadav et al., 2019a), porous
nanomaterials (Yao et al., 2014; Lee et al., 2019) inorganic
nanoparticles (Giraldo et al., 2013; Ray and Shipley, 2015; Boix
et al., 2020), metal oxides (Lee, 1975; Kikuchi et al., 2006; Chen et al.,
2012; Ghiloufi et al., 2016), clay-based nanocomposites (Darder
et al., 2005; Das et al., 2018; Yadav et al., 2019b), and graphene oxide
(Zhao et al., 2011; Tan et al., 2015; Yari et al., 2015).
Clay materials have a low cost and are most abundant so they are
considered efficient adsorbent materials. For the adsorption of heavy
metals most commonly used clay minerals are Kaolinite,
Montmorillonite, and Bentonite (Beatrice and Olusola, 2020). To
improve the adsorption performance, many researchers used
modified clay minerals. For instance, a low-cost adsorbent was
Frontiers in Materials frontiersin.org
02
Daniel Reta and Desissa 10.3389/fmats.2023.1277467
3. produced by modifying raw kaolinite clay with concentrated
sulphuric acid to remove copper and nickel from waste water
(Chai et al., 2020). However, these clay minerals do not have
magnetic properties that limit the reusability of clays for many
cycles of operation (Wu et al., 2013). To prevent these flaws, the
synthesis of composites of clay minerals with magnetic
nanoparticles helps in the recovery of adsorbents (Ahmed et al.,
2022; Fındık, 2023). Furthermore, incorporating nanoparticles into
composites enhances the surface area and pore structure of clays.
(Yan et al., 2016; Olusegun and Mohallem, 2020). Spinel ferrites are
commonly utilized as magnetic supports for various solid
adsorbents due to their chemical and magnetic characteristics
(Ahmed et al., 2022). Among magnetic spinel ferrites, CoFe2O4
has excellent physical and chemical stability, high surface area, high
saturation magnetization, high coercivity, and strong adsorption
capacity (Liu et al., 2007; Mathew and Juang, 2007; Santhosh et al.,
2015). However, CoFe2O4 magnetic particles have agglomeration
challenges, which can be minimized by synthesizing the CoFe2O4
using cellulose template synthesis.
Moreover, graphene oxide (GO) may increase the surface area of
clay and contain adsorption-friendly functional groups such as
hydroxyl, epoxides, and carboxyl groups (Santhosh et al., 2015;
Ahmed et al., 2022). As a result of these characteristics, GO appears
to be a promising alternative for modifying clay minerals such as
kaolinite to improve adsorption ability (Lertcumfu et al., 2020).
Magnetic NPs incorporating graphene oxide have also recently been
reported for heavy metal adsorption. Zhang et al., (Zhang et al.,
2014), for example, reported the synthesis of magnetic CoFe2O4-
reduced graphene oxide and its application in the removal of lead
and mercury ions from aqueous solutions. Ren et al. (Ren et al.,
2023) used a high-gravity reactor to manufacture a CoFe2O4-
graphene oxide nanocomposite for Pb(II) removal and then
applied it to chromium removal.
In this work, we synthesized composites from kaolinite clays and
cellulose-template Cobalt ferrite (CoFe2O4)/Graphene oxide (GO)
for adsorption of lead ions from an aqueous solution. Cellulose was
extracted from the Ensete ventricosum (false banana). The samples
were then examined using X-ray diffraction (XRD), Fourier
Transform-Infrared spectroscopy (FTIR), scanning electron
microscopy (SEM), thermo-gravimetric analysis-differential
thermal analysis (TGA-DTA), and Brunauer-Emmett-Teller
(BET). The adsorption performance of the synthesized composite
materials was determined by Atomic absorption spectroscopy
(AAS). The effects of contact time, adsorbent dose, and solution
pH on Pb (II) adsorption were examined. Adsorption isotherm and
kinetics were also investigated in order to determine the mechanism
of adsorption.
2 Materials, chemicals, and methods
2.1 Materials and chemicals
Analytical grade chemicals were used for this work, including
ferric nitrate nonahydrate (Fe(NO3)3.9H2O), cobalt nitrate
hydrate (Co(NO3)2.6H2O, sodium hydroxide (NaOH), graphite
powder, potassium permanganate (KMnO4), sulfuric acid
(H2SO4), phosphoric acid (H3PO4), hydrochloric acid (HCl),
formic acid (CH2O2), acetic acid (CH₃COOH), N,
N-dimethylformamide (DMF), hydrogen peroxide (H2O2),
distilled water, and ethanol. The clay was collected from
Wollega, Ethiopia. In addition, the false banana by-product was
collected from Adama City, Ethiopia.
2.2 Methods
2.2.1 Pretreatment of clay
The collected clay (Figure 1A) was washed with distilled water
(DH2O) and dried overnight in an oven at 90°C. The dried clay
powder was then passed through a 75 mesh filter to create a fine
powder. (Figure 1B).
2.2.2 Cellulose extraction
The false banana waste was cleaned to eliminate dust, dried in an
oven at 80°C, sliced, and then extracted in three phases
(Veeramachineni et al., 2016; Melikoğlu et al., 2019) as described below.
2.2.2.1 Alkaline pretreatment (stage I)
First, the false banana byproduct was boiled with 2% NaOH (1:
40) w/v for 2 h to remove the remaining dust. Alkaline pretreatment
was performed on a hot plate at 90°C for 1.5 h in 3.0 L 5% NaOH
solutions with a solid to liquid ratio of dry material of 1:10 (w/v).
Byproduct residues were continuously filtered and cleaned with hot
distilled water.
2.2.2.2 Formic acid, acetic acid, and hydrogen peroxide
treatment (stage II)
The pulps were further treated with a mixture of 20% formic acid
(FA)/20% acetic acid (AA)/7.5% H2O2 (2:1:2) solution on the
hotplate at 90°C for 1.5 h, at a byproduct to liquid ratio of 1:10.
Finally, the delignified pulps were filtered to separate the cooking
liquor (which contains lignin and hemicellulose) from cellulose and
washed with hot water.
2.2.2.3 Bleaching (stage III)
The pulps were bleached separately with 7.5% H2O2 in alkaline
media of 4% and 10% NaOH solutions at a fiber ratio of 1:10, first at
room temperature for 30 min, then on a water bath at 70°C for
30 min. Finally, the pulps were washed repeatedly with hot distilled
water to remove residual lignin and dried in an oven at 60°C until a
constant weight was achieved.
FIGURE 1
(A) collected clay and (B) pretreated clay.
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4. 2.2.3 Synthesis of graphene oxide (GO)
Figure 2 shows how graphene oxide (GO) was produced from
graphite powder using an improved process with little modification
(Marcano et al., 2010). The first stage includes oxidizing graphite with
KMnO4 as the oxidizing agent. For this purpose, 360 mL H2SO4 and
40 mL H3PO4 are placed into an Erlenmeyer flask while being
constantly and vigorously stirred. Then slowly about 9 g KMnO4
and 3 g graphite (3:1) were added to the H2SO4/H3PO4 mixture by
keeping the reaction mixture at 50°C for 12 h. After the oxidation step,
the resulting mixture was kept overnight in a beaker containing 400 g of
ice flakes and 3 mL of H2O2 to stop the reaction of KMnO4. The sample
was centrifuged twice with deionized water (200 mL), HCl (200 mL),
and ethanol (200 mL) to remove the supernatant from graphene.
Finally, the compacted cake was dried in an oven at 100 °C overnight.
2.2.4 Synthesis of composites
Initially, binary composites (cellulose templated CF-GO) were
synthesized by altering the weight percentage of GO, after which was
ternary composite synthesis using kaolinite clay and various weight
ratios of CoFe2O4-0.3GO (CF-0.3GO).
2.2.4.1 Synthesis of cellulose templated CF-GO
CF-GO composite with different graphene content (20, 25, and 30 wt
%) was synthesized by the hydrothermal method with some modification
(Fu and Wang, 2011). In separate beakers, a determined amount of
graphene oxide powder was added to 50 mL distilled water and 0.4 g
cellulose was added to 25 mL distilled water and sonicated ultrasonically
for 30 min to distribute the powders uniformly. The cellulose solution was
put into the GO solution, which was then stirred for 30 min to create a
homogenized solution. The necessaryamountof Fe (NO3)3.9H2O and Co
(NO3)2.6H2O in a 2:1 ratio was added to the sonicated solution, followed
by stirring for 60 min at room temperature. After that, 2 M NaOH
solution was dropped to the solution under constant stirring to adjust the
pH around 10 then stirring for 10 min. The resulting mixture was placed
in a 100 mL stainless autoclave lined with Teflon and heated to 180°C for
12 h. After allowing the reaction mixture to cool to room temperature, the
precipitate was centrifuged and washed with distilled water and ethanol
several times. Finally, the solution was dried in an oven at 80°C for 12 h
and then calcined at 400°C for 3 h in a muffle furnace. To compare, the
same method was utilized to make CoFe2O4 without cellulose.
2.2.4.2 Formulating composites from Kaolinite clay and CF-
GO composite
After the synthesis of CF-GO, we formulated composite materials
with kaolinite clay. First, the measured amount of kaolinite powder
and different weight percent of CF-0.3GO (30, 45, 60, and 75 wt%)
was dispersed by sonicating in 40 mL of N, N-Dimethylformamide in
separate beakers for 30 min. The result was uniform dispersion. The
CF-0.3GO solutions were then placed into a kaolinite solution,
followed by another 30 min of sonication. The resulting solution
was then agitated at room temperature for 3 h to generate a
homogenized solution. The precipitate was then centrifuged and
washed numerous times with distilled water and ethanol. Finally,
the produced CF/GO/Kaolinite composite was dried for 12 h at 80°C.
2.3 Characterizations
Adsorbent phase purity was investigated using x-ray powder
diffraction (XRD-700, Shimadzu, South Korea) with copper K
radiation (λCuKa = 1.5418 Å), a scan speed of 4.0 deg/min, 40 kV,
30 mA, and a 2- scanning range from 4°–80°. FTIR (FT/IR-4000 series,
FIGURE 2
Schematic procedure for the improved synthesis of graphene oxide (GO).
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5. JASCO) was utilized to identify functional groups from a wave
number of 400–4,000 cm−1
, and TGA-DTA (DTG-60H, Shimadzu,
South Korea) was used to test the thermal stability of the samples
throughout a temperature range of 23°C–1000°C, and SEM
(COXIEM-30, Shimadzu, South Korea) was used to determine
surface morphology of the samples. BET (Quantachrome
Instruments version 11.0) was used to calculate the specific surface
area and porosity distribution of the samples. The samples’ adsorption
capacity towards Pb (II) ion was determined using an AAS (ZEEnit
700P, Atomic Flame Mode, Analytik Jena).
2.4 Adsorption performance measurement
For the adsorption investigation, a lead standard solution of
1,000 mg L−1
Pb (II) in a diluted nitric acid standard for AAS
(AVS TITRINORM) was utilized. Then, under typical equilibrium
conditions, a series of adsorption tests were performed. To choose the
best sample from the developed binary composites, 4.5 mg adsorbents
were added to a 50 mg L−1
concentration of 15 ml of Pb (II) solution in
separate beakers. The samples were then sonicated for 10 min before
being stirred for 150 min. Effect of contact time was studied for the
binary samples by adjusting the time from 30–90 min. In addition,
adsorbent dosage for the binary samples was optimized by varying
doses from 0.6–2.1 g L−1
. For the ternary composites, 22.5 mg
adsorbent was utilized for a 10 mg L−1
concentration of Pb (II) in
15 mL of solution. The effect of pH was also studied by varying the
pH values from 2 to 10 by adding 0.1 M NaOH and 0.1 M H2SO4.
Kinetic investigations were carried out by varying the period from
30–120 min. Adsorbent reusability was achieved by magnetically
extracting the adsorbents from the solution and washing numerous
times with distilled water. Allow the adsorbent powder to dry in an
oven at 90°C for 3 h before reusing it.
2.5 Desorption experiment
For desorption study, 1.5 g L−1
of produced CF/GO/Kaolinite
composite was poured in 50 mL of 10 mg L−1
Pb (II) solution at
laboratory conditions of optimal initial pH, 300 rpm mixing speed,
25°C temperature, and 60 min contact time. After the adsorption
test, the adsorber was separated from the aqueous phase and rinsed
with distilled water several times to washout the lead ion from the
adsorber surface. At the end of the intended time, the sample was
then centrifuged several times with deionized water (200 mL), and
ethanol (200 mL) to separate the solution and solid phase and the
lead ion concentration was measured.
3 Results and discussions
3.1 Phase purity analysis
The XRD patterns of materials made of graphene oxide,
CoFe2O4, and CoFe2O4-GO with different graphene content are
shown in Figure 3. The diffraction pattern of graphene oxide shows a
strong peak at 2θ = 11.3° (d-spacing of 7.76 Å) corresponds to the
(001) plane which confirms the success in the GO synthesis
(Tul Ain et al., 2019). It can be seen that the diffraction peaks of
almost all CoFe2O4 with different graphene content can be traced
back to spinel-like CoFe2O4 (JCPDS 022-1086). The diffraction
peaks at 2θ values of 18.3, 30.0, 35.4, 43.1, 53.5, 56.3, and 62.4,
71.1, 74.0, and 75.2 can be assigned to the crystal planes (111), (220),
(311), (400), (422), (511), (440), (622), (533), and (620) of spinel
CoFe2O4, respectively (Zong et al., 2014; Zawrah, 2018). GO (001)
pattern is not observed in CF-GO. This can be explained by the
reduction of GO to graphene during the hydrothermal and
calcination process (Fu and Wang, 2011).
Moreover, the reduced GO layer may decorated the CoFe2O4
nanocrystals, resulting in the disappearance of the diffraction peak
FIGURE 3
XRD pattern of, from bottom to top, graphene oxide (GO),
CoFe2O4 (CF), CF-0.2GO, CF-0.25GO, and CF-0.3GO.
FIGURE 4
XRD Pattern of, pure kaolinite and different composition of CF-
0.3GO (GCF) in the kaolinite.
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6. of graphene of the (001) crystallographic plane. The XRD pattern,
illustrated in Figure 4, was used to estimate the phase composition of
the prepared clay. The 2θ diffraction pattern has a range of 10–80.
JCPD files 058-2004 and 046-1045 indicate the existence of high-
intensity diffraction peaks at 2θ of 12.39°, 19.85°, 24.96°, and 26.55°,
the corresponding crystal orientation are (001), (020), (002), and
(101), respectively (Zen et al., 2018; Mustapha et al., 2019). The
JCPD document confirms that the main peaks of pretreated clay are
kaolinite and quartz, which are usually found in kaolin as one of the
main components.
It is found that kaolinite (Al2Si2O5 (OH) 4) has a very strong peak;
there is also a sharp quartz peak. Characteristic peaks in the X-ray
diffraction pattern of kaolinite/(CoFe2O4-0.3GO) samples with
different weight fractions of CoFe2O4-0.3GO (30%, 45%, 60%, and
75%) is also shown in Figure 4. With an increase of GCF weight
fraction, (001) peak intensity of kaolinite decreased, which indicates that
a composite is effectively formed between kaolinite and (CoFe2O4-
0.3GO). Like kaolinite powder, the ternary composites has sharp and
significant peaks at 2θ of 12.39°, 19.85°, 24.96°, and 26.55° with the
corresponding indices of (001), (020), (002), and (101), respectively.
This indicates a high existence of kaolinite in these compounds (JCPDS.
No. 058-2004) (Olusegun and Mohallem, 2020). The diffraction peaks
of CoFe2O4 are also located at 2θ of 17.8°, 30.5°, 35.5°, 43.2°, 57.1°, and
62.7° with corresponding (111), (220), (311), (400), (511), and (400)
crystallographic planes, respectively, according to JCPDS No. 022-
1086 crystallization level. As a result, the XRD patterns demonstrate
that binary and ternary composites were successfully formed.
3.2 Morphological analysis
Figures 5A–E shows the surface morphology of kaolinite (K),
graphene oxide (GO), CF-0.3GO (without cellulose), CF-0.3GO (with
cellulose) and 0.25K/0.75[(CF-0.30GO)], respectively. Figure 5 shows
several layers of kaolin in which the kaolin particles are distributed with
fewer aggregations. These results also showed some porous structure of
the kaolinite lattice. As shown in Figure 5B layers of GO sheets were well
exfoliated. The CoFe2O4/GO particles without cellulose template
synthesis (Figure 5C) showed high agglomeration and larger particle
size due to the magnetic property of CoFe2O4. In contrast, the CoFe2O4/
GO composite with cellulose template synthesis showed a smaller
particle size with porous morphology. This is happening because
cellulose is a biopolymer with long chains and protects the
formation of high agglomeration during synthesis as exhibited in
Figure 5D. In addition, the porous structure is also exhibited in this
morphology. Although the particles were homogenous they were
aggregated at some point as seen in the SEM image. Unlike the
kaolinite clay, Figure 5E depicts the homogeneous distribution of
smaller particles, which may imply that the CF-0.3GO was spread
uniformly across the surface of the kaolinite clay and modified the
kaolinite structure.
3.3 FTIR analysis
The existence of functional groups was determined by
examining the FTIR spectra of the GO, CF-GO, K, and K/(CF-
GO). The large peak at 3416 cm-1 for GO (Figure 6A) corresponds
to OH stretching vibration. In addition, the five peaks at 1726, 1584,
1403, 1221, 1048 cm-1
belong to C=O stretching, aromatic C–C,
C–O carboxyl, epoxy C–O and alkoxy (Li et al., 2015; Wang et al.,
2019). For CF-GO, the stretching vibration O–H indicates that the
peak is narrower than that of GO, and the peaks of oxygenates are
quite attenuated or completely attenuated, indicating that the GO
content in the CF-GO compound may be reduced (Fu and Wang,
2011), and the adsorption peak near 1622 cm−1
can be traced back to
the stretching vibration of the non-oxidized carbon.
The result of 616 cm−1
showed that CF/GO corresponds to the
valence vibrational bond of Co–O and Fe–O (metal-oxygen bond). The
FTIR spectrum of the kaolinite was shown in Figure 6B. It exhibits
absorption bands at 3691 and 3620 cm−1
caused by the OH stretching
vibration, and absorption bands at 1630 cm−1
, 1035 cm−1
, 1105 cm−1
,
and 916 cm−1
caused by an H-O-H interlayer, a tetrahedral sheet of Si-
O-Si group, Si-O stretching vibration, and Al-OH, respectively.
(Mustapha et al., 2019). The peaks at 750 and 467 cm−1
correspond
to quartz, while the bands at 430 cm−1
in kaolinite correspond to the
tensile modes of Si-O, Al-O, and Si-O-Si bonds. This information
provides a functional interface group involved in the adsorption process
of kaolinite. The CF/GO/K peak at 1622 cm−1
is significantly reduced,
indicating that there is a strong interfacial interaction between GO, CF,
and K, which improves the mechanical strength of the composite
(Huang et al., 2020). After the kaolinite was corrected with GO and
CoFe2O4, the peak area and intensity of the obtained composite
material changed significantly, which may depend on the interaction
between the functional groups in GO and the kaolinite structure
(Foroutan et al., 2020a).
3.4 BET surface area and pore size analysis
Figure 7 summarizes the Brunauer-Emmett-Teller (BET) surface
area and total pore volume of pretreated kaolinite, optimal binary, and
ternary composite samples. The specific surface area of binary
composite CF-0.3GO was 266.20 m2
/g, while the ternary composite
0.25K/0.75[(CF-0.30GO)] was 577.11 m2
/g. In addition, the pretreated
kaolinite sample had a surface area of 519.52 m2
/g. The total pore
volume of CF-0.3GO and 0.25K/0.75[(CF-0.30GO)] samples was
0.089 cm3
/g and 0.214 cm3
/g, respectively, whereas kaolinite clay
pore volume was 0.15 cm3
/g.
The results indicate that the surface area and total pore volume
values of ternary composites are relatively high when compared to pure
kaolinite structures. The homogeneous dispersion of CF-0.3GO
particles on Kaolinite creates a new surface, which contributes to the
composite’s increased specific surface area (Foroutan et al., 2020a). The
theoretical specific surface area of graphene is known to be as high as
2630 m2
/g (Fang et al., 2019). However, because of the more significant
weight contribution from magnetic cobalt ferrite particles on the surface
of graphene sheets, the specific surface area of the CF-0.3GO is
substantially lower than the theoretical value (Ji et al., 2012).
3.5 Thermal property analysis
Figures 8A–C exhibit thermal analysis of kaolinite, CoFe2O4, and
K/CF-GO composite sample from room temperature up to 800°C. The
TGA and associated DTA curves reveal that all samples have different
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7. weight loss stages. The initial stage of weight loss for kaolinite, CoFe2O4,
and K/(CF-GO) is around 3.29%, 2.55%, and 1.88%, respectively, and
corresponds to the evaporation of water molecules from the surface into a
crystalline structure (Romero-Guerrero et al., 2018). The second weight
loss is caused by coordinated water molecules dehydrating
(dehydroxylation) and clay decomposition. This is due to the
degradation of organic components contained in the sample material,
specifically Kaolinite and K/(CF-GO). The second weight loss of CF could
be attributed to decarburization of cobalt ferrite particles (Sumathi and
Kirankumar, 2016). The overall weight loss of CF was about 4.1 % and the
thermal stability of CF can reach up to 800°C.
The onset temperature (Tonset) at the second stage of weight loss is
around 426°C, 150°C, and 400°C for K, CF, and K/CF-GO samples,
respectively. For the same stage of weight loss, the equivalent ending
temperature (Tfinish) is approximately 616°C, 500°C, and 700°C for K, CF,
and K/CF-GO samples, respectively. The overall weight loss of Kaolinite
was around 13.67%, whereas the K/CF-GO was approximately 6.31%.
This suggests that the introduction of stable CF particles into the kaolinite
improves the thermal stability of K/CF-GO.
3.6 Magnetic property of CoFe2O4-
Graphene/Kaolinite adsorbents
The magnetic properties of CoFe2O4 enhance the separation for the
prepared composites. We studied the magnetic separation properties of
the CoFe2O4-Graphene/Kaolinite adsorbents. As demonstrated in
Figure 9, the catalyst with homogeneous dispersion is highly
responsive to an external magnetic field and can be easily isolated
from the reaction mixture using a permanent magnet in less than 1 min.
3.7 Adsorption performance analysis
To determine the adsorption behavior of the composite, a series
adsorption test was carried out with compositions (1–x)CF/(x)GO
(x = 0.20, 0.25, 0.30, weight percentage of GO). The removal
efficiency/adsorption (%) and adsorption capacity of the
materials can be estimated using Eqs 1, 2, as shown below
(Alshameri et al., 2019).
FIGURE 5
The surface morphology of (A) kaolinite (K), (B) graphene oxide (GO), (C) CF-GO (without cellulose), (D) CF-0.3GO (with cellulose) and (E) K/CF-GO.
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8. Adsorption %
( )
Ci − Cf
Ci
× 100 (1)
qe mg g−1
V Ci − Ce
( )
M
(2)
where Ci and Cf are the initial and final metal ion concentration; qe
and Ce are equilibrium adsorption capacity and concentration of the
metal ions at equilibrium; V is the volume of solution (L) and M is
the mass of adsorbent in grams. Figure 10 depicts the adsorption
capability of (1-x)CF/(x)GO with x = 0.20, 0.25, and 0.30 weight
ratios of GO. The sample with x = 0.3, i.e., CF-0.3GO, showed the
maximum adsorption capacity of roughly 23.6 mg g−1
among the
produced binary composites. As a result, this sample was chosen for
future research and given the named GCF.
As shown in Figure 10, the adsorption capacity of Pb (II) using
CF-GO increased as the amount of GO increased. Moreover,
graphene oxide has a large surface area and contains many
functional oxygen groups, such as hydroxyl and carboxyl groups
(Chen et al., 2017; Lertcumfu et al., 2020). Therefore, with the
increase of GO, the increase in the adsorption capacity of Pb (II) can
be explained by the increase in surface area and surface-active sites
of the adsorbent (Wang et al., 2017; He et al., 2018). This result
indicates that the addition of graphene oxide improves the
adsorption performance of CoF2O4 on Pb (II).
3.7.1 Effect of contact time and adsorbent dosage
on GCF
The effect of contact time on the decrease of Pb (II) content in
GCF is shown in Figure 11A. Pb adsorption is carried out in GCF,
Ci = 10 mg L−1
and adsorbent dose = 60 mg L−1
to optimize the
contact time between ions and adsorbent at room temperature.
Initially, the adsorption rate of Pb (II) increases rapidly with time
and then reaches equilibrium. The adsorption occurs quickly, due to
the presence of active and vacant sites on the surface of the adsorber
in the initial stage (Foroutan et al., 2020a). Figure 11A clearly
illustrates that the optimal period for Pb removal is 90 min. At
this point, the adsorption rate equals the desorption rate, and as time
passes, the active site becomes inaccessible, resulting in a decrease in
FIGURE 6
FTIR spectra of the (A) GO, CF/GO (CF-0.3GO), and (B), K
(kaolinite), CF/GO/K 0.25K/0.75 [(CF-0.30GO)], and CF/GO samples.
FIGURE 7
The BET specific surface area and total pore volume of samples.
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9. driving force and a decline in the adsorption rate (Santhosh et al.,
2015). However, increasing the contact time results in a decrease in
the amount of Pb. This brief effect could be attributed to metal ion
saturation of the adsorbent surface, followed by the adsorption and
desorption processes (Mustapha et al., 2019). As a result, 90 min is
thought to be the optimal time to maximize GCF adsorbent dose.
The effect of GCF adsorbent dosage on Pb ion removal was
investigated by increasing the dose from 0.6 to 2.1 g L−1
, as
shown in Figure 11B.
The elimination effectiveness of Pb ions was raised with a rise of
adsorbent dose, which can be associated with the existence of a lot of
active sites on the surface of adsorbent for adsorption
FIGURE 8
TGA-DTA analysis of (A) kaolinite (K), (B) CoFe2O4 (CF), and (C) K/CF-GO 0.25K/0.75[(CF-0.30GO)].
FIGURE 9
Images of 0.75[(CF-0.3GO)/0.25K suspension without (A) and
with (B) a magnetic field.
FIGURE 10
The equilibrium adsorption capacity of CF-GO composites with
different GO loading initial concentrations of 50 mg L−1
, at a
temperature of 25°C.
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10. (Foroutan et al., 2019). Because all of the active sites may not be
readily available for adsorption, saturation will result. The saturation
factor for Pb(II) ions was 1.5 g L−1
for GCF, with a removal efficiency
of 55%. As a result, 1.5 g L−1
adsorbent was taken as the optimal
adsorbent dosage values for more detailed examinations. After
optimizing the contact time and the dose of the binary
compound (GCF), the ternary composites, i.e., (y)[(CF-0.30GO)]/
(1-y)K, where y = 0.3, 0.45, 0.60, and 0.75, were synthesized. The
adsorption capacity was then assessed. The adsorption capacity of
the produced ternary composites is shown in Figure 12. Among
other composite materials, a sample with the composition 0.25K/
0.75[(CF-0.30GO)] had the highest adsorption capacity, around
4.2 mg g−1
. This sample is then employed in further experiments,
such as pH fluctuations, contact time, adsorption isotherm and
kinetics.
3.7.2 Effect of pH and contact time for the ternary
composite
The effect of pH on the adsorption performance of 0.25K/0.75
[(CF-0.30GO)] was investigated, as shown in Figure 13A, because
this has a direct effect on the adsorption performance. Both metal
ions have an initial concentration of 10 mg L−1
at 25°C.
The pH range of Pb ions with the same metal ion concentration
is 2–10. Figure 13A shows that the adsorption increases with the
increase of pH under acidic conditions (2–4) significantly, and then
reaches a peak at pH 4 and then all points are flatted. At pH 4, the
adsorption capacity and removal efficiency become 6.6 mg g−1
and
99%, respectively.
At low pH (pH = 2), the removal ability of the Pb ion was 63.5%,
which may be due to the high concentration of H+
ion in the medium,
so the ion occupies the active sites (Elass et al., 2011). The initial
pH value increases, the amount of H+
in the medium decreases, and
the competition between H+
and metal ions on the adsorber surface
might be reduced, which significantly improves the efficiency of the
adsorption method (Naeem et al., 2019).
The percentage of Pb (II) adsorbed onto the present composite
was also examined as a function of contact time (Figure 13B). First,
the adsorption rate of Pb (II) increases rapidly with time and the
adsorption capacity becomes higher after 30 min. Then there is an
almost small increase in adsorption rates. Compared with the
adsorption from 30 min to 120 min, the adsorption capacity after
90 min was 6.64 mg g−1
, as a result, the 90 min time was chosen as
the equilibrium time for the isotherm and kinetics study.
3.8 Adsorption isotherm analysis
The Freundlich, Langmuir, and Temkin isotherm models were
used to assess the adsorption capacity of the ternary composite
material, 0.25K/0.75[(CF-0.30GO)]. The Freundlich isotherm is a
nonlinear sorption model that assumes a monolayer adsorption
FIGURE 11
Effect of (A) contact time and (B) adsorbent dosage on the percentage of lead ion on to GCF, initial concentration of 10 mg L−1
, T = 25°C.
FIGURE 12
Adsorption capacity (qe) of CoFe2O4 (CF), CF-0.3-GO (GCF), and
K/GCF composites with different GCF loading on kaolinite, initial
concentration of 10 mg L−1
, T = 25°C.
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11. process on heterogeneous surfaces and provides no over-loading
even at high concentrations (Lindholm, 2004). This procedure
also involves interaction between the adsorbed species (Bany-
Aiesh et al., 2015). The equation for this model is given in
equation (3) below.
qe KFC1/n
e (3)
Where:
1/n = an adsorption intensity on adsorbing surfaces that varies
with the heterogeneity of the adsorbed monolayer.
KF = Freundlich constant, which quantifies sorption capacity.
Both of n and KF are related to the strength of the adsorbent-
sorbent contact and the distribution of bond strength among the
surface locations of heterogeneous sorbents. Figure14A, which is a
nonlinear plot produced by plotting qe versus Ce, can be used to
calculate the values of KF and n, which are stated in Table 1. The
non-linear version of the Freundlich isotherm appears to offer an
adequate and relevant model of the adsorption process based on the
R2
value (0. 93).
The Langmuir isotherm model is a non-linear theoretical
explanation of the adsorption process that suggests that
adsorption occurs on homogeneous surfaces with no interaction
between deposited Pb (II) (Alatalo et al., 2013). Its expression is
given by Eq. 4 below.
qe
q maxbCe
1 + bCe
(4)
Where:
b (1mg−1
) = Absorption ability corresponds to the Langmuir
adsorption constant.
qmax = The adsorbent’s maximal adsorption capability (mg g−1
)
for a full monolayer.
Figure 14B and Table 1 illustrate some values derived from a
non-linear plot of qe against Ce using Eq. 4. The plot of qe versus Ce
(14b) was found to be non-linear, with an R2
value of (0.24),
indicating that the Langmiur model was not acceptable for
predicting the adsorption isotherm of lead ions.
Temkin Isotherm features a component that explicitly examines
interactions between adsorbing species and adsorbate (Temkin and
Pyzhev, 1940; Bany-Aiesh et al., 2015). This isotherm assumes that
adsorption has a uniform distribution of binding energies up to
maximum binding energy and that the heat of adsorption of all
molecules in the layer decreases linearly with coverage due to
adsorbate-adsorbent interactions. The equation explaining the
Temkin isotherm model is provided below in Eq. 5:
qe
RT
b
ln KTCe
( ) (5)
Where:
KT = The equilibrium binding constant of the Temkin isotherm
(L/g)
R = universal gas constant (8.314 J/mol/K)
T = Temperature at 298 K.
B1
RT
b
(6)
Based on the non-linear Temkin isotherm, as illustrated in
Figure 14C. According to the correlation coefficient (R2
= 0.78),
the composite adsorption moderately followed the Temkin model as
well. The non-linear isotherm constants and coefficients of the
Temkin isotherm model are also shown in Table 1. In summary,
the R2
value for the Freundlich adsorption isotherms is closer to
1 than for the Langmuir and Temkin adsorption isotherms,
indicating that multilayer adsorption occurs in this system.
3.9 Adsorption Kinetics
A kinetic model suited for data analysis, mass transfer, and
chemical reactions is required to investigate the mechanism of
controlling adsorption. The adsorption data in this study
conforms to two kinetic models: Lagergren pseudo-first-order
and pseudo-second-order. The kinetic models were studied using
the derived data in Table 2. The first-order kinetic model is
FIGURE 13
Effect of (A) pH (B) contact time on percentage of lead adsorption onto 0.25K/0.75[(CF-0.30GO)] composite material, initial conc. 10 mg/L,T = 25°C.
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Daniel Reta and Desissa 10.3389/fmats.2023.1277467
12. appropriate for solid-liquid systems, and the system equation is as
follows (Xu et al., 2013; Shukla and Kisku, 2015; Saleh et al., 2016).
For the Pseudo-first-order, the corresponding equation can be
written as:
log qe − qt
log −
k1
2.303
t (7)
Where, qe and qt are the adsorption capacity (mg g−1
) at
equilibrium and time t, respectively, and k1 is the rate constant
of the pseudo-first-order kinetic model. The slope and intercept
of the log (qe-qt) vs. t plot can be used to get the k1 and qe
values.
For the Pseudo-second-order, the corresponding equation can
be written as:
t
qt
1
k2q2
e
+
1
qe
t (8)
Where qe and qt are the sorption capability (mg g−1
) at
equilibrium and time t, respectively, and k2 is that the rate
constant of the pseudo-second-order kinetic model. The k2
and qe values may be calculated from the intercept and slope
of the plot of t/qt against t. Figures 15A, B show the linear
FIGURE 14
A graph depicting (A) the Freundlich isotherm, (B) the Langmuir isotherm, and (C) the Temkin isotherm model for 0.25K/0.75[(CF-0.30GO)]
composite material.
TABLE 1 Isotherm constants and correlation coefficients by non-linear
regression.
Isotherm models Parameters Values R2
Freudlich n 11.37 ± 3.15 0.93
KF (L g−1
) 1.86E14 ± 1.4
Langmiur b (1/mg) 0.0036 0.24
qmax (mg g−1
) 104751.37 ± 1.5
Temkin B1 157.52 ± 47 0.78
KT 16.31 ± 0.9
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Daniel Reta and Desissa 10.3389/fmats.2023.1277467
13. diagrams of the pseudo-first-order and pseudo-second-order
kinetic models of Pb (II) adsorption on 0.25K/0.75[(CF-
0.30GO)], respectively.
The values of the correlation coefficient (R2
) obtained from
the linear fitting curve of each model are provided and Table 3
summarizes the fitting parameters. For adsorbent, the R2
value
obtained from the pseudo-first-order model is comparatively low
(R2
= 0.99488). In contrast, the pseudo-second-order model is
more consistent with the experimental data with R2
= 0.9999.
Furthermore, the calculated equilibrium adsorption capacity
(qe,(cal)) is very consistent with the experimental equilibrium
adsorption capacity (qe,(exp)).
Based on these results, the pseudo-second-order kinetic model
can better describe the adsorption of Pb (II) in 0.25K/0.75[(CF-
0.30GO)]. The pseudo-second-order kinetic model is based on the
assumption that the rate-limiting step is controlled by chemical
adsorption (Li et al., 2013). This indicates that the adsorption of
Pb(II) on 0.25K/0.75[(CF-0.30GO)] composite is controlled by
chemical adsorption.
3.10 Comparison of specific surface area and
adsorption capacity with other adsobers
One of the distinctive qualities of the adsober that can affect the
adsorption process and improve the ability and effectiveness of the
adsorption process is the specific surface area and pores in the
adsober surface. Specific surface area values for GCF and K/GCF
TABLE 2 Parameters for plotting adsorption kinetics for the sample of 0.25K/0.75[(CF-0.30GO)].
Time (min) qe (mg g−1
) qt (mg g−1
) qe-qt Log(qe-qt) t/qt
30 6.64 6.586 0.054 −1.267606 4.554
60 6.64 6.58 0.06 −1.221848 9.117
90 6.64 6.64 0.0 - 13.533
120 6.64 6.61 0.03 −1.522878 18.147
FIGURE 15
(A) Pseudo-first order, and (B) Pseudo-second order kinetic models for 0.25K/0.75(CF-0.3GO) composite material.
TABLE 3 Calculated parameters from Pseudo-first and Pseudo-second-order kinetic models for the sample of 0.25K/0.75[(CF-0.30GO)] composite material.
Model Parameters Values R2
Pseudo-first-order qe,exper. (mg g−1
) 0.06751 0.99488
qe,calc. (mg g−1
) 6.6405
K1 (min−1
) −0.0000564
Pseudo-second-order qe,exper. (mg g−1
) 6.6401 0.9999
qe,calc. (mg g−1
) 6.6405
K2 (min−1
) 0.5815
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Daniel Reta and Desissa 10.3389/fmats.2023.1277467
14. were 266.20 m2
/g and 577.11 m2
/g, respectively, according to the
lead ion adsorption method. The capacity and efficiency of adsobers
are determined by a variety of elements, including the adsober’s
primary source, techniques of modification, and active sites present
on the adsober surface. At pH 4, the removal efficiency of the
optimized ternary composite (K/GCF) was 99% in this study.
Furthermore, at pH 2, the optimized binary composite (GCF)
and K/GCF removal efficiencies were 55% and 63.5%,
demonstrating that uniform particle dispersion improves the
surface area and performance of the ternary composite sample.
The lead removal efficiency of GCF and K/GCF was compared with
the results of other adsobers at diffrent pH values (Table 4). The
results reveal that the generated adsobers are more feasible for
adsorbing the lead ion from aqueous solutions than many other
adsobers.
3.11 Reusability of the adsorbent
The 0.25K/0.75[(CF-0.30GO)] adsorbent was tested for up to
three adsorption-desorption cycles for the reuse of Pb (II) aqueous
solution (Figure 16). The test was done at the optimized pH value (at
pH of 4) and reaction time (90 min) at room temperature. The
results show that as the adsorption-desorption stage increases, the
adsorption percentage of Pb (II) decreases. This decrease in
efficiency may be related to the damage or change of the active
center of the adsorber (Foroutan et al., 2020b). The removal
efficiency of the lead ion using the present adsorbent was 99.5,
99.4, and 96.2 % in the first, second, and third cycles, respectively. In
addition, it should be noted that at the third cycle of the adsorption
process, the reduction in the amount of Pb (II) adsorption using the
adsorber is less than 4%. The results show that the obtained
adsorbent can be used for up to three cycles to remove lead ions
from an aqueous solution without significantly reducing the
adsorption capacity. Table 5 compares the reusability of the
produced nanocomposite with that of different sorbents. The
repeated adsorption/desorption process decreases the
contaminant level to a lower volume.
4 Conclusion
In this study, Graphene oxide, CoFe2O4, CoFe2O4-GO (CF-GO), and
K/(CF-GO) were successfully synthesized by improved, hydrothermal,
and solution methods, respectively. Among the binary composites, CF-
0.3GO showed a better adsorption capacity of about 23.6 mg g−1
from the
binary composite samples at the initial Pb concentration of 50 mg L−1
. In
FIGURE 16
Effect of recycling 0.25K/0.75[(CF-0.30GO)]on the adsorption
efficiency.
TABLE 4 Comparision of percentage removal of different adsorbents for lead
removal.
Adsorbents pH Removal
efficiency (%)
References
GCF 2 55% This work
K/GCF 2 63.5 This work
K/GCF 4 99 This work
Zeolite-A/reduced GO 11 93.9 Farghali et al. (2021)
natural kaolinite clay 6 98 Jiang et al. (2010)
Melanin-impregnated
activated carbon
5 91.1 Manirethan and
Balakrishnan (2020)
bentonite modified with
imidazole
5 90 Kakaei et al. (2020)
CuO/ZnO-tetrapods 10 97% Sharma et al. (2020)
MnFe2O4/GO 6 98.8 Katubi et al. (2021)
ethylenediamine
functionalized
magnetic GO
4 98 Zarenezhad et al.
(2021)
glutathione-functionalized
NiFe2O4/GO
5 94 Khorshidi et al. (2020)
Polypyrrole-Fe3O4-
seaweed nanocomposite
5 97.2% Sarojini et al. (2021)
TABLE 5 Comparison of the reuse capacities of different adsorbents for lead removal.
Adsorbent No. of cycles Removal efficiency (%) References
K/GCF 3 96.2 This work
Polypyrrole-Fe3O4-seaweed nanocomposite 2 94.5 Sarojini et al. (2021)
5 62.5
Nanochitosan/sodium alginate/microcrystalline cellulose beads 2 93 Vijayalakshmi et al. (2017)
Magnetic inverse Fe3O4 nanoparticles 5 80 Lingamdinne et al. (2017)
Frontiers in Materials frontiersin.org
14
Daniel Reta and Desissa 10.3389/fmats.2023.1277467
15. addition, the sample with a composition of 0.25K/0.75[(CF-0.30GO)]
showed the best adsorption capacity of about 4.2 mg g−1
at the initial Pb
concentration of 10 mg L−1
from the ternary composites and was selected
for further studies. The materials were characterized using XRD, SEM,
FTIR, and TGA-DTA. The XRD results showed that the pretreated clay
was contained a high content of kaolinite clay with little quartz amount.
The XRD pattern of the synthesized CoFe2O4 and GO confirmed the
formation of pure CoFe2O4 particles and graphene oxide. The effective
formation of the ternary composite was also confirmed by the XRD
results. The FTIR data of (CF-GO)/K confirmed the presence of various
oxygen-containing functional groups which enhance the adsorption
capacity by the reactions of Pb (II) with active surface groups. TGA-
DTA data revealed that the thermal stability of kaolinite enhanced with
the incorporation of CoFe2O4 and GO through the structure. The effect of
pH (2–10) and contact time (30–90 min) were also studied for 0.25K/0.75
[(CF-0.30GO)] composite. At pH of 4, the adsorption capacity and
removal efficiency was 6.62 mg g−1
and 99 %, respectively, and becomes
constant. Adsorption studies revealed that the adsorption capacity of
ternary composites can be well described by the Freundlich isoterm
model. The adsorption kinetics best fitted with Pseudo-second-order
adsorption. Finally, the reusability of the present composite was studied
after separating the catalyst magnetically for up to 3 cycles with a small
reduction in removal efficiency. Therefore, the experimental results of this
study specify that the present composite could be a potential candidate for
the removal of Pb (II).
Data availability statement
The original contributions presented in the study are included in
the article/Supplementary Material, further inquiries can be directed
to the corresponding authors.
Author contributions
YD: Conceptualization, Data curation, Formal Analysis,
Investigation, Methodology, Resources, Software, Visualization,
Writing–original draft, Writing–review and editing. TD:
Conceptualization, Data curation, Formal Analysis, Funding
acquisition, Investigation, Methodology, Project administration,
Resources, Software, Supervision, Validation, Visualization,
Writing–review and editing.
Funding
The authors declare financial support was received for the
research, authorship, and/or publication of this article. This
research project was funded by Adama Science and Technology
University under the number ASTU/SM-R/216/21, Adama, Ethiopia.
Acknowledgments
We would like to express our gratitude to Material Sceince and
Engineering departemt, Adama Science and Technology University,
Ethiopia for their technical competence and financial support in
carrying out this study.
Conflict of interest
The authors declare that the research was conducted in the
absence of any commercial or financial relationships that could be
construed as a potential conflict of interest.
Publisher’s note
All claims expressed in this article are solely those of the authors and
do not necessarily represent those of their affiliated organizations, or
those of the publisher, the editors and the reviewers. Any product that
may be evaluated in this article, or claim that may be made by its
manufacturer, is not guaranteed or endorsed by the publisher.
Supplementary material
The Supplementary Material for this article can be found online
at: https://www.frontiersin.org/articles/10.3389/fmats.2023.1277467/
full#supplementary-material
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