The document summarizes research on using functionalized multi-walled carbon nanotubes (MWCNTs) to remove chromium (Cr3+) ions from wastewater through adsorption. The researchers found that MWCNTs achieved 99.83% removal of Cr3+ ions at an optimum dosage of 25 mg in a pH 6 solution. Equilibrium adsorption experiments showed that the Langmuir isotherm model fit the data better than the Freundlich model, indicating monolayer adsorption of Cr3+ ions onto the MWCNT surfaces. Fourier transform infrared spectroscopy characterization confirmed the presence of functional groups like carboxyl that contribute to the adsorption of Cr3+ ions.
Equilibrium and kinetic study on chromium (vi) removal from simulatedGJESM Publication
Gooseberry seed (Phyllanthus acidus) was used as an adsorbent to determine its feasibility for the removal of Cr(VI). Various parameters such as pH, temperature, contact time, initial metal concentration and adsorbent dosage were investigated to determine the biosorption performance. Equilibrium was attained within 60 minutes and maximum removal of 96% was achieved under the optimum conditions at pH 2. The adsorption phenomenon demonstrated here was monolayer represented by Langmuir isotherm with R2 value of 0.992 and the Langmuir constants k and q0 was found to be 0.0061 (L/mg) and 19.23 (mg/g). The adsorption system obeyed Pseudo second order kinetics with R2 value of 0.999. The results of the present study indicated that gooseberry seed powder can be employed as adsorbent for the effective removal of hexavalent chromium economically.
Removal of cadmium from aqueous solution using cobalt silicate precipitation ...IJSIT Editor
Cobalt silicate precipitation tube (CoSPT), prepared through ‘silica garden’ route was found to be a
potential adsorbent for removal of cadmium from aqueous medium. Detail adsorption study of Cd(II) on
CoSPT was investigated. Batch adsorption studies were carried out as a function of contact time, adsorbent
dose, adsorbate concentration (50-300 mg L-1), temperature (298-323K). Cd(II) loading on CoSPT was
dependent on initial Cd(II) concentration. Experimental adsorption data were modeled using Freundlich and
Langmuir isotherm equations. pH variation study revealed that the adsorption increased with increase in pH
of the solution. Cd(II) loading capacity of CoSPT was estimated at 319 mg g-1, which ranks high amongst
efficient Cd(II) adsorbents. Adsorption data were analyzed using two kinetic models, Lagergren first order
and pseudo second order. It was observed that pseudo second order rate equation represented the best
correlation.
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
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IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Equilibrium and kinetic study on chromium (vi) removal from simulatedGJESM Publication
Gooseberry seed (Phyllanthus acidus) was used as an adsorbent to determine its feasibility for the removal of Cr(VI). Various parameters such as pH, temperature, contact time, initial metal concentration and adsorbent dosage were investigated to determine the biosorption performance. Equilibrium was attained within 60 minutes and maximum removal of 96% was achieved under the optimum conditions at pH 2. The adsorption phenomenon demonstrated here was monolayer represented by Langmuir isotherm with R2 value of 0.992 and the Langmuir constants k and q0 was found to be 0.0061 (L/mg) and 19.23 (mg/g). The adsorption system obeyed Pseudo second order kinetics with R2 value of 0.999. The results of the present study indicated that gooseberry seed powder can be employed as adsorbent for the effective removal of hexavalent chromium economically.
Removal of cadmium from aqueous solution using cobalt silicate precipitation ...IJSIT Editor
Cobalt silicate precipitation tube (CoSPT), prepared through ‘silica garden’ route was found to be a
potential adsorbent for removal of cadmium from aqueous medium. Detail adsorption study of Cd(II) on
CoSPT was investigated. Batch adsorption studies were carried out as a function of contact time, adsorbent
dose, adsorbate concentration (50-300 mg L-1), temperature (298-323K). Cd(II) loading on CoSPT was
dependent on initial Cd(II) concentration. Experimental adsorption data were modeled using Freundlich and
Langmuir isotherm equations. pH variation study revealed that the adsorption increased with increase in pH
of the solution. Cd(II) loading capacity of CoSPT was estimated at 319 mg g-1, which ranks high amongst
efficient Cd(II) adsorbents. Adsorption data were analyzed using two kinetic models, Lagergren first order
and pseudo second order. It was observed that pseudo second order rate equation represented the best
correlation.
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
Engineering Research Publication
Best International Journals, High Impact Journals,
International Journal of Engineering & Technical Research
ISSN : 2321-0869 (O) 2454-4698 (P)
www.erpublication.org
Computer Science
Active and Programmable Networks
Active safety systems
Ad Hoc & Sensor Network
Ad hoc networks for pervasive communications
Adaptive, autonomic and context-aware computing
Advance Computing technology and their application
Advanced Computing Architectures and New Programming Models
Advanced control and measurement
Aeronautical Engineering,
Agent-based middleware
Alert applications
Automotive, marine and aero-space control and all other control applications
Autonomic and self-managing middleware
Autonomous vehicle
Biochemistry
Bioinformatics
BioTechnology(Chemistry, Mathematics, Statistics, Geology)
Broadband and intelligent networks
Broadband wireless technologies
CAD/CAM/CAT/CIM
Call admission and flow/congestion control
Capacity planning and dimensioning
Changing Access to Patient Information
Channel capacity modelling and analysis
Civil Engineering,
Cloud Computing and Applications
Collaborative applications
Communication application
Communication architectures for pervasive computing
Communication systems
Computational intelligence
Computer and microprocessor-based control
Computer Architecture and Embedded Systems
Computer Business
Computer Sciences and Applications
Computer Vision
Computer-based information systems in health care
Computing Ethics
Computing Practices & Applications
Congestion and/or Flow Control
Content Distribution
Context-awareness and middleware
Creativity in Internet management and retailing
Cross-layer design and Physical layer based issue
Cryptography
Data Base Management
Data fusion
Data Mining
Data retrieval
Data Storage Management
Decision analysis methods
Decision making
Digital Economy and Digital Divide
Digital signal processing theory
Distributed Sensor Networks
Drives automation
Drug Design,
Drug Development
DSP implementation
E-Business
E-Commerce
E-Government
Electronic transceiver device for Retail Marketing Industries
Electronics Engineering,
Embeded Computer System
Emerging advances in business and its applications
Emerging signal processing areas
Enabling technologies for pervasive systems
Energy-efficient and green pervasive computing
Environmental Engineering,
Estimation and identification techniques
Evaluation techniques for middleware solutions
Event-based, publish/subscribe, and message-oriented middleware
Evolutionary computing and intelligent systems
Expert approaches
Facilities planning and management
Flexible manufacturing systems
Formal methods and tools for designing
Fuzzy algorithms
Fuzzy logics
GPS and location-based app
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Monitoring of the Sulfur and Nano Silver in Water by Method of Laser Spectros...IJERA Editor
We developed new automatic method that combines the method of forced lumines-cence and stimulated Brillouin scattering (SBS). We used the method for the pathogens monitoring in water supply system earlier. We have researched spectral peaks of gases and show that method allows determining H2S content with 0.01% accuracy and determining the content constituents of nano silver in water.
KINETICS, EQUILIBRIUM AND THERMODYNAMICS STUDIES ON BIOSORPTION OF HEAVY META...Drm Kapoor
Batch studies were conducted to assess biosorption potential of Aspergillus niger and Aspergillus flavus dead biomass, operated under various pH (5, 6 and 7), temperature (20, 30 and 40ºC) and initial metal concentration (300, 600 and 900ppm) conditions. The maximum sorption by A. flavus being a better adsorbent showed to be 257mg/g for Cr (III) at 40C leading to 85.6% biosorption. Metal uptake was preeminent at pH 6 and decreased at pH 7. Results revealed amplifying uptake in biosorption with the increase in temperature and initial metal concentration. Kinetics and equilibrium studies were carried out in which pseudo-second-order kinetic model and Langmuir adsorption isotherm best represented the biosorption with regression coefficient values > 0.982 respectively. The calculated thermodynamic parameters (∆G, ∆H and ∆S) showed that the biosorption of each of the metal ions on A. flavus was spontaneous, feasible and endothermic. A. flavus was efficient for removal of toxic metals.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Bioadsorption of Pb2+ and Cu2+ on Eucalyptus Camaldulensis LeavesIJEAB
Herein, the efficiency of Eucalyptus camaldulensis leaves as biosorbent for lead and copper was investigated. The particle size distribution was determined by Granulometric analysis and the functional groups were identified by FT-IR spectroscopy. The effects of contact time, pH and initial metal ions concentration were investigated. The experimental kinetic data were well fitted by the pseudo-second order kinetic model and Langmuir isotherm with a maximum adsorption capacity up to 71 mg g-1 and 37 mg g-1 for Cu2+ and Pb2+ respectively. The selectivity was examined in a binary ions solution where the adsorbent showed preference for lead over copper.
Isothermal, Kinetic and Thermodynamic Studies of the Adsorption of Erythrosin...IJAEMSJORNAL
Isothermal, kinetic and thermodynamic studies of the adsorption of erythrosine dye onto activated carbon from Periwinkle shell was carried out. The Periwinkle shell were washed, dried, carbonized at 400oC, crushed, sieved, chemically activated at 800oC, cooled, washed and dried at 110oC. Variable influencing factors, such as contact time, temperature and concentration were studied through single-factor experiment, while other factors are kept constant (at 30min, 30oC and 50mg/L) in each adsorption experiment. From the adsorption isotherms, the correlation coefficient for Redlich-Peterson is closer to unity than others used in the adsorption. The adsorption kinetic followed pseudo-second order reaction, while the thermodynamic parameters, (∆H) = 13.49KJ/mol, (∆S) = 43.48J/mol.K and (∆G) = 0.4, 0.06, -0.15, -0.27, -0.54, -7.30KJ/mol. These results obtained show that activated carbon from Periwinkle shell will be a good low-cost adsorbent for the removal of erythrosine from aqueous solution.
New RP HPLC method for the simultaneous estimation of sulbactum and ceftriaxo...SriramNagarajan19
A simple and selective LC method is described for the determination of Sulbactum and Ceftriaxone tablet dosage forms. Chromatographic separation was achieved on a C18 column using mobile phase consisting of a mixture of mixture of 60 volumes of 20mM Phosphate buffer pH 3.5: 40 volumes of Acetonitrile (60:40 v/v) with detection of 210 nm. Linearity was observed in the range 30-70 µg /ml for Sulbactum (r2 =0.9998) and 60-140µg /ml for Ceftriaxone (r2 =0.9983) for the amount of drugs estimated by the proposed methods was in good agreement with the label claim. The proposed methods were validated. The accuracy of the methods was assessed by recovery studies at three different levels. Recovery experiments indicated the absence of interference from commonly encountered pharmaceutical additives. The method was found to be precise as indicated by the repeatability analysis, showing %RSD less than 2. All statistical data proves validity of the methods and can be used for routine analysis of pharmaceutical dosage form.
Quality control of drug fleroxacin dosage, its monitoring in biological fluids, and research of drug’s metabolism and action are an important analytical task.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Monitoring of the Sulfur and Nano Silver in Water by Method of Laser Spectros...IJERA Editor
We developed new automatic method that combines the method of forced lumines-cence and stimulated Brillouin scattering (SBS). We used the method for the pathogens monitoring in water supply system earlier. We have researched spectral peaks of gases and show that method allows determining H2S content with 0.01% accuracy and determining the content constituents of nano silver in water.
KINETICS, EQUILIBRIUM AND THERMODYNAMICS STUDIES ON BIOSORPTION OF HEAVY META...Drm Kapoor
Batch studies were conducted to assess biosorption potential of Aspergillus niger and Aspergillus flavus dead biomass, operated under various pH (5, 6 and 7), temperature (20, 30 and 40ºC) and initial metal concentration (300, 600 and 900ppm) conditions. The maximum sorption by A. flavus being a better adsorbent showed to be 257mg/g for Cr (III) at 40C leading to 85.6% biosorption. Metal uptake was preeminent at pH 6 and decreased at pH 7. Results revealed amplifying uptake in biosorption with the increase in temperature and initial metal concentration. Kinetics and equilibrium studies were carried out in which pseudo-second-order kinetic model and Langmuir adsorption isotherm best represented the biosorption with regression coefficient values > 0.982 respectively. The calculated thermodynamic parameters (∆G, ∆H and ∆S) showed that the biosorption of each of the metal ions on A. flavus was spontaneous, feasible and endothermic. A. flavus was efficient for removal of toxic metals.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Bioadsorption of Pb2+ and Cu2+ on Eucalyptus Camaldulensis LeavesIJEAB
Herein, the efficiency of Eucalyptus camaldulensis leaves as biosorbent for lead and copper was investigated. The particle size distribution was determined by Granulometric analysis and the functional groups were identified by FT-IR spectroscopy. The effects of contact time, pH and initial metal ions concentration were investigated. The experimental kinetic data were well fitted by the pseudo-second order kinetic model and Langmuir isotherm with a maximum adsorption capacity up to 71 mg g-1 and 37 mg g-1 for Cu2+ and Pb2+ respectively. The selectivity was examined in a binary ions solution where the adsorbent showed preference for lead over copper.
Isothermal, Kinetic and Thermodynamic Studies of the Adsorption of Erythrosin...IJAEMSJORNAL
Isothermal, kinetic and thermodynamic studies of the adsorption of erythrosine dye onto activated carbon from Periwinkle shell was carried out. The Periwinkle shell were washed, dried, carbonized at 400oC, crushed, sieved, chemically activated at 800oC, cooled, washed and dried at 110oC. Variable influencing factors, such as contact time, temperature and concentration were studied through single-factor experiment, while other factors are kept constant (at 30min, 30oC and 50mg/L) in each adsorption experiment. From the adsorption isotherms, the correlation coefficient for Redlich-Peterson is closer to unity than others used in the adsorption. The adsorption kinetic followed pseudo-second order reaction, while the thermodynamic parameters, (∆H) = 13.49KJ/mol, (∆S) = 43.48J/mol.K and (∆G) = 0.4, 0.06, -0.15, -0.27, -0.54, -7.30KJ/mol. These results obtained show that activated carbon from Periwinkle shell will be a good low-cost adsorbent for the removal of erythrosine from aqueous solution.
New RP HPLC method for the simultaneous estimation of sulbactum and ceftriaxo...SriramNagarajan19
A simple and selective LC method is described for the determination of Sulbactum and Ceftriaxone tablet dosage forms. Chromatographic separation was achieved on a C18 column using mobile phase consisting of a mixture of mixture of 60 volumes of 20mM Phosphate buffer pH 3.5: 40 volumes of Acetonitrile (60:40 v/v) with detection of 210 nm. Linearity was observed in the range 30-70 µg /ml for Sulbactum (r2 =0.9998) and 60-140µg /ml for Ceftriaxone (r2 =0.9983) for the amount of drugs estimated by the proposed methods was in good agreement with the label claim. The proposed methods were validated. The accuracy of the methods was assessed by recovery studies at three different levels. Recovery experiments indicated the absence of interference from commonly encountered pharmaceutical additives. The method was found to be precise as indicated by the repeatability analysis, showing %RSD less than 2. All statistical data proves validity of the methods and can be used for routine analysis of pharmaceutical dosage form.
Quality control of drug fleroxacin dosage, its monitoring in biological fluids, and research of drug’s metabolism and action are an important analytical task.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
SYNTHESIS AND CHARACTERIZATION OF KAOLINITE COATED WITH CU-OXIDE AND ITS EFFE...Premier Publishers
In this paper, a novel copper oxide coated kaolinite was prepared as an adsorbent of Hg(II) ions from aqueous media. The materials used for this study were synthesized, characterised and the product tested for mercury ion removal using standard laboratory procedures. Reactivity and removal kinetic models derived from Freundlich isotherm were used to investigate contact time and pH effects on the coefficient of protonation and rate of mass transfer of Hg(II) ions to the reactive sites, Proton coefficient of 0.89 indicated a decrease in proton consumption function when compared with uncoated kaolinite. At the 12th h reaction time, a maximum adsorption capacity of 85% was achieved. Mass transfer rates of 0.9359h-1 and 0.0748h-1 for the first and second reaction phases indicated a reduction when compared with uncoated kaolinite. These changes may be ascribed to masking of reaction sites and exposed surface area of the Cu-Oxide coated kaolinite.
Kinetic, thermodynamic and equilibrium studies on removal of hexavalent chrom...Ratnakaram Venkata Nadh
Removal of Cr(VI) by biosorption on two agro waste materials, casuarinas fruit powder (CFP) and sorghum
stem powder (SSP), has been investigated. The prepared adsorbent materials were characterized by SEM, EDX,
FTIR and BET. These biomaterials effectively removed Cr(VI) with a maximum removal of 93.35% and 63.75% using
15 gL−1 and 5 gL−1 of CFP and SSP, respectively, at 60 oC with 20mgL−1 initial Cr(VI) concentration in solution. In both
cases of adsorbents, kinetic data of adsorption fitted well in pseudo-second-order in terms of correlation coefficient
(R2). This helps in proposing the process of adsorption as chemical coordination, which is correlated with the thermodynamic
study results conducted at different values of temperature. Langmuir, Freundlich and D-R models were evaluated
for description of metal sorption isotherms. Values of coefficients of intra-particle diffusion and mass transfer have
also been determined at different values of temperature.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Chemical Examination Of Sandbox (Hura Crepitans) Seed: Proximate, Elemental A...IOSRJAC
A study in terms of proximate, elemental and fatty acid contents of (Hura crepitans) seed was investigated using standard analytical techniques. The results of proximate composition in % were as follows: moisture 12.82 ± 0.01, crude protein 24.76 ±0.04, crude fibre 10.15 ± 0.03, fat 10.68 ± 0.01, ash 3.16 ± 0.02 and carbohydrate 34.75 ± 0.05. The elemental composition of the seed showed Na, K, Ca and Mg in mg/100g to be 6.00 ± 0.01, 123.00 ± 0.02, 10.40 ± 0.03, 112.00 ± 0.01 respectively while other elements determined in mg/kg were Fe and Zn with 7.10 ±0.04 and 2.60± 0.01. The (%) free fatty acid compositions of the seed oil were as follows: lauric (1.310 ±0.015), palmitic (0.389 ±0.012), palmitoleic (1.211 ±0.013), stearic (2.436 ± 0.004), oleic (6.138 ±0.003), linoleic (8.625 ±0.001) and linolenic (2.469 ± 0.102). The results revealed linoleic and oleic acids to be the most common in terms of abundance while palmitic acid was the least. The seed of Hura crepitans could be described as a good food because it contained significant amount of essential nutrients required by man.
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Biosorption of hg (ii) from aqueous solutions using butea monospermaeSAT Journals
Abstract
The objective of this study is to investigate the feasibility of using Butea monosperma leaves powder (BMLP) for the removal of
mercury from aqueous solution at the normal pH of the solution and at room temperature (30oC). Results show that BMLP has a good
biosorption capacity for mercury. The biosorption isotherms were analyzed using Freundlich, Langmuir and Temkin models. The
Freundlich model yielded the best fit for the experimental biosorption equilibrium data. The maximum monolayer biosorption
capacity as determined from the Langmuir model is 62.235 mg/g of biosorbent for initial concentration of 150 ppm mercury in the
solution. The biosorption energy, ΔQ indicates that the biosorption reaction was endothermic. The kinetic data fitted the Ho’s pseudosecond-
order model with correlation coefficient 0.9985 and 0.9620 for initial concentration of 100 ppm and 150 ppm mercury in the
solution. The studies suggest that the sorbent can be used for the removal of mercury from aqueous solutions.
Keywords: Biosorption, Mercury, Isotherms, Kinetics
Biosorption of hg (ii) from aqueous solutions using butea monospermaeSAT Journals
of using Butea monosperma leaves powder (BMLP) for the removal of
mercury from aqueous solution at the normal pH of the solution and at room temperature (30oC). Results show that BMLP has a good
biosorption capacity for mercury. The biosorption isotherms were analyzed using Freundlich, Langmuir and Temkin models. The
Freundlich model yielded the best fit for the experimental biosorption equilibrium data. The maximum monolayer biosorption
capacity as determined from the Langmuir model is 62.235 mg/g of biosorbent for initial concentration of 150 ppm mercury in the
solution. The biosorption energy, ΔQ indicates that the biosorption reaction was endothermic. The kinetic data fitted the Ho’s pseudosecond-
order model with correlation coefficient 0.9985 and 0.9620 for initial concentration of 100 ppm and 150 ppm mercury in the
solution. The studies suggest that the sorbent can be used for the removal of mercury from aqueous solutions.
Removal of Heavy Metals from Aqueous Solutions by Modified Activated Carbon f...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Removal of Heavy Metals from Aqueous Solutions by Modified Activated Carbon f...
2015-Moosa-CNTs
1. ISSN(Online): 2319 - 8753
ISSN (Print) :2347 - 6710
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 4, Issue 2, February 2015
Copyright to IJIRSET DOI: 10.15680/IJIRSET.2015.0402057 275
Chromium Ions Removal from Wastewater
Using Carbon Nanotubes
Ahmed A. Moosa*, Ali Mousa Ridha, Ibtihal Najem Abdullha
Department of Materials Engineering Technology, Engineering Technical College, Baghdad, Middle Technical
University, Baghdad, Iraq*
ABSTRACT: Functionalized MWCNTs were used for the removal of heavy metal Cr+3
ions from wastewater. The
optimum conditions for batch adsorption of Cr3+
ions and the maximum adsorption efficiency were found to be 99.83%
for MWCNTs at 25 mg; and pH 6. The results showed that MWCNTs have large adsorption capacity due to their
higher surface area. The equilibrium isotherm of (MWCNTs) shows that the Langmuir isotherm fits the experimental
data better than Freundlich adsorption.
KEYWORDS: Adsorption, Heavy metal removal, Chromium removal, Carbone Nanotubes
I. INTRODUCTION
Heavy metals in wastewaters are one of the most serious worldwide environmental problems. Heavy metals do not
degrade biologically in the environment and can accumulate in living tissues particularly in human bodies causing
significant physiological disorders.[1-2]
Chromium is a heavy metals and exist in several different forms such as chromium (III), and chromium (VI). The
main sources of Cr are metallurgical, electroplating, tannery, mining, and paint industries [3-4].
Various techniques have been adapted to remove heavy metals from wastewater. These techniques include precipitation,
electrochemical treatment solvent extraction, ion exchange and adsorption. Adsorption has been proven to be a cost
effective, widely used and simple technique. [5]
Carbon nanotubes (CNTs) are allotropes of carbon which have a cylindrical or tubular structure [6] . CNTs can be
Single -walled carbon nanotubes (SWNT) , Double wall (DWNT) and Multi-walled carbon nanotubes (MWNT) .
CNTs have novel properties which are used in many applications such as : electronics, optics, water treatment and
other fields of material sciences [7].
CNTs have large specific surface area and small, hollow, and layered structures [8]. CNTs have been proven to be
effective sorbents for the removal of metal ions as well as their complexes due to their large specific surface area as
well as the presence of a wide spectrum of surface functional groups [9].
Carbon Nanotubes (CNTs) were found to have great potential to be a good adsorbent for the adsorption of Cr (III) in
aqueous solution. The adsorption parameters, such as the amount of MWCNTs, contact time, agitation speed, pH, were
studied for the removal of Cr 3+
[10]. The results showed that the removal of Cr 3+
is mainly attributed to the affinity of
Cr 3+
to the physical and chemical properties of the CNTs. Rao et al. [11] studied the removal of divalent metal ions
(Cd2+
, Cu2+
, Ni2+
, Pb2+
, Zn2+
) from aqueous solution using functionalized CNTs raw and surface oxidized carbon
nanotubes (CNTs) for sorption. The sorption mechanisms appear mainly attributable to chemical interactions between
the metal ions and the surface functional groups of the CNTs. The utilization of CNTs for the treatment of water and
wastewater containing divalent metal ions is gaining more attention as a simple and effective means of pollution
control. In Iraq; wastewater is discharged to river without treatment which causes water pollution. The aim of present
work is to investigate the adsorption characteristics of Cr3+
onto chemically modified CNTs.
2. ISSN(Online): 2319 - 8753
ISSN (Print) :2347 - 6710
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 4, Issue 2, February 2015
Copyright to IJIRSET DOI: 10.15680/IJIRSET.2015.0402057 276
II. MATERIAL AND METHODS
A. ADSORBATE
Chromium nitrate salt Cr(NO3)3.9H2O was used as Cr metal ions. Analytical-grade of Chromium nitrate salt, (99%
purity, and molecule weight 400.15 g/mol, company Escrow,China). A 1000 mg/L standard stock solution of Cr3+
ions
was prepared by dissolving 7.692 g of chromium nitrate salt (Cr (NO3)3.9H2O, 99% purity, Escrow, China) into
(1000mL) of deionized water and stirred using magnetic stirrer.
B. CARBON NANOTUBES
MWCNTs used in this work were purchased from Cheap Tubes Inc. USA. MWCNTs was produced by CVD
method and purified by plasma with purity of ˃99 % and diameter 13-18 nm with length 1-12 µm.
C. FUNCTIONALIZATION OF MWCNTs
0.5 g of MWCNTs were immersed in 500 ml of mixture of concentrated (HNO3:H2SO4) (1:3 by volume) at room
temperature and ultrasonicated in high power ultrasonic path (frequency 60 KHz, power 140 W) for 30 min, the
solution then was diluted 15 times and filtered in vacuum filtration system using filter papers with 0.2 μm in pore size.
MWCNTs were washed many times during filtration using deionized water until the pH reached 7. The MWCNTs
were dried in air for 24 hrs and then dried in vacuum oven at 100o
C for 2hrs. The CNTs were characterized using FTIR
[12-13].
D. BATCH ADSORPTION SYSTEM
D.1 EFFECT OF ADSORBENT WEIGHT
To determine the optimum weight of MWCNTs as an adsorbent , a different weights (5, 15, 25, 50, 75,100, 125,150)
mg of MWCNTs was mixed with 50 mL of chromium ions solution Cr3 +
. The solution was then shaken for about 3hrs
in a rotary shaker at fixed speed 140 rpm and temperature of 25o
C. After shaking the solutions were filtered in vacuum
filtration system. The remaining of Cr3+
ion concentrations in the filtrate were measured by atomic-absorption
spectrophotometer. All experiments were performed at the pH 7 of the solution and 100 mg/L initial concentration of
Cr3+
ion solution. The desired pH was adjusted using 1 M HCl and 1 M NaOH.
D.2 EFFECT OF pH
To obtain the optimum of pH of Cr3+
solution pH adsorption onto MWCNTs, a different Cr3+
solution pH ( 2, 4, 6,
8, 10) were used with 50 mL of Cr3+
metal ions solution at initial concentration of 100 mg/L. The pH of each samples
was adjusted by 1M of concentrated HCl acid and 1M NaOH by pH meter. The metal ion solutions Cr3+
of different pH
was added to the bottles containing optimum weight of weight of MWCNTs . The bottles were then shaken in a rotary
shaker for 3 hrs at 140 rpm and 25o
C. The MWCNTs solution was then filtered using filter paper with vacuum. The
remaining of Cr3+
ion concentrations in the filtrate were determined by using the atomic-absorption spectrophotometer.
The optimum pH of Cr3+
metal ion solutions for removal of Cr3+
metal from aqueous solution was then selected
E. Equilibrium Isotherms
Equilibrium isotherms experiments were carried out using optimum mass of MWCNTs and the optimum pH of Cr3+
metal ion solutions for removal of Cr3+
metal from aqueous solution. A 50mL of Cr3+
ion solution with different initial
concentration (20,40,60,80,100, and 120 mg/L) was added in bottles containing the optimum adsorbent dosage of
MWCNTs and optimum pH of solution. The solution was then shaken at a fixed speed of 140 rpm in rotary shaker
using water bath at different temperatures of 25, 35 and 45o
C for 3hrs. The shaker bath provides temperature indicator
controller that controls the temperature for the desired value. After shaking the solutions were filtered using vacuum
filtration. The remaining of Cr3+
ion concentrations in the filtrate were determined by using the atomic-absorption
spectrophotometer.
The adsorption capacity, qe (i.e the mass of solute adsorbed per mass of adsorbent) was then plotted versus the
equilibrium concentration of the solution, Ce to obtain the equilibrium isotherm curves.
The adsorption of metal ions onto the adsorbent surface at specific time was estimated from mass balance equation [14]:
q =
( )
(1)
Where q is quantity of adsorbate (mg/g) , V is the total volume of adsorbate solution (L). Co and Ce are the initial and
equilibrium concentration of adsorbate solution at equilibrium in (mg/L) respectively .W is the adsorbant weight (g).
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The percentage of adsorption is given by[15]:
% Adsorption = ∗ 100 (2)
Where
Co = Initial concentration of adsorbate solutions (mg/L).
Ce = Concentration of adsorbate solution at equilibrium (mg/L).
E.1 LANGMUIR ISOTHERM
The Langmuir represents the equilibrium distribution of metal ions between the solid and liquid phases [16-17].
The Langmuir isotherm is represented in Eq. (3) [18-20]:
q L= (3)
The above equation can be rewritten as:
= + (4)
Where: Ce is the equilibrium concentration of adsorbate in the solution (mg/L) , qe is the equilibrium adsorbate
concentration (mg/g) on the adsorbent , b (L/g) are Langmuir constants, qm (mg/g) the maximum adsorption capacity.
E.2 FREUNDLICH ISOTHERM
The Freundlich isotherm can be derived assuming a logarithmic decrease in the enthalpy of adsorption with the
increase in the fraction of occupied sites and is commonly given by the following non-linear Equations [19-20].
q = k C
/
(5)
The logarithmic form of the equation becomes:
log = log + log (6)
Where Kf and n are Freundlich constants characteristic of the system.
III. RESULTS AND DISCUSSION
A. FTIR
The Fourier Transform Infrared Spectrophotometer, FTIR, spectra of oxidized MWCNTs is shown in Figure 1.
There are four major peaks, located at 3410.15, 2370, 1701.22 and 1566.2 cm−1
. The peak at 3410.15 cm−1
can be
assigned to the O-H stretch from carboxyl groups (O=C−OH and C−OH). The peak at 2364 cm−1
can be associated
with the O−H stretch from strongly hydrogen-bonded −COOH [7]. It can be seen that the peak in 1701.22 cm−1
is
associated with -C=O stretching of the carboxyl group. The peak at 1566.2 cm−1
is related to the carboxylate anion
stretch model [21]. The many oxygen-containing functional groups that were generated on the surface of modified
CNTs, providing various adsorption sites, and increasing the adsorption capacity [22]. Functionalization process by
acidic oxidation of carbon surface can offer not only a more hydrophilic surface but also a larger number of oxygen-
containing function groups, which increase the ion-exchange capability of carbon material. The specific area of
MWCNTs as measured by the BET method was found to be 63.17 (m2
/g). MWCNTs have high surface area.
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Figure 1 FTIR of Functionalized multi wall carbon nanotubes.
B. EFFECT OF ADSORBENT WEIGHT OF MWCNTs ON ADSORPTION PROCESS
Different weights (5, 15, 25, 50, 75,100, 125,150) mg of MWCNTs were used to study the effect of MWCNTs
weight on adsorption efficiency for the removal of Cr3+
at pH 7. Figure 2 shows the percentage removal of Cr3+
ions
increases with the increase of the weight of MWCNTs. This is due to the availability of more sorption active sites and
high surface area until equilibrium is reached. This is in good agreement with the work of [23]. The functional groups
make MWCNTs more suitable for the adsorption of Cr3+
at smaller weight. The maximum adsorption efficiency
(99.99%) occurs at small weight, 25 mg of MWCNTs.
Figure 2 The effect of MWCNTs on the adsorption process.
97
97.5
98
98.5
99
99.5
100
100.5
0 50 100 150 200
%AdsorptionEfficency
Weight of MWCNTs,mg
Weight Effect
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C. EFFECT OF CHROMIUM SOLUTION pH ONTO MWCNTs ON ADSORPTION PROCESS
The adsorption efficiency of MWCNTs for the removal of Cr3+
ions increased at pH 4-6 as shown in Figure 3. The
adsorption efficiency increases gradually with increasing pH. The minimum adsorption observed at pH 2 values might
be due to the fact that the higher concentration and mobility of hydrogen ions (H+
) present at lower pH favored the
preferential adsorption of hydrogen ions than Cr3+
metal ions. Also , the MWCNTs surface are predominantly covered
by H+
at low pH values which prevents metal ions from approaching the binding sites[24]. Increasing the pH from 2
to pH 6 will increase the Cr3+
adsorption due to the fact that the metal ionic species become less stable in solution. At
higher pH values (i.e., pH 6-10) , the adsorption efficiency decreased, which may have been due to the precipitation of
chromium in the form of hydroxide. The maximum adsorption efficiency (99.91 %) occurred at the pH 6 which is in
agreement with the work of Kosa, et al., [24].
Figure 3 Effect of pH on the adsorption efficiency of Cr3+
onto MWCNTs.
D. ISOTHERM OF MWCNTs
The data of the functionalized MWCNTs at optimum conditions (surface area 63.17 m2
/g, pH 6, 25mg) were used
at different Co (20, 40, 60, 80, 100,120 mg/L) to construct the experimental model and the Langmuir and Freundlich
isotherm at 25o
C . These data were then used in Figure 4.20 and Table 4.4. Based on correlation coefficient R2
(from
Table 4.4) it can be concluded that the Langmuir model yields better fit to the experimental data than the Freundlich
adsorption isotherm.
The effect of different temperatures (25, 35, 45 o
C) on the adsorption isotherm of Cr+3
ions onto MWCNTs was
investigated. The results from Table 1 shows that the Langmiur adsorption isotherm gives the best fit to the adsorption
isotherm for the temperatures (25, 35, 45 o
C).
The values of Langmuir constants b, qm and correlation coefficient R2
increased with temperature due to the increase in
the negative charges of the surface thus, higher adsorption occurred at higher temperatures . This is in agreement with
the work of [25].
88
90
92
94
96
98
100
102
0 2 4 6 8 10 12
%AdsorptionEfficency
pH
pH Effect
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Figure 4 Adsorption isotherms of experimental and theoretical models of MWCNTs (25o
C and 25mg).
Table 1 Langmuir & Freundlich adsorption isotherm parameters of MWCNTs at different temperatures.
Adsorbents
Temp.
o
C
Langmuir parameters Freundlich parameters
qm B R2
1/n K R2
MWCNTs
25 238.09 420 0.9906 0.29 612.20 0.8274
35 270.27 925 0.9948 0.45 2645.45 0.888
45 270.27 1850 0.9989 0.47 4234.47 0.9403
E. THERMODYNAMIC PARAMETERS OF MWCNTs
Figures 5 shows plot of lnb vs. (1/T) for MWCNTS. Table 2 shows the changes in the free energy of adsorption
(ΔG°), enthalpy (ΔH°) and entropy (ΔS°). The negative values of ΔG° indicate that process is spontaneous. The positive
value of ΔH° indicated the endothermic nature of the process, which means there is a strong interaction between
MWCNTs and Cr3+
ions and the adsorption increases with temperature.. The positive value of ΔS° indicates the affinity
between MWCNTs and the Cr3+
ions and structural changes in MWCNTS as reported by Chen et al., [26]; Teker and
Imamoglu [27].
0
50
100
150
200
250
300
0 0.01 0.02 0.03 0.04 0.05 0.06
Equilibriumcapacityq,mg/g
Equilibrium Concentration, Ce , mg/l
Nonlinear Theoretical
Experimental
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Figure 5 Plot of Lnb vs. 1/T for MWCNTs.
Table 2 Thermodynamic parameters of MWCNTs.
Adsorbent T (K) ∆Go
(kJ/mol) ∆Ho
(kJ/mol) ∆So
(kJ/mol.K)
MWCNTs
298 -41.89
58.43 0.34
308 -45.25
318 -48.62
IV. CONCLUSIONS
The functionalized MWCNTS is an effective adsorbent and can be successfully used for removing of Cr3+
ions from
wastewater. The maximum adsorption efficiency of MWCNTs is 99.98% at 25 mg and at pH 6. The equilibrium
isotherm of (MCNTs) shows that the Langmuir isotherm fits the experimental data better than Freundlich adsorption.
The negative values of ΔG° indicate that process is spontaneous. The positive value of ΔH° indicates the reaction is
endothermic. The positive value of ΔS° indicates the random character of adsorption of Cr3+
ions on the MWCNTs.
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16.8
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