This document summarizes a study on dispersing reduced graphene in organic solvents through noncovalent functionalization with end-functional polymers. The researchers prepared an aqueous dispersion of reduced graphene oxide through chemical reduction, then tested its dispersibility in various organic solvents. To disperse the graphene in nonsolvents, they noncovalently functionalized it with amine-terminated polymers via sonication. FTIR and Raman spectroscopy confirmed the amine groups on the polymers interacted with carboxyl groups on the graphene surface, enhancing dispersibility in organic media.
Photocatalytic Properties of GO-(Cd0.8-Zn0.2)S Nanocomposites Prepared by Che...IJLT EMAS
Graphene oxide - (Cd0.8-Zn0.2)S nanocomposite
material was synthesized by the simple and economically viable
chemical precipitation method at different temperatures and its
photocatalytic properties were investigated. Measurement of
photocatalytic degradation of Rhodamine B dye was carried out
under visible light. The photocatalytic efficiency of the
synthesized nanocomposites was calculated and the effect of bath
temperature on the photocatalytic efficiency was studied. The
studies suggest that the prepared nanocomposites exhibit
reasonably good photocatalytic properties. Better photocatalysis
is observed at lower bath temperatures for preparation of the
nanocomposites. Photocatalytic efficiency close to 70% has been
obtained for the synthesised GO-(Cd0.8-Zn0.2) S nanocomposites
which can be further improved by optimizing the preparative
conditions
adsorption of methylene blue onto xanthogenated modified chitosan microbeadsSiti Nadzifah Ghazali
This document presents a study on using xanthogenated-modified chitosan microbeads (XMCM) to remove methylene blue dye from wastewater. The study characterized XMCM using FTIR, pH, and pHzpc analysis. Batch experiments examined the effect of adsorbent dosage and initial pH on dye removal efficiency. Equilibrium isotherm data fitted well to the Langmuir model, indicating monolayer adsorption. The maximum adsorption capacity of XMCM for methylene blue was determined to be 21.62 mg/g. The study demonstrated the potential of XMCM for wastewater treatment applications.
This document summarizes a study that synthesized titanium dioxide-graphene oxide (TiO2-GO) and titanium dioxide-thermally reduced graphene oxide (TiO2-TGO) composites with varying concentrations of GO/TGO. The composites were characterized using various techniques and their photocatalytic activity for degrading phenol in an aqueous solution was evaluated. The TiO2-0.25% TGO composite exhibited the highest photocatalytic activity, attributed to optimal phenol adsorption and reduced electron-hole pair recombination rates. Photocatalytic testing under nitrogen confirmed the role of graphene in transporting and storing electrons, suppressing recombination.
Oxidation of Acetaminophen by Fluidized-bed Fenton Process: Optimization usin...Oswar Mungkasa
prepared by M.C. Lu*, R.M. Briones**, and M.D.G. de Luna**, *** *Department of Environmental Resources Management, Chia Nan University of Pharmacy and Science, Tainan 717, Taiwan (E-mail: mmclu@mail.chna.edu.tw) ** Environmental Engineering Graduate Program, University of the Philippines, 1011 Diliman, Quezon City, Philippines (Email: rowenambriones@yahoo.com) *** Department of Chemical Engineering, University for Urban Environments in Asia, 25-28 May 2011, Manila, Philippines. organized by International Water Association (IWA).
Present study aims to investigate the efficiency of newly synthesized adsorbent polyvinyl
alcohol-alginate bound nano magnetite microspheres modified with cetyltrimethyl ammonium bromide [PVAANM/CTAB]
in removal of anionic dye ‘Alizarin Red S’ from aqueous medium. The effect of agitation time,
influence of pH, amount of adsorbent, initial dye concentration and temperature were systematically studied by
batch sorption system. Various isotherms and kinetic models have been fitted with experimental data to evaluate
mechanism of adsorption. Characterization of the so-prepared adsorbent was accomplished by FTIR, XRD,
SEM and TEM analysis. The experimental data fitted very well with Freundlich and Temkin isotherm model.
The sorption kinetics follows pseudo second order kinetic model. PVA-ANM/CTAB has been found an effective,
economic, eco-friendly and efficient adsorbent as it showed ≥ 98% removal at pH 8 and could be regenerated
by acetic acid and reused.
Use of titanium dioxide photocatalysis on the remediationBruno B Garcia
This study investigated the photocatalytic degradation of two azo dyes found in textile wastewater using titanium dioxide (TiO2) photocatalysis. The effects of TiO2 concentration, UV irradiation time, solution pH, initial dye concentration, and hydrogen peroxide concentration on degradation were examined. Optimal conditions for highest degradation rates were determined. Results showed that complete decolorization of solutions could be achieved using an efficient photocatalyst under suitable operational parameters.
Thermodynamics and adsorption studies of rhodamine-b dye onto organoclayInnspub Net
Thermodynamics and adsorption studies were conducted with a dye of Rhoda mine-B (RB) on organoclay (OC). Adsorption of the dye was investigated with an initial dye concentration at pH 7±0.3, 298, 308 and 318 K. The adsorption experiments were carried out isothermally at three different temperatures. The Langmuir and Freundlich isotherm models were used to describe the equilibrium data and the results were discussed in details. The thermodynamic parameters such as standard free energy (∆G°), entropy change (∆S°) and enthalpy (∆H°) were calculated for OC. These values showed that adsorption of RB on OC was a spontaneous and endothermic process.
Homogeneous Photocatalytic Degradation of Acid Alizarin Black Using Hydrogen ...Haydar Mohammad Salim
This document summarizes research on degrading the acid dye Alizarin Black using hydrogen peroxide and UV light (UV/H2O2). The research aims to study how the degradation of Alizarin Black is affected by dye concentration, hydrogen peroxide concentration, and pH. Results showed that degradation was most effective at a dye concentration of 100 mg/L and increased with higher hydrogen peroxide amounts. Degradation was also favored under neutral conditions compared to acidic or basic conditions. Kinetic studies found pseudo-first order degradation rates increased with higher hydrogen peroxide volumes and decreased with higher dye concentrations.
Photocatalytic Properties of GO-(Cd0.8-Zn0.2)S Nanocomposites Prepared by Che...IJLT EMAS
Graphene oxide - (Cd0.8-Zn0.2)S nanocomposite
material was synthesized by the simple and economically viable
chemical precipitation method at different temperatures and its
photocatalytic properties were investigated. Measurement of
photocatalytic degradation of Rhodamine B dye was carried out
under visible light. The photocatalytic efficiency of the
synthesized nanocomposites was calculated and the effect of bath
temperature on the photocatalytic efficiency was studied. The
studies suggest that the prepared nanocomposites exhibit
reasonably good photocatalytic properties. Better photocatalysis
is observed at lower bath temperatures for preparation of the
nanocomposites. Photocatalytic efficiency close to 70% has been
obtained for the synthesised GO-(Cd0.8-Zn0.2) S nanocomposites
which can be further improved by optimizing the preparative
conditions
adsorption of methylene blue onto xanthogenated modified chitosan microbeadsSiti Nadzifah Ghazali
This document presents a study on using xanthogenated-modified chitosan microbeads (XMCM) to remove methylene blue dye from wastewater. The study characterized XMCM using FTIR, pH, and pHzpc analysis. Batch experiments examined the effect of adsorbent dosage and initial pH on dye removal efficiency. Equilibrium isotherm data fitted well to the Langmuir model, indicating monolayer adsorption. The maximum adsorption capacity of XMCM for methylene blue was determined to be 21.62 mg/g. The study demonstrated the potential of XMCM for wastewater treatment applications.
This document summarizes a study that synthesized titanium dioxide-graphene oxide (TiO2-GO) and titanium dioxide-thermally reduced graphene oxide (TiO2-TGO) composites with varying concentrations of GO/TGO. The composites were characterized using various techniques and their photocatalytic activity for degrading phenol in an aqueous solution was evaluated. The TiO2-0.25% TGO composite exhibited the highest photocatalytic activity, attributed to optimal phenol adsorption and reduced electron-hole pair recombination rates. Photocatalytic testing under nitrogen confirmed the role of graphene in transporting and storing electrons, suppressing recombination.
Oxidation of Acetaminophen by Fluidized-bed Fenton Process: Optimization usin...Oswar Mungkasa
prepared by M.C. Lu*, R.M. Briones**, and M.D.G. de Luna**, *** *Department of Environmental Resources Management, Chia Nan University of Pharmacy and Science, Tainan 717, Taiwan (E-mail: mmclu@mail.chna.edu.tw) ** Environmental Engineering Graduate Program, University of the Philippines, 1011 Diliman, Quezon City, Philippines (Email: rowenambriones@yahoo.com) *** Department of Chemical Engineering, University for Urban Environments in Asia, 25-28 May 2011, Manila, Philippines. organized by International Water Association (IWA).
Present study aims to investigate the efficiency of newly synthesized adsorbent polyvinyl
alcohol-alginate bound nano magnetite microspheres modified with cetyltrimethyl ammonium bromide [PVAANM/CTAB]
in removal of anionic dye ‘Alizarin Red S’ from aqueous medium. The effect of agitation time,
influence of pH, amount of adsorbent, initial dye concentration and temperature were systematically studied by
batch sorption system. Various isotherms and kinetic models have been fitted with experimental data to evaluate
mechanism of adsorption. Characterization of the so-prepared adsorbent was accomplished by FTIR, XRD,
SEM and TEM analysis. The experimental data fitted very well with Freundlich and Temkin isotherm model.
The sorption kinetics follows pseudo second order kinetic model. PVA-ANM/CTAB has been found an effective,
economic, eco-friendly and efficient adsorbent as it showed ≥ 98% removal at pH 8 and could be regenerated
by acetic acid and reused.
Use of titanium dioxide photocatalysis on the remediationBruno B Garcia
This study investigated the photocatalytic degradation of two azo dyes found in textile wastewater using titanium dioxide (TiO2) photocatalysis. The effects of TiO2 concentration, UV irradiation time, solution pH, initial dye concentration, and hydrogen peroxide concentration on degradation were examined. Optimal conditions for highest degradation rates were determined. Results showed that complete decolorization of solutions could be achieved using an efficient photocatalyst under suitable operational parameters.
Thermodynamics and adsorption studies of rhodamine-b dye onto organoclayInnspub Net
Thermodynamics and adsorption studies were conducted with a dye of Rhoda mine-B (RB) on organoclay (OC). Adsorption of the dye was investigated with an initial dye concentration at pH 7±0.3, 298, 308 and 318 K. The adsorption experiments were carried out isothermally at three different temperatures. The Langmuir and Freundlich isotherm models were used to describe the equilibrium data and the results were discussed in details. The thermodynamic parameters such as standard free energy (∆G°), entropy change (∆S°) and enthalpy (∆H°) were calculated for OC. These values showed that adsorption of RB on OC was a spontaneous and endothermic process.
Homogeneous Photocatalytic Degradation of Acid Alizarin Black Using Hydrogen ...Haydar Mohammad Salim
This document summarizes research on degrading the acid dye Alizarin Black using hydrogen peroxide and UV light (UV/H2O2). The research aims to study how the degradation of Alizarin Black is affected by dye concentration, hydrogen peroxide concentration, and pH. Results showed that degradation was most effective at a dye concentration of 100 mg/L and increased with higher hydrogen peroxide amounts. Degradation was also favored under neutral conditions compared to acidic or basic conditions. Kinetic studies found pseudo-first order degradation rates increased with higher hydrogen peroxide volumes and decreased with higher dye concentrations.
#scichallenge2017 Photocatalytic Degradation of Synthetic Wastewaters Contain...Seher Elif Mekik
#scichallenge2017
In our project, it was aimed to purify wastewaters containing methylene blue component and harmful to environment from methylene blue. For this purpose, synthetic methylene blue waste water was formed and chemically treated by photocatalysis.
Degradation of Ethanolamine by Fluidized-bed Fenton ProcessOswar Mungkasa
prepared by J. Anotai*,**, C.M. Chen***, L. Bellotindos**** and M.C. Lu*** Department of Environmental Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand (E-mail: jin.ano@kmutt.ac.th) ** National Center of Excellence for Environmental and Hazardous Waste Management (NCE-EHWM), Chulalongkorn University, Bangkok, Thailand *** Department of Environmental Resources Management, Chia-Nan Univer for Urban Environments in Asia, 25-28 May 2011, Manila, Philippines. organized by International Water Association (IWA).
Dye removal from waste water by using low cost adsorbent: A review Satish Movaliya
This document provides a literature review on using low-cost adsorbents for dye removal from wastewater. It discusses various adsorbents that have been used such as sugarcane bagasse, sawdust, coconut coir pith, and clay. The review examines factors that affect dye adsorption such as pH, adsorbent dosage, and contact time. It also discusses commonly used isotherm models like Langmuir and Freundlich to analyze adsorption equilibrium. The review concludes that more research is needed to develop efficient, selective, and eco-friendly low-cost adsorbents as well as continuous processes and desorption methods.
This document summarizes a study on the adsorption of a Schiff base ligand onto granulated initiated calcined Iraqi montmorillonite clay via columnar method. The ligand was synthesized from the condensation reaction of hydrazine hydrate and 4-hydroxy-3-methoxybenzaldehyde. Adsorption experiments were conducted in columns packed with the clay at different pH levels, ligand concentrations, and contact times. The equilibrium adsorption data fit the Langmuir, Freundlich and Temkin isotherm models. The maximum adsorption capacity was found to be 5.7347 mg ligand per 1g clay. The highest removal rate of 75.7% occurred at pH 7. Kinetic data followed pseudo
This document presents a study on enhancing the efficiency of adsorption processes using activated carbon through microwave activation and a high gravimetric rotating packed bed technology. The study aims to optimize preparation conditions for activated carbon from agricultural waste using microwaves. Response surface methodology and Taguchi experiments were used to determine optimal preparation parameters. The prepared activated carbon was then used in a rotating packed bed reactor to minimize contact time for dye and heavy metal removal. Kinetic and isotherm studies showed the adsorption followed pseudo-second order kinetics and best fit the Langmuir isotherm model. Optimization of process parameters for the rotating packed bed reactor enhanced removal efficiency.
This document describes an experiment on separating a tertiary butyl alcohol-water azeotropic mixture using lithium bromide salt. Tertiary butyl alcohol and water form an azeotrope that is difficult to separate. The experiment investigated adding varying amounts of lithium bromide salt to the azeotropic mixture during extractive distillation. It was found that adding 35g of lithium bromide allowed 88.98% of the tertiary butyl alcohol to be separated, breaking up the azeotrope more effectively than using a solvent alone. Lithium bromide increased the boiling point of the mixture and changed the relative volatility between tertiary butyl alcohol and water, facilitating their separation
Removal of basic dye from aqueous solution by adsorption on melon husk inAlexander Decker
This document discusses a study that investigated the adsorption behavior of the cationic dye methylene blue in single, binary, and ternary solutions using melon husk as an adsorbent. Experiments showed that adsorption equilibrium was reached within 120 minutes for all systems. Kinetic data fit best to a pseudo-second order model. Isotherm data fit best to the Langmuir model for single systems and Freundlich model for binary and ternary systems. Adsorption was found to be thermodynamically feasible and exothermic for single and binary systems but endothermic for ternary systems.
Synthesis, Structure Investigation and Dyeing Assessment of Novel Bisazo Disp...IOSR Journals
Novel bisazo-disperse dyes were prepared by the coupling of diazotized solutions of various aromatic diamines with 2,4-dihydroxybenzophenone. The resultant bisazo disperse dyes were characterized by elemental analysis, IR and 1H NMR spectral studies. The UV Visible absorption spectral data were investigated in dimethylformamide. and are discussed in terms of structural property relationship. Their dyeing assessment of bisazo disperse dyes has been made on polyester fabrics. The results show that a better hue was obtained on polyester fabrics and have mild to moderate fastness properties.
Removal of Methylene Blue from Aqueous Solution by Adsorption using Low Cost ...ijsrd.com
The present study deals with removal of methylene blue (basic dye)from aqueous solution using a low cost activated carbon prepared from Delonix regia(gulmohar seed pods).Batch adsorption studies were conducted by varying the contact time adsorbent dosage and pH
This document summarizes a graduation thesis on removing ibuprofen from aqueous solutions using adsorption on lentil and rice husk. It discusses the materials and methods used, including the adsorbents (rice husk and lentil husk), adsorbate (ibuprofen), and experimental procedures. The results and discussion section analyzes the effect of pH, adsorbent concentration, and temperature on ibuprofen adsorption. Optimum removal conditions were found to be pH 3, 20g/L rice husk concentration, and room temperature. Adsorption data fitted the Langmuir isotherm model well.
This document summarizes research on the catalytic wet peroxide oxidation of olive oil mill wastewater over zeolite-based catalysts. The researchers prepared a Cu/13X catalyst by ion exchange and tested its activity and stability for reducing phenolic compounds in wastewater. Characterization showed the ion exchange did not affect zeolite structure but a post-treatment calcination at 1273K decreased surface area and increased copper oxide particles. Testing showed the catalyst reduced total phenols in wastewater by over 80% and TOC by 20% with low copper leaching. The research aims to develop an effective treatment to reduce toxicity of olive oil wastewater before conventional biological processing.
This document investigates the ability of hexadecyltrimethylammonium cation pillared bentonite (HDTMA-bentonite) to remove thorium from aqueous solutions. The HDTMA-bentonite was characterized using various techniques and its ability to adsorb thorium was tested under different conditions such as solution pH, contact time, initial thorium concentration, and temperature. The results showed that HDTMA-bentonite has a higher adsorption capacity for thorium than unmodified bentonite. The maximum adsorption occurred at pH 3.5 and 60 minutes contact time. Adsorption kinetics followed the pseudo-second-order model and the process was exothermic and spontaneous. H
Lignin isolation from coconut coir, characterization and depolymerization usi...Richa Chaudhary
Lignin isolation from coconut coir using Klason, organosolv, and soda methods and the depolymerization of isolated lignin to value-added chemicals using a solid base catalyst.
Eco friendly dyeing of viscose fabric with reactive dyesiaemedu
This document summarizes a study on eco-friendly dyeing of viscose fabric with reactive dyes. The study synthesized and characterized polyacrylic acid and a cross-linking agent called glycerol-1,3-dichlorohydrin. Viscose fabric was pretreated with polyacrylic acid and the cross-linking agent and then dyed with various reactive dyes without using salt, alkali or other chemicals in the dyebath. The dyed fabrics were evaluated for color strength and fastness properties and compared to conventionally dyed samples. The goal was to develop a non-polluting reactive dyeing process for cellulosic fabrics like viscose.
Eco friendly dyeing of viscose fabric with reactive dyesiaemedu
This document summarizes research on eco-friendly dyeing of viscose fabric with reactive dyes using polyacrylic acid and cross-linking agents. The researcher synthesized and characterized polyacrylic acid and the cross-linking agent glycerol-1,3-dichlorohydrin. Viscose fabric was treated with optimized concentrations of polyacrylic acid and a cross-linking agent, then dyed with various reactive dyes without salt or alkali at neutral pH. Different dyeing processes were tested and dye uptake was evaluated. The treated fabric showed improved dyeability with reactive dyes at neutral pH without conventional chemicals.
This document summarizes research on the synthesis of a Schiff base compound from vanillin and p-toluidine using a solvent-free mechanochemical method. Key points:
- The reaction produced a pale yellow solid Schiff base compound in high yield (over 95%) with good purity.
- Characterization using UV-Vis, FTIR and GC-MS confirmed the structure of the target compound.
- The solvent-free mechanochemical synthesis was an effective green method that avoided use of volatile solvents and acid catalysts.
Graphene is a one-atom thick sheet of carbon atoms arranged in a honeycomb lattice. It is the strongest material known and has excellent electrical and thermal conductivity. There are two main methods to produce graphene - mechanical exfoliation and chemical vapor deposition. Graphene has many potential applications, including solar panels, batteries, composites, and electronics. While graphene shows promise, challenges remain in producing large quantities of high quality graphene material for integration into commercial applications.
CARBON NANOTUBES-TREATMENT AND FUNCTIONALIZATIONArjun K Gopi
Carbon nanotubes are fullerene-related structures consisting of graphene cylinders closed at either end with pentagonal rings. There are two main types: single-walled nanotubes (SWNTs), which have diameters around 1 nanometer, and multi-walled nanotubes (MWNTs) made of multiple concentric graphene cylinders. Functionalization of carbon nanotubes is important for applications and can occur through non-covalent interactions like wrapping of surfactants or polymers or through covalent bonding by attaching molecules to existing defects or through reactions to functionalize the graphene sidewalls. The document discusses different methods of non-covalent and covalent functionalization of carbon nanotubes.
h-BN has potential as an ideal dielectric material for 2D electronics. As a gate dielectric, h-BN provides improved carrier mobility and resists dielectric breakdown at high electric fields. When used as a substrate, h-BN enhances graphene conductivity and mobility while improving reliability by facilitating better heat dissipation than conventional dielectrics like SiO2. Overall, h-BN shows promise as an ubiquitous dielectric that can fulfill critical roles in 2D heterostructures and devices.
#scichallenge2017 Photocatalytic Degradation of Synthetic Wastewaters Contain...Seher Elif Mekik
#scichallenge2017
In our project, it was aimed to purify wastewaters containing methylene blue component and harmful to environment from methylene blue. For this purpose, synthetic methylene blue waste water was formed and chemically treated by photocatalysis.
Degradation of Ethanolamine by Fluidized-bed Fenton ProcessOswar Mungkasa
prepared by J. Anotai*,**, C.M. Chen***, L. Bellotindos**** and M.C. Lu*** Department of Environmental Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand (E-mail: jin.ano@kmutt.ac.th) ** National Center of Excellence for Environmental and Hazardous Waste Management (NCE-EHWM), Chulalongkorn University, Bangkok, Thailand *** Department of Environmental Resources Management, Chia-Nan Univer for Urban Environments in Asia, 25-28 May 2011, Manila, Philippines. organized by International Water Association (IWA).
Dye removal from waste water by using low cost adsorbent: A review Satish Movaliya
This document provides a literature review on using low-cost adsorbents for dye removal from wastewater. It discusses various adsorbents that have been used such as sugarcane bagasse, sawdust, coconut coir pith, and clay. The review examines factors that affect dye adsorption such as pH, adsorbent dosage, and contact time. It also discusses commonly used isotherm models like Langmuir and Freundlich to analyze adsorption equilibrium. The review concludes that more research is needed to develop efficient, selective, and eco-friendly low-cost adsorbents as well as continuous processes and desorption methods.
This document summarizes a study on the adsorption of a Schiff base ligand onto granulated initiated calcined Iraqi montmorillonite clay via columnar method. The ligand was synthesized from the condensation reaction of hydrazine hydrate and 4-hydroxy-3-methoxybenzaldehyde. Adsorption experiments were conducted in columns packed with the clay at different pH levels, ligand concentrations, and contact times. The equilibrium adsorption data fit the Langmuir, Freundlich and Temkin isotherm models. The maximum adsorption capacity was found to be 5.7347 mg ligand per 1g clay. The highest removal rate of 75.7% occurred at pH 7. Kinetic data followed pseudo
This document presents a study on enhancing the efficiency of adsorption processes using activated carbon through microwave activation and a high gravimetric rotating packed bed technology. The study aims to optimize preparation conditions for activated carbon from agricultural waste using microwaves. Response surface methodology and Taguchi experiments were used to determine optimal preparation parameters. The prepared activated carbon was then used in a rotating packed bed reactor to minimize contact time for dye and heavy metal removal. Kinetic and isotherm studies showed the adsorption followed pseudo-second order kinetics and best fit the Langmuir isotherm model. Optimization of process parameters for the rotating packed bed reactor enhanced removal efficiency.
This document describes an experiment on separating a tertiary butyl alcohol-water azeotropic mixture using lithium bromide salt. Tertiary butyl alcohol and water form an azeotrope that is difficult to separate. The experiment investigated adding varying amounts of lithium bromide salt to the azeotropic mixture during extractive distillation. It was found that adding 35g of lithium bromide allowed 88.98% of the tertiary butyl alcohol to be separated, breaking up the azeotrope more effectively than using a solvent alone. Lithium bromide increased the boiling point of the mixture and changed the relative volatility between tertiary butyl alcohol and water, facilitating their separation
Removal of basic dye from aqueous solution by adsorption on melon husk inAlexander Decker
This document discusses a study that investigated the adsorption behavior of the cationic dye methylene blue in single, binary, and ternary solutions using melon husk as an adsorbent. Experiments showed that adsorption equilibrium was reached within 120 minutes for all systems. Kinetic data fit best to a pseudo-second order model. Isotherm data fit best to the Langmuir model for single systems and Freundlich model for binary and ternary systems. Adsorption was found to be thermodynamically feasible and exothermic for single and binary systems but endothermic for ternary systems.
Synthesis, Structure Investigation and Dyeing Assessment of Novel Bisazo Disp...IOSR Journals
Novel bisazo-disperse dyes were prepared by the coupling of diazotized solutions of various aromatic diamines with 2,4-dihydroxybenzophenone. The resultant bisazo disperse dyes were characterized by elemental analysis, IR and 1H NMR spectral studies. The UV Visible absorption spectral data were investigated in dimethylformamide. and are discussed in terms of structural property relationship. Their dyeing assessment of bisazo disperse dyes has been made on polyester fabrics. The results show that a better hue was obtained on polyester fabrics and have mild to moderate fastness properties.
Removal of Methylene Blue from Aqueous Solution by Adsorption using Low Cost ...ijsrd.com
The present study deals with removal of methylene blue (basic dye)from aqueous solution using a low cost activated carbon prepared from Delonix regia(gulmohar seed pods).Batch adsorption studies were conducted by varying the contact time adsorbent dosage and pH
This document summarizes a graduation thesis on removing ibuprofen from aqueous solutions using adsorption on lentil and rice husk. It discusses the materials and methods used, including the adsorbents (rice husk and lentil husk), adsorbate (ibuprofen), and experimental procedures. The results and discussion section analyzes the effect of pH, adsorbent concentration, and temperature on ibuprofen adsorption. Optimum removal conditions were found to be pH 3, 20g/L rice husk concentration, and room temperature. Adsorption data fitted the Langmuir isotherm model well.
This document summarizes research on the catalytic wet peroxide oxidation of olive oil mill wastewater over zeolite-based catalysts. The researchers prepared a Cu/13X catalyst by ion exchange and tested its activity and stability for reducing phenolic compounds in wastewater. Characterization showed the ion exchange did not affect zeolite structure but a post-treatment calcination at 1273K decreased surface area and increased copper oxide particles. Testing showed the catalyst reduced total phenols in wastewater by over 80% and TOC by 20% with low copper leaching. The research aims to develop an effective treatment to reduce toxicity of olive oil wastewater before conventional biological processing.
This document investigates the ability of hexadecyltrimethylammonium cation pillared bentonite (HDTMA-bentonite) to remove thorium from aqueous solutions. The HDTMA-bentonite was characterized using various techniques and its ability to adsorb thorium was tested under different conditions such as solution pH, contact time, initial thorium concentration, and temperature. The results showed that HDTMA-bentonite has a higher adsorption capacity for thorium than unmodified bentonite. The maximum adsorption occurred at pH 3.5 and 60 minutes contact time. Adsorption kinetics followed the pseudo-second-order model and the process was exothermic and spontaneous. H
Lignin isolation from coconut coir, characterization and depolymerization usi...Richa Chaudhary
Lignin isolation from coconut coir using Klason, organosolv, and soda methods and the depolymerization of isolated lignin to value-added chemicals using a solid base catalyst.
Eco friendly dyeing of viscose fabric with reactive dyesiaemedu
This document summarizes a study on eco-friendly dyeing of viscose fabric with reactive dyes. The study synthesized and characterized polyacrylic acid and a cross-linking agent called glycerol-1,3-dichlorohydrin. Viscose fabric was pretreated with polyacrylic acid and the cross-linking agent and then dyed with various reactive dyes without using salt, alkali or other chemicals in the dyebath. The dyed fabrics were evaluated for color strength and fastness properties and compared to conventionally dyed samples. The goal was to develop a non-polluting reactive dyeing process for cellulosic fabrics like viscose.
Eco friendly dyeing of viscose fabric with reactive dyesiaemedu
This document summarizes research on eco-friendly dyeing of viscose fabric with reactive dyes using polyacrylic acid and cross-linking agents. The researcher synthesized and characterized polyacrylic acid and the cross-linking agent glycerol-1,3-dichlorohydrin. Viscose fabric was treated with optimized concentrations of polyacrylic acid and a cross-linking agent, then dyed with various reactive dyes without salt or alkali at neutral pH. Different dyeing processes were tested and dye uptake was evaluated. The treated fabric showed improved dyeability with reactive dyes at neutral pH without conventional chemicals.
This document summarizes research on the synthesis of a Schiff base compound from vanillin and p-toluidine using a solvent-free mechanochemical method. Key points:
- The reaction produced a pale yellow solid Schiff base compound in high yield (over 95%) with good purity.
- Characterization using UV-Vis, FTIR and GC-MS confirmed the structure of the target compound.
- The solvent-free mechanochemical synthesis was an effective green method that avoided use of volatile solvents and acid catalysts.
Graphene is a one-atom thick sheet of carbon atoms arranged in a honeycomb lattice. It is the strongest material known and has excellent electrical and thermal conductivity. There are two main methods to produce graphene - mechanical exfoliation and chemical vapor deposition. Graphene has many potential applications, including solar panels, batteries, composites, and electronics. While graphene shows promise, challenges remain in producing large quantities of high quality graphene material for integration into commercial applications.
CARBON NANOTUBES-TREATMENT AND FUNCTIONALIZATIONArjun K Gopi
Carbon nanotubes are fullerene-related structures consisting of graphene cylinders closed at either end with pentagonal rings. There are two main types: single-walled nanotubes (SWNTs), which have diameters around 1 nanometer, and multi-walled nanotubes (MWNTs) made of multiple concentric graphene cylinders. Functionalization of carbon nanotubes is important for applications and can occur through non-covalent interactions like wrapping of surfactants or polymers or through covalent bonding by attaching molecules to existing defects or through reactions to functionalize the graphene sidewalls. The document discusses different methods of non-covalent and covalent functionalization of carbon nanotubes.
h-BN has potential as an ideal dielectric material for 2D electronics. As a gate dielectric, h-BN provides improved carrier mobility and resists dielectric breakdown at high electric fields. When used as a substrate, h-BN enhances graphene conductivity and mobility while improving reliability by facilitating better heat dissipation than conventional dielectrics like SiO2. Overall, h-BN shows promise as an ubiquitous dielectric that can fulfill critical roles in 2D heterostructures and devices.
Graphene is a single layer of graphite, which is a pure crystalline form of carbon. It was first isolated in 2004 by researchers at the University of Manchester. Graphene has exceptional properties such as being the thinnest, strongest, most conductive and flexible material known. It is light, transparent and an excellent conductor of heat and electricity. These properties give graphene potential applications in areas like batteries, touchscreens, composites and biotechnology. Further research aims to utilize graphene's tunable bandgap for applications like transistors and integrated circuits.
Graphene is a single layer of carbon atoms arranged in a hexagonal lattice. It is the thinnest material known and has remarkable properties such as strength, conductivity, and transparency. Graphene was first isolated in 2004 and has potential applications in electronics, solar cells, touchscreens, and more. It could replace silicon in transistors and integrated circuits due to its high electron mobility and thermal and electrical conductivity. Graphene is seen as an important material that will change electronics and enable new technologies in the future.
Graphene materials for opto and electronic applications 2014 Report by Yole D...Yole Developpement
What is the industrial potential behind the graphene academic R&D hype?
$141M GRAPHENE MATERIALS MARKET IN 2024 WILL BE DRIVEN MAINLY BY TRANSPARENT CONDUCTIVE ELECTRODES AND ENERGY STORAGE APPLICATIONS
Graphene is a two-dimensional (2D) material with exceptional properties, such as ultrahigh electrical and thermal conductivities, wide-range optical transmittance and excellent mechanical strength and flexibility. These properties make it a promising material for emerging and existing applications in printed & flexible circuitry, ultrafast transistors, touch screens, advanced batteries and supercapacitors, ultrafast lasers, photodetectors and many other non-electronic applications.
Although graphene technology is still in its infancy, remarkable progress has been made in the last few years developing graphene production methods. Numerous opto and electronic devices based on graphene have been demonstrated on lab-scale models. However, the numerous challenges of graphene technology should not be underestimated. The lack of bandgap in graphene is its key fundamental challenge. Other technology challenges are related to the development of industrial methods to produce graphene with high and consistent quality at acceptable costs.
Although today there is no graphene-based electronic application in mass production, several companies already offer commercially graphene materials. The graphene material market value in 2013 was about $11 million, represented principally by the demand for the R&D and prototyping. Two scenarios for the future market growth are presented in the report. According to the base scenario, the global annual market value for graphene materials in opto and electronic applications will reach $141 million in 2024, featuring a 2013-2019 CAGR of 18.5%. Accelerated market growth is expected after 2019, with a 2019-2024 CAGR of 35.7%. In 2024, the graphene material market will be represented mainly by the demand for transparent conductive electrodes and advanced batteries and supercapacitors.
HOW CAN GRAPHENE TECHNOLOGY CHALLENGES AND APPLICATION POTENTIAL BE TRANSFORMED INTO BUSINESS OPPORTUNITIES?
In order to reach the best possible performance on lab-scale devices, high quality materials are required. Material suppliers able to consistently deliver high-quality materials have a competitive advantage on the graphene market.
The booming interest in graphene technologies has led to a high demand on graphene equipment. As shown in the report, CVD equipment makers today mainly focus on the R&D equipment used to produce high-quality graphene.
More information on that report at http://www.i-micronews.com/reports/Graphene-materials-opto-electronic-applications/3/416/
This document provides an overview of graphene including:
1. Graphene is a one-atom thick sheet of carbon atoms arranged in a hexagonal lattice. It is the thinnest material known and has remarkable mechanical, electrical, and thermal properties.
2. Graphene has high strength, conductivity, transparency, and flexibility. It is almost completely transparent yet very dense.
3. Potential applications of graphene include use in integrated circuits, transistors, transparent conductive electrodes, solar cells, sensors, and composites. However, challenges remain around cost reduction, large-scale growth, and applications in airplanes and energy storage.
Graphene is a two-dimensional material composed of carbon atoms arranged in a hexagonal lattice. It has unique electrical, mechanical, and optical properties. In 2004, Geim and Novoselov developed the "scotch tape" method to isolate single-atom thick graphene sheets from graphite. This discovery led to the 2010 Nobel Prize in Physics. Graphene is synthesized through exfoliation of graphite or epitaxial growth on metal substrates. Potential future applications of graphene include use in biological engineering, optical electronics like touchscreens, ultrafiltration, photovoltaics, composite materials, and supercapacitors.
Nitrogen-doped graphene-supported copper complex: a novel photocatalyst for C...Pawan Kumar
A copper(II) complex grafted to nitrogen-doped graphene (GrN700–CuC) was synthesized and then
demonstrated as an efficient photocatalyst for CO2 reduction into methanol under visible light irradiation
using a DMF/water mixture. The chemical and microstructural features of GrN700–CuC nanosheets were
studied by FTIR, XPS, XRD and HRTEM analyses. Owing to its truly heterogeneous nature, GrN700–CuC
could be easily recovered after the photocatalytic reaction and showed efficient recyclability for
subsequent runs.
This document summarizes a method for synthesizing water-soluble graphene through a three step process: 1) prereduction of graphene oxide using sodium borohydrate to remove most oxygen functionality, 2) controlled sulfonation using aryl diazonium salt to introduce sulfonic acid groups for solubility while minimally impacting graphene properties, and 3) postreduction using hydrazine to remove remaining oxygen functionality. Characterization with 13C NMR and FTIR indicates restoration of the graphene sp2 carbon network. The introduced sulfonic acid groups allow individually dispersed graphene sheets in water, maintaining stability through electrostatic repulsion.
Nitrogen-doped graphene-supported copper complex: a novel photocatalyst for C...Pawan Kumar
A copper(II) complex grafted to nitrogen-doped graphene (GrN700–CuC) was synthesized and then
demonstrated as an efficient photocatalyst for CO2 reduction into methanol under visible light irradiation
using a DMF/water mixture. The chemical and microstructural features of GrN700–CuC nanosheets were
studied by FTIR, XPS, XRD and HRTEM analyses. Owing to its truly heterogeneous nature, GrN700–CuC
could be easily recovered after the photocatalytic reaction and showed efficient recyclability for
subsequent runs.
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Graphene is a one atom thick layer of carbon atoms arranged in a honeycomb lattice. It has excellent mechanical and electrical properties. The document discusses the use of graphene and chemically modified graphene as catalysts. Graphene can be modified through doping with nitrogen or boron to introduce a band gap and alter its conductivity. These doped graphene materials show potential as metal-free catalysts for organic reactions, fuel cells through oxygen reduction, and nitrogen fixation through electrochemical nitrogen reduction. Doped graphene catalysts offer advantages over traditional metal catalysts including lower cost and stability.
Graphene oxide grafted with iridium complex as a superior heterogeneous catal...Pawan Kumar
A novel graphene oxide (GO)-immobilized heteroleptic iridium complex was synthesized and demonstrated
as a first heterogenized homogeneous catalyst for the production of dimethylformamide (DMF)
from carbon dioxide, hydrogen, and dimethylamine. The synthesized hybrid catalyst showed comparable
activity as homogeneous heteroleptic iridium complex with additional benefits such as facile recovery
and recycling of the catalyst. After completion of the reaction, the heterogeneous catalyst was easily
recovered by filtration, and reused for subsequent recycling processes without any significant change in
the catalytic efficiency
Graphene oxide grafted with iridium complex as a superior heterogeneous catal...Pawan Kumar
A novel graphene oxide (GO)-immobilized heteroleptic iridium complex was synthesized and demonstrated
as a first heterogenized homogeneous catalyst for the production of dimethylformamide (DMF)
from carbon dioxide, hydrogen, and dimethylamine. The synthesized hybrid catalyst showed comparable
activity as homogeneous heteroleptic iridium complex with additional benefits such as facile recovery
and recycling of the catalyst. After completion of the reaction, the heterogeneous catalyst was easily
recovered by filtration, and reused for subsequent recycling processes without any significant change in
the catalytic efficiency.
Graphene oxide grafted with iridium complex as a superior heterogeneous catal...Pawan Kumar
A novel graphene oxide (GO)-immobilized heteroleptic iridium complex was synthesized and demonstrated
as a first heterogenized homogeneous catalyst for the production of dimethylformamide (DMF)
from carbon dioxide, hydrogen, and dimethylamine. The synthesized hybrid catalyst showed comparable
activity as homogeneous heteroleptic iridium complex with additional benefits such as facile recovery
and recycling of the catalyst. After completion of the reaction, the heterogeneous catalyst was easily
recovered by filtration, and reused for subsequent recycling processes without any significant change in
the catalytic efficiency.
The document summarizes a study on the oriented interfacial microstructures that form in single fiber polymer composites containing graphene fibers. Graphene oxide fibers were produced via wet spinning and then chemically reduced to graphene fibers. These graphene fibers were embedded in isotactic polypropylene (iPP) matrix and subjected to isothermal melt crystallization. Polarized optical microscopy and scanning electron microscopy showed that the iPP crystallizes perpendicularly to the fiber axis, forming a transcrystalline interphase around the graphene fiber. Various factors that influence the transcrystallization process were investigated.
This research article studied the effect of pH on the properties of aqueous colloidal dispersions of graphene oxide (GO) and chemically converted graphene (CCG). GO was prepared using a modified Hummer's method and CCG was prepared by chemical reduction of GO. The particle size, zeta potential, and light absorption of GO and CCG colloids were analyzed as a function of pH achieved by titration with HCl or NaOH. The GO colloid was stable between pH 4-11, while the CCG colloid was stable in the narrower range of pH 7-10. Both colloids exhibited average particle sizes of ~1 micron at low pH and 300-500 nm at higher pH
Water purification using graphene from sugar (1)Akhthar Edavanna
This document discusses using graphene produced from sugar for water purification. It begins with an introduction to water purification and graphene. Graphene is a single layer of carbon atoms that shows higher adsorption capacity than activated carbon. The preparation of a graphene-sugar composite is then described, involving heating sugar to produce graphene and mixing it with activated carbon. This composite is effective at removing contaminants from water like heavy metals and pesticides. It can be reused for multiple purification cycles, making it economically viable. The conclusion states that this provides an inexpensive and environmentally friendly method for water purification using a green process to produce graphene from sugar.
This document summarizes a study that investigated using aluminum dross and iron nanoparticles as catalysts for heterogeneous Fenton oxidation of phenalkamine condensate wastewater. Phenalkamine condensate has high pH, COD and low BOD/COD ratio, making biological treatment ineffective. Aluminum dross is a waste from aluminum smelting that is mostly landfilled. Iron nanoparticles were synthesized using laterite soil and cashew apple extract. The document characterized the catalysts and evaluated their ability to remove COD from phenalkamine condensate at different pH, H2O2, and catalyst concentrations. Optimal conditions achieved 75.83% COD removal using aluminum dross and 88.91% using
Biological and Medical Applications of Graphene NanoparticlesAI Publications
Graphene which is one of the latest additions to nanocarbon family has peculiar band structure, extraordinary thermal and electronic conductance and room temperature quantum Hall effect. It is used in for various applications in diverse fields ranging from catalysis to electronics. In addition to being components in electronic devices, GO have been used in nanocomposite materials, polymer composite materials, energy storage, biomedical applications, catalysis and as a surfactant with some overlaps between these fields Graphene oxide is a unique material that can be viewed as a single monomolecular layer of graphite with various oxygen containing functionalities such as epoxide, carbonyl, carboxyl and hydroxyl groups.
Visible light assisted photocatalytic reduction of CO2 using a graphene oxide...Pawan Kumar
A new heteroleptic ruthenium complex containing 2-thiophenyl benzimidazole ligands was synthesized
using a microwave technique and was immobilized to graphene oxide via covalent attachment. The synthesized
catalyst was used for the photoreduction of carbon dioxide under visible light irradiation without
using a sacrificial agent, which gave 2050 μmol g−1 cat methanol after 24 h of irradiation
Grinding graphene characteristics after physical processjournal ijrtem
ABSTRACT : Graphene features higher thermal conductivity than copper. However, despite its superior property, the research on its applicable technology was limited since the van der Waals’ forces between graphene. As a solution to such problem, research on making graphene distributed evenly in solvent is being actively conducted via physical and chemical method. Because the chemical method is likely to have harmful effect on the environment, we used the environmental-friendly process that does not consume toxic chemicals, and suitable for application. In this study, ball milling process controllable a range of experiment conditions more easily and conveniently than other physical methods was conducted so as to disperse graphene evenly in solvent and improve the thermal conductivity. Therefore, the effect of milling process was confirmed in TEM image and Raman ratio, and the shearing force makes the edge of graphene piece defective. When graphene is evenly dispersed, the wide specific surface area absorbs a great deal of light, improving absorbance. We confirmed the absorbance of pristine graphene was showed below milling graphene and considerable thermal conductivity increase compared to pristine graphene.
Keywords: Ball milling, Graphene, Nano-fluid, Physical process, Thermal conductivity
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
2020 international journal of electrochemical scienceAbdelfattah Amari
The document summarizes a study comparing the electrochemical response of boron-doped graphene nanosheets and un-doped graphene nanosheets modified glassy carbon electrodes toward biomolecules like ascorbic acid, uric acid, and dopamine. Cyclic voltammetry shows significant differences in the peak potentials of the biomolecules on the different surfaces. Testing with uric acid over 20 cycles found that boron-doped graphene nanosheets modified glassy carbon has better resistance to fouling by oxidation products compared to un-doped graphene nanosheets modified glassy carbon. Characterization confirms the presence of boron doping in the graphene nanosheets.
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
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তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
বিসিএস ও ব্যাংক এর লিখিত পরীক্ষা ...+এছাড়া মাধ্যমিক ও উচ্চমাধ্যমিকের স্টুডেন্টদের জন্য অনেক কাজে আসবে ...
How to Make a Field Mandatory in Odoo 17Celine George
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BÀI TẬP BỔ TRỢ TIẾNG ANH 8 CẢ NĂM - GLOBAL SUCCESS - NĂM HỌC 2023-2024 (CÓ FI...
55.noncovalent functionalization of graphene with end functional polymers
1. PAPER www.rsc.org/materials | Journal of Materials Chemistry
Noncovalent functionalization of graphene with end-functional polymers†
Eun-Young Choi,ab Tae Hee Han,a Jihyun Hong,a Ji Eun Kim,a Sun Hwa Lee,a Hyun Wook Kima
and Sang Ouk Kim*a
Received 14th September 2009, Accepted 27th November 2009
First published as an Advance Article on the web 20th January 2010
DOI: 10.1039/b919074k
Stable dispersion of reduced graphene in various organic solvents was achieved via noncovalent
functionalization with amine-terminated polymers. An aqueous dispersion of reduced graphene was
prepared by chemical reduction of graphene oxide in aqueous media and was vacuum filtered to
generate reduced graphene sheets. Good solvents and nonsolvents for the dried reduced graphene were
evaluated using a solubility test. To achieve stable dispersion in the evaluated nonsolvents, amine-
terminated polystyrene was noncovalently functionalized to the graphene, while graphene sheets were
phase transferred via sonication from aqueous phase to the organic nonsolvent phase, including the
amine-terminated polymers. Thorough FTIR and Raman spectroscopy investigation verified that the
protonated amine terminal group of polystyrene underwent noncovalent functionalization to the
carboxylate groups at the graphene surface, providing the high dispersibility in various organic media.
Introduction from negatively charged functional groups remaining at the
reduced graphene surface.
Graphene is an emerging carbon nanomaterial that is potentially Unlike aqueous dispersibility, the organo-dispersibility of
useful in a variety of technological areas, such as electronics,1–3 graphene has been less explored so far. Haddon and co-workers28
sensors,4 electromechanics,5 solar cells,6,7 memory devices,8 demonstrated that covalent functionalization with octadecyl-
hydrogen storage9,10 ultracapacitors,11 and so on. Since the amine yields exfoliated graphene in organic solvents. M€llen and
u
unexpected separation of single-layer graphene sheet from co-workers29 produced chloroform-soluble graphene through
natural graphite through the laborious micromechanical surfactant-supported functionalization. Ruoff and co-workers30
cleavage method,1 various synthesis methods for graphene have prepared an organosoluble polystyrene-graphene composite by
been developed, including epitaxial growth,12 thermal exfoliation means of chemical reduction with N,N-dimethylhydrazine of
of graphite oxide,13 gas phase synthesis,14,15 chemical reduction phenyl isocyanate-treated graphene oxide. Polymer-assisted
from graphene oxide,16–20 and liquid phase exfoliation of organo-dispersion of graphene is particularly advantageous for
graphite.21–23 Nevertheless, the mass production of highly func- preparing graphene-polymer nanocomposites with remarkably
tional, fully exfoliated graphene sheets still remains as a formi- enforced electrical and mechanical properties.30,31
dable challenge. In this work, we exploited organo-dispersed graphene in
Oxidative exfoliation of natural graphite by acid treatment various solvents mediated by noncovalent functionalization with
and subsequent chemical reduction has been evaluated as one of end-functional polymers. First, an aqueous dispersion of reduced
the most efficient methods for low-cost, large-scale production of graphene was prepared by chemically reducing graphene oxide
graphene. Graphene oxide, an oxidized derivative of graphene according to recently reported preparation method.18 The dis-
generated in this approach, is readily dispersable in aqueous persibilitiy of the dried reduced graphene was investigated in
media. This aqueous dispersibility is greatly advantageous a broad spectrum of organic solvents. For the evaluated non-
for processing graphene into films, sheets, composites and so solvents, the stable dispersion of graphene was achieved via
on.16–18,24–27 Ruoff and co-workers16 prepared stable aqueous noncovalent functionalization with amine-terminated, end-func-
dispersion of polymer-coated reduced graphene by reducing tional polymers. The carboxylate functional groups of reduced
graphene oxide sheets using hydrazine in the presence of poly- graphene remaining after chemical reduction acted as function-
(sodium-4-pyrene sulfonate).17 Li et al.18 demonstrated that alization sites for the protonated terminal amine groups of the
a dispersant-free aqueous dispersion of reduced graphene can be end-functional polymer. The noncovalent grafting via ionic
prepared by maintaining a high pH value during chemical interaction was confirmed by attenuated total reflection Fourier
reduction and thus controlling electrostatic stabilization arising transform infrared (ATR-FTIR) and Raman spectroscopy.
a
Department of Materials Science and Engineering, KAIST, Daejeon, Experimetal
305-701, Republic of Korea. E-mail: sangouk.kim@kaist.ac.kr
b
Nuclear Fuel Cycle Group, Korea Atomic Energy Research Institute,
Materials
Daejeon, 305-353, Republic of Korea
Graphite was purchased from GK (product MGR 25 998 K).
† Electronic supplementary information (ESI) available: ATR-FTIR
spectra, UV-Vis spectroscopy and thermogravimetric analysis. See The hydrazine and ammonia for the reduction of graphene
DOI: 10.1039/b919074k oxide were purchased from Junsei. H2SO4 (Merck), KMnO4
This journal is ª The Royal Society of Chemistry 2010 J. Mater. Chem., 2010, 20, 1907–1912 | 1907
2. (Sigma-Aldrich) and H2O2 (Sigma-Aldrich) were used as (Nanoman, Veeco). Raman spectra were recorded from 1800 cmÀ1
received. o-Xylene, acetone, pyridine, 1-methyl-2-pyrrolidone to 100 cmÀ1 on a high resolution dispersive Raman microscope
(NMP), 1,3-dimethyl-2-imidazolidinone, N,N-dimethylforma- (LabRAM HR UV/Vis/NIR, Electrooptics). The dispersions of
mide (DMF), g-butyrolactone, dimethyl sulfoxide (DMSO), grapheme oxide and reduced graphene in aqueous or organic
1-propanol, ethanol (EtOH), methanol (MeOH) and ethylene solvents were analyzed by UV-Vis spectroscopy (Shimadzu UV-
glycol (EG) were purchased from Sigma-Aldrich. Hexane, VIS-NIR scanning spectrophotometer, UV-3101 PC).
benzene, tetrahydrofuran (THF), and dichloromethane were
purchased from Junsei. End-functional polymers including
amine terminated polystyrene (PS–NH2) (Mw ¼ 3,000 g molÀ1), Results and discussion
carboxylic acid terminated polystyrene (PS–COOH) (Mw ¼
Dispersibility of reduced graphene in various organic solvents
3,000 g molÀ1) and hydroxyl terminated poly(methyl methacry-
late) (PMMA-OH) (Mw ¼ 6,000 g molÀ1) were purchased from An aqueous dispersion of reduced graphene was prepared by
Polymer Source, Inc. chemical reduction of graphene oxide in aqueous media without
any dispersing agent. A detailed investigation on the chemical
Preparation of reduced graphene composition and physical properties revealed that the reduced
graphene sheets decorated with chemical functionalities such as
Graphite oxide was prepared by a modified Hummers method.32 hydroxyl groups and carboxylic acid groups were dispersed in
Dialysis of the as-prepared the graphite oxide was carried out to aqueous medium (ESI†). We also observed aqueous dispersion of
completely remove residual salts and acids. The gel-like graphite reduced graphene shows long-term (several months) stability
oxide was freeze-dried, and a fine brown powder was obtained. caused by negatively charged functional groups at the reduced
Aqueous graphene oxide dispersion of 0.1 wt% was prepared by graphene.18 The electrical conductivity is a good indicator of the
mild sonication, yielding a homogeneous brown dispersion. extent to which graphene oxide has been reduced. A graphene
The graphene oxide dispersion was further centrifuged to film was prepared by vacuum filtration and dried at 110 C to
remove unexfoliated graphite oxide (15000 r.p.m., 10 min). evaporate any residual moisture for conductivity measurement.
The concentration of the remaining exfoliate dispersion The average conductivity was measured to be about 1500 S mÀ1.
was $0.030 wt%. A reduced graphene dispersion was prepared It indicates that the conjugated sp2-carbon network is extensively
by chemically reducing the aqueous graphene oxide dispersion. restored in the reduced graphene.
After the graphene oxide dispersion was heated in an oil bath at The dispersibility of reduced graphene in various (16 kinds)
100 C under reflux, 15 ml of ammonia solution (28 wt% in water) organic solvents was tested in the following procedure. Firstly,
and 30 ml of hydrazine (80 wt% in water) were added. After dried graphene paper was prepared by vacuum filtration of the
chemical reduction for 2 h, the obtained mixture was cooled to aqueous reduced graphene dispersion. A few pieces of the gra-
room temperature and excess hydrazine and ammonia were phene paper and an organic solvent were loaded in a vial
removed by dialysis. The resultant reduced graphene dispersion (reduced graphene concentration: 0.4 mg mlÀ1) and sonicated for
was centrifuged to remove flocculated aggregates caused by 5 h. The colloidal stability of the prepared dispersion was eval-
chemical reduction (15000 r.p.m., 10 min) and the concentration uated for 1 month. Fig. 1(a) shows the photographs of reduced
of the finally obtained dispersion was 0.0090 wt%. Graphene graphene dispersions in water and various organic solvents
paper was made by vacuum filtration of the homogeneous 1 month after preparation. Black or grey colors of the vials
dispersion through a polyvinylidene fluoride membrane filter indicate that the dried and reduced graphene can be dispersed in
(47 nm in diameter, 0.45 mm pore size; Millipore). the corresponding solvents. The dispersibility in various solvents
is summarized in Table 1. The reduced graphene formed a stable
Preparation of polymer functionalized reduced graphene dispersion in NMP, 1,3-dimethyl-2-imidazolidinone, g-butyr-
End-functional polymers (0.10–2.0 wt%, 1 ml) were dissolved in olactone, 1-propanol, DMF, EtOH and EG (a limited amount of
organic solvents (dichloromethane, o-xylene, benzene, and precipitate was observed in these solvents). UV-Vis absorption
hexane). The prepared organic polymer solution was added to spectroscopy was employed to confirm the dispersibility of the
the vial containing aqueous reduced graphene dispersion reduced graphene, as shown in Fig. 1(b). The absorption peaks of
(0.0090 wt%, 1 ml). The vial including phase-separated organic the graphene were observed at 270 nm for 1-propanol, EtOH and
and aqueous phases was subjected to 5 h sonication for the EG, confirming the stable dispersibility of reduced graphene in
noncovalent functionalization and phase transfer of graphene. those solvents.33 We note that the spectra for NMP, 1,3-
dimethyl-2-imidazolidinone, g-butyrolactone, and DMF were
plotted in the wavelength above 269 nm, because it was impos-
Characterization of reduced graphene and polymer
sible to compensate their strong absorption below 269 nm.
functionalized reduced graphene
Fig. 2 shows an AFM image of graphene sheets deposited on
ATR-FTIR analyses were performed with Bruker Optiks, a silicon wafer by drop-casting a reduced graphene dispersion
IFS66V SÀ1, where a microscope (HYPERION 3000) was fitted in 1,3-dimethyl-2-imidazolidinone. The measured thickness
with an ATR objective as the internal reflectance element and of $0.91 demonstrates that the reduced graphene is fully exfo-
a mercury-cadmium-telluride (MCT) detector. KBr pellet liated into individual sheets.18
samples were used. The number of scans was 68, and the scanning Hansen solubility parameter34 including dd (dispersion cohe-
resolution was 2 cmÀ1. Atomic force microscopy (AFM) images of sion parameter), dP (polarity cohesion parameter), and dH
reduced graphene were taken in the tapping mode AFM (hydrogen bonding cohesion parameter) provides very useful
1908 | J. Mater. Chem., 2010, 20, 1907–1912 This journal is ª The Royal Society of Chemistry 2010
3. Fig. 1 (a) Photographs of reduced graphene dispersed in water and 16 organic solvents via 5 h sonication. The photographs were taken 1 month after
the preparation of the reduced graphene dispersion. (b) UV-Vis absorption spectra of reduced graphene dispersed in good solvents. The spectra of NMP,
1,3-dimethyl-2-imidazolidinone, DMF, and g-butyrolactone are only shown in the wavelength range from 269 nm to 400 nm due to compensation for
their strong absorption at 269 nm.
Table 1 Dispersibility of reduced graphene in the tested solvents and
their 70 Hansen solubility parameters
Hansen solubility
parameters [MPa1/2]32 Dispersibility
of reduced
No. Solvent dD dP dH dP + dH graphene
1 Hexane 14.9 0.0 0.0 0.0 No
2 Benzene 18.4 0.0 2.0 2.0 No
3 o-Xylene 17.8 1.0 3.1 4.1 No
Fig. 2 (a) An AFM image (1 mm  1 mm ) of isolated reduced graphene 4 Dichloromethane 18.2 6.3 6.1 12.4 No
sheets deposited onto an Si wafer from dispersion in 1,3-dimethyl-2- 5 THF 16.8 5.7 8.0 13.7 No
imidazolidinone, (b) a thickness profile of graphene sheets marked by the 6 Pyridine 19.0 8.8 5.9 14.7 No
7 Acetone 15.5 10.4 7.0 17.4 No
black line in (a), where the height differences are 1.77 nm between the two 8 NMP 18.0 12.3 7.2 19.5 Yes
black arrows, 0.91 nm between the two red arrows and 1.24 nm between 9 1,3-dimethyl-2- 18.0 10.5 9.7 20.2 Yes
the two green arrows, respectively. imidazolidinone
10 g-butyrolactone 19.0 16.6 7.4 24.0 Yes
information to predict dispersibility of graphene in organic 11 1-propanol 16.0 6.8 17.4 24.2 Yes
solvents.33 Ruoff and co-workers demonstrated that reduced 12 DMF 17.4 13.7 11.3 25.0 Yes
13 DMSO 18.4 16.4 10.2 26.6 No
graphene sheets could be well dispersed in several organic 14 EtOH 15.8 8.8 19.4 28.2 Yes
solvents having high dP + dH value.35 As summarized in Table 1, 15 MeOH 15.1 12.3 22.3 34.6 No
the organic solvents tested in this study are listed up with dP + dH 16 EG 17.0 11.0 26.0 37.0 Yes
values. The solvents (NMP, 1,3-dimethyl-2-imidazolidinone, g- 17 Water 15.5 16.0 42.3 58.3 No
butyrolactone, 1-propanol, DMF, EtOH and EG) had relatively
high dP + dH values compared to nonsolvents (hexane, benzene,
o-xylene, dichloromethane, THF, pyridine and acetone) for
reduced graphene. However, as previously commented by Ruoff
Noncovalent functionalization of reduced graphene by
ad co-workers, reduced graphene was not dispersable in DMSO,
end-functional polymers
MeOH and water despite their high dP + dH. We note that among
various nonsolvents for reduced graphene, the small pieces of Reduced graphene could be dispersed in nonsolvents through
reduced graphene paper were not even split into smaller pieces in noncovalent grafting with an end-functional polymer, PS–NH2.
hexane, benzene, dichloromethane or water after 5 h sonication, Among the various nonsolvents for reduced graphene, hexane,
while they were split into small pieces and swollen in o-xylene, benzene, o-xylene and dichloromethane, which are immiscible
THF, pyridine, acetone, DMSO and MeOH. This indicates that with the aqueous phase, were used for the noncovalent func-
hexane, benzene, dichloromethane and water are highly incom- tionalization. Fig. 3(a) shows the photograph taken before
patible to reduced graphene. sonication. In each vial, the dark phase corresponds to the
This journal is ª The Royal Society of Chemistry 2010 J. Mater. Chem., 2010, 20, 1907–1912 | 1909
4. of pure PS–NH2 at 1600 cmÀ1 became significantly broadened
after functionalization to graphene. This confirms that ionic
interaction occurred between the protonated terminal amine
groups of PS–NH2 and the carboxylate groups on the graphene
sheet.36 Fig. 5 exhibits dispersive Raman spectra of PS–NH2
functionalized reduced graphene, reduced graphene, graphene
oxide and graphite. The G band of graphene oxide is broadened
and shifted from 1567 cmÀ1 to 1596 cmÀ1, and the D band
becomes significantly stronger than graphite.17 The Raman
spectrum of reduced graphene shows higher D/G intensity ratio
(1.05) than graphene oxide (0.92) implying the decreased size of
the sp2 domains upon chemical reduction of the graphene
oxide.37 The G band of reduced graphene observed at 1589 cmÀ1
markedly shifted to 1596 cmÀ1 after PS–NH2 functionalization,
Fig. 3 Phase transfer of reduced graphene (0.009 wt%) from the aqueous indicating a better exfoliation of graphene layers.38–41 The
phase to the organic phase via PS–NH2 functionalization. (a) Before carboxylate groups of graphitic materials induced by acid-
sonication, dark phases were aqueous dispersions of reduced graphene, treatment have been used to provide a functionalization sites for
and transparent phases were PS–NH2 (1.3 wt%) dissolved organic amine-containing molecules.42 Similar noncovalent ionic func-
solvents. (b) After 5 h sonication, phase transfer occurred, except in tionalization of carbon nanotubes was used in our previous
hexane. (c) A schematic illustration of phase transfer via noncovalent work.41,43–45 In the present work, we demonstrate that the
functionalization. carboxylate groups remaining at reduced graphene after the
hydrazine reduction of graphene oxide provide sufficient func-
aqueous dispersion of reduced graphene and the transparent tionalization sites for PS–NH2. Furthermore, a high dis-
phase corresponds to the PS–NH2 (1.3 wt%) dissolved non- persibility in a broad spectrum of organic solvents is anticipated
solvents. The aqueous phases with reduced graphene were in our approach, owing to the large size and chemical diversity of
located at the bottom and the organic phases with PS–NH2 the polymeric dispersant.43
(transparent phases) were located on the top side for o-xylene Noncovalent functionalization of reduced graphene in benzene
(density: 0.879 g mlÀ1), benzene (density: 0.874 g mlÀ1) and was tested in the presence of various polymers including PS,
hexane (density: 0.659 g mlÀ1), due to their low density. On the PMMA–OH, PS–COOH and PS–NH2, as shown in Fig. 6. The
other hand, aqueous phase was located on the top side and noncovalent functionalization occurred only with PS–NH2. Other
dichloromethane with PS–NH2 was at the bottom due to the high polymers simply caused the dilution of dark water phases without
density of dichloromethane (density: 1.325 g mlÀ1). After 5 h phase transfer. The dilution occurred as reduced graphene sheets
sonication, the organic phases except hexane became dark, moved to the water–benzene interface due to the attractive
indicating that the reduced graphene sheets were phase trans- interactions between reduced graphene in water phase and poly-
ferred to the organic phases (Fig. 3(b)). A schematic description mers in benzene phase. However, complete phase transfer did not
of the phase transfer is presented in Fig. 3(c). occur in the absence of amine terminated polymers.
The reduced graphene was transferred from aqueous to The phase transfer of reduced graphene to the benzene phases
organic phase due to the noncovalent (ionic) interaction between with various concentrations of PS–NH2 is demonstrated in
the protonated terminal amine groups (NH3+) of PS–NH2 and Fig. 7. After 5 h sonication, reduced graphene was well-dispersed
carboxylate groups (COOÀ) of reduced graphene. As shown in in benzene phase containing 0.4 wt% or 0.7 wt% of PS–NH2,
the ATR-FTIR spectra of Fig. 4, the peak for the N–H bending while it remained at the water–benzene interface in other vials
Fig. 4 ATR-FTIR spectra of pure PS–NH2 and PS–NH2 functionalized Fig. 5 Dispersive Raman spectra of PS–NH2 functionalized reduced
reduced graphene. graphene, reduced graphene, graphene oxide and graphite.
1910 | J. Mater. Chem., 2010, 20, 1907–1912 This journal is ª The Royal Society of Chemistry 2010
5. graphene processing, which may broaden the application area of
highly functional two-dimensional carbon materials.
Acknowledgements
This work was supported by the National Research Laboratory
(NRL) Program (R0A-2008-000-20057-0), and the World Class
University (WCU) program (R32-2008- 000-10051-0) funded by
Fig. 6 Photographs for phase transfer of reduced graphene (0.009 wt%) the Korean government (MEST).
in the presence of various polymers: (a) before and (b) after 5 h sonica-
tion. Benzene phases include PS, PMMA–OH, PS–COOH and PS–NH2
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