This document examines the use of complexing agents like EDTA, NTA, IDA, and citric acid to selectively separate Co2+ and Ni2+ ions using cation exchange resins. The key findings are:
1) The presence of complexing agents can significantly enhance the selectivity of Co2+ over Ni2+ by complexing the Ni2+ ions and preventing their exchange onto the resin.
2) The selectivity is strongly dependent on solution pH and the concentration of complexing agent. High selectivity can be achieved at an appropriate pH range and complexing agent concentration.
3) Stronger complexing agents like EDTA and NTA can achieve effective separation at lower pH ranges, while weaker
A new Schiff base 4-chlorophenyl)methanimine
(6R,7R)-3-methyl-8-oxo-7-(2-phenylpropanamido)-5-thia-1-
azabicyclo[4.2.0]oct-2-ene-2-carboxylate= (HL)= C23H20
ClN3O4S) has been synthesized from β-lactam antibiotic
(cephalexin mono hydrate(CephH)=(C16H19N3O5S.H2O) and 4-
chlorobenzaldehyde . Figure(1) Metal mixed ligand complexes
of the Schiff base were prepared from chloride salt of
Fe(II),Co(II),Ni(II),Cu(II),Zn(II) and Cd (II), in 50% (v/v)
ethanol –water medium (SacH ) .in aqueous ethanol(1:1)
containing and Saccharin(C7H5NO3S) = sodium hydroxide.
Several physical tools in particular; IR, CHN, 1H NMR, 13C
NMR for ligand and melting point molar conductance, magnetic
moment. and determination the percentage of the metal in the
complexes by flame(AAS). The ligands and there metal
complexes were screened for their antimicrobial activity against
four bacteria (gram + ve) and (gram -ve) {Escherichia coli,
Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus}.
The proposed structure of the complexes using program, Chem
office 3D(2006). The general formula have been given for the
prepared mixed ligand complexes Na2[M(Sac)3(L)], M(II) = Fe
(II), Co(II) , Ni(II), Cu (II), Zn(II) , and Cd(II).
HL= C29H24 ClN3O4S, L= C29H23 ClN3O4S -.
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
Visible light assisted hydrogen generation from complete decomposition of hyd...Pawan Kumar
Hydrogen is considered to be an ideal energy carrier, which produces only water when combined with
oxygen and thus has no detrimental effect on the environment. While the catalytic decomposition of
hydrous hydrazine for the production of hydrogen is well explored, little is known about its photocatalytic
decomposition. The present paper describes a highly efficient photochemical methodology for the production
of hydrogen through the decomposition of aqueous hydrazine using titanium dioxide nanoparticles
modified with a Rh(I) coordinated catechol phosphane ligand (TiO2–Rh) as a photocatalyst under visible
light irradiation. After 12 h of visible light irradiation, the hydrogen yield was 413 μmol g−1 cat with a hydrogen
evolution rate of 34.4 μmol g−1 cat h−1. Unmodified TiO2 nanoparticles offered a hydrogen yield of
83 μmol g−1 cat and a hydrogen evolution rate of only 6.9 μmol g−1 cat h−1. The developed photocatalyst
was robust under the experimental conditions and could be efficiently reused for five subsequent runs
without any significant change in its activity. The higher stability of the photocatalyst is attributed to the
covalent attachment of the Rh complex, whereas the higher activity is believed to be due to the synergistic
mechanism that resulted in better electron transfer from the Rh complex to the conduction band of TiO2.
A new Schiff base 4-chlorophenyl)methanimine
(6R,7R)-3-methyl-8-oxo-7-(2-phenylpropanamido)-5-thia-1-
azabicyclo[4.2.0]oct-2-ene-2-carboxylate= (HL)= C23H20
ClN3O4S) has been synthesized from β-lactam antibiotic
(cephalexin mono hydrate(CephH)=(C16H19N3O5S.H2O) and 4-
chlorobenzaldehyde . Figure(1) Metal mixed ligand complexes
of the Schiff base were prepared from chloride salt of
Fe(II),Co(II),Ni(II),Cu(II),Zn(II) and Cd (II), in 50% (v/v)
ethanol –water medium (SacH ) .in aqueous ethanol(1:1)
containing and Saccharin(C7H5NO3S) = sodium hydroxide.
Several physical tools in particular; IR, CHN, 1H NMR, 13C
NMR for ligand and melting point molar conductance, magnetic
moment. and determination the percentage of the metal in the
complexes by flame(AAS). The ligands and there metal
complexes were screened for their antimicrobial activity against
four bacteria (gram + ve) and (gram -ve) {Escherichia coli,
Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus}.
The proposed structure of the complexes using program, Chem
office 3D(2006). The general formula have been given for the
prepared mixed ligand complexes Na2[M(Sac)3(L)], M(II) = Fe
(II), Co(II) , Ni(II), Cu (II), Zn(II) , and Cd(II).
HL= C29H24 ClN3O4S, L= C29H23 ClN3O4S -.
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
Visible light assisted hydrogen generation from complete decomposition of hyd...Pawan Kumar
Hydrogen is considered to be an ideal energy carrier, which produces only water when combined with
oxygen and thus has no detrimental effect on the environment. While the catalytic decomposition of
hydrous hydrazine for the production of hydrogen is well explored, little is known about its photocatalytic
decomposition. The present paper describes a highly efficient photochemical methodology for the production
of hydrogen through the decomposition of aqueous hydrazine using titanium dioxide nanoparticles
modified with a Rh(I) coordinated catechol phosphane ligand (TiO2–Rh) as a photocatalyst under visible
light irradiation. After 12 h of visible light irradiation, the hydrogen yield was 413 μmol g−1 cat with a hydrogen
evolution rate of 34.4 μmol g−1 cat h−1. Unmodified TiO2 nanoparticles offered a hydrogen yield of
83 μmol g−1 cat and a hydrogen evolution rate of only 6.9 μmol g−1 cat h−1. The developed photocatalyst
was robust under the experimental conditions and could be efficiently reused for five subsequent runs
without any significant change in its activity. The higher stability of the photocatalyst is attributed to the
covalent attachment of the Rh complex, whereas the higher activity is believed to be due to the synergistic
mechanism that resulted in better electron transfer from the Rh complex to the conduction band of TiO2.
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
Equilibrium and Kinetics Adsorption of Cadmium and Lead Ions from Aqueous Sol...theijes
Sourcing cheap adsorbents for the treatment of waste water is imperative for local environments. The adsorption of cadmium (Cd) and lead (Pb) from aqueous solution onto bamboo activated carbon prepared by chemical activation with ZnCl2 was investigated. The unwashed chemical activated bamboo carbon (UCABC) achieved up to 87.81% and 96.45% removal of Cd and Pb at pH-5 and 11, respectively. Removal equilibrium was attained within 1hr and 2.5hrs for Cd and Pb, respectively. The Cd and Pb adsorption increased with adsorbent dosage decrease while removal rate (%) increased with Cd and Pb concentration. Adsorption isotherm of Cd and Pb onto UCABC was determined and correlated with four isotherm models (Langmuir, Freundlich, Temkin and Hills). The equilibrium data fitted into Freundlich Cd (R2 = 0.9873, SSE = 0.045), Pb (R2 =0.9903, SSE = 0.051); Temkin Cd (R2 =0.9730, SSE = 0.052), Pb (R2 = 0.9079, SSE = 0.056); Hills Cd (R2 = 0.9961, SSE = 0.048), Pb (R2.= 0.9183, SSE = 0.053) and Langmuir Cd (R2 = 0.9653, SSE = 0.302), Pb (R2 = 0.9899, SSE = 0.136) isotherms. The Freundlich fitting showed isotherm adsorption capacity constants Kf = 7.843 and 5.098 (mg/g) for Cd and Pb, respectively. Furthermore, their adsorption kinetics correlated with the Pseudo-first order, Pseudo-second order and Intra-particle diffusion models and could be best described by the Pseudo-second order equation, suggesting chemisorptions as the limiting process. This study demonstrated that the UCABC can remove Cd2+ and Pb+ ions from aqueous solution to avert expensive commercial adsorbents
Magnetic Fe3O4@MgAl–LDH composite grafted with cobalt phthalocyanine as an ef...Pawan Kumar
Magnetically separable layered double hydroxide MgAl–LDH@Fe3O4 composite supported cobalt
phthalocyanine catalyst was synthesized and used for the aerobic oxidation of mercaptans to corresponding
disulfides under alkali free conditions. The catalyst exhibited excellent activity for the oxidation of
mercaptans using molecular oxygen as an oxidant which can be effectively recovered by using an external
magnetic field. In addition, the covalent immobilization of cobalt phthalocyanine to MgAl–LDH@Fe3O4
support prevents the leaching of the catalyst and improves its activity and stability
IOSR Journal of Applied Chemistry (IOSR-JAC) is an open access international journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
IOSR Journal of Applied Chemistry (IOSR-JAC) is an open access international journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Synthesis and Characterization of Atmospheric Residue Hydrodemetalization (Ar...IOSR Journals
Synthesis and characterization of atmospheric residue hydrodemetalization (ARDHM) catalyst for crude oil processing have been carried out. The catalyst was synthesized by loading of small amount of Ni and Mo metals onto the Indonesian natural zeolite from Klaten (ZA sample). The natural zeolite was treated with 3M HCl solution to produce the ZAA sample. The Ni and Mo metal was impregnated onto the ZAA sample using (NH4)6Mo7O24.4H2O followed by Ni(NO3)2.6H2O precursor solution, then calcined at 450ºC for 5 h and reduced at 400ºC for 3 h produced the NiMo/ZAA catalyst. The zeolite samples were characterized by means of total acid amount determined by pyridine vapour adsorption, the TO4 site (T = Si or Al) analyzed by Infra Red Spectrometer (IR), Crystallinity by X-ray Diffraction (XRD), and surface performance by Scanning Electron Microscope (SEM), and metal content measured by Atomic Absorption Spectroscopy (AAS). The catalyst activity was tested in hydrodemetalization process using nickel porphyrin, tiophene or pyridine as petroleum residue model compounds carried out at 360, 370, 380 and 390ºC, LHSV 0.2 h-1. The HCl treatment to the ZA sample caused dealumination, did not defect the crystalline matter and increased total acid amount. Loading of Ni and Mo metal onto the ZAA sample increased acidity, did not defect the crystalline of mordenite and also did not block the zeolite pore. Nickel removal from nickel porphyrin (Np) was easier than N remofal from pyridine; on the other hand, nickel removal from nickel porphyrin was more difficult than S removal from pyridine. The spent catalyst was deactivated by coke deposition and it can be regenerated and reused
The International Journal of Engineering and Science (IJES)theijes
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.
Isotherm Modeling and Thermodynamic Study of the Adsorption of Toxic Metal by...CrimsonpublishersEAES
Isotherm Modeling and Thermodynamic Study of the Adsorption of Toxic Metal by the Apricot Stone by Moussa Abbas*, Tounsia Aksil and Mohamed Trari in Environmental Analysis & Ecology Studies
Extraction of selected rare earth elements from anthracite acid mine drainage...GuanrongSong1
Rare earth elements (REEs) are valuable raw materials which are in great demand in modern high
technology industries. Developing methods to produce/recover REEs from waste is significant to the
national security of any developed country. This study was focused on investigating the use of supercritical
CO2 (sCO2) to extract REEs from anthracite acid mine drainage (AMD). Four different mine
drainage water source locations at Blaschak Coal Corp. in Pennsylvania, USA were selected for sample
collection. An extraction process was developed and demonstrated for two of those water sources
containing the highest concentration of REEs. A method involving metal ion coagulation, their dissolution
from the sludge into a concentrated aqueous HNO3 solution, complexation with organic ligands and
sCO2 extraction was developed to recover REEs from AMD. Specifically, sodium aluminate (NaAlO2) was
used as the coagulant to concentrate REEs from the AMD into a solid precipitate. Consequently, over 99%
of the REEs in AMD is concentrated in the remaining sludge. During the coagulation process, the effects
of pH and NaAlO2 concentration on REE precipitation were investigated. Fuming nitric acid (HNO3) was
used to digest the pre-concentrated sludge and tributyl phosphate (TBP) was used to form REE/TBP/
HNO3, a non-polar complex with selected REEs, specifically, cerium (Ce), lanthanum (La) and neodymium
(Nd). HNO3 concentration and organic/aqueous phase ratio were considered as the variables to improve
complexation efficiency. Dynamic extraction experiments using sCO2 and REE/TBP/HNO3 solutions were
then conducted at optimal conditions of 60 C and 20 MPa. The overall REE extraction efficiencies are
found to increase with the atomic number of the REE. As a result, the average overall REE extraction
efficiencies of 41.8%, 40.1% and 58.2% for Ce, La and Nd, respectively, are obtained. The potential improvements
in the overall extraction efficiency are also discussed.
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
Equilibrium and Kinetics Adsorption of Cadmium and Lead Ions from Aqueous Sol...theijes
Sourcing cheap adsorbents for the treatment of waste water is imperative for local environments. The adsorption of cadmium (Cd) and lead (Pb) from aqueous solution onto bamboo activated carbon prepared by chemical activation with ZnCl2 was investigated. The unwashed chemical activated bamboo carbon (UCABC) achieved up to 87.81% and 96.45% removal of Cd and Pb at pH-5 and 11, respectively. Removal equilibrium was attained within 1hr and 2.5hrs for Cd and Pb, respectively. The Cd and Pb adsorption increased with adsorbent dosage decrease while removal rate (%) increased with Cd and Pb concentration. Adsorption isotherm of Cd and Pb onto UCABC was determined and correlated with four isotherm models (Langmuir, Freundlich, Temkin and Hills). The equilibrium data fitted into Freundlich Cd (R2 = 0.9873, SSE = 0.045), Pb (R2 =0.9903, SSE = 0.051); Temkin Cd (R2 =0.9730, SSE = 0.052), Pb (R2 = 0.9079, SSE = 0.056); Hills Cd (R2 = 0.9961, SSE = 0.048), Pb (R2.= 0.9183, SSE = 0.053) and Langmuir Cd (R2 = 0.9653, SSE = 0.302), Pb (R2 = 0.9899, SSE = 0.136) isotherms. The Freundlich fitting showed isotherm adsorption capacity constants Kf = 7.843 and 5.098 (mg/g) for Cd and Pb, respectively. Furthermore, their adsorption kinetics correlated with the Pseudo-first order, Pseudo-second order and Intra-particle diffusion models and could be best described by the Pseudo-second order equation, suggesting chemisorptions as the limiting process. This study demonstrated that the UCABC can remove Cd2+ and Pb+ ions from aqueous solution to avert expensive commercial adsorbents
Magnetic Fe3O4@MgAl–LDH composite grafted with cobalt phthalocyanine as an ef...Pawan Kumar
Magnetically separable layered double hydroxide MgAl–LDH@Fe3O4 composite supported cobalt
phthalocyanine catalyst was synthesized and used for the aerobic oxidation of mercaptans to corresponding
disulfides under alkali free conditions. The catalyst exhibited excellent activity for the oxidation of
mercaptans using molecular oxygen as an oxidant which can be effectively recovered by using an external
magnetic field. In addition, the covalent immobilization of cobalt phthalocyanine to MgAl–LDH@Fe3O4
support prevents the leaching of the catalyst and improves its activity and stability
IOSR Journal of Applied Chemistry (IOSR-JAC) is an open access international journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
IOSR Journal of Applied Chemistry (IOSR-JAC) is an open access international journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Synthesis and Characterization of Atmospheric Residue Hydrodemetalization (Ar...IOSR Journals
Synthesis and characterization of atmospheric residue hydrodemetalization (ARDHM) catalyst for crude oil processing have been carried out. The catalyst was synthesized by loading of small amount of Ni and Mo metals onto the Indonesian natural zeolite from Klaten (ZA sample). The natural zeolite was treated with 3M HCl solution to produce the ZAA sample. The Ni and Mo metal was impregnated onto the ZAA sample using (NH4)6Mo7O24.4H2O followed by Ni(NO3)2.6H2O precursor solution, then calcined at 450ºC for 5 h and reduced at 400ºC for 3 h produced the NiMo/ZAA catalyst. The zeolite samples were characterized by means of total acid amount determined by pyridine vapour adsorption, the TO4 site (T = Si or Al) analyzed by Infra Red Spectrometer (IR), Crystallinity by X-ray Diffraction (XRD), and surface performance by Scanning Electron Microscope (SEM), and metal content measured by Atomic Absorption Spectroscopy (AAS). The catalyst activity was tested in hydrodemetalization process using nickel porphyrin, tiophene or pyridine as petroleum residue model compounds carried out at 360, 370, 380 and 390ºC, LHSV 0.2 h-1. The HCl treatment to the ZA sample caused dealumination, did not defect the crystalline matter and increased total acid amount. Loading of Ni and Mo metal onto the ZAA sample increased acidity, did not defect the crystalline of mordenite and also did not block the zeolite pore. Nickel removal from nickel porphyrin (Np) was easier than N remofal from pyridine; on the other hand, nickel removal from nickel porphyrin was more difficult than S removal from pyridine. The spent catalyst was deactivated by coke deposition and it can be regenerated and reused
The International Journal of Engineering and Science (IJES)theijes
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.
Isotherm Modeling and Thermodynamic Study of the Adsorption of Toxic Metal by...CrimsonpublishersEAES
Isotherm Modeling and Thermodynamic Study of the Adsorption of Toxic Metal by the Apricot Stone by Moussa Abbas*, Tounsia Aksil and Mohamed Trari in Environmental Analysis & Ecology Studies
Extraction of selected rare earth elements from anthracite acid mine drainage...GuanrongSong1
Rare earth elements (REEs) are valuable raw materials which are in great demand in modern high
technology industries. Developing methods to produce/recover REEs from waste is significant to the
national security of any developed country. This study was focused on investigating the use of supercritical
CO2 (sCO2) to extract REEs from anthracite acid mine drainage (AMD). Four different mine
drainage water source locations at Blaschak Coal Corp. in Pennsylvania, USA were selected for sample
collection. An extraction process was developed and demonstrated for two of those water sources
containing the highest concentration of REEs. A method involving metal ion coagulation, their dissolution
from the sludge into a concentrated aqueous HNO3 solution, complexation with organic ligands and
sCO2 extraction was developed to recover REEs from AMD. Specifically, sodium aluminate (NaAlO2) was
used as the coagulant to concentrate REEs from the AMD into a solid precipitate. Consequently, over 99%
of the REEs in AMD is concentrated in the remaining sludge. During the coagulation process, the effects
of pH and NaAlO2 concentration on REE precipitation were investigated. Fuming nitric acid (HNO3) was
used to digest the pre-concentrated sludge and tributyl phosphate (TBP) was used to form REE/TBP/
HNO3, a non-polar complex with selected REEs, specifically, cerium (Ce), lanthanum (La) and neodymium
(Nd). HNO3 concentration and organic/aqueous phase ratio were considered as the variables to improve
complexation efficiency. Dynamic extraction experiments using sCO2 and REE/TBP/HNO3 solutions were
then conducted at optimal conditions of 60 C and 20 MPa. The overall REE extraction efficiencies are
found to increase with the atomic number of the REE. As a result, the average overall REE extraction
efficiencies of 41.8%, 40.1% and 58.2% for Ce, La and Nd, respectively, are obtained. The potential improvements
in the overall extraction efficiency are also discussed.
Visible light assisted hydrogen generation from complete decomposition of hyd...Pawan Kumar
Hydrogen is considered to be an ideal energy carrier, which produces only water when combined with
oxygen and thus has no detrimental effect on the environment. While the catalytic decomposition of
hydrous hydrazine for the production of hydrogen is well explored, little is known about its photocatalytic
decomposition. The present paper describes a highly efficient photochemical methodology for the production
of hydrogen through the decomposition of aqueous hydrazine using titanium dioxide nanoparticles
modified with a Rh(I) coordinated catechol phosphane ligand (TiO2–Rh) as a photocatalyst under visible
light irradiation. After 12 h of visible light irradiation, the hydrogen yield was 413 μmol g−1 cat with a hydrogen
evolution rate of 34.4 μmol g−1 cat h−1. Unmodified TiO2 nanoparticles offered a hydrogen yield of
83 μmol g−1 cat and a hydrogen evolution rate of only 6.9 μmol g−1 cat h−1. The developed photocatalyst
was robust under the experimental conditions and could be efficiently reused for five subsequent runs
without any significant change in its activity. The higher stability of the photocatalyst is attributed to the
covalent attachment of the Rh complex, whereas the higher activity is believed to be due to the synergistic
mechanism that resulted in better electron transfer from the Rh complex to the conduction band of TiO2
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
Reduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
tReduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Electrochemical study of anatase TiO2 in aqueous sodium-ion electrolytesRatnakaram Venkata Nadh
In this paper, a basic electro-analytical study on the behavior of anatase TiO2 in aqueous NaOH has been presented using cyclic voltammetry technique (CV). The study has explored the possibility of using TiO2 as anode material for ARSBs in presence of 5 M NaOH aqueous electrolyte. CV profiles show that anatase TiO2 exhibits reversible sodium ion insertion/de-insertion reactions. CV studies of TiO2 anode in aqueous sodium electrolytes at different scan rate shows that the Na+ ion insertion reaction at the electrode is diffusion controlled with a resistive behavior. Proton insertion from aqueous sodium electrolytes into TiO2 cannot be ruled out. To confirm the ion inserted and de-inserted, CV studies are done at different concentration of NaOH and it is found that at lower concentrations of NaOH, proton insertion process competes with Na+ ion insertion process and as the concentration increases, the Na+ ion insertion process becomes the predominant electrode reaction making it suitable anode materials for aqueous sodium batteries in 5 M NaOH.
A comprehensive birds eye view of catalysis in green chemistry. Includes descriptions of photocatalysis,zeolites and nanoparticles as efficient green catalysts.A simple and crisp presentation with minimum words and alot of figures and colors.
Recent advancements in tuning the electronic structures of transitional metal...Pawan Kumar
The smooth transition from finite non-renewables to renewable energy conversion technologies will require efficient electrocatalysts which can harness intermittent energies to store in the form of chemical bonds. The oxygen evolution reaction (OER) impedes the widespread usage of water electrolyzers to convert H2O into H2 and persists as a bottleneck, including other energy conversion devices with sluggish four H+/e− kinetics. In this context, designing highly active and stable catalysts capable of driving a lower overpotential in the OER to produce continuous hydrogen (H2) is a primary demanded. This chapter discussed the mechanism of the OER in conventional adsorbate oxygen and lattice oxygen participation in transition metal oxides (TMOs). Further, the influences of surface engineering, doping, and defects in the TMOs and understanding the electronic structure to screen electrodes towards the structure–activity relationship are highlighted. Specifically, the adsorption strength of O 2p is understood in detail as its binding ability over the surface of TMOs can be correlated directly to the OER activity. The iterative development of TMOs in terms of understanding electronic structural attributes is essential for the commercial deployment of energy conversion technologies. The comprehensive outlook of this chapter investigates thoroughly how TMOs can be used as significant materials for the OER in the near future.
Paladio soportado sobre hidrotalcita como un catalizador para la reacción de ...52900339
Resumen
Se estudió la eficacia de diversas sales de paladio como catalizador en la reacción de acoplamiento cruzado de Suzuki, y la influencia de la base y de temperatura utilizados en su conversión, El uso de PdCl2 soportado sobre hidrotalcita como catalizador en presencia de carbonato de potasio como se encontró base para proporcionar los mejores resultados. Las temperaturas de reacción superiores a 90 °C garantizarse niveles de conversión a la par con los de muchos catalizadores homogéneos.
Taurus Zodiac Sign_ Personality Traits and Sign Dates.pptxmy Pandit
Explore the world of the Taurus zodiac sign. Learn about their stability, determination, and appreciation for beauty. Discover how Taureans' grounded nature and hardworking mindset define their unique personality.
3.0 Project 2_ Developing My Brand Identity Kit.pptxtanyjahb
A personal brand exploration presentation summarizes an individual's unique qualities and goals, covering strengths, values, passions, and target audience. It helps individuals understand what makes them stand out, their desired image, and how they aim to achieve it.
RMD24 | Debunking the non-endemic revenue myth Marvin Vacquier Droop | First ...BBPMedia1
Marvin neemt je in deze presentatie mee in de voordelen van non-endemic advertising op retail media netwerken. Hij brengt ook de uitdagingen in beeld die de markt op dit moment heeft op het gebied van retail media voor niet-leveranciers.
Retail media wordt gezien als het nieuwe advertising-medium en ook mediabureaus richten massaal retail media-afdelingen op. Merken die niet in de betreffende winkel liggen staan ook nog niet in de rij om op de retail media netwerken te adverteren. Marvin belicht de uitdagingen die er zijn om echt aansluiting te vinden op die markt van non-endemic advertising.
Discover the innovative and creative projects that highlight my journey throu...dylandmeas
Discover the innovative and creative projects that highlight my journey through Full Sail University. Below, you’ll find a collection of my work showcasing my skills and expertise in digital marketing, event planning, and media production.
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1. Water Research 37 (2003) 845–852
Use of complexing agents for effective ion-exchange separation
of Co(II)/Ni(II) from aqueous solutions
Ruey-Shin Juang*, Yi-Chieh Wang
Department of Chemical Engineering, Yuan Ze University, Chung-Li 320, Taiwan
Received 10 May 2002; accepted 29 August 2002
Abstract
Cation-exchange separation of Co2+/Ni2+ from aqueous solutions using water-soluble complexing agents of
ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), and citrate was
experimentally studied at 298 K. Experiments were carried out as a function of initial aqueous pH (1.0–6.0),
concentration of total metals (1.5–45.0 mol/m3), the concentration ratio of two metals (0.1–10) and of complexing agent
to the total metals (0–1). It was shown that the exchange selectivity strongly depended on solution pH and was not
completely related to the affinity of any metal with the complexing agents. When a certain level of complexing agent was
present, highly effective separation could be achieved at an appropriate pH range (for an equimolar metal solution, e.g.,
pH 2–3 with EDTA and NTA as well as pH>3 with IDA and citrate). The application potential of this method was
highlighted for the separation of Co2+ from binary mixtures in the presence of trace amount of Ni2+ due to its high
selectivity and the smaller amount of the complexing agents needed.
r 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Co/Ni separation; Cation exchange; EDTA; NTA; IDA; Citrate
1. Introduction crystallization, it is difficult to separate in a simple and
economical way.
Process effluents containing Co2+ and Ni2+ are often In the past years, successful development of Co2+/
encountered in chemical process industries. The major Ni2+ separation by solvent extraction has been received
source for production of Co2+ and Ni2+ appears to be much attention using organophosphorus acids from
from certain raw materials such as oxide and sulfide weakly acidic and neutral solutions (pH>5) [4–6] as well
ores/concentrates, spent lithium secondary batteries, as using amines at a high chloride concentration [7].
and sludge/wastes/scrap/dust of spent catalysts [1–3]. Nevertheless, the separation of Co2+/Ni2+ is still
Hydrometallurgical processes of leaching and dissolu- difficult particularly in more acidic sulfate solutions
tion of such raw materials under pressure or atmo- (e.g., pHo3), which are often obtained in hydrometal-
spheric conditions using HCl or H2SO4 result in leach lurgical operations [4]. In addition, conventional solvent
liquors containing Co2+ and Ni2+ along with some extraction processes are operated in devices such as
impurities. The similar physicochemical properties of packed towers, mixer-settlers, etc., which seek to
Co2+ and Ni2+ make their separation from aqueous maximize the contact area of the two phases for mass
solutions a challenging task. Using conventional meth- transfer [7]. The intimate mixing that occurs in these
ods such as chemical precipitation, oxidation and devices can lead to the formation of stable emulsions,
thereby inhibiting phase separation and product recov-
*Corresponding author. Tel.: +886-3-4638-800; fax: +886- ery. The solvent extraction systems avoid using liquids
3-4559-373. having similar densities, a situation which appears to
E-mail address: cejuang@ce.yzu.edu.tw (R.-S. Juang). promote this problem. Additional limitations present in
0043-1354/03/$ - see front matter r 2002 Elsevier Science Ltd. All rights reserved.
PII: S 0 0 4 3 - 1 3 5 4 ( 0 2 ) 0 0 4 2 3 - 2
2. 846 R.-S. Juang, Y.-C. Wang / Water Research 37 (2003) 845–852
Nomenclature V volume of the solution (m3)
W weight of dry resins (kg)
Ce aqueous-phase metal concentration at equili-
brium (mol/m3) Greek letters
C0 initial aqueous-phase metal concentration a molar concentration ratio of the complexing
(mol/m3) agent to total metals
Hx L complexing agent (x ¼ 4 for EDTA, 3 for bCo=Ni exchange selectivity of Co2+/Ni2+ defined in
NTA, IDA and citric acid) Eq. (2)
Kf overall formation constant of metal and
anionic ligand in the unit of mol/dm3 Subscripts
qe amount of metal exchange at equilibrium 0 initial
(mol/kg) tot total
packed towers include loading requirements and flood- complex Ni2+ to allow effective separation of trace
ing restrictions. An alternative way is thus highly amount of Co2+ from Ni2+ in emulsion liquid
needed. membranes containing di(2-ethylhexyl)phosphoric acid
Ion exchange has been also widely used for recovery (D2EHPA) as mobile carriers.
and concentration of metals from aqueous streams in To our knowledge, little attention has been paid to
chemical process and water treatment industries, due to solid ion-exchange resin systems. In this work, the
its simplicity to build-up, well-understood operating complexing agents EDTA, NTA, IDA, and citrate were
principles, and considerable performance data [8]. selected because their 1:1 overall formation constants
However, selective recovery of one or more metals from with Co2+ and Ni2+ are high enough, but a certain
a multicomponent mixture using common organic difference still exists among these constants [18,19].
cation-exchange resins is generally not feasible, espe- Experiments were carried out at different initial aqueous
cially for those metals having the same valence. pH values (1.0–6.0), concentrations of total metals (1.5–
Although the resins with specific chelating groups (for 45.0 mol/m3), the concentration ratios of two metals
example, the iminodiacetic acid (IDA) in Chelex-100 (0.1–10) and of complexing agent to total metals (0–1).
resin) can preferentially exchange some metals (e.g., The suitable conditions of the proposed method were
Cu2+), the high production cost and specific affinity of finally suggested for highly selective separation of Co2+
such resins make them rather limited for practical uses. and Ni2+ from binary solutions.
An attempt was thus made in this work to selectively
separate Co2+/Ni2+ using common strong-acid cation-
exchange resins by adding water-soluble complexing 2. Materials and methods
agents as masking reagents for Ni2+.
In practice, such a complexation-enhanced separation 2.1. Resins and solutions
concept has been applied to similar systems such as
cation-exchange membrane dialysis and electrodialysis Strong-acid cation-exchange resins Purolite NRW100
[9–14], solvent extraction [15] and liquid membranes (with -SO3H group) were used in this work. They were
[16,17]. Previous studies have shown that selective made of poly(styrene) and cross-linked with divinylben-
transport of metals is achieved by adding anionic zene. Physical and chemical properties of the resin are
ligands as masking reagents to the feed phase in listed in Table 1. Prior to use, the resin was washed with
membrane dialysis [10–12]. The anionic ligands com- NaOH (1 mol/dm3), HCl (1 mol/dm3), and n-hexane to
monly used include FÀ, SCNÀ, PO3À, ethylenediamine-
4 remove possible organic and inorganic impurities, and
tetraacetic acid (EDTA), nitrilotriacetic acid (NTA), was finally washed with deionized water (Millipore
citrate, oxalate and glycine. This can differentiate the Milli-Q) three times. The resins were converted to Na+
equilibrium uptake of metals on the membrane so as to form by column flushing with 1 mol/dm3 NaCl for 12 h.
increase the membrane selectivity for metals. However, They were finally washed with deionized water and dried
the enhancement of selectivity is inevitably at the in vacuum oven at 333 K.
expense of a decrease of mass transfer rate due to a Analytical reagent grade of EDTA, NTA, IDA, and
reduction of driving force, the concentration gradient. citric acid were purchased from Merck Co. The aqueous
On the other hand, Azis et al. [15] studied the enhanced phase was prepared by dissolving CoSO4 and NiSO4
separation of rare-earth metals by solvent extraction (Merck) and different amounts of complexing agents in
from aqueous solutions containing diethylenetriamine- deionized water. The initial aqueous pH was adjusted to
pentaacetic acid. Li et al. [16] also employed EDTA to be in the range 1.0–6.0 by adding a small amount of
3. R.-S. Juang, Y.-C. Wang / Water Research 37 (2003) 845–852 847
Table 1
Physical and chemical properties of the resin Purolite NRW100
Properties Purolite NRW100
Matrix Polystyrene DVB, gel type
Functional group Sulfonic acid—SO3À
Ionic form H+ (>99.9%)
Exchange capacity (equiv/ 4.5
kg of dry resin)
Moisture content (%) 50–55
Particle size (mm) 0.425–1.2
Specific gravity 1.20
pH limit None
0.1 mol/dm3 HCl or NaOH. The initial concentration of
total metals varied from 1.5 to 45.0 mol/m3. The
concentration ratios of the two metals (0.1–10) and of
complexing agent to total metals (0–1) in aqueous phase
were prepared.
2.2. Experimental procedures
In exchange experiments, an aliquot of dry resins Fig. 1. Effect of added EDTA on the amount of exchange of
Co2+ and Ni2+.
(0.3 g) and 100 cm3 of aqueous phase were placed in a
125 cm3 glass-stoppered flask and shaken at 120 rpm for
12 h using a shaker (Firstek Model B603, Taiwan). The with a stronger complexing affinity (that is, Ni2+ in this
temperature of the water bath was controlled at 298 K. case as shown in Table 2) significantly decreases, to even
Preliminary runs had shown that the exchange reactions zero, with increasing a or pH values. In this regard, a
studied were complete after 4 h. After equilibrium, the higher solution pH favors the separation of Co2+ from
aqueous-phase concentrations of metals were deter- Ni2+; however, this is not necessarily the case using
mined using an atomic absorption spectrophotometer stronger complexing agents such as EDTA and NTA at
(Varian Model 220FS, USA). The solution pH was high enough a values (>0.75). As also shown in Figs. 1
measured with a pH meter (Horiba Model F22, Japan). and 2 only, the difference of qe values between Co2+ and
The resin-phase concentration of each metal at equili- Ni2+ increases first and then decreases with increasing
brium, qe (mol/kg), was calculated according to the amounts of added EDTA and NTA (a). At low pH
(o2) and low a values (o0.75), the decrease in qe value
ðC0 À Ce ÞV
qe ¼ ; ð1Þ for Co2+ with decreasing the pH is a result of the
W
competition of exchange of H+ with free Co2+.
where C0 and Ce are the initial and equilibrium aqueous- Korngold et al. [20] have studied the removal of
phase concentrations of metal ions, respectively (mol/ Cu2+, Ni2+, Co2+ and Cd2+ from tap water containing
m3), and W =V is the dosage of dry resins (3 kg/m3). small amounts of salts of carboxylic acid by cation-
Each experiment was duplicated under identical condi- exchange resins having IDA group, Purolite S930. From
tions. Reproducibility of the measurements was within the column tests, they also indicated that the presence of
4%. one carboxylic group salts such as acetate has little effect
on amount of exchange, but the presence of salts with
two or four carboxylic groups such as tartrate and
3. Results and discussion EDTA dramatically decreases the exchange efficiency to
even zero. However, the effect of such carboxylic acid
3.1. Exchange equilibria in binary systems salts on separation performance of metals was not
discussed in their study.
Figs. 1–4 show the effects of equilibrium pH (pHeq) As shown in Figs. 3 and 4, the effect of metal
on amounts of exchange (qe ) in binary systems by complexation on the amount of exchange is weaker at
adding different amounts of EDTA, NTA, IDA and low pH (o2) using weaker complexing agents IDA and
citrate, respectively. In these figures, a is defined as the citrate. This behavior can be explained as follows. It is
molar concentration ratio of complexing agent to the known that EDTA, NTA, IDA, and citric acid exist in a
total metals. It is found that the qe value of the metal number of protonated forms in aqueous solutions. They
4. 848 R.-S. Juang, Y.-C. Wang / Water Research 37 (2003) 845–852
Fig. 2. Effect of added NTA on the amount of exchange of Fig. 4. Effect of added citrate on the amount of exchange of
Co2+ and Ni2+. Co2+ and Ni2+.
single Co2+ and Ni2+ systems are unavailable and those
of Cu2+ are thus referred to because Cu2+ have
comparable log Kf values of the 1:1 complexes (20.5
for EDTA, 14.2 for NTA, 11.5 for IDA and 7.2 for
citrate) with Co2+ and Ni2+ [19].
In an equimolar solutions of Cu2+ and EDTA (H4L),
it was found that the anions CuL2À dominates at
pH>3.2 and the anions CuHLÀ at pHo3.2 [21]. The
exchangeable Cu2+ ions are absent in the pH range
tested. In the case of citric acid (H3L), the dominant
species are the free Cu2+ ions at pHo4.0 and are CuLÀ
at pH>6.8. Within pH 4.0 and 6.8, the neutral species
CuHL dominate [21]. On the other hand, the anions
CuLÀ dominate at pH 2.0–11.0 and the free Cu2+ ions
at pHo2.0 in NTA (H3L) system [22]. Results of the
Cu-IDA system are essentially similar to those of the
Cu-NTA system except that each dominating pH range
is somewhat different.
3.2. Exchange selectivity in binary systems
Fig. 3. Effect of added IDA on the amount of exchange of In order to quantitatively know the effect of
Co2+ and Ni2+. equilibrium pH and a values on separation factor, the
exchange selectivity of Co2+ over Ni2+, bCo=Ni ; is
defined as
form stable complexes with most metals in a 1:1 molar
ðqCo;e =qNi;e Þ
ratio [19]. Table 2 lists the related overall formation bCo=Ni ¼ : ð2Þ
constants Kf at zero ionic strength and 298 K. The pH ðCCo;0 =CNi;0 Þ
diagrams of species distribution can be calculated from a Figs. 5 and 6 show the results of binary equimolar
set of mass-balance equations. Literature results of solutions. As expected, the effective separation of Co2+/
5. R.-S. Juang, Y.-C. Wang / Water Research 37 (2003) 845–852 849
Table 2
The overall formation constants (log Kf ) for the complexes of metals and anionic ligands at 298 K and zero ionic strength [19]a
Ion L=OHÀ L=SO2À
4 L=citrate3À L=IDA3À L=NTA3À L=EDTA4À
H+ HL (14.0) HL (1.99) HL (6.40) HL (9.73) HL (10.33) HL (11.12)
H2L (11.16) H2L (12.63) H2L (13.27) H2L (17.80)
H3L (14.29) H3L (14.51) H3L (14.92) H3L (21.04)
H4L (16.02) H4L (23.76)
H5L (24.76)
Co2+ CoL (4.3) CoL (2.4) CoL (6.3) CoL (7.9) CoL (11.7) CoL (18.1)
CoL2 (9.2) CoHL (10.3) CoL2 (13.2) CoL2 (15.0) CoHL (21.5)
CoL3 (10.5) CoH2L (12.9) CoOHL (14.5)
Ni2+ NiL (4.1) NiL (2.3) NiL (6.7) NiL (9.1) NiL (12.8) NiL (20.4)
NiL2 (9.0) NiHL (10.5) NiL2 (15.7) NiL2 (17.0) NiHL (24.0)
NiL3 (12.0) NiH2L (12.9) NiOHL (15.5) NiOHL (21.8)
a
Kf is in the unit of mol/dm3.
Ni2+ by organic cation-exchange resins is impossible at
a ¼ 0 under the pH ranges studied.
Two types of figures are observed. In the presence of
strong complexing agent such as EDTA and NTA
(Fig. 5), the selectivity is acceptable (>5, for example)
only if a > 0:5: A maximum selectivity is obtained at
a ¼ 1 to be 70.6 at pH 2 with EDTA and to be 10.9 at
pH 3 with NTA. For the weaker complexing agents such
as IDA and citrate (Fig. 6), the exchange separation is
impossible at pHo3 regardless of the amounts of the
complexing agents added. At pH>3, the selectivity
increases with increasing solution pH and a values under
the conditions studied; and a highest selectivity of 15.1
and 4.4 is obtained at pH 5.7 and a ¼ 1 using IDA and
citrate, respectively.
It should be noted that the exchange selectivity at a
given pH (e.g., pH 4) does not fully follow the affinity of
the complexing agents, i.e., EDTA>NTA>IDA>ci-
trate. This can be understood because not only the
absolute values of Kf ’s but also their differences play an
important role in exchange selectivity. If we take the Kf
values based on the formation of 1:1 complexes ML,
except for MHL in citrate systems, the difference in Kf Fig. 5. Effect of added EDTA and NTA on exchange
values of Co2+ and Ni2+ with EDTA, NTA, IDA and selectivity of Co2+/Ni2+.
citrate are 2.3, 1.1, 1.2 and 0.2, respectively.
As indicated above, separation of Co2+/Ni2+ by
solvent extraction has been of practical interest [1–6]. A
selectivity of 36.4 was reported when the loaded organic the selectivity to be 2.2, 21 and 380, respectively.
phase (20 vol% D2EHPA+20% LIX860+kerosene) Recently, the sodium salts of organophosphorus acids
containing 1.26 g/dm3 Ni(II) and 0.25 g/dm3 Co(II) such as D2EHPA, PC88A and Cyanex 272 have been
was stripped with 0.3 mol/dm3 H2SO4 [4]. A selectivity proposed as highly effective extractants for separation of
of 30–70 was obtained at an organic loading ratio of 0.6 Co2+/Ni2+ [1,2]. However, the stripping of the loaded
using 25.7 vol% 2-ethylhexylphosphonic acid mono-2- organic phase and the regeneration of extractants for
ethylhexyl ester (PC88A) in 90% xylene and 10% 2- continuous operations appear to be somewhat difficult.
ethylhexyl alcohol [5]. Danesi et al. [6] applied toluene Compared to the use of anionic ligands in different
solutions of D2EHPA, PC88A, and di(2,4,4-trimethyl- processes, the selectivity obtained in this work is
pentyl)phospninic acid (Cyanex 272) to separate trace acceptable. For example, Li et al. [16] added EDTA in
amounts of Co2+/Ni2+ (10À3–1 mol/m3). They found the external phase to complex Ni2+ to separate trace
6. 850 R.-S. Juang, Y.-C. Wang / Water Research 37 (2003) 845–852
Fig. 7. Effect of total metal concentration on exchange
selectivity of Co2+/Ni2+ in the presence of EDTA.
concentration (not shown). The amount of Co2+
exchange is larger than that of Ni2+ using EDTA, even
Fig. 6. Effect of added IDA and citrate on exchange selectivity that Ni2+ is initially in large excess of Co2+ in the
of Co2+/Ni2+.
aqueous phase. This is not the case with NTA because of
its weaker complexing ability than EDTA.
amount of Co2+ from Ni2+ in an emulsion liquid Figs. 8 and 9 show the corresponding exchange
membrane containing D2EHPA as carriers. The selec- selectivity of Co2+/Ni2+. It is found that the selectivity
tivity of Co2+ to Ni2+ was found to be very high (up to increases with increasing the concentration ratio of
200). This may be due to the synergistic effect of EDTA- Co2+ and Ni2+. When Co2+ is initially in excess of
masking for Ni2+ and the preferential D2EHPA- Ni2+, the selectivity increases first with increasing
complexation for Co2+. Similar to solvent extraction, equilibrium pH and reaches a plateau at pH beyond
the repeated emulsion formation/breaking and phase 3–5. Under the conditions examined, the exchange
separation makes emulsion liquid membranes more selectivity is about 70 with EDTA and 20 with NTA
complicated than ion exchange. at pH>4 and CCo,0/CNi,0=10/1. These results indicate
The effect of total metal concentration Ctot on the present method to be especially promising for
exchange selectivity is shown in Fig. 7 in the presence of selective separation of Co2+ from a binary mixture
EDTA (a ¼ 0:5). A high initial solution pH favors containing trace amount of Ni2+, because of its high-
exchange separation and the selectivity increases first exchange selectivity and the less consumption of
but then decreases with increasing Ctot : Because the complexing agents. The used complexing agents could
solution contains equimolar Co2+ and Ni2+, most of the be likely regenerated by an electrolytic membrane
EDTA will complex with Ni2+. Increasing Ctot means an process [23,24]. Metal complexes remaining in the
increase in amount of free Co2+ in solution, thus aqueous solutions are dissociated in an electrolytic cell
increasing amount of exchange. When the amount of equipped with a cation-exchange membrane, which
free metals in solution exceeds the saturated exchange allows the metals to be deposited on the cathode and
capacity of the resins (pH-dependent); however, Co2+ prevents the complexing agents such as EDTA from
exchange is limited by equilibrium relationship and Ni2+ oxidation at the anode.
will compete with Co2+ for cation exchange. This leads
to a reduction of selectivity. Such trends are essentially
affected by the dosage of the resins and the a value.
4. Conclusions
3.3. Effect of concentration ratio of two metals on The effects of adding EDTA, NTA, IDA, and citrate
exchange selectivity on separation of Co2+/Ni2+ by cation exchange using
strong-acid Purolite NRW100 resins were studied at
The effect of concentration ratio of two metals on 298 K. In the absence of complexing agents, effective
amount of exchange is also studied at a fixed total metal separation was impossible under the ranges examined.
7. R.-S. Juang, Y.-C. Wang / Water Research 37 (2003) 845–852 851
3–5 when Co2+ was initially in excess of Ni2+ in the
aqueous phase. Under the conditions studied, the
selectivity was 70 with EDTA and 20 with NTA at
pH>4 and CCo,0/CNi,0=10/1. The present method was
proven to be promising for selective separation of Co2+
from binary mixtures containing trace amount of Ni2+,
because of its high selectivity and the smaller amount of
complexing agents needed.
Acknowledgements
Support for this work by the ROC National Science
Council under Grant NSC90-2214-E-155-001 is grate-
Fig. 8. Effect of concentration ratio of Co2+ and Ni2+ on fully appreciated.
exchange selectivity of Co2+/Ni2+ in the presence of EDTA.
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