A rapid and practical green route for the N-formylation of amines with formic acid using Amberlite IR-120 as a catalyst is described.This method provides an efficient and much improved modification over the reported m...A rapid and practical green route for the N-formylation of amines with formic acid using Amberlite IR-120 as a catalyst is described.This method provides an efficient and much improved modification over the reported methods in terms of yield,reaction time,and work-up procedure.A wide variety of substituents is tolerated,which is not the case for existing procedures.展开更多
The ion exchange resin Amberlite IRA-400 in iodide and bromide form where equilibrated separately with the respective labeled iodide and bromide ion solution of different concen-trations varying from 0.005M to 0.100M ...The ion exchange resin Amberlite IRA-400 in iodide and bromide form where equilibrated separately with the respective labeled iodide and bromide ion solution of different concen-trations varying from 0.005M to 0.100M in the temperature range of 32.0 oC to 48.0 oC. The dis-tribution coefficient Kd values calculated for iodide and bromide ion exchange increases with rise in ionic concentration of the external solution, however with rise in temperature the Kd values calculated where found to decrease. Also the Kd values calculated where higher for iodide exchange than bromide exchange. Among the different alternative techniques available for obtaining the Kd values, the radio-active tracer technique used in the present ex-perimental work offers high detection sensitivity. It is expected that the distribution coefficient data obtained from such experimental work will significant in environmental impact assessment on the disposal of radioactive waste.展开更多
Objective: To compare the protective effects of removingcirculatory TNF by specific immunoadsorption and by nonspeciflc Amberlite XAD-7 adsorption on experimental endotoxin shock. Methods: New Zealand white rabbits re...Objective: To compare the protective effects of removingcirculatory TNF by specific immunoadsorption and by nonspeciflc Amberlite XAD-7 adsorption on experimental endotoxin shock. Methods: New Zealand white rabbits receiving a lethal dose of endotoxin underwent hemoperfusion through immunoadsorbent or Amberlite BAD-7. Plasma TNF levels. efficiency of the adsorbents and the survival rate were observed. Results: After 2 h of hemopcrfusion through immunoadsorhent or Amberlite XAD-7. plasma TNF levels were significantly lower than those in the control group(P<0.01). and the best result was shown by immunoadsorption (P<0. 01). The 12 h and 18 h survival rates were 70% and 30% in the immunoadsorption group, and 30% and 5% in the Amberlite XAD-7 group respectively (P<0. 05). Conclusion: Compared with the nonspecific Amberlite XAD-7 adsorption,the specific imrnunoadsorption might be a more effective method of removing circulatory TNF and improve the survival rate in endotoxin shock.展开更多
Synthetic resin, Amberlite XAD-4 was linked covalently with the third generation supramolecule, octa-O-methoxy resorcin [4] arene through -N=N-group to form chelating resin, which has been characterized and effectivel...Synthetic resin, Amberlite XAD-4 was linked covalently with the third generation supramolecule, octa-O-methoxy resorcin [4] arene through -N=N-group to form chelating resin, which has been characterized and effectively used for the separation and preconcentration of metal ions such as Ni(II), Cu(II), Zn(II) and Cd(II). Critical parameters such as pH, flow rate, sorption capacity, breakthrough studies, distribution coefficient, preconcentration factor, concentration of eluting agents responsible for quantitative extraction of metal ions were optimized. The synthesized resin showed good binding affinity towards Ni(II), Cu(II), Zn(II) and Cd(II) under selective pH conditions. Good breakthrough capacity and fast exchange kinetics of the resin lead to effective separation of metal ions from their binary and ternary mixture by column method on the basis of pH and eluting agents. The resin could be reused for about 8 -10 cycles. The proposed method having the analytical data with the relative standard deviation (RSD) 2% and with recoveries of analytes higher than 98%, reflects upon the reproducibility and reliability of the method which has been successfully applied in the separation and determination of Ni(II), Cu(II), Zn(II) and Cd(II) ions in synthetic, natural and ground water samples.展开更多
The selectivity behaviour of ion exchange resin Amberlite IR-120 for inorganic cations like sodium and potassium was predicted on the basis of thermodynamic data. The equilibrium constant K values calculated for uni-u...The selectivity behaviour of ion exchange resin Amberlite IR-120 for inorganic cations like sodium and potassium was predicted on the basis of thermodynamic data. The equilibrium constant K values calculated for uni-univalent ion exchange reaction systems were observed to increase with rise in temperature, indicating endothermic ion exchange reactions. From the K values calculated at different temperatures the enthalpy values were calculated. The low enthalpy and higher K values for K+ ion ex-change reaction indicates more affinity of the resin for potassium ions as compared to that for sodium ions also in the solution. The technique used in the present experimental work will be useful in understanding the selectivity behav-iour of different ion exchange resins for ions in the solution. Although the ionic selectivity data for the ion exchange resins is readily available in the literature, it is expected that the informa-tion obtained from the actual experimental trials will be more helpful. The technique used in the present experimental work when applied to dif-ferent ion exchange resins will help in there characterization.展开更多
The extraction of chromium(III) from a model waste solution and also from a waste solution of an Indian tannery with Amberlite IR 120 resin is described, and the performance of this resin is compared with other simila...The extraction of chromium(III) from a model waste solution and also from a waste solution of an Indian tannery with Amberlite IR 120 resin is described, and the performance of this resin is compared with other similar resins. The parameters that were optimized include effect of mixing time, pH, loading and elution behaviours of chromium(III) for this resin. Sorption of chromium(III) on Amberlite IR 120 followed Freundlich isotherm and Langmuir isotherm model, and the maximum sorption capacity was determined to be 142.86 mg Cr(III)/g of the resin. Higher Freundlich constant (Kf) values (6.30 and 13.46 for aqueous feed of 500 and 1000 ppm Cr(III)) indicated strong chemical interaction through ion exchange mechanism of the metal ion with the resin. The kinetic data showed good fit to the Lagergren first order model for extraction of chromium(III). Desorption of chromium(III) from the loaded resin increased with the increase in concentration of eluent (5-20% H2SO4). With 20% (v/v) sulphuric acid solution 94% chromium(III) was eluted in three stages. Elution of the Cr(III) in the column experiments was however, found to be lower (82%) than that of the shake flask data. In case of Indian tannery’s waste solution, it was observed that almost total chromium was extracted in four stages with Amberlite IR 120.展开更多
A procedure for preconcentration of Mn(Ⅱ), Fe(Ⅱ), Co(H), Cu(Ⅱ), Cd(Ⅱ), Zn(Ⅱ), Pb(Ⅱ) and Ni(Ⅱ) based on retention of their complexes with 8-hydroxyquinoline (HQ) on Amberlite XAD-2000 resin in ...A procedure for preconcentration of Mn(Ⅱ), Fe(Ⅱ), Co(H), Cu(Ⅱ), Cd(Ⅱ), Zn(Ⅱ), Pb(Ⅱ) and Ni(Ⅱ) based on retention of their complexes with 8-hydroxyquinoline (HQ) on Amberlite XAD-2000 resin in a column was proposed for the analysis of environmental samples by flame AAS. Various parameters such as pH, eluent type, volume, concentration, flow rate and volume of sample solution, and matrix interference effect on the retention of the metal ions were investigated. The optimum pHs for the retention of metal complexes in question were about 6 except for Mn^2+ for whose value is 8. The loading capacity of the adsorbent for these metals and their recoveries from the resin under the optimum conditions were in the range 6.82-9.26 mg·g^-1 and 95%-101%, respectively. The enrichment factor was calculated as 100 and the limit of detection was in the range 0.3-2.2 μg·L^-1 (n=20, blank+ 3s). The proposed enrichment method was applied to tap water, stream water and vegetable samples. The validation of the procedure was carried out by analysis of certified reference material and standard addition. The analytes were determined with a relative standard deviation lower than 6% in all samples.展开更多
The direct determination of toxic metal ions, in environmental samples, is difficult because of the latter's presence in trace concentration in association with complex matrices, thereby leading to insufficient sensi...The direct determination of toxic metal ions, in environmental samples, is difficult because of the latter's presence in trace concentration in association with complex matrices, thereby leading to insufficient sensitivity and selectivity of the methods used. The simultaneous removal of the matrix and preconcentration of the metal ions, through solid phase extraction,serves as the promising solution. The mechanism involved in solid phase extraction(SPE)depends on the nature of the sorbent and analyte. Thus, SPE is carried out by means of adsorption, ion exchange, chelation, ion pair formation, and so forth. As polymeric supports, the commercially available Amberlite resins have been found very promising for designing chelating matrices due to its good physical and chemical properties such as porosity, high surface area,durability and purity. This review presents an overview of the various works done on the modification of Amberlite XAD resins with the objective of making it an efficient sorbent. The methods of modifications which are generally based on simple impregnation, sorption as chelates and chemical bonding have been discussed. The reported results, including the preconcentration limit, the detection limit, sorption capacity, preconcentration factors etc., have been reproduced.展开更多
New adso rbent material was obtained by modification of commercial Amberlite XAD7 with thiourea that represents a non-toxic,cheap and environmentally friendly extractant.Prepared adsorbent was used for removal of neod...New adso rbent material was obtained by modification of commercial Amberlite XAD7 with thiourea that represents a non-toxic,cheap and environmentally friendly extractant.Prepared adsorbent was used for removal of neodymium ions from aqueous solutions.Thiourea modified Amberlite involved in this study shows good adsorption capacities(74.3 mg/g) and excellent efficiency during Nd removal process.In order to elucidate the mechanism of the Nd adsorption process kinetic,thermodynamic and equilibrium studies were performed,establishing this way which kinetic model better describes the Nd adsorption process.Moreover the thermodynamic studies prove that the Nd adsorption on thiourea modified Amberlite XAD7 is an endothermic and spontaneous process.展开更多
文摘A rapid and practical green route for the N-formylation of amines with formic acid using Amberlite IR-120 as a catalyst is described.This method provides an efficient and much improved modification over the reported methods in terms of yield,reaction time,and work-up procedure.A wide variety of substituents is tolerated,which is not the case for existing procedures.
文摘The ion exchange resin Amberlite IRA-400 in iodide and bromide form where equilibrated separately with the respective labeled iodide and bromide ion solution of different concen-trations varying from 0.005M to 0.100M in the temperature range of 32.0 oC to 48.0 oC. The dis-tribution coefficient Kd values calculated for iodide and bromide ion exchange increases with rise in ionic concentration of the external solution, however with rise in temperature the Kd values calculated where found to decrease. Also the Kd values calculated where higher for iodide exchange than bromide exchange. Among the different alternative techniques available for obtaining the Kd values, the radio-active tracer technique used in the present ex-perimental work offers high detection sensitivity. It is expected that the distribution coefficient data obtained from such experimental work will significant in environmental impact assessment on the disposal of radioactive waste.
文摘Objective: To compare the protective effects of removingcirculatory TNF by specific immunoadsorption and by nonspeciflc Amberlite XAD-7 adsorption on experimental endotoxin shock. Methods: New Zealand white rabbits receiving a lethal dose of endotoxin underwent hemoperfusion through immunoadsorbent or Amberlite BAD-7. Plasma TNF levels. efficiency of the adsorbents and the survival rate were observed. Results: After 2 h of hemopcrfusion through immunoadsorhent or Amberlite XAD-7. plasma TNF levels were significantly lower than those in the control group(P<0.01). and the best result was shown by immunoadsorption (P<0. 01). The 12 h and 18 h survival rates were 70% and 30% in the immunoadsorption group, and 30% and 5% in the Amberlite XAD-7 group respectively (P<0. 05). Conclusion: Compared with the nonspecific Amberlite XAD-7 adsorption,the specific imrnunoadsorption might be a more effective method of removing circulatory TNF and improve the survival rate in endotoxin shock.
文摘Synthetic resin, Amberlite XAD-4 was linked covalently with the third generation supramolecule, octa-O-methoxy resorcin [4] arene through -N=N-group to form chelating resin, which has been characterized and effectively used for the separation and preconcentration of metal ions such as Ni(II), Cu(II), Zn(II) and Cd(II). Critical parameters such as pH, flow rate, sorption capacity, breakthrough studies, distribution coefficient, preconcentration factor, concentration of eluting agents responsible for quantitative extraction of metal ions were optimized. The synthesized resin showed good binding affinity towards Ni(II), Cu(II), Zn(II) and Cd(II) under selective pH conditions. Good breakthrough capacity and fast exchange kinetics of the resin lead to effective separation of metal ions from their binary and ternary mixture by column method on the basis of pH and eluting agents. The resin could be reused for about 8 -10 cycles. The proposed method having the analytical data with the relative standard deviation (RSD) 2% and with recoveries of analytes higher than 98%, reflects upon the reproducibility and reliability of the method which has been successfully applied in the separation and determination of Ni(II), Cu(II), Zn(II) and Cd(II) ions in synthetic, natural and ground water samples.
文摘The selectivity behaviour of ion exchange resin Amberlite IR-120 for inorganic cations like sodium and potassium was predicted on the basis of thermodynamic data. The equilibrium constant K values calculated for uni-univalent ion exchange reaction systems were observed to increase with rise in temperature, indicating endothermic ion exchange reactions. From the K values calculated at different temperatures the enthalpy values were calculated. The low enthalpy and higher K values for K+ ion ex-change reaction indicates more affinity of the resin for potassium ions as compared to that for sodium ions also in the solution. The technique used in the present experimental work will be useful in understanding the selectivity behav-iour of different ion exchange resins for ions in the solution. Although the ionic selectivity data for the ion exchange resins is readily available in the literature, it is expected that the informa-tion obtained from the actual experimental trials will be more helpful. The technique used in the present experimental work when applied to dif-ferent ion exchange resins will help in there characterization.
文摘The extraction of chromium(III) from a model waste solution and also from a waste solution of an Indian tannery with Amberlite IR 120 resin is described, and the performance of this resin is compared with other similar resins. The parameters that were optimized include effect of mixing time, pH, loading and elution behaviours of chromium(III) for this resin. Sorption of chromium(III) on Amberlite IR 120 followed Freundlich isotherm and Langmuir isotherm model, and the maximum sorption capacity was determined to be 142.86 mg Cr(III)/g of the resin. Higher Freundlich constant (Kf) values (6.30 and 13.46 for aqueous feed of 500 and 1000 ppm Cr(III)) indicated strong chemical interaction through ion exchange mechanism of the metal ion with the resin. The kinetic data showed good fit to the Lagergren first order model for extraction of chromium(III). Desorption of chromium(III) from the loaded resin increased with the increase in concentration of eluent (5-20% H2SO4). With 20% (v/v) sulphuric acid solution 94% chromium(III) was eluted in three stages. Elution of the Cr(III) in the column experiments was however, found to be lower (82%) than that of the shake flask data. In case of Indian tannery’s waste solution, it was observed that almost total chromium was extracted in four stages with Amberlite IR 120.
文摘A procedure for preconcentration of Mn(Ⅱ), Fe(Ⅱ), Co(H), Cu(Ⅱ), Cd(Ⅱ), Zn(Ⅱ), Pb(Ⅱ) and Ni(Ⅱ) based on retention of their complexes with 8-hydroxyquinoline (HQ) on Amberlite XAD-2000 resin in a column was proposed for the analysis of environmental samples by flame AAS. Various parameters such as pH, eluent type, volume, concentration, flow rate and volume of sample solution, and matrix interference effect on the retention of the metal ions were investigated. The optimum pHs for the retention of metal complexes in question were about 6 except for Mn^2+ for whose value is 8. The loading capacity of the adsorbent for these metals and their recoveries from the resin under the optimum conditions were in the range 6.82-9.26 mg·g^-1 and 95%-101%, respectively. The enrichment factor was calculated as 100 and the limit of detection was in the range 0.3-2.2 μg·L^-1 (n=20, blank+ 3s). The proposed enrichment method was applied to tap water, stream water and vegetable samples. The validation of the procedure was carried out by analysis of certified reference material and standard addition. The analytes were determined with a relative standard deviation lower than 6% in all samples.
基金the financial supports given to this work by Ministry of Higher Education (MOHE) Malaysia, project grant Q.J130000.2544.04H03Research Management Centre (RMC), Universiti Teknologi Malaysia (UTM.J.09.01/13.14/1/88J1d2 (49))
文摘The direct determination of toxic metal ions, in environmental samples, is difficult because of the latter's presence in trace concentration in association with complex matrices, thereby leading to insufficient sensitivity and selectivity of the methods used. The simultaneous removal of the matrix and preconcentration of the metal ions, through solid phase extraction,serves as the promising solution. The mechanism involved in solid phase extraction(SPE)depends on the nature of the sorbent and analyte. Thus, SPE is carried out by means of adsorption, ion exchange, chelation, ion pair formation, and so forth. As polymeric supports, the commercially available Amberlite resins have been found very promising for designing chelating matrices due to its good physical and chemical properties such as porosity, high surface area,durability and purity. This review presents an overview of the various works done on the modification of Amberlite XAD resins with the objective of making it an efficient sorbent. The methods of modifications which are generally based on simple impregnation, sorption as chelates and chemical bonding have been discussed. The reported results, including the preconcentration limit, the detection limit, sorption capacity, preconcentration factors etc., have been reproduced.
文摘New adso rbent material was obtained by modification of commercial Amberlite XAD7 with thiourea that represents a non-toxic,cheap and environmentally friendly extractant.Prepared adsorbent was used for removal of neodymium ions from aqueous solutions.Thiourea modified Amberlite involved in this study shows good adsorption capacities(74.3 mg/g) and excellent efficiency during Nd removal process.In order to elucidate the mechanism of the Nd adsorption process kinetic,thermodynamic and equilibrium studies were performed,establishing this way which kinetic model better describes the Nd adsorption process.Moreover the thermodynamic studies prove that the Nd adsorption on thiourea modified Amberlite XAD7 is an endothermic and spontaneous process.
基金Project(2013ZX07504)supported by the National Science and Technology Major Project of ChinaProject(2018JJ2484)supported by the Natural Science Foundation of Hunan Province,China。