The ion-exchange equilibrium of bovine serum albumin (BSA) on an anion exchanger was studied.The usefulness of steric mass-action (SMA) model was analyzed for describing protein ion-exchange equilibrium in different b...The ion-exchange equilibrium of bovine serum albumin (BSA) on an anion exchanger was studied.The usefulness of steric mass-action (SMA) model was analyzed for describing protein ion-exchange equilibrium in different buffer systems.The results showed that the SMA model was useful in the prediction of protein adsorption decrease with increasing ionic strength in a wide pH range.However,at higher salt concentrations where very low protein adsorption was achieved,the model predicted adsorption capacity was higher than the experimental results.At lower pH close to the isoelectric point of BSA,the accuracy of the model prediction further decreased.It is considered that the SMA model could be further improved by taking into account the factors influencing the three-dimensional structure of proteins (e.g., pH) and the effect of salt concentration on the intermolecular interactions of proteins.展开更多
L-phenylalanine, one of the nine essential amino acids for the human body, is extensively used as an ingredient in food, pharmaceutical and nutrition industries. A suitable equilibrium model is required for purificati...L-phenylalanine, one of the nine essential amino acids for the human body, is extensively used as an ingredient in food, pharmaceutical and nutrition industries. A suitable equilibrium model is required for purification of L-phenylalanine based on ion-exchange chromatography. In this work, the equilibrium uptake of L-phenylalanine on a strong acid-cation exchanger SH11 was investigated experimentally and theoretically. A modified Donnan ion-exchange （DIX） model, which takes the activiW into account, was established to predict the uptake of L-phenylalanine at various solution pH values. The model parameters including selectivity and mean activity coefficient in the resin phase are presented. The modified DIX model is in good agreement with the experimental data. The optimum operating pH value of 2.0, with the highest t-phenylalanine uptake on the resin, is predicted by the model. This basic information combined with the general mass transfer model will lay the foundation for the prediction of dynamic behavior of fixed bed separation process.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
In many crystalline exchangers, such as zeolite, there are different exchange sites which can be occupied by cations A and B, The sites belonging to different site groups are intimately mixed together throughout the c...In many crystalline exchangers, such as zeolite, there are different exchange sites which can be occupied by cations A and B, The sites belonging to different site groups are intimately mixed together throughout the crystal. The number of possible sites exceeds the number of cations needed to neutralize the negative charge of the framework, some sites then remain unfilled. The purpose展开更多
文摘The ion-exchange equilibrium of bovine serum albumin (BSA) on an anion exchanger was studied.The usefulness of steric mass-action (SMA) model was analyzed for describing protein ion-exchange equilibrium in different buffer systems.The results showed that the SMA model was useful in the prediction of protein adsorption decrease with increasing ionic strength in a wide pH range.However,at higher salt concentrations where very low protein adsorption was achieved,the model predicted adsorption capacity was higher than the experimental results.At lower pH close to the isoelectric point of BSA,the accuracy of the model prediction further decreased.It is considered that the SMA model could be further improved by taking into account the factors influencing the three-dimensional structure of proteins (e.g., pH) and the effect of salt concentration on the intermolecular interactions of proteins.
基金Supported by the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT1066)National Natural Science Foundation of China(No.21306086)Applied Basic Research Programs of Science and Technology Commission Foundation of Jiangsu Province(No.BK20151452)
文摘L-phenylalanine, one of the nine essential amino acids for the human body, is extensively used as an ingredient in food, pharmaceutical and nutrition industries. A suitable equilibrium model is required for purification of L-phenylalanine based on ion-exchange chromatography. In this work, the equilibrium uptake of L-phenylalanine on a strong acid-cation exchanger SH11 was investigated experimentally and theoretically. A modified Donnan ion-exchange （DIX） model, which takes the activiW into account, was established to predict the uptake of L-phenylalanine at various solution pH values. The model parameters including selectivity and mean activity coefficient in the resin phase are presented. The modified DIX model is in good agreement with the experimental data. The optimum operating pH value of 2.0, with the highest t-phenylalanine uptake on the resin, is predicted by the model. This basic information combined with the general mass transfer model will lay the foundation for the prediction of dynamic behavior of fixed bed separation process.
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.
基金Project supported by the National Natural Science Foundation of China
文摘In many crystalline exchangers, such as zeolite, there are different exchange sites which can be occupied by cations A and B, The sites belonging to different site groups are intimately mixed together throughout the crystal. The number of possible sites exceeds the number of cations needed to neutralize the negative charge of the framework, some sites then remain unfilled. The purpose
