Isopiestic molalities, vapor pressures and osmotic coefficients of aqueous Li 2B 4O 7 solutions from 0.027 5 to 2.939 7 mol/kg were determined at 298.15 K by using an improved apparatus. The rule of the changes in vap...Isopiestic molalities, vapor pressures and osmotic coefficients of aqueous Li 2B 4O 7 solutions from 0.027 5 to 2.939 7 mol/kg were determined at 298.15 K by using an improved apparatus. The rule of the changes in vapor pressure over aqueous Li 2B 4O 7 solutions was revealed, which indicated that the bond of borate anions with water are better than that of NaCl. The different formation reaction equilibria for the species containing boron of boric acid and borate anions B(OH) - 4, B 3O 3(OH) - 4 and B 4O 5(OH) 2- 4 in Li 2B 4O 7(aq) solutions were taken into account. The stoichiometric equilibrium constants for the formation reactions of the boron species and the ion-interaction parameters were estimated simultaneously by using Pitzer equations of osmotic coefficient with minor modifications. Sixteen parameters were obtained with a standard deviation 0.005 5 for the ion-interaction model.展开更多
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
文摘Isopiestic molalities, vapor pressures and osmotic coefficients of aqueous Li 2B 4O 7 solutions from 0.027 5 to 2.939 7 mol/kg were determined at 298.15 K by using an improved apparatus. The rule of the changes in vapor pressure over aqueous Li 2B 4O 7 solutions was revealed, which indicated that the bond of borate anions with water are better than that of NaCl. The different formation reaction equilibria for the species containing boron of boric acid and borate anions B(OH) - 4, B 3O 3(OH) - 4 and B 4O 5(OH) 2- 4 in Li 2B 4O 7(aq) solutions were taken into account. The stoichiometric equilibrium constants for the formation reactions of the boron species and the ion-interaction parameters were estimated simultaneously by using Pitzer equations of osmotic coefficient with minor modifications. Sixteen parameters were obtained with a standard deviation 0.005 5 for the ion-interaction model.
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.
