Recovery of Organic Acids Using Ion-Exchanger-Impregnated Resins

摘要

The recovery of organic acids from aqueous solutions using ion-exchanger-impregnated resins has been investigated. The key parameters for process design are equilibria, mass transfer kinetics and loss of the liquid ion exchanger (bleeding). The maximum bleeding was observed when the resin was used for the first time. The ion exchanger concentration in the aqueous phase decreases to a final concentration lower than 1 mg/L after the first usage. The equilibria of citric and tartaric acid have been investigated for the different macroporous resins XAD4 and XAD16 impregnated with tri-n-octylamine (TOA). A modified Langmuir isotherm taking the loading of ion exchanger TOA on the resin into account is able to describe the equilibrium in both test systemsd in dependence of the temperature. Experiments in a stireed vessel have been carried out to characterize the intraparticular mass transfer. The results have been used to predict the effective pore diffusion coeficient using the tortuosity.