Adsorption of H_3PO_4, NaH_2PO_4, Na_2HPO_4, and Na_3PO_3 on strongly basic ion exchanger

摘要

The possibility of recovering phosphate ions using a strongly basic ion exchanger was investigated. An OH-type DIAION SA10A was used to measure the adsorption equilibria of H_3PO_4, H_2PO_4~-, HPO_4~(2-), and PO_4~(3-) ions. The results appeared technically feasible. In all the systems, the experimental adsorption isotherms show a high amount of phosphate adsorption. Morevoer, differences in the adsorption behaviors were observed. These differences were highly influenced by the pH of the equilibrated solutions. The ion-exchange reaction models were tehn proposed. By the mass action law, theoretical equations for the adsorption isotherms were derived and the unknown experimental equilibrium constants were determined. The proposed models were able to correlate the experimental data well and able to explain the peculiarities in the adsorption isotherms.