Ion-exchange sorption of thiosulfate and tetrathionate on protonated poly(4-vinyl pyridine)

Abstract

In order to explore the possibility of using cross-linked poly(4-vinyl pyridine), PVP, for selective removal of thioanions in waste water by ion exchange, the sorption behavior of S 2O 3 2− and S 4O 6 2− on the resin, operating in an acid salt form, has been studied. The results are compared with those obtained on a conventional gel-type weak-base resin, Amberlite IRA-68. The thioanions are selectively sorbed in preference to other common ions and are rapidly stripped with dilute sodium hydroxide or ammonia. The equilibrium sorption is described by the Langmuir isotherm. Protonated PVP has more than 50% higher sorption capacity compared to protonated IRA-68 and has faster sorption kinetics. The S 4O 6 2− anion has greater diffusivity as well as a higher binding constant with both resins compared to the S 2O 3 2− anion. the sorption rate of both S 2O 3 2− and S 4O 6 2− is particle-diffusion controlled and is well described by the unreacted-core model for unchanging particle size.