A Procedure to Monitor Sulfonation of Macroporous Styrene‐Divinylbenzene Resins

Abstract

The ratio between the number of functional groups grafted in micro and macropores for Purolite C 150 resin, a macroporous styrene‐divinylbenzene copolymer, with –SO₃H functional groups, was evaluated using a kinetic procedure based on a bidisperse pore model. The proposed procedure requires potentiometric measurement at constant temperature in batch system of the fractional approach to equilibrium for H⁺/Na⁺ ion exchange process on the macroporous resin in concentrated external solution, 1.00 mol/L NaCl. The macropore integral interdiffusion coefficients were computed at each point on the fractional approach to equilibrium versus time curve, for different values of the β/α parameter of the model, which is three times the ratio of micropore and macropore uptake at equilibrium. Several discrimination criteria were used to select a reliable β/α value. The result for Purolite C 150 resin is β/α ≤ 0.03; the ratio between the sulfonic groups grafted onto micro and macropores is equal to or lower than 1/100.

Acknowledgements

This paper was presented in part at IEX 2004 Conference, Cambridge, UK, July 2004. This work was supported by the CNCSIS, Romania, under grant No. 40528/5.11.2003, code 137. The authors wish to thank Purolite International Limited for supplying the resins.