Retention of chromate ion by conventional and N-ethylpyridinium strongly basic anion exchange resins

Abstract

A comparative analysis of the behaviour of two strong base anion exchangers with different chemical structures, namely a noncommon strong base anion exchanger containing 4-vinyl-1-ethylpyridinium chloride structural units from the quaternization of the gel type 4-vinylpyridine:8% divinylbenzene copolymer and a commercial type I and gel styrene strong base anion exchanger, Purolite A 400, in the retention process of CrO 4 2− anion from K 2CrO 4 aqueous solutions was investigated. For this, using the batch method, the ion-exchange equilibrium and kinetics studies were performed. From these studies the following aspects were observed: (a) the two resins had the retention capacities of CrO 4 2− anion of the same values with those of their exchange capacities, a higher value being for the pyridine resin; (b) the ion-exchange isotherms and the separation factors showed that both resins exhibited a much higher preference for CrO 4 2− anion over Cl − anion, the higher preference having the styrene resin; (c) for both resins appeared the same ion-exchange rates and using Boy–Adamson diffusion equation, the ion diffusion apparent coefficients were calculated, they having values of 1.587 × 10 −8 cm 2/s and 2.140 × 10 −8 cm 2/s for pyridine resin and Purolite A 400, respectively.