Effect of polymeric matrix on the adsorption of reactive dye by anion-exchange resins

Two ion-exchange resins with similar properties, namely, polystyrene anion-exchange resin SAER and polyacrylic anion-exchange resin AAER, were applied for orange G removal to investigate the effect of polymeric structure on adsorption. Despite having similar adsorption capacities, AAER exhibited an initial reaction rate that was 2.0-4.4 times greater than that of SAER. Moreover, the adsorption isotherm on AAER followed the Langmuir equation, whereas the adsorption on SAER was better described by the Freundlich equation. AAER adsorption was dominated by ion exchange, as indicated by the ratio of released Cl- to adsorbed orange G, which was 1.10. By contrast, this ratio was 0.754 in SAER, indicating that other interactions aside from ion exchange were involved in the adsorption of SAER, such as hydrophobic and pi-pi-interactions. AAER showed higher regeneration efficiency than SAER using NaCl solution as the desorption agent. These results demonstrated that AAER was a more suitable adsorbent for orange G removal. (C) 2016 Published by Elsevier B.V. on behalf of Taiwan Institute of Chemical Engineers.