Adsorption characteristics of fumaric acid onto weakly basic hypercrosslinked polystyrene ion-exchangers

A new weakly basic ion-exchanger (called XC-11), with a hypercrosslinked macroporous polystyrene matrix and a high specific surface area, was synthesized. When traditional weakly basic ion-exchange resins were employed in adsorption experiments, it was found that their sphericity after attrition decreased drastically when they were used ten times cyclically to adsorb and desorb famaric acid from actual manufacturing effluent. This indicated that a traditional weakly basic exchange resin could not be applied in practice for the recovery of fumaric acid from industrial wastewater. However, the mechanical strengths of the self-synthesized new weakly basic ion-exchanger XC-11 and the hypercrosslinked polymeric adsorbent NDA-150 remained virtually unchanged under the same conditions, indicating their feasibility for practical applications. Thus, the adsorption of fumaric acid from aqueous solutions onto XC-11 and the commercially available hypercrosslinked polymeric adsorbent (NDA-150) taken as a reference was investigated from both a dynamic and thermodynamic standpoint. Favourable adsorption behaviour towards fumaric acid was observed with both adsorbents, the equilibrium adsorption data obtained being very well fitted by the Freundlich model. ne corresponding Freundlich constants, K, and free energy changes, Delta G, indicated that the adsorption capacity of XC-11 towards fumaric acid was greater than that of NDA-150.The pseudo-first-order and pseudo-second-order kinetic models were applied to describe the kinetic data, with the pseudo-second-order model providing a perfect fit. It was also found that the adsorption of fumaric acid onto XC-11 proceeded faster than the corresponding process onto NDA-150.