A novel adsorbent based on functionalized three-dimensionally ordered macroporous cross-linked polystyrene for removal of salicylic acid from aqueous solution

A novel polymeric adsorbent with three-dimensionally ordered macroporous (3DOM) structure was prepared. Poly(2-hydroxyethyl methacrylate) (PHEMA) was controllably grafted from the pore wall of 3DOM cross-linked polystyrene (3DOM CLPS-g-PHEMA) by surface-initiated atom-transfer radical polymerization (SI-ATRP) technique. Batch adsorption runs of salicylic acid from aqueous solution onto 3DOM CLPS-g-PHEMA were investigated as well as the relationship of the grafted amount with the adsorption capacity. When the grafted amount was 22.1%, the 3DOM CLPS-g-PHEMA exhibited the optimum adsorption capacity. Commercial macroporous resin XAD-4 was chosen as the comparison. Adsorption isotherm experimental results indicated that isotherms of salicylic acid adsorption onto 3DOM CLPS-g-PHEMA adsorbent could be represented by Langmuir and Freundlich models and the Freundlich model was shown to be the most suitable. The 3DOM CLPS-g-PHEMA exhibited a much higher adsorption capacity of salicylic acid than that of XAD-4, attributing to the special structure of 3DOM polymer and the grafted polymeric chains on the pore walls. The adsorption capacities increased with temperature increasing, and the isosteric enthalpy changes were calculated with a derivative Van't Hoff equation. Kinetics studies showed that the salicylic acid uptake onto 3DOM CLPS-g-PHEMA followed the pseudo-second order model. In addition, the spent 3DOM CLPS-g-PHEMA could be regenerated by extracted with ethanol, the regenerated 3DOM CLPS-g-PHEMA also exhibited the high adsorption capacity. We envision that the novel 3DOM polymeric adsorption will play a significant role in developing a new generation adsorbent. (C) 2012 Elsevier B.V. All rights reserved.