β-Cyclodextrin functionalized polystyrene porous monoliths for separating phenol from wastewater

A beta-cyclodextrin (beta-CD) functionalized polystyrene porous monolith was prepared by the following procedure: First, beta-CD was modified with allyl bromide leading to allyl-beta-cyclodextrin (allyl-beta-CD); then a concentrated emulsion was prepared using a mixture of allyl-beta-CD, styrene, and divinyl benzene as the continuous phase and water as the dispersed phase. In the third step, a beta-cyclodextrin (3-CD) functionalized polystyrene porous monolith was obtained by copolymerization of allyl-beta-CD and styrene followed by removal of the water phase. Since the allyl-beta-CD contained both hydrophilic and hydrophobic groups, it tended to move towards the water/oil interface. As a result, the internal surfaces of the porous monolith were enriched with beta-CD. This enrichment was indicated by X-ray photoelectron spectroscopy characterization. The high content of beta-CD and the high specific surface area of the porous monolith both contributed to a high adsorption capacity. For example, the maximum adsorption of phenol was 5.74 mg/g. Importantly, the porous monolith could be easily regenerated and recycled through desorption with ethanol and it was found that the adsorption properties remained stable for at least five adsorption/desorption cycles. (C) 2014 Elsevier Ltd. All rights reserved.