Synthesis, characterization, and adsorption behavior of aniline modified polystyrene resin for phenol in hexane and in aqueous solution

Macroporous crosslinked poly(p-vinylbenzylaniline) (PVBA) was synthesized and its adsorption isotherms for phenol in hexane and in aqueous solution were comparatively measured. It was shown that the adsorption isotherms in hexane were straight lines and passed through the origin, whereas those in aqueous solution could be simulated by Freundlich isotherms. Adsorption enthalpies of phenol onto PVBA were calculated, and the results indicated that the adsorption was an exothermic process. Comparison of the adsorption behaviors of PVBA, poly(p-vinylbenzylmethylamine) (PVBMA), and poly(p-vinylbenzyl-p-nitroaniline) (PVBNA) for phenol in hexane suggested that hydrogen bonding and pi-pi stacking were primarily responsible for the adsorption, the nitrogen atom and benzene ring of PVBA acted as hydrogen bonding acceptors and formed hydrogen bonding with the hydrogen atom of hydroxyl group of phenol. Investigation of the adsorption mechanism in aqueous solution revealed that hydrogen bonding and hydrophobic interaction were the main driving forces.