Adsorption of phenol and p-chlorophenol from aqueous solutions on poly (styrene-co-divinylbenzene) functionalized materials

Two new poly (styrene-co-divinylbenzene) polymers functionalized with amino-phosphinic acid groups (P1) and with carboxylic acid groups (P2) were prepared and their adsorption capacities for phenol and p-chlorophenol (PCP) in aqueous solutions were investigated and compared to that of the commercially available XAD-4 resin. Elemental analysis, infrared spectroscopy, thermogravimetric analysis and porosity measurements were used to characterize the polymers. The kinetics studies demonstrated that the adsorption of phenol and PCP onto P1, P2 and XAD-4 adsorbents followed the pseudo-second order model. The experimental equilibrium data were fitted with Langmuir, Freundlich, Redlich-Peterson, and Sips isotherms. P2 polymer showed the best adsorption capacity which may be attributed to the carboxyl groups that have good affinity for the formation of hydrogen bonding with phenol and PCP. The lower adsorption capacity of phenol and PCP onto the P1 polymer compared to P2 and XAD-4 may be explained by the steric hindrance determined by the bulky aminophosphinic acid groups grafted onto P1 polymer. P2 polymer exhibited larger adsorption capacity for both phenol and PCP when compared with the commercially available XAD-4 which suggested the potential application of this resin in removal of phenolic pollutants from wastewaters. (C) 2013 Elsevier B.V. All rights reserved.