Enhanced Adsorption of p-Nitrophenol from Aqueous Solutions Using a Functionalized Styrene-Divinylbenzene Copolymer

The effect of styrene-divinylbenzene copolymer functionalization by carboxylic acid groups on the adsorption of p-nitrophenol (p-NP) from aqueous solutions was investigated. The adsorption capacity of p-NP onto the functionalized copolymer (CP-F) was compared with that of the precursor copolymer, the chloromethylated styrene-divinylbenzene copolymer (CP-N). The two copolymers were characterized by Fourier transform infrared (FTIR) spectroscopy, thermal analysis (DSC-TG), specific surface area and particle size measurements, pore size distribution, scanning electron microscopy (SEM), and elemental analysis (EDX). The adsorption of p-NP was substantially enhanced after the polymer functionalization, and it was demonstrated that hydrogen bonding is principally responsible for the high adsorption capacity of CP-F in comparison with CP-N. The adsorption kinetics of p-NP adsorption onto CP-F was well described by the pseudosecond-order model. From the four investigated isotherms, Langmuir, Freundlich, Redlich-Peterson, and Sips, the equilibrium data were better described by the Sips model. The maximum adsorption capacity of the CP-F polymer resulting from the Sips isotherm was 243.37 mg g(-1). The capacity of regeneration and reuse of the CP-F polymer was evaluated in three consecutive cycles of adsorption-desorption.