Adsorption of Benzenesulfonic Acid on a Novel Dual Functional Weakly Basic Anion Exchanger from Aqueous Solution

A novel weakly basic anion exchange resin AEC-5 bearing two differently sized functional groups was prepared through chloromethylated PS-DVB copolymer beads reaction with a mixture of dibutylamine and dimethylamine. To better understand the benefits of AEC-5 for removing benzenesulfonic acid (BSA) from aqueous solution, adsorption properties of BSA on AEC-5 were compared with two monofunctional anion exchange resins, a commercial exchanger D301 derived from dimethylamine and a synthesized resin AEC-4 derived from dibutylamine. Adsorption isotherms and effect of solution pH, temperature, time, and coexisting Na2SO4 on sorption behavior were investigated and column adsorption-regeneration tests were carried out. AEC-5 showed a greater adsorption capacity than both monofunctional anion exchangers for BSA in the presence of Na2SO4. Equilibrium and kinetic data could be well matched with the Langmiur isotherm model and pseudo-second-order model respectively. AEC-5 had better adsorption kinetics than AEC-4. Thermodynamic parameters were also analyzed and results indicate that BSA adsorption on AEC-5 is an exothermic and spontaneous process. AEC-5 is very likely to be a potential alternative adsorbent, which is believed to possess an excellent selectivity for BSA over sulfate, acceptable kinetics, and desorption characteristics, for its application in industrial wastewater treatment.