A new amine-modified hypercrosslinked polymeric adsorbent for removing phenolic compounds from aqueous solutions

A new amine-modified hypercrosslinked polymeric resin, AH-6 for the removal of phenolic compounds from their aqueous solutions was prepared by introducing dimethylamine groups onto the matrix of the conventional hypercrosslinked polymeric adsorbent NDA100. The adsorption of four phenolic compounds, i.e. phenol, p-cresol, p-chlorophenol and p-nitrophenol, onto the NDA100 resin with or without amine modification was investigated using the commercial styrene-type weakly alkaline resin D301 as a reference. The Freundlich isotherm equation was employed to fit the adsorption process. The aminated hypercrosslinked polymeric resin exhibited a higher adsorption capacity towards phenol and p-chlorophenol than both the unmodified hypercrosslinked polymeric resin NDA100 and the styrene-type weakly alkaline resin D301. To interpret the adsorption behaviour of the AH-6 resin, a dual function interaction mechanism involving pi-pi interaction between the AH-6 resin matrix and the benzene ring of the adsorbate and hydrogen-bonding interaction between the hydroxyl groups of the adsorbate and the amine group of the adsorbent was proposed. In contrast, hydrogen-bonding or donor-acceptor interaction may govern the adsorption of p-nitrophenol.