Sorption enhancement of aromatic sulfonates onto an aminated hyper-cross-linked polymer

A macroreticular resin adsorbent CHA-101 was aminated by dimethylamine, and a novel sorbent named M-101 was obtained. Several industrially important aromatic sulfonates including sodium benzenesulfonate (BS), sodium p-toluenesulfonate (TS), and sodium 2-naphthalenesulfonate (NS) were selected as general solutes to evaluate the performance of the newly synthesized resin particles. X-ray photoelectron spectroscope (XPS) analyses was used to determine the protonation degree of amino group at different solution pH, and the effect of pH on the sorption of these solutes onto M-101 can be explained by the ion exchange mechanism. The experimentally observed sequence of the sorption capacity of the tested organic sulfonates onto M-101 indicates that the pi-pi interaction between the solute molecule and the polymer matrix plays an important role in uptake of organic sulfonates from aqueous solution. Sodium sulfate was selected as a typical competitive inorganic anion, and improved selectivity of BS sorption over sulfate on M-101 was observed by comparison with a common macroporous weak base anion exchanger D-301. In addition, both sorption and desorption kinetics of M-101 were also found to be faster than that of D-301. Analyses of sorption isotherms and thermodynamics proved that BS sorption on M-101 was an exothermic and more selective process than on D-301. Both column tests and field applications proved M-101 to be an effective sorbent that can be used to remove aromatic sulfonates from aqueous solution.