Thiourea modified hyper-crosslinked polystyrene resin for heavy metal ions removal from aqueous solutions

A hyper-crosslinked resin chemically modified with thiourea (TM-HPS) was synthesized, characterized, and evaluated for the removal of heavy metal ions (Pb2+, Cd2+, and Cu2+) from aqueous solutions. The structural characterization results showed that a few thiourea groups were grafted on the surface of the resin with a big BET surface area and a large number of narrow micropores. Various experimental conditions such as pH, contact time, temperature, and initial metal concentration of the three heavy metal ions onto TM-HPS were investigated systematically. The results indicated that the prepared resin was effective for the removal of the heavy metal ions from aqueous solutions. The isotherm data could be better fitted by Langmuir model, yielding maximum adsorption capacities of 689.65, 432.90, and 290.69 mg/g for Pd2+, Cd2+, and Cu2+, respectively. And the adsorption kinetics of the three metal ions followed the pseudo-second-order equation. FTIR and XPS analysis of TM-HPS before and after adsorption further revealed that the adsorption mechanism could be a synergistic effect between functional groups and metal ions and electrostatic attraction, which may provide a new insight into the design of highly effective adsorbents and their potential technological applications for the removal of heavy metal ions from aqueous solutions. (C) 2017 Wiley Periodicals, Inc.