Chelating properties of salicylhydroxamic acid-functionalized polystyrene resins and its application to efficient removal of heavy metal ions from aqueous solutions

Salicylhydroxamic acid(SHA) was covalently bound onto crosslinked polystyrene spheres(CPSs) via the Friedel-Crafts alkylation reaction between chloromethylated CPSs and SHA in the presence of SnCl4 as the Lewis acid catalyst. The resulted SHA-CPSs possessed very strong chelating ability for heavy metal ions. In particular, the saturated adsorption amount of SHA-CPSs for Cu2+ ions could reach as high as 34.2 mg/g at 318 K. The chelating capability of SHA-CPSs towards heavy metal ions was pH and temperature dependent. SHA-CPSs also showed selective metal coordination with the chelating capacity decreasing in the order of Cu2+ >Zn2+>>Pb2+. The adsorption isotherms conformed well to the Langmuir model, and the adsorption process was found to be entropy-driven and endothermic. Besides, SHA-CPSs possessed the excellent reusability.