Highly qualified homogeneous poly(benzylsulfone) plate affinity membrane with mercapto group (PSF-SH) was prepared successively through reactions between chloromethyl polysulfone matrix membrane and thiourea, and then alkalic hydrolysis. The mercapto-functionalized polysulfone affinity membrane was utilized for the adsorption of Hg2+ cations through the coordination of the mercapto group and Hg2+ cations, in which the effects of the morphological and the structure of the affinity membrane on the chelating properties were investigated. The chelating conditions, including concentration of Hg2+, and temperature and pH of the introductory solution had significant influence on the chelating capacity of PSF-SH affinity membrane. The highest static and dynamic chelating capacity of PSF-SH plate membrane for Hg2+ cations were 398 and 403 mu g/cm(2) per membrane, respectively, which demonstrated that the resultant polymer membrane was a highly efficient affinity chromatography for Hg2+. The affinity membrane containing mercapto group can be conveniently recovered by dilute hydrochloric acid for coordination of Hg2+ cations, which would have wide application for the treatment of waste water containing heavy metal cations. (c) 2006 Wiley Periodicals, Inc.