Crosslinked styrene (St)/maleic anhydride (MA) copolymers were synthesized, hydrolyzed with dicarboxylic acid, and converted to bear dihydroxyphosphino functionalities. The St-MA copolymers were prepared by azobisisobutyronitrile-initiated polymerization in toluene at 90 degreesC in the presence of 2, 10, or 20% divinylbenzene crosslinker. The MA moiety was hydrolyzed into dicarboxylic acid to improve the hydrophilicity of the copolymers. The phenyl ring of St was phosphorylated with phosphorus trichloride in the presence of aluminum chloride and then hydrolyzed and oxidized with nitric acid at room temperature. The structures of the hydrolyzed and dihydroxyphosphino-functionalized copolymers were confirmed by Fourier transform infrared spectroscopy and elemental analysis. The complexation behavior of these functionalized copolymers toward metal ions in 25 ppm aqueous solutions was observed over time periods of up to 7 h. The adsorption toward Pb(+2) was highest, followed by those of Cu(+2), Cr(+3), and Ni(+2). On the dihydroxyphosphino-functionalized St-MA (20% divinylbenzene) copolymer, the adsorption of Pb(+2) showed a linear relationship with the concentrations and fit the Langmuir isotherm. The kinetics of Pb(+2) adsorption on this dihydroxyphosphino-functionalized copolymer also fit the rate equation of the moving boundary model, t = [1 - 3(1 - X)(2/3) + 2(1 - X)], where X is the fractional conversion. The metal-ion adsorption kinetics of this copolymer appeared to be particle diffusion control, in which the moving boundary advanced from the surface toward the center. (C) 2003 Wiley Periodicals, Inc.