Microporous poly( 2-hydroxyethylmethacrylate) (PHEMA) membranes carrying ethylene diamine (EDA) and Cibacron Blue F3GA were prepared for the removal of heavy metal ions (i.e. mercury, copper, lead and cadmium) from aqueous solutions containing different amounts of these ions (5-700 mu g 1(-1)) and at different pH values (2.0-8.0). The non-specific adsorption of heavy metal ions on the underived membranes was very low (3.3 mmol/m(2) for Hg(II), 0.5 mmol/m(2) for Cu(II), 1.2 mmol/m(2) for Pb(II) and 1.1 mmol/m(2) for Cd(II)). Cibacron Blue F3GA attachment significantly increased the heavy metal adsorption (16.3 mmol/m(2) for Hg(II), 19.9 mmol/m(2) for Cu(II), 23.4 mmol/m(2) for Pb(II) and 38.4 mmol/m(2) for Cd(LI)). When the heavy metal ions competed (in the case of the adsorption from a mixture) the adsorption capacities were 7.1 mmol/m(2) for Hg(II), 17.9 mmol/m(2) for Cu(II), 6.2 mmol/m(2) for Pb(II) and 9.1 mmol/m(2) for Cd(lI). The observed order in adsorption was found to be Cd(II) > Pb(II) > Cu(II) > Hg(II) for non-competitive conditions. The adsorption of heavy metal ions increased with increasing pH and reached a plateau value at around pH 5.0. Desorption of heavy metal ions was achieved using 0.1 M HNO3. These membranes are suitable for repeated use for more than five cycles without considerable loss of adsorption capacity. (C) 2000 Elsevier Science B.V. All rights reserved.