Removal of heavy metal ions from aquatic solutions by membrane chromatography

Polyvinylalcohol membranes were prepared by a solvent casting technique. Me tal-complexation ligand, i.e. monochlorotriazinyl-dye Cibacron Blue F3GA wa s then attached. These membranes with a high water content of 119%, and con taining 8.7 mmol Cibacron Blue F3GA/m(2) were used in the adsorption/stripp ing of some selected heavy metal ions [Cu(II), Hg(II), Pb(II) and Cd(II)] f rom aquatic solutions containing varying initial concentration of metal ion s. Adsorption rates were very high, and equilibrium was achieved in about 1 0 min. The non-specific adsorption of heavy metal ions on the plain membran es was low [0.63 mmol/m(2) for Cu(II), 0.75 mmol/m(2) for Hg(II), 0.94 mmol /m(2) for Pb(II) and 1.22 mmol/m(2) for Cd(II)]. The maximum adsorptions of heavy metal ions onto the Cibacron Blue F3GA-attached affinity membranes f or non-competitive conditions were 16.9 mmol/m(2) for Hg(II), 19.2 mmol/m(2 ) for Cu(II), 25.8 mmol/m(2) for Pb(II), 32.4 mmol/m(2) for Cd(II). The obs erved order in adsorption was found to be Cd(II) > Pb(II) > Cu(II) > Hg(II) . Different behavior was observed for competitive adsorption. The order of affinity was Cu(II) > Cd(II) > Hg(II) > Pb(II). Regeneration of polyvinylal cohol membranes was done by using 0.1 M HNO3 in 30 min. Heavy metal ions co uld be repeatedly adsorbed and stripped without significant decrease in ads orption capacity. The experimental data of adsorption from solutions contai ning metal ions were found to correlate well with Langmuir isotherm equatio n. (C) 2000 Elsevier Science B.V. All rights reserved.