Synthesis and Sorption Properties Towards Toxic Metal Ionsof Composites Based on Silica Gel and Adsorped 4-Vinylpyridine and Tert-Butyl Methacrylate Copolymers

Background. Organo-mineral composite materials sufficiently enlarge adsorption properties of porous inorganic materials and effective sorbents could be obtained for the toxic metal ions extraction from the waste water. The presented paper describes the synthesis of the new organo-mineral composites obtained by adsorption on the silica gel surface of 4-vinylpyridine (4-VP) and tert-butyl methacrylate (TBMA) copolymers with different molar ratios of co-monomers and investigates their sorption properties towards Cu(II), Cd(II), Pb(II) and Fe(III) ions. Methods. The molar content of 4-vinylpyridine links in the synthesized copolymers was determined using 1H NMR spectra. Weight fractions of copolymers in the synthesized composites were determined by thermogravimetric analysis. The sorption capacity of the synthesized composites towards Cu(II), Cd(II), Pb(II) and Fe(III) ions were investigated in a static mode, equilibrium concentrations of metal ions were detected by atomic-absorption method. Results. Copolymerization of 4-vinylpyridine and tert-butyl methacrylate with starting molar ratios 1 : 4, 1 : 1, 4 : 1 was carried out at 75 °C in an argon atmosphere in the balk. The organo-mineral composites were formed by adsorption of these copolymers on the silica gel surface in the mass ratio of copolymer:silica as 1 : 4. It was found that the fractions of adsorbed copolymers in composites obtained are: 13?6 ± 0,1 wt. % for the copolymer with starting molar ratio 4-VP : TBMA = 1 : 4 (composite 1); 15,7 ± 0,1 wt. % for the copolymer with starting molar ratio 4-VP:TBMA = 1 : 1 (composite 2) and 16,0 ± 0,1 wt. % for the copolymer with starting molar ratio 4-VP : TBMA = 4 : 1(composite 3). It was found out that the sorption capacity of the synthesized composites 1–3 towards Cu(II), Cd(II), Pb(II) and Fe(III) ions in 2–3 times higher in comparison with the sorption capacity of parent silica gel. Conclusions. The best sorption properties were determined for composite 3 with the highest content of 4-VP monomer in the adsorbed copolymer.