Adsorption Properties of Functional Silicas Towards Some Toxic Metal Ions in Water Solutions

Processes of preconcentration of heavy toxic metal ions, such as Pb(II), Cd(II), Zn(II), Hg(II), and Mo(VI) on the silica with covalently bound complexing phenolic-type analytical reagents 8-hydroxyquinoline, 1-(2-pyridylazo)-2-naphthol, 4-(2-pyridylazo)resorcinol have been studied. Structures of the surface complexes of toxic metals with grafted analytical reagents were determined using IR, ESR and electronic diffuse reflectance spectroscopies. Possibility of simultaneous determination of micro amounts of heavy metals was demonstrated using the x-ray fluorescence analysis of modified adsorbents after absorption of metal ions from their multicomponent mixtures in natural and artificial water solutions. Silica gel with adsorbed polyionene (1,4-MePh) was shown to have high adsorption properties towards some metal-containing anions, in particular MoO^2-₄, WO^2-₄ and Cr₂O^2-₇ in water solutions. Adsorption isotherms of these metal-containing anions on initial silica gel and silica-supported polyionene were investigated.

Keywords: modified silica; immobilized 8-hydroxyquinoline; 1-(2-pyridylazo)-2- naphthol; 4-(2-pyridylazo)resorcinol; polyionene; preconcentration; heavy metal ions; x-ray fluorescence analysis