Polycondensation of Silicate with Hydroxocomplexes of Some Amphoteric Elements in Aqueous Solution

Reactions of aqueous solution of silicate with hydroxocomplexes of Al(III), Sn(IV), Zn(II) and Ga(III) have been experimentally studied. All studied reactions have produced gel in the whole volume of reaction mixture, and according to our hypothesis the essence of these reactions is polycondensation between silicate anions and anions of hydroxocomplex of the given amphoteric element, with formation of crosslinked inorganic polymer. Criterion for studying the course of the tested reactions has been the gel-point time of the reaction mixture. Dependences of the gel-point time on temperature, on KOH concentration and on molar ratios of silicate/amphoteric element in reaction mixture have been recorded. Products of the studied reactions have been analyzed by means of X-ray fluorescent spectrometry. All obtained results are in accord with the hypothesis of polycondensation reaction between silicate and hydroxocomplexes, and indicate that the reaction between silicate and hydroxoaluminate is merely one case of a more general chemical reaction.