Extraction of gallium, indium and thallium from aquatic media using amino silica gel modified by gallic acid

The surface of amino-functionalized silica gel was modified with gallic acid to give a newly chelating matrix for extraction of Ga(III), In(III) and Tl(III). The pH ranges for the sorption and elution were opimized. The sorption capacities of the matrix are 0.29, 0.32, 0.35 mmol g(-1) for Ga(III), In(III) and Tl(III), respectively, the preconcentration factor is 250, and the lower limits of detection are 5.80, 1.82 and 1.11 mu g L-1, respectively. The interference by Al(III) can be masked by addition of fluoride, that of Fe(III) ion by its reduction to Fe(II) ion. The method was successfully applied to the analysis and separation of these ions from spiked water samples, zinc granules and lead sheet.