Synthesis of (Ti/Si) mixed oxides for the removal of Cr(VI) in simulated effluents

The use of agroindustry residues as precursor materials in the absorption processes has taken a significant importance due to their great absorptive porous characteristics; however, the most critical drawback of the heavy metals is the difficulty of eliminating them, particularly, the Cr(VI), which is widely used in tannery but, at the same time, is considered a powerful cancerogenic and mutagenic agent. For this reason, it is crucial to seek strategies to eliminate, or form complexes for future immobilization, such heavy metals. This research proposes the synthesis of a mix of silica/titanium (Si/Ti) using the rice husk as the source of silica, and titanium tetrachloride as a precursor of titanium for the removal of the Cr(VI) in simulated effluents. TGA, IR-ATR analysis, SEM, powder diffraction and fluorescence were applied to verify the efficiency of the reaction and the adsorptive capacity. Three variables were considered significant in the adsorption process: pH; amount of dosage; and concentration of Cr(VI) contaminant, which were assessed independently for silica oxide, from which a removal rate of 53.4 %, pH 1, 1,5 g adsorbent/L and initial concentration of Cr(VI) 0.08 mg/L was obtained. For the mixed oxide from a removal percentage of 97.2 % was obtained, with the best removal conditions at a pH of 1.5 g/L adsorbent dosage amount and Cr(VI) contaminant concentration of 0.08 mg /L.