Abstract
The TiO2/bentonite composite was synthesized by modifying calcium-based bentonite with Nano-TiO2. The products before and after modification were characterized via the approach of X-ray power diffraction(XRD) and scanning electron microscope(SEM).The effect of TiO2/bentonite composite on mercury removal from aqueous solutions of HgCl2was studied at different dosage, pH, adsorption time and the initial concentration of Hg2+ was investigated and compared with the bentonite by indoor simulation experiment, as well as the orthogonal experiments to determine the optimal condition of Hg2+ adsorption. The experimental results showed:after modified by TiO2, TiO2/bentonite composite particles were apparently smaller, the basal spacing was increased and with a loose and porous structure. The adsorption rates of TiO2/bentonite composite on Hg2+ were increased compared with bentonite. The Hg2+ adsorption rates were increased with the increasing dosages, pH and adsorption time. The adsorption rates were higher than 98.0% when the dosage was 1.5 g·L-1, pH 7.0, and the adsorption time was 120 min. The adsorption rates became smaller with increasing initial concentration of Hg2+. False secondary dynamic equation could describe the adsorption of TiO2/bentonite composite on Hg2+, and the chemical adsorption was dominant. The adsorption isotherm of Hg2+ conformed to Langmuir equation, indicating that the adsorption of Hg2+ was typical monolayer adsorption. The optimal experimental condition was:dosage of 2.0 g·L-1, pH 8.0, adsorption time of 16 h and the initial Hg2+concentration of 45 mg·L-1. Under this condition, the adsorption rate was 99.9%, and the equilibrium concentration of Hg2+ was 0.034 mg·L-1.
Published Version
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