Effect of Preparation Conditions on the Adsorption of Heavy Metal Ions from Aqueous Solution by Mesoporous Silica Materials Prepared Using Organic Template (HDTMAB)

This paper describes the simple hydrothermal preparation of self-adsorbing mesoporous materials using hexadecyltrimethyl ammoniumbromide (HDTMAB) as the template without any functionalization. The template was readily removed upon calcination, as confirmed through Fourier transform infrared spectroscopic analysis. The effects of preparation methods were explored under various experimental conditions. We found that the temperature, time, calcination conditions, and pH all affected the distribution of pore sizes and the surface area, whereas higher pH (strong base) did not favor the preparation of a porous medium because of OH inhibition. We obtained a relatively high surface area (1568.72 m(2).g(-1)) and large pore size (3.07 nm) under the optimal reaction conditions. A study of the Langmuir adsorption of metal ions (e.g., Pb2+, Cu2+, Ni2+) revealed that it was a physical phenomenon with the maximum adsorption occurring for the sample prepared under the optimized experimental conditions, with Pb2+ (6.61 mg.g(-1)) exhibiting enhanced adsorption relative to Cu2+ (3.46 mg.g(-1)) and Ni2+ (2.25 mg.g(-1)) because of its larger ionic radius and higher electronegativity. Thus, such as-synthesized mesoporous materials hold great potential for use in the removal of heavy metal ions from aqueous solutions compared to commercially available powdered activated carbon (PAC).