Synthesis Method of Mesoporous Silicas with Chelating Ligands for Heavy Metal Ion Removal in Aqueous Solutions

摘要

PURPOSE: A method of synthesizing mesoporous silica suitable to selective adsorption for heavy metal ion dissolved in wastewater, especially from plating industries. In this method, tetrealkoxysilanes such as tetramethoxysilane or tetraethoxysilane are used as structural precursor of the mesoporous silica. Dodecyl amine, a kind of neutral amine surfactant, is used to prevent destruction of hydroxyl radicals in silica walls during the calcining process. In addition, such reagents as 3-aminopropyl triethoxy silane and 3-mercaptopropyltrimethoxy silane are used to introduce amine and thiol group, which are reactive with heavy metal ions, on silica walls. CONSTITUTION: The mesoporous silica is synthesized by (i) after dissolving dodecyl amine into ethanol, mixing the mixture solution with tetraethoxy silane; (ii) addition of 3-aminopropyl triethoxy silane and 3-mercaptopropyltrimethoxy silane into the mixture solution at the point that the mixture solution become milky after the hydration and condensation of tetraethoxysilane, and then agitating severely for more than 20hrs; (iii) drying the obtained mesoporous silica at an ambient temperature for more than 24hrs, and then soxhlet extraction with ethanol for more than 72hrs to eliminate residual surfactants and organic silane; (iv) drying resultant mesoporous silica at an ambient temperature for more than 24hrs, and then heating at 100deg.C for 1hr.