Preparation of mesoporous silica from coal slag and its metal ion adsorption behavior

A novel mesoporous silica (MS) with the high specific surface area up to 1,199 m2/g was prepared from coal slag by SO 3 2− leaching and hydrothermal synthesis. Its application in metal ion removal was explored using Pb2+, Cu2+, Co2+ and Cd2+ as the model ions. The effects of adsorption time, pH, initial metal ion concentration, adsorbent dosage and adsorption temperature on the metal ion adsorption behaviors of the as-prepared MS were systematically, and the maximum adsorption capacities were measured to be 55.76 mg·g−1, 33.49 mg·g−1, 24.29 mg·g−1 and 22.98 mg·g−l for Pb2+, Cu2+, Co2+ and Cd2+, respectively. The metal ion adsorption on the as-prepared MS followed pseudo-second-order kinetics, and the adsorption isotherm fitted the Langmuir isotherm model, indicating that the adsorption was spontaneous, endothermic and enthalpy driven.