Synthesis of Mesoporous Calcium Silicate by Template Method and Its Adsorption Characteristic for Pb2+

Abstract

Mesoporous calcium silicate (MCS) was synthesized by template method using calcium nitrate tetrahydrate and sodium metasilicate nonahydrate as raw materials, cetyl trimethyl ammonium bromide-tetramethyl ammonium hydroxide as template. Its structure was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunuaer–Emmett–Teller (BET) surface analysis, and scanning electron microscopy (SEM). The adsorption characteristics of MCS for Pb2+ were investigated. Results show that MCS possesses a slit-pore structure with a specific surface area of 131.22 m2·g−1 and pore size (DBJH) of 20 nm. The maximum adsorption capacities for Pb2+ is 437.94 mg·g−1 at 293 K, which is much higher than those reported in the literature. The equilibrium data of Pb2+ adsorbed by MCS fitted the Langmuir and Redlich–Peterson models, and more closely with the Redlich–Peterson model. The adsorption of MCS for Pb2+ was a spontaneous endothermic reaction driven by increased entropy involving both physical and chemical modes. Thus, it is evident that MCS can be a promising excellent adsorbent for the treatment of Pb2+-containing wastewater.