A facile procedure for the synthesis of δ-Na2Si2O5 using rice husk ash as silicon source

Abstract

δ-Na2Si2O5, a potential builder in detergents, was prepared from rice husk ash by a simple sintering at 720°C for 120min. The sample was characterized by X-ray diffraction (XRD), Raman spectroscopy (Raman), differential thermal analysis (DTA), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscope (TEM), and EDTA titration. The XRD pattern confirmed the crystallization of δ-Na2Si2O5 obtained at 720°C. The Raman shift at 552cm−1 and 1052cm−1 indicated the presence of a layered silicate tetrahedron structure in the sample. The loss of weight when the sample was heated from 120°C to 516°C in the TG curve was close to the theoretical weight loss calculated from the reaction formula and a broad exothermic peak at ∼715°C in the DTA curve demonstrated a phase transformation, consistent with previous reports. The SEM and TEM images indicated the typical structure of δ-Na2Si2O5 crystallization.The sample exhibited an excellent blinding capacity to Ca2+ and Mg2+; the optimal binding capacities were found to be 396mg/g and 435mg/g, respectively.