Physical and Adsorptive Characterization of Precipitated Magnesium Silicate from Rice Hull Ash Silica

Abstract

Precipitation of magnesium silicate from sodium silicate and MgCl2 and MgSO4 solutions was investigated at four different reactant feed rates and two temperatures (25 degrees C and 50 degrees C). Sodium silicate solutions were produced from rice hull ash silica. The final product was characterized by scanning electron microscopy, X-ray diffraction, thermogravimetric analysis/differential thermal analysis, crystal size distribution, and filtration rate measurements. Physical characteristics of the studied magnesium silicates were determined by the Brauner-Emmett-Teller method and their adsorption capacities were compared to commercial magnesium silicate (Florisil). The adsorption was spontaneous and endothermic. The best fit of the kinetic results was achieved by a pseudo-second-order equation. The equilibrium data were found to be well represented by the Freundlich isotherm equation.