Preparation and characterization of aluminum oxide coated extracted silica from rice husk ash for monoglyceride removal in crude biodiesel production

In this study, aluminum oxide was coated on extracted silica from rice husks (AO_RHA). First, the silica was produced by heating the rice husk at 700 degrees C for 6 h following precipitation using NaOH and H2SO4 (RHA). The coating process was carried out using AlCl3 solution. The effect of stirring times, pH, and calcination conditions were investigated. The characterization of AO_RHA was performed using BET, XRD, FTIR, and ICP techniques. This study demonstrated the influence of the AO_RHA structure on monoglyceride removal. Langmuir and Freundlich adsorption isotherms were used to model the equilibrium isotherms and determine the isotherm constants. The adsorption capacity increased after the excess methanol was removed. In addition, the spent AO_RHA was regenerated and can be efficiently reused up to four times. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.