Preparation of Porous Silica from Rice Husk Char via Acid Treatment and Calcination, and Its Adsorption Properties for Methylene Blue

Development of value-added utilization method for rice husk char (RHC) generated from rice husk gasification power plants is desirable. Amorphous porous silica was obtained by simple calcination of RHC; however, acid treatment prior to calcination improved its purity and increased its specific surface area. In the adsorption of Methylene Blue (MB) by the prepared porous silica, acid treatment enhanced its adsorption capacity and suppressed the increase in the pH of the MB solution. According to the Langmuir adsorption isotherm, the maximum adsorption capacity of the porous silica obtained by calcining acid-treated RHC at 500°C was 26.81 mg/g, which was 3.5 times higher than that of the porous silica obtained by calcining RHC at 500°C without acid treatment.