Synthesis of mesoporous SiO2 from rice husk for removal of organic dyes in aqueous solution

Mesoporous SiO2 was prepared from rice husk for removal of methylene blue (MB) from aqueous solution. As-prepared SiO2 was characterized by FE-SEM, TEM, XRD, FT-IR and N-2 adsorption/desorption isotherm. The effects of SiO2 dosage and contact time on adsorption of dye were investigated. The optimal dosage of SiO2 for removing methylene blue was 0.05 g and the removal efficiency of methylene blue reached to 91.9 % after 50 min of adsorption. The adsorption kinetic of methylene blue was studied to understand the mechanism of adsorption process. The kinetic data was analyzed by pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The results showed that rate of adsorption dye followed pseudo-second-model with a good regression correlation (R-2 = 0.999), the value of rate constant for adsorption process was calculated as 0.017 (g.mg(-1).min(-1)) and film diffusion was the rate limiting step. In addition, the cyclic test for as-prepared SiO2 was investigated and the removal efficiency was remained at 80.2% at 3(rd) cyclic experiment.