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

Abstract

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, ET-IR and N₂ 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 stadied 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 (R₂ = 0.999), the value of rate constant for adsorption process was calculated as 0.017 (g.mg⁻¹min⁻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 3ʳᵈ cyclic experiment.