Microwave assisted KOH activation has been utilized for preparation of biomass adsorption material based on agricultural waste rice husks (RH). Batch experiments were conducted to evaluate the sorption performance of cationic dye methylene blue (MB) by modified rice husks (MRH) from aqueous solutions. The effects of solution initial pH, dosage of the adsorbents, salt concentration, the dyeing and finishing auxiliary concentration, contact time and temperature on MB adsorption were investigated. The results showed that MRH had a wide appropriate pH range of 5?11 for MB adsorption, which showed the potential applicability in the actual water body. With NaCl concentration increasing from 0 to 0.2 mol/L, the removal efficiency of MB decreased from 58.24% to 1.86%; while, MB removal increasesd with increasing SDBS concentration. The sorption process for MB onto MRH was an endothermic reaction and the adsorption process reached equilibrium within 30?45 min. The obtained product MRH had a maximum MB adsorption capacity of 109.9 mg/g. The experimental kinetic data were well described by the pseudo-second order model and the best ?tting for MB experimental equilibrium data was achieved with the Langmuir isotherm, which was a rapid and monolayer adsorption process. Film diffusion was the rate-limiting step which was primarily responsible for the adsorption of MB on MRH. Physical adsorption inside the pores of biomass materials and O?H functional groups adsorption both contributed to the adsorption mechanism.
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