Kinetic analysis and mechanisms for adsorption of methylene blue from aqueous solution onto δ-MnO₂

In order to improve the effect of advanced treatment of dye wastewater, the kinetics and mechanisms of adsorption of a cationic dye, methylene blue, from aqueous solutions by δ-MnO₂ was investigated using batch rate experiments. Researches were performed at various strength of mixing, initial dye concentrations, solid loads and pH values. Apparent kinetic model and mechanisms of dye removal were also investigated. Results indicate that the adsorption process obeyed the pseudo-second-order kinetic model. The mass transfer and intraparticle pore diffusion are rate-controlling steps. The adsorption capacity is 0.244 mg/mg under the condition. The relatively high capacity and quick velocity of sorption make MnO₂ a potential sorbent for advanced treatment of dye wastewater.