Adsorption behaviors of methylene blue from aqueous solution on mesoporous birnessite

In this paper, mesoporous birnessite-type manganese oxide (delta-MnO2) was synthesized using potassium permanganate and citric acid monohydrate through a simple redox method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) surface area measurement were employed to characterize the synthetic birnessite. The birnessite was evaluated as an adsorbent for the removal of methylene blue (MB) from the aqueous solution. The effects of birnessite dosage, initial pH, initial concentration and adsorption time, and temperature were investigated by batch experiments, and results showed the mesoporous birnessite possessed high adsorption efficiency and capacity towards MB. Adsorption isotherm and kinetics studies revealed that the equilibrium adsorption data and adsorption kinetics were well-described by Langmuir isotherm model and the pseudo-second-order kinetic model, respectively. Owing to characteristics of low cost, high-efficiency, and energy-saving, the mesoporous birnessite can be used as an efficient adsorbent for dyeing wastewater treatment. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.