Efficient removal of Pb(II) with manganese oxide modified from low grade pyrolusite

In this paper, the manganese oxide (HMO) modified from low-grade pyrolusite by the NaOH molten roasting and washing processes was used as a low-cost and efficient adsorbent for toxic metal removal. The HMO showed excellent selective sorption and regeneration for Pb2+. Furthermore, the equilibrium adsorption isotherm was well-fitted by Langmuir models. The adsorption process was described by the pseudo-secondary kinetics. Characterization results of X-ray diffraction, energy-dispersive X-ray spectroscopy, infrared, and X-ray photoelectron spectroscopy showed that Pb2+ adsorption by HMO mainly depended on complexation reaction between hydroxyl groups on the surface and Pb2+ from aqueous solution.