Lead adsorption from aqueous solution using manganese oxides recovered from spent alkaline batteries

Abstract

Lead is a highly toxic element and can cause serious illnesses, as a consequence of this, stringent limits have been set for this element, especially regarding drinking water. In this paper, the potential of manganese oxides (MnOx) as adsorbents for the removal of lead (as Pb II) from synthetically contaminated water was investigated. These oxides were recovered from alkaline batteries by a bio-hydrometallurgical process through potassium permanganate (KMnO4) precipitation. The MnOx was characterized by Scanning Electronic Microscopy (SEM), Energy Dispersive Spectroscopy (SEM-EDS) and X Ray Diffraction (XRD) analysis. The surface area of the material was determined using the N2 isotherm by the BET method. Batch tests were performed on untreated manganese oxides at different temperatures (10, 25 and 40°C), utilizing initial adsorbate concentration ranging from 5 to 100 mg L-1 and contact times between 1 minute and 30 minutes. The Langmuir isotherm provided the best correlation for the adsorption process, with a maximum adsorption capacity of 9.51 (mg g–1) at 10 °C. Kinetic studies revealed that the lead adsorption onto MnOx followed a pseudo-second order kinetic model, while the thermodynamic study has highlighted that the adsorption of lead is exothermic and spontaneous.