Treatment from abandoned mine landfill leachates. Adsorption technology

This study defines the optimal parameters that allow the use of red mud waste from the Bayer process to remove heavy metals from leachate from an abandoned mine. First, the influence of parameters such as pH, contact time, initial metal concentration, adsorbent dose and the presence of co-ions in Cd2+, Zn2+ and Ni2+ adsorption were investigated in synthetic solutions. Metals uptake increased with increasing pH, contact time and adsorbent dosage. The presence of co-ions suppressed the uptake of heavy metals, divalent ions having a more negative effect than monovalent ions. The adsorption of heavy metals was found to fit the Langmuir isotherm. Maximum Cd2+, Zn2+ and Ni2+ uptake values were calculated as 12.58 mg/g, 12.05 mg/g and 11.06 mg/g, respectively. The results obtained in the tests with landfill leachate showed that red mud is effective in simultaneously removing several heavy metals, more than 99% Cd, Ni, Zn and As being uptaken. (C) 2019 The Authors. Published by Elsevier B.V.