Alternative treatment for metal ions removal from acid mine drainage using an organic biomixture as a low cost adsorbent

Acid mine drainage, characterized by low pH and elevated heavy metal ion concentrations, causes severe harm to the environment. In this study, the feasibility of a new organic biomixture adsorbent for removing Fe3+, Zn2+, Cu2+ and Mn2+ metal ions from synthetic acid mine drainage was evaluated. This kinetic study showed fast metal ions adsorption within the first four to eight hours, and adsorption over 80% in the organic biomixture. The equilibrium adsorption isotherms resulted in a metal ion uptake greater than 84%, and the Freundlich model fitted well the data. The Freundlich affinity coefficient (Kf) ranged from 1.44 to 3.82 in the following order: Zn2+>Cu2+>Fe3+>Mn2+. Scanning electron microscope images revealed the heterogeneous structure of the biomixture, and energy-dispersive X-ray analysis after adsorption confirmed the ability of the biomixture to remove the metal ions. In the fixed-bed column, the Thomas model described (R-2>0.95) the adsorption process of metal ions contained in the treated acid mine drainage well. The adsorption capacity (q0) of this system resulted in 164.2 mg g(-1), 129.2 mg g(-1), 26.0 mg g(-1) and 15.3 mg g(-1) of Fe3+, Zn2+, Cu2+ and Mn2+, respectively. This study confirmed the efficiency of an organic biomixture to adsorb metal ions and provide new and valuable information for the future design of low-cost treatments to reduce acid mine drainage pollution. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study confirmed the efficiency of an organic biomixture in adsorbing metal ions from acid mine drainage, providing valuable information for designing low-cost treatments in the future. The biomixture showed fast and high adsorption rates for Fe3+, Zn2+, Cu2+ and Mn2+ metal ions, fitting well with the Freundlich model. Energy-dispersive X-ray analysis confirmed the biomixture's ability to remove metal ions, and the Thomas model described the adsorption process well.