Effective removal of arsenate from wastewater using aluminium enriched ferric oxide-hydroxide recovered from authentic acid mine drainage

K L Muedi; H G Brink; V Masindi; J P Maree

doi:10.1016/j.jhazmat.2021.125491

Effective removal of arsenate from wastewater using aluminium enriched ferric oxide-hydroxide recovered from authentic acid mine drainage

J Hazard Mater. 2021 Jul 15:414:125491. doi: 10.1016/j.jhazmat.2021.125491. Epub 2021 Feb 23.

Authors

K L Muedi¹, H G Brink², V Masindi³, J P Maree⁴

Affiliations

¹ Department of Chemical Engineering, Faculty of Engineering, Built Environment and Information Technology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa.
² Department of Chemical Engineering, Faculty of Engineering, Built Environment and Information Technology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa. Electronic address: deon.brink@up.ac.za.
³ Department of Environmental Sciences, School of Agriculture and Environmental Sciences, University of South Africa (UNISA), P. O. Box 392, Florida 1710, South Africa.
⁴ ROC Water Technologies, P. O. Box 70075, Die Wilgers, Pretoria 0041, South Africa.

PMID: 33652214
DOI: 10.1016/j.jhazmat.2021.125491

Abstract

This study explored an eco-friendly approach for the synthesis of novel aluminium enriched ferric oxide-hydroxide (Fe/AlO(OH)) from authentic acid mine drainage (AMD). The synthesized Fe/AlO(OH) was subsequently tested for arsenate removal capabilities. Fe/AlO(OH) was synthesized from bona fide AMD via selective precipitation, thermal activation, and vibratory ball milling. One-factor-at-a-time (OFAAT) method was used to optimize operational parameters, which include adsorbent dosage, concentration, pH, agitation time, and temperature. Optimized conditions were observed to be 150 ppm of As(V), Solid: Liquid ratio - 1 g: 250 mL, contact time of 60 min, and ambient temperature and pH. Limited temperature and pH effects on adsorption were observed. Equilibrium data fits using Langmuir-, Freundlich-, Two surface Langmuir-, Dubinin-Radushkevich-, and Dubinin-Astokov isotherm models showed highly favorable adsorption conditions, the highest known maximum adsorption capacity for As(V) of 102-129 mg g^-1, and coupled physisorption/diffusion limited adsorption. Thermodynamic analysis showed positive Gibbs free energy (ΔG°), negative enthalpy change (ΔH°), and positive entropy change (ΔS°) - likely a result of an inner sphere complexation of the As(V) with the Fe/Al surface. Considering the obtained results, valorization of AMD for the synthesis of Fe/AlO(OH) was viable and effective. This initiative could potentially minimize the footprints of AMD and arsenic pollution.

Keywords: Acid mine drainage; Adsorption; Aluminium; Arsenic; Ferric oxide-hydroxide.

Publication types

Research Support, Non-U.S. Gov't