Novel hybrid metal loaded chelating resins for removal of toxic metals from acid mine drainage Caroline Lomalungelo Dlamini, Lueta-Ann De Kock, Kebede Keterew Kefeni, Bhekie Brilliance Mamba and Titus Alfred Makudali Msagati ABSTRACT Fe, Zr and Ti oxides nanoparticles were each embedded onto a weak acid chelating resin for support, by the precipitation method, to generate three hybrid adsorbents of hydrated Fe oxide (HFO-P), hydrated Zr oxide (HZO-P) and hydrated Ti oxide (HTO-P). This paper reports on the characterization, performance and potential of these generated nanoadsorbents in the removal of toxic metal ions from acid mine drainage (AMD). The optimum contact time, adsorbent dose and pH for Al(III) adsorption were established using the batch equilibrium technique. The metal levels were measured using the inductively coupled plasma-optical emission spectrometer (ICP-OES). The SEM-EDS results confirmed the presence of the metal oxides within the hybrid resin beads. HFO-P, HZO-P and HTO-P adsorbed Al(III) rapidly from synthetic water with maximum adsorption capacities of 54.04, 58.36 and 40.10 mg/g, respectively at initial pH 1.80 ± 0.02. The adsorption of Al(III) is of the second-order in nature (R 2 > 0.98). The nanosorbents removed 10 selected metals from environmental AMD and the metal removal efficiency was in the order HTO-P > HZO-P > HFO-P. All three hybrid nanosorbents can be used to remove metals from AMD; the choice would be dependent on the pH of the water to be treated. Key words | acid mine drainage, adsorption, hybrid chelating resin, metal removal, nanosorbent HIGHLIGHTS • AMD has the potential to degrade the environment and ecosystem • Nanoparticles can be employed to treat AMD with high efficiency • Hybrid metal chelates has the potential for AMD remediation Caroline Lomalungelo Dlamini Lueta-Ann De Kock Kebede Keterew Kefeni Bhekie Brilliance Mamba Titus Alfred Makudali Msagati (corresponding author) College of Science Engineering and Technology, Nanotechnology and Water Sustainability Research Unit, University of South Africa, Florida Science Campus E-mail: msagatam@unisa.ac.za INTRODUCTION Mining and mineral processing activities are very important with respect to the economic and social benefits for the country in which the mining activities are conducted. How- ever, if not well managed, the environmental consequences of mining activities are massive because mining produces dumps containing metal sulphide ores covering vast areas of the mine site. When these metal sulphides, especially pyrite (FeS 2 ), are exposed to air and water they can easily result in acid mine drainage (AMD) (Mulopo ). In addition, the mine tailings and waste rocks are smaller in size than their natural geologic materials, thus have a greater surface area and more prone to generation of AMD ( Johnson ). The environmental pollution caused by AMD generated from gold mines is a worldwide serious pro- blem due to the presence of other mineral ores that occur with the gold-bearing mineral deposits (Coelho et al. ), which upon oxidation, exacerbate AMD pollution. In addition to low pH, AMD is characterized by high levels of metal ions which have devastating effects on the environment. Toxic metals are recalcitrant bio-accumulative systemic toxins that can affect both soft and hard tissues in the human body (Simate & Ndlovu ), resulting in 1 © IWA Publishing 2020 Water Science & Technology | in press | 2020 doi: 10.2166/wst.2020.285 Uncorrected Proof Downloaded from https://iwaponline.com/wst/article-pdf/doi/10.2166/wst.2020.285/700257/wst2020285.pdf by guest on 16 July 2020