Muedi, Khathutshelo LilithMasindi, VhahangweleMaree, Johannes PhilippusBrink, Hendrik Gideon2023-09-212023-09-212022-10-19Muedi, K.L.; Masindi, V.; Maree, J.P.; Brink, H.G. Rapid Removal of Cr(VI) from Aqueous Solution Using Polycationic/ Di-Metallic Adsorbent Synthesized Using Fe3+/Al3+ Recovered from Real Acid Mine Drainage. Minerals 2022, 12, 1318. https://DOI.org/10.3390/min12101318.2075-163X (online)10.3390/min12101318http://hdl.handle.net/2263/92356DATA AVAILABILTY : The data presented in this study are openly available in the University of Pretoria Research Data Repository at https://doi.org/10.25403/UPresearchdata.21342765.The mining of valuable minerals from wastewater streams is attractive as it promotes a circular economy, wastewater beneficiation, and valorisation. To this end, the current study evaluated the rapid removal of aqueous Cr(VI) by polycationic/di-metallic Fe/Al (PDFe/Al) adsorbent recovered from real acid mine drainage (AMD). Optimal conditions for Cr(VI) removal were 50 mg/L initial Cr(VI), 3 g PDFe/Al, initial pH = 3, 180 min equilibration time and temperature = 45 C. Optimal conditions resulted in 95% removal of Cr(VI), and a maximum adsorption capacity of Q = 6.90 mg/g. Adsorption kinetics followed a two-phase pseudo-first-order behaviour, i.e., a fast initial Cr(VI) removal (likely due to fast initial adsorption) followed by a slower secondary Cr(VI) removal (likely from Cr(VI) to Cr(III) reduction on the surface). More than 90% of adsorbed Cr(VI) could be recovered after five adsorption–desorption cycles. A reaction mechanism involving a rapid adsorption onto at least two distinct surfaces followed by slower in situ Cr(VI) reduction, as well as adsorption-induced internal surface strains and consequent internal surface area magnification, was proposed. This study demonstrated a rapid, effective, and economical application of PDFe/Al recovered from bona fide AMD to treat Cr(VI)-contaminated wastewater.en© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.Chromium removalAcid mine drainageWastewater streamsCircular economyWastewater beneficiationPolycationic/di-metallic adsorbent (nanocomposite)Article