Magnetically-Recyclable Cu-Fe3O4 Nanocomposite Aerogel (CFA) for the Removal of Cr(VI)

Abstract The widespread presence of highly toxic Cr(VI) in water systems poses severe threats to both environment and human health. In this study, we report a magnetically recyclable Cu−Fe3O4 nanocomposite aerogel (CFA) for efficient removal of Cr(VI). The CFAs, prepared via a bimetallic ion co-gelation strategy, possessed a rich 3D nanoporous network structure and exhibited high metal dispersion, thereby providing abundant adsorption sites for Cr(VI). Batch adsorption experiments demonstrated that the CFA achieved an exceptional Cr(VI) treatment capacity (197.6 mg/g, pH = 2.1). Furthermore, the CFA exhibited over 99% Cr(VI) removal efficiency under low initial concentrations (<5 ppm, pH = 5.6). The CFA not only captured Cr(VI) via physicochemical adsorption, but also enabled the in situ reduction of highly toxic Cr(VI) to Cr(III), which was driven by the redox couples of Cu/Cu(I)/Cu(II) and Fe(II)/Fe(III) within the material structure. Additionally, the incorporation of Fe3O4 imparted magnetic properties to the aerogel, enabling rapid separation and recovery under an external magnetic field. With its integrated capabilities for efficient adsorption, reductive detoxification and rapid magnetic separation, the CFA provides a viable solution to the challenges facing current Cr(VI) wastewater treatment technologies.