Selective Extraction of Cu ²⁺ and Sb ³⁺ Using a Porous Composite Electrode Based on FeNi-MOF/Natural Agricultural Waste

Against the background of global water pollution worsening, the efficient removal of heavy metal ions from wastewater remains an important environmental challenge. Traditional methods face limitations in selectivity and energy consumption, while electrochemically assisted treatment utilizing Faradaic materials has emerged as a promising solution due to its high selectivity and reaction efficiency. In this study, using agricultural waste as raw materials, the active materials with defects and functional groups are prepared via carbonization, combined with in situ growth and postsynthetic modification. By regulating monocarboxylic acid addition, the FeNi-BDC(FA10)-O/C electrode is synthesized, featuring enhanced stability in aqueous environments and abundant redox-active metal sites for Faradaic reactions. It achieves extraction capacities of 31.09 mg·g–1 for Cu2+ and 20.15 mg·g–1 for Sb3+ through reversible electrochemical capture/release. The electrode exhibits a favorable stability and regeneration efficiency. Redox-active MOFs show high feasibility for toxic cation separation, supporting the application of 3D porous materials in wastewater treatment.