Ultra-efficient recovery of radioactive Cs/Sr/Tb/Eu from wastewater via in situ co-synthesized ternary transition metal catalyzed bioelectrocatalytic reduction system

The persistent threat posed by radioactive metal contamination necessitates the development of innovative and sustainable remediation strategies. In this study, we proposed a self-sustaining bioelectrocatalytic reduction system (BECRs) incorporating an in situ co-synthesized ternary Fe/Cu/Co@Z-CF cathode derived from zeolite imidazole salt skeleton (ZIF) -functionalized carbon felt. The engineered electrode demonstrated outstanding electrocatalytic performance, characterized by an ultrahigh exchange current density of 7.68 × 10 −3 A cm −2 and minimal charge transfer resistance of 0.11 Ω. These properties were attributed to the synergistic redox cycling of Fe-Cu-Co species and the enhanced exposure of active sites facilitated by the ZIF structure. Under optimized conditions at pH 11, the BECRs achieved removal efficiencies exceeding 98.28 % for targeted radionuclides (Cs + : 99.00 %, Sr 2+ : 98.28 %, Tb 3+ : 99.95 %, Eu 3+ : 99.97 %) while generating a stable bio-voltage of 730 mV. The removal mechanisms operated synergistically through three primary pathways: direct electroreduction of metals to elemental or metallic oxide forms at the catalytic cathode; electroflocculation mediated by in situ formation of Fe(OH) x species and microbial adsorption by enriched pollutant-resistant microbial consortia, notably with a 16.3 % increase in Bacteroidota abundance. Density Functional Theory (DFT) calculations revealed charge complementarity among Fe/Cu/Co sites, accelerating oxygen reduction kinetics. Crucially, the electrode demonstrated negligible metal leaching across pH 3–11, confirming ecological safety. Kinetic analysed distinguish radionuclide-specific pathways: pseudo-first-order for Cs⁺/Sr²⁺ versus pseudo-second-order for Tb 3+ /Eu 3+ , informing selective recovery strategies. This work established a green, energy-positive paradigm for radioactive wastewater treatment, achieving simultaneous decontamination, resource recovery (metallic Cs/Sr/Tb/Eu) with significant potential for closed-loop nuclear effluent management.