Rapid self-assembled electroactive biohybrid cathode-driven electron transfer for enhanced uranium bioremediation

Efficient and eco-friendly purification of uranium-bearing wastewater is essential for the safety of the water ecosystem and sustainable development of the nuclear energy industry. Although bioelectrochemical systems show great prospect for uranium bioremediation, the uranium removal efficiency is often limited by the ineffective quality of biofilm formation and unsatisfactory electron transfer. Here we propose a rapid self-assembled biofilm formation strategy to construct a sulfate-reducing bacteria-carbon cloth biohybrid cathode (CF-PQ7) modified with cotton-derived carbon fibers for the simultaneous removal of uranium and sulfate. Electrochemical characterizations show that pyridinic-N and graphitic-N species in highly conductive carbon fibers promote electron transfer at the uranium reduction interface between the biofilm and the electrode by optimized electron transfer dynamics. Moreover, spectroscopic and biofilm analysis demonstrate that a rapid self-assembled electroactive biofilm is formed by coating polyquaternium-7 in situ on the microbial surface to improve the viability and detoxification capacity of the biofilm. Impressively, CF-PQ7 biocathode demonstrates uranium removal efficiency of 93.8 %, achieving a 7.8-fold and 3.9-fold increase compared to sulfate-reducing bacteria and bare electrode, respectively, indicating its promising potential for uranium bioremediation. This work provides a safe, clean, and sustainable uranium reduction strategy and puts forward new perspectives and opportunities for uranium-bearing wastewater remediation.