Bimetallic metal-organic frameworks-modified hybrid capacitive deionization for enabling concurrent desalination and antibiotic resistance genes removal

Abstract

Freshwater scarcity necessitates the use of unconventional water sources, yet their direct use poses ecological risks, including soil salinization and the dissemination of antibiotic resistance genes (ARGs). Capacitive deionization (CDI) is a promising brackish water desalination technology, but conventional carbon electrodes often suffer from performance limitations due to co-ion effects and slow ion diffusion. This study reported a Fe₁Ni₃-MOFs@AC composite electrode-based hybrid CDI (HCDI) for simultaneous removal of salinity and ARGs, signifying a critical advancement for treating complex saline wastewater. When polarization was applied at 1.5 V, the Fe₁Ni₃-MOFs@AC composite electrode exhibited a specific capacitance 30.4 F/g and a salt adsorption capacity of 26.0 mg/g, which were 103% and 83% higher than those of the pristine activated carbon (AC) electrode. The improved HCDI performance of the Fe₁Ni₃-MOFs@AC composite electrode should result from its hierarchical porous structure, which enhances rapid charge-transfer kinetics and ion diffusion rates. Meanwhile, the system demonstrated exceptional durability, maintaining a high desalination capacity with no significant degradation over 35 cycles. Within 30 min, the electrode removed >94% of sulA, tetL, and chL ARGs, far exceeding the levels in non-polarized controls. Coexisting salt ions synergistically enhanced the 3% removal efficiency of ARG through co-adsorption. This work establishes MOF-enhanced HCDI as a robust platform for concurrent desalination and ARG mitigation, offering an energy-efficient solution for sustainable water reuse in agricultural and industrial applications.