Highly efficient treatment of complex uranium-organic wastewater via a self-driven photoelectrochemical system with TNR/Si PVC photoanode and nickel foam cathode

Abstract

This study introduces an eco-friendly, self-driven photoelectrochemical system (SDPS) capable of synergistically achieving 99.4 % UO₂²⁺ recovery and 97.7 % tetracycline hydrochloride (TCH) removal, while generating a maximum power output density (P_max) of approximately 580 μW/cm² using only sunlight. This SDPS employs a TiO₂ nanorod array (TNR) film to absorb short wavelength light (λ < 412 nm) generating electron-hole pairs. Meanwhile, the rear Si photovoltaic cell (Si PVC) absorbs longer wavelengths, creating a self-bias potential that enhances electron-hole separation and drives electrons towards the 3D cross-linked nickel foam (NF) cathode, continuously generating electrical energy in the external circuit. The retained holes and derived •OH with high redox potential can oxidize TCH, breaking UO₂²⁺-TCH complexation, while electrons reduce dissolved UO₂²⁺ to insoluble UO₂ by 88.5 %, and anchored on the NF cathode. This SDPS demonstrates robust performance in various conditions, including high salinity and TCH concentrations, a wide range of pH levels, and different coexisting ions. Moreover, this SDPS exhibits remarkable versatility in treating various types of uranium-containing organic wastewater, maintaining exceptional performance under both real sunlight and simulated seawater conditions, with only a slight performance decline observed after 20 cycles of use. This innovative resource treatment strategy overcomes the issues with stable uranium-organic complexes, catalyst recovery, and the need for sacrificial agents, offering a robust solution for extracting uranium, environmental preservation and sustainable nuclear energy development.