Coupling uranyl upcycling with photoelectrochemical urea degradation for radioactive organic wastewater management

Abstract

Abstract Radioactive organic wastewater management concerning metal source recovery and organic matter degradation conforms well to the notion of circular economy and environmental protection, but the concurrent conversion in an integrated process is challenging and has been rarely studied. Here, we introduce a high-performance photoelectrochemical system for uranyl extraction and the simultaneous degradation of co-existing urea to manage the treatment of uranyl-containing radioactive organic wastewater generated from the production of nuclear fuel for fourth-generation high-temperature gas-cooled reactor. Cost-efficient self-standing Ni-modified TiO 2 nanotube arrays (Ni/TiO 2 ) and β-cyclodextrin polymer (P-CDP@CC) were used as photoanode and cathode, respectively. Concurrent photoanodic urea degradation and cathodic uranyl reduction towards UO 2 from low-level radioactive organic wastewater demonstrated a uranyl extraction efficiency of 99.08% and the urea degradation efficiency of nearly 100% under a current density of 4.5 mA/cm 2 within 8 hours in a single-compartment electrolysis cell. This work provides an effective, environmentally benign approach to upcycle uranium resources and purify organic pollutants from complicated wastewater matrix.