Removal and recovery of aqueous uranium using photocatalytic reduction method: Performance and implication

Abstract

The effective extraction and recovery of uranium (U) from aqueous systems are pivotal to the sustainable development of the nuclear power industry and environmental protection. In this study, immobilized photocatalyst TiO2 nanotube arrays (TNAs) were synthesized and characterized, and the photocatalytic extraction of hexavalent U (U(VI)) from wastewater was investigated. The anodization voltage and annealing temperature used for the synthesis influenced the surface morphology and crystallographic composition characteristics of the obtained TNAs, which were found to impose a crucial influence: TNAs with an anodization voltage of 15 V and annealing temperature of 600 ℃ enabled rapid U(VI) extraction. Other factors, such as the solution pH, initial U(VI) concentration, inorganic ions, and EDTA, which could influence the photocatalytic extraction performance of TNAs, were also investigated. The efficiency of U(VI) extraction was found to be >54 % after 3-cycles over 120 min of UV-light irradiation. A possible mechanism was proposed to explain the photocatalytic extraction of U(VI). Furthermore, an electrooxidation method for recovering U from TNAs was also proposed investigated, and the efficiency in 3-cycles was all higher than 83 %. The recovery product of U was found as a mixture of UO3 and UO3·H2O. Finally, a photocatalytic U recovery process was designed to remove and recover U from U-containing wastewater. This work potentially helps opening a new avenue for cost-effective U removal and recovery from U-containing wastewater.