Facile synthesis of TiO₂-PAN photocatalytic membrane with excellent photocatalytic performance for uranium extraction from seawater

Uranium, as an important nuclide, has attracted extensive attention because of its high energy density, clean and pollution-free characteristics. Herein, a TiO₂-polyacrylonitrile photocatalytic membrane (TPM) was prepared by phase conversion method for efficient uranium extraction. TPM photocatalytic membrane is composed of TiO₂, PAN and conductive carbon cloth, in which TiO₂ is the main active substance in the photoreduction process and PAN is the membrane-forming substrate material. Carbon cloth can improve the conductivity of the polymer substrate and improve the photocatalytic efficiency to a certain extent ((The uranium extraction reaction rate of the carbon cloth-based TPM membrane was 1.35 and 1.41 times higher than that of the non-substrate and non-woven fabric-based membranes, respectively). TPM photocatalytic membrane has excellent photoreduction performance of hexavalent uranium. Under the optimal reaction conditions (C₀ = 100 mg/g, pH = 5), the capacity of uranium extracted is 263.92 mg/g. In addition, TPM photocatalytic membrane also exhibited good reusability (uranium extraction capacity after the fifth cycle is 246.13 mg/g) and selective uranium extraction ability (K_dU/K_dV = 41.78, and the removal rate of uranium is 74.63 %). The extraction mechanism of uranium can be summarized as the reduction of hexavalent uranium by photogenerated electrons excited in photocatalytic membrane under light condition. In general, this work provides a new strategy for designing simple, low-cost and efficient photocatalytic materials for uranium extraction from seawater.