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 (KdU/KdV = 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.