The synthesis of a novel conjugated microporous polymer and application on photocatalytic removal of uranium(Ⅵ) from wastewater under visible light

Photocatalytic reduction of uranium(Ⅵ) is an efficient and non-pollutant strategy for removal of uranium(Ⅵ) from waste water. However, most current photocatalysts are limited in practical application due to low visible light utilization and low activity on acidic condition. In this work, a new conjugated microporous polymer (CMP) named TT-TPP has been synthesized by C–H arylation between 5, 10, 15, 20-tetrakis(4-bromophenyl)-porphyrin and thieno[3,2-b]thiophene. TT-TPP exhibits excellent chemical stability and photochemical property. It can be used for visible light driven photocatalytic reduction of U(VI) on highly acidic condition (pH = 2–5) with high uranium removal capacity (3571.2 mg g−1). Even in 3 M NaNO3 solution, the removal rate of U(Ⅳ) could reach to 89.9%. TT-TPP still exhibits an excellent uranium selectivity over these competing metal cations, and 97.6% U(Ⅳ) in simulated radioactive wastewater is removed. The X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and the fourier transform infrared spectroscopy (FT-IR) confirmed the reduced uranium was in the form of UO2⋅nH2O. In addition, TT-TPP also shows excellent photocatalytic U(VI) reduction performance under natural sunlight irradiation.