Creation of symmetric methyl-functionalized COF for highly efficient U(VI)removal from water

Due to its high mobility, biological toxicity, and radioactivity, U(VI) poses a serious threat to ecosystems and human health. To enhance the efficient removal of U(VI) under air atmosphere conditions without sacrificial agents, this work successfully synthesized a highly effective photocatalyst based on COFs featuring symmetric methyl structural units. This was achieved using relatively inexpensive materials as raw materials and leveraging the Schiff base reaction. The dosage of COFs at 0.2 g/L has been shown to achieve a removal efficiency of up to 98 % for 100 mg/L of U(VI). Following 5 cycles, the material maintains a percentage above 90 %, and the COFs exhibit a high degree of selectivity within high-salinity environments. The presence of a symmetric methyl group optimizes the electronic structure, enhances photoinduced charge separation, and improves redox activity. Additionally, it facilitates the generation of H 2 O 2 , which reacts in situ with U(VI) to form the insoluble compound (UO 2 ) O 2 ·2H 2 O. This work presents an innovative method for the cost-effective preparation of efficient non-metallic photocatalysts.