Fabrication of Sandwich Structure Membrane and its Performance for Photocatalytic Reduction of Cr(VI) 

Abstract

The regenerated cellulose membrane (RC) was synthesized by dissolving cotton cellulose in NaOH/CO(NH2)2 system. The Polydopamine/Bismuth Tungstate/RC composite membrane (RCPB) with visible light catalytic activity was synthesized via loading polydopamine-modified bismuth tungstate (PDA/BWO) composite on the RC by blending method. The RCPB/PAN/RCPB sandwich structure membrane was synthesized through combining the polyacrylonitrile (PAN) nanofiber membrane and RCPB by scraping method, which could reduce aqueous Cr(VI) under visible light. Characterization analysis showed that the tensile strength, elongation at break, roughness and initial water contact angle of RCPB/PAN/RCPB were 32.1 MPa, 5.34%, 0.658 µm and 69.0°, respectively. The photoreduction percent of Cr(VI) by RCPB/PAN/RCPB could reach 99.7% within 120 min with a rate constant of 0.0869 min–1, and the photoreduction percent remained above 84.6% after four cycles. The introduction of PAN further improved the mechanical properties and recycling ability of RCPB. Meanwhile, the capture experiment revealed that the main active substance for photocatalytic reduction of Cr(VI) by RCPB/PAN/RCPB was photogenerated e-. This work provides a new idea for the treatment of Cr(VI)-containing wastewater.