Design and performance investigation of novel efficient photocatalysts PVP-modified PVDF/BiOBr photocatalytic membranes for wastewater treatment

Abstract

Photocatalytic composite membranes (BPMs) are preferred materials for wastewater treatment due to their high photocatalytic activity and ease of recovery. However, conventional blending modification methods for preparing BPMs often lead to drawbacks such as uneven distribution of photocatalysts, low loading efficiency, facile detachment of photocatalysts, poor reusability, and a limited specific surface area of the membranes. These issues significantly diminish their photocatalytic activity and restrict their practical applications. To address these challenges, this thesis introduces a novel preparation method for PVP-modified PVDF/BiOBr photocatalytic membranes, using a combination of electrospinning and solvothermal techniques. This approach enhances the stability of BiOBr microspheres on the PVDF nanofiber membranes, effectively tackling the issue of loading powder photocatalysts. These membranes, composed of PVDF nanofibers and uniformly sized BiOBr microspheres, exhibit a significant specific surface area of 15.69 m²/g. The modified PVDF/BiOBr photocatalytic membranes demonstrate remarkable degradation efficiencies: 100 % degradation of Rhodamine B (RhB) in 25 min, 93.8 % degradation of tetracycline (TC) in 30 min, and 74.6 % degradation of hexavalent chromium ions (Cr⁶⁺) in 60 min. Moreover, after five cyclic experiments, the photocatalytic degradation rate of sample M₃ remains above 99 % with a minimal loss rate of only 0.5 %. The method developed for preparing PVDF/BiOBr photocatalytic membranes represents a universally applicable and straightforward strategy for fabricating advanced membrane materials. This preparation technique not only provides innovative design ideas and fabrication methods for new photocatalytic materials but also extends to other functional materials. The PVDF/BiOBr photocatalytic membrane materials hold great promise in offering technical and theoretical support for photocatalytic wastewater treatment.