Durable and Recyclable BiOBr/silk Fibroin-Cellulose Acetate Composite Film for Efficient Photodegradation of Dyes under Visible Light Irradiation

A stable and recyclable of BiOBr/silk fibroin-cellulose acetate composite film was prepared by blending-wet phase transformation and in situ precipitate techno-logy.The cellulose acetate film modified by silk fibroin formed a finger-shaped porous structure,which provided a large space for the uniform growth of BiOBr nanosheets and facilitated the shuttle flow of dyes in film.The morpho-logy,phase structure,and optical properties of the compo-site films were characterized using various techniques,and their photocatalytic performance for dye wastewater was evaluated under visible light irradiation.Results showed that the BiOBr/SF-CA composite film exhibited efficient photocatalytic activity with 99.9％of rhodamine B degradation rate.Moreover,the composite film maintained high catalytic stability because Bi as the active species deposited on the film showed almost no loss.Finally,the possible photocatalytic mechanisms in the BiOBr/SF-CA composite film were speculated through radical-trapping experiments and electron spin resonance testing.