Research paperBiOCl-montmorillonite as a photocatalyst for highly efficient removal of Rhodamine B and Orange G: Importance of the acidity and dissolved oxygen

•UV irradiated BiOCl-Mt has an efficient photocatalytic effect on dye degradation.•Bronsted acid derived from Mt can promote effective separation of ecb−/hvb+ pairs.•Dissolved oxygen is beneficial to the photocatalytic degradation on BiOCl-Mt.

A BiOCl-Mt material assembled from BiOCl and Na-montmorillonite (Na-Mt) was characterized by XRD, FT-IR, TEM, XPS and UV-vis DRS. Na-Mt was clearly demonstrated to be capable of improving BiOCl's photocatalytic performance. The focus was placed on the evaluation of BiOCl-Mt in the terms of photocatalytic activity for cationic Rhodamine B (RhB) and anionic Orange G (OG). Both can be removed more efficiently using BiOCl-Mt compared with pure BiOCl under ultraviolet light irradiation. Although hvb+ and O2− are the two primary reactive species, the improved photocatalytic degradation performance is primarily attributed to the enhanced separation of photogenerated charge carriers in the catalyst. The Bronsted acidity derived from montmorillonite acid sites and the dissolved oxygen in the solution are capable of promoting dye photocatalysis because they effectively capture the photogenerated electrons. Under optimized conditions, TOC mineralization with rates of 82.3% for RhB and 85.9% for OG was obtained in a BiOCl-Mt catalysed photocatalysis process. The mechanism responsible for the oxidative decomposition of the two different dyes is primarily hole-driven. BiOCl-Mt was stable during the process, with its structures remaining almost unchanged after it was recycled three times. Therefore, BiOCl-Mt will have a promising worldwide application in dye-containing wastewater treatment.

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