Photo-degradation of methylene blue in the presence of 2-anthraquinone sulfonate and cyclohexanol

Hydroxyl radical is a highly reactive oxygen species and can be used to oxidize many pollutants and toxic organic compounds. 2-Anthraquinone sulfonate (2-AQS) was found capable of producing hydroxyl radicals under UVA exposure. In this study, the photo-induced oxidative degradation of methylene blue (MB) by 2-anthraquinone sulfonate was investigated. Results indicated that 2-anthraquinone sulfonate was able to photo-degrade methylene blue. Addition of some chemical such as cyclohexanol could significantly increase the photo-degradation of methylene blue by 2-anthraquinone sulfonate. The degradation process was investigated by using LC–MS. Potential photochemical reaction mechanism of 2-anthraquinone sulfonate was proposed in this paper. Influence of solution pH value and different ratios of 2-AQS, cyclohexanol and MB mixture on the degradation of methylene blue were also studied.

► 2-anthraquinone sulfonate (2-AQS) degraded methylene blue under UVA.
► Addition of cyclohexanol improved the degradation.
► 2-AQS generated reactive oxygen species in the system under UVA irradiation.
► Alkaline condition is preferred for the degradation.