Microwave solvothermal-assisted calcined synthesis of Bi2WxMo1−XO6 solid solution photocatalysts for degradation and detoxification of bisphenol A under simulated sunlight irradiation

Abstract

• Bi 2 W 0.25 Mo 0.75 O 6 microspheres showed the best photocatalytic activity. • Removal efficiencies of BPA and TOC were 96.2% and 87.1% at 15 mg L −1 BPA. • Photo-hole, O 2 − and OH contributed to photocatalytic degradation of BPA. • Degradation pathways were proposed according to intermediates and active species. • Bioluminescence/QSAR analysis confirmed toxicity reduction during BPA degradation. A series of (x = 0, 0.25, 0.5, 0.75, 1) solid solution photocatalysts was designed and synthesized by the combination of microwave solvothermal method and post-treatment calcination. The physicochemical and optical properties of the as-prepared solid solution photocatalysts were characterized by various techniques. The photocatalytic activity was also evaluated through the photodegradation of bisphenol A (BPA) under simulated sunlight irradiation. Results showed that all photocatalysts were flower-like, and the Bi 2 W 0.25 Mo 0.75 O 6 microspheres showed the best photocatalytic activity. The removal efficiencies of BPA and total organic carbon were 96.2% and 87.1% at BPA concentration of 15 mg L −1 in 120 and 180 min, respectively. During the reaction process, O 2 − and h + played the dominant role, while OH also contributed to the BPA degradation. Twelve intermediate products were identified, and they were gradually mineralized to CO 2 and H 2 O. On the basis of the analysis of active species and intermediates determined, the main degradation pathways for BPA were proposed, namely, hydroxylation, alkylic-oxidation, dehydrogenation, and aromatic ring opening. The toxicity change during BPA degradation was also investigated by standardized bioluminescence assay of inhibition rate on luminescent bacterium Vibrio qinghaiensis sp . Q67 in combination with quantitative structure–activity relationship analysis. The inhibition effect of BPA and its intermediates to V. qinghaiensis sp . Q67 was gradually eliminated with the decomposition of BPA. In conclusion, the Bi 2 W 0.25 Mo 0.75 O 6 is an effective photocatalyst for degradation and toxicity reduction of BPA in aqueous solution.