A new catalytic composite of bentonite-based bismuth ferrites with good response to visible light for photo-Fenton reaction: Preparation, characterization and analysis of physicochemical changes

In this work, using bentonite as support, a new composite of bentonite-based bismuth ferrites (BFOs/Bent) which can be used as a catalyst for photo-Fenton reaction under visible light has been synthesized. The optimum synthesis conditions of BFOs/Bent were obtained, and the optimum synthesis conditions of BFOs/Bent were as follows: molar ratio of Fe(NO3)3 to Bi(NO3)3 (MFe/MBi) 1:1, dosage of Fe3+ to bentonite (MFe/mBent) 5 mmol/g, calcination temperature 500 °C, and calcination time 2 h. The catalysts prepared at different synthesis conditions were characterized, and based on the characterizations, the effects from the synthesis conditions on the physicochemical properties of BFOs/Bent were analyzed. The characterization results showed the functional components of bismuth ferrites were successfully immobilized on the bentonite, and the crystalline phases in the optimum BFOs/Bent (labeled as BiFeO3-Bi2Fe4O9/Bent) were BiFeO3 and Bi2Fe4O9. BiFeO3-Bi2Fe4O9/Bent showed good response to visible light as well as to UV light. Large specific surface area and macroporous volume were contributed to the high catalytic activity of BiFeO3-Bi2Fe4O9/Bent. It was further found that the low band gap and the effective charge separation at heterojunction were the basis for the high photocatalytic activity of BiFeO3-Bi2Fe4O9/Bent.