Photo-Fenton degradation of rhodamine B using Fe2O3-Kaolin as heterogeneous catalyst: characterization, process optimization and mechanism.

An efficient Fe2O3-Kaolin was synthesized as a heterogeneous catalyst for photo-Fenton degradation of organic contaminants. X-ray photoelectron spectroscopy analysis and high-resolution transmission electron microscope analysis confirmed the existence of Fe2O3 nanoparticles in the Fe2O3-Kaolin composite. The specific surface area of the Fe2O3-Kaolin catalyst increased from 19.47 to 39.32m(2)/g compared to kaolin. The catalytic activity of the Fe2O3-Kaolin catalyst was evaluated by the photo-Fenton degradation of rhodamine B (RhB) under visible light irradiation and the results showed that the catalyst was highly effective for the degradation of RhB in a wide pH range of 2.21-10.13. At optimal conditions, 98% discoloration and 66% mineralization of RhB were achieved in 120min. The catalyst was efficient for the degradation of methylene blue as well. Leaching test indicated that the leached iron from the catalyst was negligible and the catalyst still showed high photocatalytic activity after five reaction cycles, which all showed that the Fe2O3-Kaolin catalyst is a promising heterogeneous photocatalyst for the degradation of various dyes in wastewater. Finally, a possible photocatalytic mechanism was proposed based on photoluminescence measurements and a series of operating conditions.