Magnetic nanosized calcium ferrite particles for efficient degradation of crystal violet using a microwave-induced catalytic method: insight into the degradation pathway

BACKGROUNDMagnetic iron based catalysts with high oxidation performance are generally effective for many catalytic reactions and can be magnetically recovered after application, showing advantages over other metal oxides. In this work, a highly active nanosized CaFe2O4 was prepared by a sol-gel method. Application of the microwave-induced catalytic degradation (MICD) method to the abatement of crystal violet (CV) using the magnetic catalyst was studied. RESULTSMore than 90% of CV was degraded within 10min. The intermediate products were investigated by UV-vis, HPLC and NMR. The results confirmed that CV was completely degraded and converted into harmless products. The reaction kinetics, effect of different ion species (Cl-, SO42-, NO3-, H2PO4- and HPO42-), pH, dye initial concentration, dosage of catalyst, and degradation mechanism were comprehensively studied. It was found that CaFe2O4 presented high activity to produce hydroxyl radicals and holes for degradation of CV under microwave radiation (MW). Surface hydroxyl groups of CaFe2O4 were a critical part in the generation of radicals, and iron on CaFe2O4 surface formed active sites to catalyze CV suggesting that CaFe2O4 plays a significant role in degradation of dyes. CONCLUSIONThis work provides valuable knowledge on the development of CaFe2O4 catalyst for environmental remediation technology. (c) 2014 Society of Chemical Industry