Kinetic modeling for microwave-enhanced degradation of methylene blue using manganese oxide

Abstract

This study was originally performed to compare the MnObased degradation of aqueous methylene blue (MB) under microwave irradiation- (MW-) enhanced and conventional heating- (CH-) enhanced conditions. The degradation process and kinetics were investigated to elucidate the microwave effect on the reaction. The results showed that all three tested conditions, sole MnO MnOCH, and MnOMW, followed the third-order (second upon MB and first upon MnO kinetic model. However, a higher degradation rate of MB was available under the MW-enhanced process, which implies that the "athermal effect" of MW might be of more benefit for the generation of electrophilic oxygen ions (O 2 -, O -, and O 2 -) to degrade MB. The results showed that the degradation percentage of MB could reach 100%, corresponding to 92% total organic carbon (TOC) removal under microwave irradiation at pH 7.20 for 10 min. © 2013 Wen-Hui Kuan et al.