Degradation of malachite green solution using combined microwave and ZnFe₂O₄ powder

Dyestuff malachite green MG in aqueous solution can be degraded rapidly assisted by microwave irradiation (MW) in the presence of ZnFe₂O₄ powder. ZnFe₂O₄ acted as a MW as well as the catalyst for MG degradation, and could be used repeatedly. The effects of MW time, initial concentration of MG, addition amount, pH value and used times of ZnFe₂O₄ powder were discussed in details using UV-Vis spectra, FT-IR spectra, ion chromatography and TOC analysis technologies. The results showed that the degradation percentage of MG was nearly 100%, corresponding to 92% of TOC removal, when the mass fraction of ZnFe₂O₄ was 1.2%, MW 500 W and the irradiation time 2 min. Additionally, the above method using ZnFe₂O₄ powder as catalyst combined with MW has high degradation ratios, short reaction time, low costs, no intermediates and no secondary pollution. Therefore, it may be available for the treatment of various dyestuff wastewaters on a large scale.