Microwave enhanced Fenton process for the removal of methylene blue from aqueous solution

Fenton process is an effective treatment for organic wastewater. In this study, we introduced a microwave enhanced Fenton process to remove dye from aqueous solution. The conversion rate of methylene blue (MB) was increased and accelerated due to the assistance of microwave irradiation, with value of 93.0% after heated for only 1 min, even higher than that of treated by traditional Fenton process for 65 min. The MB conversion increases with initial concentrations of H2O2 and Fe2+ because of the increased generation of hydroxyl radicals. The MB conversion changes slightly with pH at values of below 7 and declines dramatically when the pH is higher than 8, with optimum pH value of about 3. During the microwave treatment, the maximum UV–Vis absorption peak decreased much quicker than that of other two peaks, and blue shifted from wavelength of 664–629 nm, indicating the decomposition of dimethylamino and methyl groups in MB molecules. The microwave enhanced Fenton process is a promising treatment for organic contaminants due to advantages of fast and effective processing.

• Microwave heating will dramatically increase and accelerate the removal rate of MB. • The MB removal rate increases with dosages of H2O2 and Fe2+. • The removal rate changes slightly with pH of 2.5–7, and declines sharply when pH > 8. • The maximum UV–Vis peak decreased and blue shifted after microwave/Fenton process.