Microwave-Enhanced Fenton Process for DMSO-Containing Wastewater

Microwave-enhanced Fenton process (MEFP) is proposed as a new treatment for wastewater containing dimethyl sulfoxide (DMSO), which is difficult to treat using biological processes. Effects of microwave power, irradiation time, initial pH, hydrogen peroxide (H2O2) dosage, H2O2/Fe2+ molar ratio, and initial DMSO concentration were investigated to maximize DMSO removal in batch experiments. Further, a circulating-flow system for practical utility was devised and optimized via orthogonal experiments, and kinetic experiments were conducted to study the differences between MEFP and conventional heating-assisted Fenton process. Degradation and mineralization (conversion to CO2 and H2O) of DMSO were evaluated following degradation intermediates and total organic carbon (TOC). In MEFP, 95.8% DMSO removal was achieved within 5 min with a wide pH range (2-7). MEFP could achieve a much higher mineralization level (TOC removal of 51.3%) within much shorter time (10 min) than Fenton process stirring at ambient temperature (TOC removal of 28.4% after 240 min). Compared with heating-assisted Fenton process at equal temperature, enhanced DMSO removal in MEFP might be ascribed to microwave energy absorption of DMSO and H2O2. Results indicate that microwave technology offers particular advantages in term of swiftness and high efficiency. Thus MEFP is believed to be a promising method for DMSO-containing wastewater treatment.