Degradation of methylene blue dye by UV/H2O2 advanced oxidation process: reaction kinetics, residual H2O2 and specific energy consumption evaluation

In the present study, the degradation of methylene blue (MB) dye, a common pollutant from textile and printing industries was observed using UV/H2O2 advanced oxidation process. Effect of process variables like pH (3???11), H2O2 dosage (2.5???12.5) mM and initial MB dose (10???100) mg/L on decol-orization efficiency of dye was investigated. An acidic pH of 3 was found to be favorable for decol-orization of MB. Degradation of MB followed pseudo-first-order removal kinetics. Rate constants of MB decolorization increased with increase in H2O2 concentration and decrease in initial dye con-centration. The results showed that about 89.85% residual H2O2 remained in the system even after 75 min treatment time. To ensure the minimum residual H2O2 in effluent and optimum MB removal, H2O2 dose was optimized at 12.5 mM with specific energy consumption of 271.6 kWh/kg dye. Thus, in the described experimental range of conditions, UV/H2O2 oxidation of MB may be an efficient, inexpensive and clean alternative treatment for decolorization of textile wastewater containing this dye.

Automated summary

In this study, the degradation of methylene blue dye using UV/H2O2 advanced oxidation process was investigated. The results showed that an acidic pH and higher H2O2 concentration can effectively enhance the decolorization efficiency. In particular, a dosage of 12.5 mM H2O2 achieved the optimal removal effect.