Degradation of Reactive Yellow 145 dye by persulfate using microwave and conventional heating

• Dye RY 145 degradation using KPS under microwave and conventional heating.
• Role of thermal and non-thermal effects on KPS assisted degradation of RY 145.
• Probable degradation mechanism of RY 145 predicted using FTIR analysis.
• Effect of carbonate and sulphate anions on RY 145 degradation.

Degradation of C. I. Reactive Yellow (RY 145), a bi-functional dye containing azo chromophore has been attempted in the presence of potassium persulfate (KPS) as an initiator in the presence of microwave irradiation. The conditions of degradation were optimized and its kinetics was studied. Complete dye degradation was observed in 3600 and 280 s, respectively, using conventional and microwave heating at the original pH (5.8) of the dye solution with COD removal of 60 and 66.5%. Under optimized conditions, efficiency of H2O2 was also compared for degrading the dye. Pseudo-first-order kinetics with higher kinetic rate constant (0.0165 × 102 s−1) and maximum energy efficiency (67.6%) was achieved through microwave assisted KPS system. Additional benefit of microwave approach was accrued by the extensive reduction in electrical energy consumption by 10638.32 kW h/m3. The effect of addition of SO42− and CO32− anions to the dye solution has indicated that the former enhances the degradation, whereas the latter reduces it. The temperature study using Arrhenius equation indicated decrease in the activation energy for the microwave system along with 2.6 times higher frequency factor than that for conventional heating. Thus, the microwave radiation assisted KPS system has been found to be the most cost effective and environmentally benign for the dye degradation process.

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