DESALINATION AND WATER TREATMENT, cilt.192, ss.315-326, 2020 (SCI-Expanded)
In this study, a chromite sample was examined as a heterogeneous catalyst in the ultrasound-assisted Fenton process for the removal of Malachite Green (MG) from aqueous solutions. Within this scope, the effects of operational parameters, scavengers, and various treatment processes on the removal efficiency of MG were studied as a function of retention time. In addition, the leachability characteristics of the chromite catalyst and intermediates produced during the degradation of MG were determined. The experimental results indicated that, for the equilibrium reaction time of 90 min, the efficiency of 88.73% was achieved with the chromite dosage of 3.0 g/L. However, the higher dosages resulted in a reduction, down to 61.61% for 5.0 g/L. Similarly, the efficiency values of 88.74% and 70.53% were obtained for the respective peroxide concentrations of 30 and 50 mM. On the other hand, the efficiency decreased gradually from 88.74% to 54.46% for initial MG concentrations of 10 and 100 mg/L, respectively. For 100 mg/L, the efficiencies of 30.31%, 64.03%, and 86.57% were obtained for the respective pH values of 3, 9, and 11. The combined effect of ultrasound and peroxide on the catalyst surface assured the optimum efficiency. Ethanol exhibited a more adverse effect than sodium chloride, where the efficiency reduced dramatically down to 38.22%. In addition, only 22.20% reduction was observed in the efficiency after four consecutive cycles. According to the leaching analysis, all of the examined metals have leaching capacities far below the toxicity levels for non-hazardous waste. GC-MS analysis confirmed the efficient degradation of MG during the process. Overall results have shown that the chromite sample provided promising results as a heterogeneous catalyst in a sono-Fenton process for the removal of MG.