O3/S2O82- enhanced degradation of reactive green 19 dye: Response surface methodology

Abstract

Reactive Green (RG19) is one of azo dye that potentially hazardous towards human due to highly recalcitrant to degrade and still lack of effective treatments. This study introduced a significant study since numerous conventional treatment processes were not capable of removing that azo dye in fast and efficient process. Therefore, increase strong potential of sulfate and hydroxyl radical resulting in an improvement towards Advanced Oxidation Processes (AOPs) which is ozonation process has been proposed to degrade RG19 dye efficiently. Ozonation (O3) and Ozone/Persulfate (O3/S2O82-) processes were tested either can be a standalone process or need a better combination of a catalyst which is sodium persulfate (Na2S2O8). The efficiency of dye degradation as follows: colour removal, chemical oxygen demand (COD) and the presence of organic molecules. The efficiency colour removal with O3 reached 75% while (O3/S2O82-) reached 85% at similar reaction time. Also, the average rate of efficiency COD removal (O3/S2O82-) yielded the highest 27.82% whereas O3 reached only 10%. After that, the effects of operational conditions had been investigated in (O3/S2O82-) process including the fixed initial concentration of the dyes, initial pH of the RG19 (2-6), Na2S2O8 concentration (25-65 mM) and contact time (3-25 min) on the colour and COD removal efficiency. Central composite design (CCD) has been applied to achieve the optimization of (O3/S2O82-) was resulting (Colour removal; R2 = 0.900, COD removal; R2 = 0.508). Hence, the optimum conditions of the process at (pH 8, 40 mM, 14 min) and can be shown specifically by mathematical modelling equation also based on interactive effect by 3D contour plot. This overall result indicates that (O3/S2O82-) process enhances a synergistic effect that could be observed in structural changes of dye molecule along RG19 degradation.Reactive Green (RG19) is one of azo dye that potentially hazardous towards human due to highly recalcitrant to degrade and still lack of effective treatments. This study introduced a significant study since numerous conventional treatment processes were not capable of removing that azo dye in fast and efficient process. Therefore, increase strong potential of sulfate and hydroxyl radical resulting in an improvement towards Advanced Oxidation Processes (AOPs) which is ozonation process has been proposed to degrade RG19 dye efficiently. Ozonation (O3) and Ozone/Persulfate (O3/S2O82-) processes were tested either can be a standalone process or need a better combination of a catalyst which is sodium persulfate (Na2S2O8). The efficiency of dye degradation as follows: colour removal, chemical oxygen demand (COD) and the presence of organic molecules. The efficiency colour removal with O3 reached 75% while (O3/S2O82-) reached 85% at similar reaction time. Also, the average rate of efficiency COD removal (O3/S2O8...