Effective degradation of Orange G and Rhodamine B by alkali-activated hydrogen peroxide: roles of HO2- and O2·.

Advanced oxidation processes offer effective solutions in treating wastewater from various industries. The process of alkali-activated hydrogen peroxide (H2O2) was superior for the treatment of alkaline dye wastewater because no additional reagents were required except H2O2. However, an important and interesting phenomenon had been observed that the primary reactive species were found different for degrading organic pollutants with the process of alkali-activated H2O2. Azo dye of Orange G (OG) and triphenylmethane dye of Rhodamine B (RhB) were chosen as the target organic pollutants. The influences of various parameters on OG and RhB degradation by alkali-activated H2O2 were evaluated. Furthermore, different scavengers, including ascorbic acid, methanol, t-butanol, isopropyl alcohol, furfuryl alcohol, and nitro blue tetrazolium, have been tested to identify the active species involved in dye degradation, and it was found that O2·- was mainly responsible for degrading OG, while HO2- anion was the primary oxidant for degrading RhB.