Mineralization and biodegradability enhancement of Methyl Orange dye by an effective advanced oxidation process

An effective process for the oxidation of Methyl Orange dye (MO) was determined by comparing the mineralization efficiency between two advanced oxidation processes (AOPs) viz., ozonolysis and gamma radiolysis in presence and absence of an added inorganic salt potassium persulfate (K₂S₂O₈). The effects of various operating parameters such as ozone flow rate and reaction temperature were optimized to achieve the best possible mineralization extent of MO by ozonolysis. The mineralization efficiency of MO was significantly enhanced during gamma radiolysis in presence of K₂S₂O₈ (γ+K₂S₂O₈) compared to in absence of K₂S₂O₈. The presence of methyl group at the amine of phenyl ring assisted the mineralization of dye during γ+K₂S₂O₈. The oxygen-equivalent chemical-oxidation capacities (OCC) of ozonolysis and γ+K₂S₂O₈ for 75% mineralization of the dye solution were calculated as 7.008 and 0.0336kg equiv. O₂ m^-3, respectively which signifies that γ+K₂S₂O₈ can be explored as an effective AOP. The non-biodegradable MO dye solution became biodegradable even after the dose of 0.5 kGy during γ+K₂S₂O₈ compared to 1 kGy in absence of K₂S₂O₈. The study concludes that a lower dose γ+K₂S₂O₈ could be one of the efficient pretreatment steps before undergoing biological degradation of dye solution.