Advanced Oxidation Processes for the Treatment of Surfactant Wastes

Advanced Oxidation Processes (AOP) using ozone, H2O2, ultrasound (US), ultraviolet radiation (UV), Fenton’s reagent (FeII+H2O2) alone or in combination involving hydroxyl radicals are considered as possible methods of clean and ecologically safe remedial treatment for the degradation of organics. In the present study, comparison of kinetics of photochemical, sonochemical and chemical oxidation of 1,000 mg/L of surfactant sodium dodecyl sulpahte (SDS) and a commercial detergent used for decontamination at Centralized Waste Management Facility, Kalpakkam using combination of processes viz., sunlight + FeII + H2O2, UV (15W) + FeII + H2O2, US (130KHz) + FeII + H2O2 and FeII + H2O2 at pH 3.0 was investigated and compared. The surfactant concentration during the course of the degradation was monitored by Methylene Blue Active Substance (MBAS) method. The kinetics of degradation of SDS was much faster than the commercial detergent in all the processes. The rate of degradation in all the processes followed a first order reaction. The photochemical, sonochemical and chemical oxidation yielded complete degradation of surfactant and the rate of degradation of the surfactants follow the order Sunlight + FeII + H2O2  UV (15W) + FeII + H2O2  US (130 KHz) + FeII + H2O2  FeII + H2O2 . Both visible and UV light in the solar spectrum were utilized efficiently for the degradation of surfactants. From the observed pH changes during the degradation formation of acidic intermediates is suspected.