Advanced oxidation of the surfactant SDBS by means of hydroxyl and sulphate radicals

The objective of the present study was to characterize the removal of the model surfactant sodium dodecylbenzene sulfonate (SDBS) from waters using several radical-based water treatment processes. Fenton's reagent has shown high efficacy in surfactant degradation at pH 2 but does not mineralize the dissolved contaminant and is ineffective at pH 7. Due to a low quantum yield (Φ < 0.12 mol−1 Einstein−1), direct photooxidation is not very effective to remove SDBS from aqueous solutions. The presence of H2O2 and K2S2O8 during irradiation generates highly oxidizing radicals that enhance the SDBS degradation rate by radical-based oxidation processes. The UV/K2S2O8 system is the most effective process, because this process can produce the generation of SO4− and HO radical for SDBS oxidation. Moreover, the results obtained in the presence of HO radical scavengers could indicate that SO4− is more selective than HO radicals. For a UV dose of 400 J m−2 the depletion yields determined were 0.4%, 15.6% and 27.8% for UV, UV/H2O2 ([H2O2] = 300 μM) and UV/K2S2O8 ([K2S2O8] = 300 μM) respectively, confirming that UV/K2S2O8 process is the most efficient to oxidize SDBS.