Degradation of two commercial anionic surfactants by means of ozone and/or UV irradiation

Two commercial anionic surfactants, namely sodium dodecylsulfate (SDS) and tetraethylammonium dodecylbenzenesulfonate (DBS), have been submitted to different oxidizing treatments: ozone, ozone at basic pH, sonication, ozone/sonication, ozone/hydrogen peroxide, UV, and UV/ozone. The best results were achieved with O-3/UV and O-3 at basic pH where hydroxyl radical is generated; under these conditions, nearly complete elimination of the surfactant was achieved after 10 min of treatment (compared with 50% elimination of DBS and 20% of SDS in ozonation at acidic pH, where molecular O-3 is the actual oxidizing agent). The total organic carbon decrease was only moderate and never exceeded 50%. On the other hand, surface tension increased to reach values close to that of distilled water (72 mN/m) in only 15 min of treatment, indicating that ozone is very useful to destroy the species having active surface properties.