Deep Destruction of the Triton X-100 Nonionic Surfactant in Water by Advanced Oxidation Processes Involving Ozone

Alkylphenolpolyethoxylates whose bioresistant metabolites (alkylphenols, short-chain alkylphenolpolyethoxylates and alkylphenoxycarboxylic acids) are compounds with hormonal activity that pose a serious threat to living organisms are among the main types of nonionic surfactants widely used in industry and everyday life. Advanced oxidation processes (AOPs)-in particular, photocatalytic processes-are capable of effectively removing such impurities from an aqueous medium. However, photocatalytic oxidation of some synthetic surfactants with oxygen until their complete mineralization proceeds slowly. The combined use of a photocatalyst and oxidizing agents that are stronger than oxygen contributes to an increase in the degree of mineralization of organic impurities and a decrease in the reaction time compared to those achieved with separate treatment by both methods, which gives rise to the lower cost of water purification and improves the environmental friendliness of the combined process. The photocatalytic processes of degradation of nonionic surfactant octylphenol ethoxylate (Triton X-100) in an aqueous medium by ozone (O-3), by ozone and UV radiation jointly (O-3/UV), and by ozone and atmospheric oxygen in a TiO2 Degussa P-25 suspension (O-3/TiO2/UV and O-2/TiO2/UV) under UV irradiation with a DB-15 low-pressure mercury quartz lamp (lambda = 254 nm) have been studied. The parameters of photocatalytic ozonation have been determined to ensure the nearly complete destruction of Triton X-100 (97% according to total organic carbon). The advantages of photocatalytic ozonation of a Triton X-100 solution in comparison with ozonation, O-3/UV treatment, and photocatalytic oxidation with air oxygen are demonstrated.