Decomposition of contaminants of emerging concern in advanced oxidation processes

The paper compared the removal degrees of selected contaminants of emerging concern in water solutions during advanced oxidation processes such as H₂O₂, O₃, UV and UV/TiO₂. The processes were conducted for 10, 30 and 60 min. The influence of the oxidizing agent dose was also investigated. The tested micropollutants belong to the group of pharmaceuticals (benzocaine, akrydyne, carbamazepine, demecolcine, ibuprofen, diclofenac, caffeine), UV blockers (dioxybenzone), hormones (β-estradiol, 17α-ethinylestradiol, mestranol, progesterone), pesticides (triallat, triclosan, oxadiazon) and food additives (butylated hydroxytoluene). The concentration of those compounds in water matrixes before and after selected oxidation processes was determined by GC-MS analysis preceded by solid phase extraction. The highest removal rate of pharmaceutical compounds was observed during the UV/TiO₂ process. The decomposition of hormones in this process exceeded 96% and the concentration of the UV filter dioxybenzone was reduced by 75%. Single UV irradiation was most effective during the decomposition of butylated hydroxytoluene, triallat and oxadiazon. Toxicological analysis conducted in post-processed water samples indicated the generation of several oxidation by-products with a high toxic potential. The occurrence of tested micropollutant derivatives was confirmed by chromatographic analyses. The identification of the formed compounds was performed based on the obtained mass spectra.