Transformation Products of Emerging Contaminants Formed during Advanced Oxidation Processes

Ecotoxicity of Malathion® 500 CE before and after UVC radiation and UV/H2O2 treatment

“…However, UVC 120 min photolysis likely generated toxic degradation byproducts for lettuce, once in 30 min of radiation exposure there was 21% of inhibition in root growth (RGI = 0.79), while at 120 min the percentage of inhibition growth increased to 36% (RGI = 0.64). Even though there were no significant differences between them, this increase of the toxicity can be associated to the formation of inorganic anions such as sulfates and phosphates due to cleavage of the P-S bonds 17,18 .…”

“…It was observed in both treatments that there was no immobility for A. aegypti (Table 1), inferring that the degradation of Malathion 500 CE was efficient, losing its larvicidal property, besides that; the byproducts generated were not toxic to the organisms 17 . Comparing the results obtained before and after treatment, the toxicity of the commercial product reduced 100% when tested on A. aegypti, demonstrating that it is a viable alternative on the treatment of this organophosphate.…”

“…For UV/H2O2, rootlets growth had high inhibition at 30 min of treatment (RGI = 0.55) and in 120 min was observed decrease of toxic effects (RGI = 0.76). It is possible that at the initial 30 min were formed intermediates by sulfur oxidation and generation of molecules from the combination of phosphorus, sulfur, carbon, hydrogen and oxygen, for example, phorate sulfoxide and phoratoxon sulfone 17,18 .…”

“…Recent works have shown the efficiency of AOPs, as photo-Fenton process 13 , UVC/H2O2 14 and others 15 , in the degradation of malathion in aqueous solutions. However, for the degradation of malathion, it is possible to obtain several by-products of the oxidation reaction, including substances like phorate sulfoxide, diethyl phosphate, pharatoxon sulfone and malaoxon, the latter being very toxic, which inhibition power under the enzyme acetylcholinesterase is 40 times higher than the parent compound 16,17 .…”

Decontamination and disinfection of water by solar photocatalysis: The pilot plants of the Plataforma Solar de Almeria

“…Information concerning degradation of contaminants using photocatalysis is available in several reviews [26,16,40] recently published. An important aspect of these types of processes is that degradation occurs through oxidation steps, meaning that different transformation products are generated during the treatment [37] The parent molecule can be completely degraded, but partially oxidized molecules remain. Transformation products are often formed by hydroxylations and ruptures of double and triple bonds.…”