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Flotation collector O-isopropyl N-ethylthionocarbamate (IPETC) is widely used for separation of sulfide ores. Its removal from water by several oxidation processes was studied. Photocatalytic oxidation with air in the presence of iron salts, utilizing solar irradiation or artificial UV-A light is very efficient. Oxidation leads through the formation of O-isopropyl N-ethylcarbamate and several other reaction intermediates to total decomposition of organic compound in the final stage in 1 day. Similar results were obtained with a Fenton type oxidation with hydrogen peroxide and iron salts. Treatment with sodium hypochlorite yields mainly O-isopropyl N-ethylcarbamate. The formation of this compound in wastewaters can be of concern, since simple alkyl carbamates are cancer suspect agents.

Disinfection is an important step in the purification of drinking and swimming pool water. The most common procedure includes chlorination, which efficiently eliminates microorganisms. However, the reaction of active chlorine with dissolved organic matter produces numerous organochlorine compounds posing a hazard to the environment and human health. UV filters belong to emerging contaminants, as their application to skin protection from UV irradiation becomes increasingly popular all over the world. Certain components of UV filters were detected in swimming pools and result in the emergence of new ecotoxicants. In the present study, 40 compounds, including numerous brominated derivatives, which result from the chlorination of avobenzone in sea water, were identified by gas chromatography–high resolution mass spectrometry. In addition, the applicability of photocatalysis to the destruction of chlorination products was studied. The procedure was found to be rather efficient and allows a decrease in the total amount of avobenzone transformation products by a factor of 10. The only compound class demonstrating stability under the applied conditions is exemplified by halogenated acetophenone derivatives. [ABSTRACT FROM AUTHOR]

Malathion, one of the most widely applied insecticides, is still used in agriculture. There are many studies regarding its degradation under different experimental conditions, but few deal with its transformation products, i.e. malaoxon and isomalathion. Thus, malathion, malaoxon, isomalathion, and Radotion (one of its over 6000 commercial forms) were studied in terms of their degradation kinetics, identification of their transformation products, their toxicity, and their degree of mineralization, during UV photolysis (λ=254nm) and TiO2 photocatalysis (λ=355nm). The degradation kinetics was similar for all four starting materials. More than 75% of theoretically expected sulfur in Px2013;S groups was oxidized after 240min of photolysis and photocatalysis. On the other hand, less than 30% of stoichiometrically predicted amounts of phosphate was detected in the photolytic experiments, but more than 80% of expected phosphate was detected after photocatalytic treatment of all four organophosphorous materials. Several transformation products were identified by mass spectra of representative gas chromatographic peaks. Oxidation and isomerization were found as the main reactions of butenedioc acid diethyl esters and their analogs. The formation of malaoxon, isomalathion or trimethyl phosphate esters correlated well with the induced toxicity (inhibition of acetylcholinesterase), which was observed in photocatalysis of malathion and Radotion, and in photolysis of malaoxon and Radotion. [Copyright &y& Elsevier]