Ozone, chlorine and sodium hypochlorite are commonly used as disinfecting agents for drinking water production. The reaction pathways of ozonation and chlorination of o-methoxybenzoic acid in aqueous solution were studied using gas chromatography-mass spectrometry (GC-MS) and high pressure liquid chromatography (HPLC). The results show that less than 1% of omethoxybenzoic acid remains in reaction. The final major products using ozone oxidation are oxalic and glyoxalic acids. Phenols appear only at insufficient ozone levels. Sodium hypochlorite leads to higher levels of primary products. Molecular chlorine leads to the formation of higher amounts of polychlorinated derivatives. Model experiments allow to propose schemes of o-methoxybenzoic acid transformation under the conditions simulating water treatment processes.
The possibility of the formation of toxic products at the stage of drinking water disinfection as a result of interaction of disinfectants, such as chlorine and sodium hypochlorite, with model organic com pounds, structural fragments of natural humic substances is investigated using gas chromatography-mass spectrometry (GC-MS). Both qualitative and quantitative analysis of the products of water chlorination of dibenzoylmethane and cinnamic acid by chlorine and sodium hypochlorite was performed under the condi tions of an equimolar amount and five and fiftyfold excess of the chlorinating agent. Detailed diagrams of the transformation of organic compounds under the conditions simulating the process of natural water dis infection are drawn. The studies indicate that the use of chlorine leads to a greater variety and higher concen trations of chlorinated products compared to sodium hypochlorite.
A study of the hydrocarbon-type content of the base summer diesel fuels of various oil refineries in Russia was carried out using the methods of gas chromatography and high-performance liquid chromatography. It is shown that the experimental results obtained using these methods, namely the content of normal paraffinic, the total content of paraffin-naphthenic and aromatic hydrocarbons, do not provide sufficient information to predict the physicochemical and performance properties of diesel fuels. The method of two-dimensional gas chromatography-mass spectrometry was applied for a more detailed study of the hydrocarbon composition of diesel fuels, which made it possible to determine the ratio of normal and isoalkanes, the content of mono-, bi- and polycyclic naphthenic and aromatic hydrocarbons, and to explain the differences between fuels with similar performance characteristics.
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