New Methods for the Determination of Chemical Oxygen Demand S.Yu. Kelina*†, D.О. Tsymbal‡, Yu.М. Dedkov§
	* Corresponding authors † Petro Mohyla Black Sea National University, Desantnikіv 68 St., 10, Mykolayiv, Ukraine, 54003; ‡ Admiral Makarov National University of Shipbuilding, Heroiv Stalingrada ave., 9, Mykolayiv, Ukraine, 54025; § The Moscow State Regional University, Radio st, 10a, Moscow, Russia 105005; *e-mail: sk21@rambler.ru
	Methods Objects Chem. Anal., 2017, 12(1), p. 17-23 https://doi.org/10.17721/moca.2017.17-23
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Abstract

Literary data on new methods of determining COD using heterogeneous photocatalyst − semiconductor nano- TiO2 were systematized. Disadvantages of traditional methods has been observed. The results of the new study oxidative systems results are presented. Proposed results of conditions of oxidation were analyzed. The reaction time, pH value, dosage of the photocatalyst, initial concentration of Cr (VI), oxidation of chloride ions, the effect of molecular oxygen, the results in the process of UV irradiation (without TiO2) and to the dark reaction (with TiO2) were considered. Stoichiometric ratios with holes and electrons, organic compounds are oxidatively degraded and K2Cr2O7, which is chemically restored were paid and studied. Proposed radical oxidation mechanism, especially the use of different chemical oxidants (K2Cr2O7, Ce (VI), KMnO4) as acceptor of photogenerated electrons considered. Advantages of new photocatalytic oxidative shown. Outstanding issues and shortcomings developed methods determined COD formulated. The results of their research systems UV-nаnо-ТіО2-K2Cr2O7 are present. Ambiguous impact on the initial concentration of K2Cr2O7 degree of oxidation of organic compounds by comparing the absorption spectra dichromate ions and UV-radiation field of the lamps shown. The limited use of d-glucose, potassium hydrotartrate and any other easily oxidized substanceas standard substances in developing methods for determining COD shows.

Keywords: phonocatalytic oxidation, catalyst nano-TiO2, chemical oxygen demand

Article language: Rus