Development of a method for determining the extent of organic matter destruction during the treatment of ecotoxicants in the process of peroxide oxidation is presented. The technique is based on the modification of the chemical oxygen demand (COD) method for samples containing a low amount of ecotoxicants. The modified COD technique consists of milder conditions: the sample preparation temperature is reduced from 150 to 90°C, and the sample heating time is reduced from 2 to 1 h. The technique was tested on reaction mixtures obtained from the process of peroxide oxidation of methyl orange (MO) with an initial concentration of 20.4 mg/L. The process was carried out in the presence of CuFe2O4/microcrystalline cellulose (MCC) and CuFe2O4 catalysts. Complete decolorization (100%) of MO was achieved at 120 min on the CuFe2O4/MCC catalyst, with a relative COD decrease of 72.4%; by 180 min, the relative COD decrease reached 83.3%.
Mishchenko et al. (Mon,) studied this question.