STUDY OF THE EFFICIENCY OF PHOTOCATALYTIC PROCESSES IN THE OXIDATION OF MODEL ORGANIC POLLUTANTS IN NATURAL WATER SOLUTIONS

The influence of the main hydrochemical parameters, ionic and elemental composition of natural waters with different anthropogenic loads on the efficiency of photocatalytic processes is investigated for the oxidation of model organic pollutants: azo dye (methyl orange, MO), phenothiazine dye (methylene blue, MB). Comparative studies of water quality in two small rivers located within the boundaries of Khabarovsk (the Krasnaya River) and beyond (the Polovinka River) from April to October 2023 were carried out using the methods of chemical analysis, mass spectrometry with inductively coupled plasma and spectrophotometry. It was shown that the highest concentrations (>5 mg/dm3) were observed for ions (HCO-3, Cl-, SO2-4) and elements (Na, Ca) in rivers draining urban areas (large highways, industrial enterprises, residential areas) and suburban territories (agricultural lands, country house areas). The efficiencies of photocatalytic destruction of anionic (MO) and cationic (MB) model pollutants dissolved in distilled water, water from small rivers, distilled water in the presence of Na+, HCO-3 Cl-, SO2-4 ions were compared. The time of photodestruction was assessed for model pollutant transformation degree equal to 90 % at the final stage of photocatalytic experiment. The degree of reduction in the efficiency of photocatalytic processes when conducting experiments in waters from small rivers was assessed with respect to the experiment in distilled water. The time of photodestruction of samples from real water bodies (at the degree of pollutant transformation 90 %) was demonstrated to increase with respect to the experiment in distilled water by a factor of 4.8-7.3 (MB) and 1.9-4.7 (MO) for the samples from the Krasnaya river, 3.7-6.3 (MB) and 1.1-2.2 (MO) for the Polovinka river. Value scattering was due to the seasonality of sampling.