O. N. Chaikovskaya

Association constants of modified humic acids with biocides of the triazole series: Cyproconazole and tebuconazole

The interaction of humic acids with biocides of triazoles in dependence on the concentration of components in solutions was investigated by spectrofluorimetry. The complex behavior of intermolecular interactions between biocides and humic acids, including donor-acceptor and hydrophobic bonds, was established. The effect of conditions of mechanochemical modification of humic acids and pH on the efficiency of interaction with biocides is shown.

Effect of simulated solar radiation on the interaction of humic acids with naphthalene

The equilibrium constants of binding of naphthalene with a series of humic acids were determined by the fluorescence quenching method. The effect of irradiation on the extent of the interaction of naphthalene with humic acids was examined. Based on the data obtained, preliminary conclusions on the structure of humic acids of raised bog peat before and after modification were made.

Spectral and chromatographic study of the effect of UV preirradiation on the biodegradation of phenols

The effect of UV radiation of a KrCl excilamp on the biodegradation of 4-nitrophenol, 2,5-dinitrophenol, and their mixture by a Penicillium tardum H-2 isolate strain and microbiocenosis of activated sludge was studied. It was shown that the efficiency of the successive photodegradation and biodegradation of nitrophenols depended on the initial concentration and the time of UV preirradiation. UV irradiation increased the efficiency of the biodegradation of 2,5-dinitrophenol with respect to the biodegradation alone. Preliminary UV irradiation inhibited the subsequent biodegradation of 4-nitrophenol by a Penicillium tardum H-2 isolate strain and activated sludge.

Phototransformation of cresols in water solutions with KrCl-laser excitation

The methyl-substituted phenols(o- and p-cresol) photolysis under UV-excitation from KrCl-laser in water solutions are presented. The irradiated solutions were investigated by spectroscopic methods. The comparison of the KrCl-laser irradiation effects with and without argon bubbling for phenol, o- and p-cresol was realized for the first time.

Role of modified humic acids from peat in the detoxification of tebuconazole

The acid-base properties of the initial and modified humic acids from high-moor peat were studied. It was found that the acid properties of humic acid preparations increased for CnCOOH groups and weakened for ArCOOH groups upon the mechanical activation of peat. The energies of dissociation and the degrees of dissociation of ionogenic acid groups were calculated. The detoxifying properties of the modified humic acid preparations toward the fungicide tebuconazole were studied.

Application of excilamps in a flow reactor for recovery of stable toxic compounds

The preliminary results of the development and tests of a prototype of a small flow reactor for utilizing stable compounds are presented. A specific feature of the reactor is the use of two excilamps with different radiation wavelengths (λ ∼ 222 nm, λ ∼308 nm) and a polypropylene microfiber material. Then, design of the test bench allows studying the degradation of organic compounds before their mineralization. In accordance with the described technique, the experimental dependences of the decrease in organic compounds on the irradiation time are measured. The energy consumption is within 100 W. The reactor has been developed for training purposes, but it can be used when developing industrial reactors. The proposed design of the reactor equipped with a unit for photocatalytic degradation allows its application for recovery of a wide class of compounds.

Physicochemical and spectroluminescent properties of the humic acids of coals

The functional group composition, spectroluminescent properties, and catalytic effect of humic acids isolated from coals were studied. The constants of the complexation of humic acids with cadmium ions were determined by a fluorescence quenching method.

Redox properties and antiradical activity of humic acids under exposure to UV and visible light

Changes in the redox and antiradical properties of humic acids upon exposure to monochromatic UV light of an excilamp and polychromatic light of a helium lamp were studied.

Photochemical transformation of methylphenols under different excitation

A method of fluorescent spectroscopy is used to study phototransformations of 4-methyiphenol and its NH2-substitutes in water excited by UV radiation of different sources. It is demonstrated that the photophysical and photochemical properties of these molecules depend on the electronic state to which they are excited.

Fluorescence investigations of cresol photolysis

The method of fluorescent spectroscopy is used to investigate the influence of the pH of the medium on phototransformations of o- and p-cresol in water under UV irradiation. It is demonstrated that the efficiency of cresol photodecomposition decreases with the increasing pH of the medium. The efficiency of cresol phototransformations in an alkaline medium is higher under irradiation at 283 nm, whereas in a neutral medium, it is higher under irradiation at 222 nm.