Žurnal analitičeskoj himii

The review analyzes research over the past 20−25 years in the field of physical chemistry of complexation of humic acids with cations, including radionuclides, in aqueous solutions. Problems have been identified in describing the reactivity of humate complexes with consideration for the objective complexity of the chemical nature of humic acids as one of the main classes of natural organic matter. The main methods of modeling complexation with humic acids, experimental methods for separating humate complexes and unbound cations (ultrafiltration, dialysis, etc.), and direct instrumental (electrochemical and spectroscopic) methods for detecting complexes were considered. Attention was also paid to the practical aspect of using humic acids for the treatment of natural water and wastewater to remove pollutants—heavy metals and radionuclides. Published data on the sorption capacity of humic acids of various origins in relation to heavy metal cations and quantitative data characterizing the stability of humate complexes were analyzed.

Hydrophilic quercetin-imprinted phloroglucinol–melamine–formaldehyde resins are obtained. The obtained samples are studied by Fourier-transform IR spectroscopy and laser diffraction. The phloroglucinol–melamine ratio (3 : 1) is optimized at the sorption capacity of the molecularly imprinted resin (1.7 μmol/g) with respect to quercetin 2.6 times higher than that of the non-imprinted resin. It is shown that the kinetics of quercetin rebinding by both molecularly imprinted and non-imprinted resins obeys the pseudo-second order model, and the isotherms follow the Freundlich model, which indicates the inhomogeneity of the resin surface. The resin imprinted with quercetin demonstrated high selectivity to morine (a structural analogue of quercetin of the flavonol class) and caffeine. At that it is shown that quercetin can be used as a pseudotemplate for the separation and preconcentration of naringenin (a representative of flavanones) and rutin (a representative of flavonols).

The regularities of the biodegradation of drotaverine hydrochloride in soil by actinobacteria of the genus Rhodococcus in the presence of native microflora were studied. A method based on liquid–liquid extraction with chloroform followed by analysis using reverse-phase HPLC was proposed for determining the pharmaceutical pollutant in soil. A decrease in the ecotoxicant concentration by a factor of 100 in the course of its biodegradation was forecasted with a given probability of 95%.

A voltammetric sensor based on carbon veil modified with graphene nanoplates and phytosynthesized cobalt oxide Co3O4 nanoparticles is proposed for the determination of tartrazine (E102) and allura red AC (E129). The use of a composite nanomodifier contributes to an increase and better separation of the oxidation currents of azo dyes on their simultaneous presence. The process of the oxidation of azo dyes is irreversible, involves two electrons, and has a mixed nature. The sensor is characterized by a low limit of detection: 30 nM for E102 and 27 nM for E129, and in the inversion mode 16 and 3 nM, respectively. The analytical range the dyes is 0.1–15 µM. The sensor has been successfully used in the analysis of fruit jellies and beverage. The advantages of the developed sensor are high performance and operational characteristics, ease of manufacture, and low cost.

A method is proposed for quantifying the specific activities of radioecologically significant radionuclides, including 14C, 99Tc, and 129I, in vitrified high-level wastes. The conditions for the separation and purification of these radionuclides from potential interfering components are optimized and the yield coefficients and purification factors are determined. The quantification of 14C entails a three-fold distillation in CO2 followed by the measurement of the 14C counting rate in the purified solution by liquid scintillation spectrometry. 129I was determined by dissolving a sample in HNO3, five-fold extraction, and the subsequent measurement of the 129I counting rate in the purified solution using liquid scintillation spectrometry. The determination of 99Тс included dissolving a sample in the presence of ClO–, double extraction-chromatographic separation of  99Тс with an adsorbent impregnated with methyltrioctylammonium nitrate, followed by the determination of its activity by inductively coupled plasma–mass spectrometry. We have applied this approach to a simulator of vitrified high-level waste, labeled with radionuclides, and achieved satisfactory results. This approach will be instrumental in the analysis of the accumulated vitrified high-level wastes at the “Mayak” Production Association (Mayak PA). The results will be important for modeling the engineering safety barriers of a deep disposal site for radioactive wastes.