Fast and ecofriendly triple sulfonamides mixture utilization using UV irradiation and spherical SnO2 nanoparticles with controllable parameters and antibacterial activity.

One of the solutions for the growing problem of water purification is photocatalytic degradation of the pollutants. Semiconductor nanoparticles are widely under study as a promising photocatalyst for this purpose. However, there is still lack of understanding of the relation between properties of nanoparticles, in their turn related with synthesis conditions, and photocatalytic efficiency, as well as of the other factors influencing the process. For the first time, a possibility to regulate photocatalytic activity of SnO2 nanoparticles under UV light via regulation of structural parameters is shown. A method for obtaining spherical nanoparticles with different parameters was developed. Obtained nanoparticles were fully characterized. Special attention was paid to the study of oxygen vacancies. With the help of quantum computational methods, it was shown, that the concentration of vacancies is around 1 per 32 tin atoms. Obtained data on oxygen vacancies were further used for the evaluation of pollutant-nanoparticle surface interaction to get closer to the calculations of real systems. On the example of methylene blue, it was shown that the greater is the amount of oxygen vacancies and the lower the amount of defects, the higher photocatalytic activity. The obtained dependence is confirmed by the fact that the photoresponse increases with a decrease of amount of defects in the sample. Degradation kinetics of sulfonamides mixture was studied, and its dependence on active complex formation was shown based on the quantum chemical calculation data. Degradation of antibiotics in water from Neva River reached more than 95% in 35 min, which indicates that developed photocatalyst efficiency is not affected by pollutants contained in open water in the centre of the metropolis. It was shown, that the use of nanoparticles allows to speed up the process of bacteria destruction under UV light, which indicates the antibacterial activity of obtained nanoparticles.

Reversed-phase dispersive liquid-liquid microextraction based on decomposition of deep eutectic solvent for the determination of lead and cadmium in vegetable oil.

In this work, a reversed-phase dispersive liquid-liquid microextraction procedure based on the decomposition of deep eutectic solvent was suggested for the first time. The procedure was utilized for fast and simple separation of lead and cadmium from vegetable oil samples. The procedure assumed mixing of oil sample and DES based on menthol, formic acid and water. Water as component of DES promoted its decomposition in sample matrix resulting menthol dissolution in the sample phase and dispersion of aqueous formic acid solution. In this procedure menthol acted as a dispersive solvent during DES decomposition for dispersion of aqueous formic acid solution. The metals were determined by the square-wave anodic stripping voltammetry. The limits of detection, were 0.01 µg kg-1 for lead and 0.006 µg kg-1 for cadmium. The RSD was less then 6% for both analytes. The enrichment factor was 36 and 39 for lead and cadmium, respectively.

Voltammetric Study of the Influence of Various Phosphate Anions on Silver Nanoparticle Oxidation.

The antibacterial properties of silver are strongly controlled by the redox couple of silver/silver(I). This work reports the influence of phosphate anions on silver nanoparticle oxidation, which is important given the abundance of phosphate species in biological systems. The three different species of anions were found to have a varying degree of influence on silver oxidation with the order PO4 (3-)>HPO4 (2-)>H2PO4 (-). It was found that in the presence of phosphate anions, the silver oxidation potential shifts to a less positive value, which indicated the increasing ease of the oxidation reaction of silver. Given that the interplay between silver and its cation is crucial to its antibacterial properties and significant concentrations of the HPO4 (2-) anion are present at biological pH (near neutral), it is essential that the influence of the dibasic anion (HPO4 (2-)) on silver oxidation dynamics be considered for biological systems.