The results of scientific, scientific-technical and innovative activities of the organizations of the Department of Chemistry and Earth Sciences of the National Academy of Sciences of Belarus received in 2014–2018 are presented. Their scientific and practical significance is demonstrated.

The adsorption capacity on the interphase surfaces of solution / air and solution / mineral material of binary mixtures of anionic (alkylbenzenesulfonic acid and its sodium salt (ABSCNa)) and nonionic surfactants (Tween-80) was studied. It has been established that the adsorption interaction of binary mixtures of surfactants with the surface of quartz and dolomite is affected by the presence of potential-determining ions that activate the surface of mineral materials, the charge and hydration of the anionic antagonists, the nature of the intermolecular interactions between the surfactant-components of the mixture. It was shown that the ABSCNa / Tween-80 mixture, characterized by low adsorption capacity to the mineral materials under study and absence of interaction between the surfactant components of the mixture, has a maximum oil displacement capacity from the surface of dolomite and quartz.

Co_0,65Zn_0,35Fe₂O₄ nanoparticles were produced by spray-drying in air in presence of NaCl from the solution of nitrates, as well as from the suspension of coprecipitated particles. The precursors obtained were annealed at 300–900 °C in the matrix of the inert component in order to increase the crystallinity degree without substantial increase of the nanoparticle size. Microstructure, morphology and magnetic properties of nanoparticles were studied by XRD, FT-IR spectroscopy, TEM / SEM and magnetometry. For the ferrites obtained from nitrate solutions partial oxidation of Co²⁺ ions to Co³⁺ occurs, which leads to the formation of two spinel phases, ferrite and cobaltite. With the increase of annealing temperature the content of cobaltite decreases and content of ferrite increases. No cobaltite formation was observed for annealing the spray-dried suspension. An increase in the temperature of the heat treatment leads to partial recrystallization of the particles and the ordering of the ferrite crystal structure, which causes an increase in the specific magnetization of the materials: from 32.8 emu/g (before annealing) to 91.3 emu/g (annealing at 900 ° C). The average diameter of nanoparticles after heat treatment does not exceed 100 nm.

The method of chemical deposition of monocrystalline bismuth thioiodide BiSI needles with a high quantum efficiency of photocurrent generation (up to 55 %) in aqueous solutions of electrolytes has been developed. It was revealed that the introduction of sulfide and iodide anions into the electrolyte solution leads to an increase of the absolute photocurrent values, as well as the presence of sulfide ions causes the significant (about 0.5 V) shift of BiSI bands energy towards more negative electrode potentials. The observed effect is of interest for increasing the photovoltage of solar cells based on BiSI and can find application in heterogeneous sensitized systems for increasing the efficiency of photoelectrons injection from a narrow-band sensitizer into a matrix of a wide-bandgap semiconductor.

Today, corrosion and corrosion protection of metals are the most important scientific, technical, economic and environmental problems. The effect of additions of sodium molybdate, ammonium metavanadate, a mixture of sodium molybdate and ammonium metavanadate, thiourea and sodium orthophosphate on the corrosive behavior of hot-dip galvanized steel in a neutral and slightly alkaline chloride-containing medium has been studied. The experimental results obtained by weight and electrochemical methods proved sodium molybdate, ammonium metavanadate, a mixture of sodium molybdate and ammonium metavanadate, thiourea and sodium orthophosphate to be corrosion inhibitors that slow down the rate of destruction of hot-dip galvanized steel in a neutral and slightly alkaline chloride-containing medium by 1.5–11 times.

It has been established that membranes of carbonate and hydrogen phosphate selective electrodes based on higher quaternary ammonium salts are preferable to be plasticized with o-nitrophenyldecyl ether, membranes of sulfate, selenate, selenite-selective electrodes with 1-bromonaphthalene, sulfite, molybdate, tungstate-selective electrodes with dibutylphthalate. The use of an optimum plasticizer allows, in general, reducing both the lower detection limit of electrodes and the values of selectivity coefficients by about 1 order (depending on the interfering ion). A qualitative explanation is given to the results obtained from the Fouoss theory and the Born model.

The reaction of pine gum rosin, turpentine and its components (α-pinene, ∆³-carene, α-terpinene) with citraconic anhydride and itaconic acid was investigated. It was shown that α-terpinene, in contrast to α-pinene and ∆³-carene, reacts with citraconic anhydride to give the unknown cycloaddition reaction product. Its structure was studied by the 2D NMR spectroscopy. Turpentine reacts with itaconic acid forming a complex mixture that contains esters of terpenic alcohols and itaconic acid. Reaction of rosin with citraconic anhydride was studied at 140–180 °С within 0.5–8 hrs in presence of catalytic amounts of H₂SO₄, MgCl₂, AlCl₃, FeCl₃ and new citraconopimaric adducts containing up to ~70 % of citraconopimaric acid as a mixture of two С¹⁵–CH₃ and С¹⁶–CH₃ isomers in equimolar ratio. The highest content of С¹⁵–CH₃ isomer of citraconopimaric acid (35.5–36.0 %) in the adducts was reached within 4–8 hrs at 180 °С in presence of 1–2 mass. % H₂SO₄. The reaction of rosin with citraconic anhydride at 140–160 °С leads to the formation of adduct containing up to 30–50 % of citraconopimaric acid isomers. The synthesized adducts may be used for production of composite materials for different applications (adhesives, polymer composite additives including rubber blends for tire production, components of grease-cooling liquids).

Synthesis of new asymmetric poly-π-conjugated amino derivatives of biphenyl and 3,5-dioxodibenzothiophene containing phenylethyl and fluorophenyl ethenyl fragments in the main chain of conjugation and cyclic fragments as the central chromophore was conducted. Due to the presence of alkylamine substituents, a bathochromic shift (by 15–25 nm) is observed for all the synthesized compounds in comparison with compounds that do not have alkylamine substituents. The compounds obtained are blue phosphorescent luminophores.

The interaction of human monooxygenases and pathogenic fungi with previously obtained esters of isomeric 7-methyl-19-nor-testosterones and a number of heteroaromatic acids – derivatives of pyridine and pyrazine, was studied. Interaction with the active center of CYP11B1 derivatives of steroids of the androstane series containing methyl group at C7 and residues of heteroaromatic acids at C17β is shown.

Geochemical parameters of bottom sediments allow quick estimating the state of the environment within the catchment of watercourses, as the composition of bottom sediments inherits the geochemical features of the components of the surrounding landscape. New data on the content of trace elements, sulfates, chlorides, nitrates, petroleum products, synthetic surfactants and phenols in the bottom sediments, obtained during complex geochemical studies in the Brest region, are presented. The concentration levels of the determined ingredients for sediments of the main types of reservoirs were determined. The maximum accumulation of nitrogen compounds, chlorides, phosphates and trace elements (nickel, cobalt, vanadium, chromium, copper, zinc and manganese) was marked in the sediments of rivers, while sulfates and lead are concentrated to a greater extent in the bottom sediments of the drainage channels. The map of pollution of bottom deposits of the territory of the Brest region of scale 1:200000 was constructed. It was found that the geochemical state of bottom sediments in the reservoirs of the Brest region is mainly in satisfactory condition, the degree of pollution by heavy metals was estimated as permissible with only 3.0 % belonging to the category of dangerous pollution level.

In the article, trends of lead content in atmospheric air of background territories and cities of Belarus according to NSEM data and their correlation with trends of lead content in the atmospheric air of cities and background territories of Europe and the USA are analyzed. Clear downward trends in lead content in the atmospheric air of the background territories of Belarus are shown: the average annual concentration of lead has decreased over the period from 1990 to 2015 by 77 %. According to EMEP stations measuring data having a continuous series of lead observations in atmospheric air since 1990, the mean annual lead content in atmospheric air at these stations decreased till 2013 on average by 86 %. A downward trend in the lead content was observed in the air of Belarusian cities and of some countries of Europe. The most significant decrease in lead content occurred in the USA, where the average annual maximum 3-month concentration decreased from 1990 to 2016 by 99 %. The relationship between trends in lead levels with trends of anthropogenic emissions is analyzed. Differences between the measured lead concentrations and calculated values by dispersion models are shown, which may be due to the incompleteness of the inventory of lead emissions in a number of countries, as well as the significant contribution of other sources of emission in addition to anthropogenic sources of lead emission into the atmosphere. To identify the reasons for these discrepancies, which may be related to the presence of unrecorded anthropogenic sources, secondary and natural sources, and other factors, additional research is needed.

As a result of the study, the effect of curing accelerators (heterocyclic amine and zinc-containing accelerator) on the structure, physico-mechanical and protective properties of coatings based on powder epoxy-polyester compositions was established. The introduction of accelerators into the compositions affects the depth and speed of the curing process of film formers and provides the possibility to reduce the curing temperature. It has been established that the use of heterocyclic amine accelerator is more effective than a zinc-containing catalyst. For compositions containing heterocyclic amine, a decrease in gel time and an increase in the complex of physico-mechanical and protective characteristics of the coatings are observed, which were evaluated for the resistance of the coatings to the static action of a 3 % solution of sodium chloride. It is shown that changes in the protective properties of coatings, depending on the composition, correlate with the structural parameters of the polymer film and are due to the formation of the spatial structure of the polymer with different cross-link density. The use of mixtures of the investigated curing accelerators leads to an increase in the density of the polymer spatial network. This provides high protective properties of coatings to the action of aggressive electrolytes by reducing the permeability of corrosive media into the coating material. For 5000 hours of testing there are no pockets of corrosion under a film and no significant disruption of the continuity of the coatings (bubbles, peeling, wrinkling and cracking) in comparison with the basic compositions that do not contain accelerators.

Information on the production and use of fluorine-containing foaming agents intended for foam extinguishing of fires with oils and other flammable liquids as well as ecological consequences are reviewed in the article. It is shown that poly- and/or perfluorinated compounds usage for fire-fighting foam production led to the emergence of a large group of hazardous chemicals in the environment, including perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS). General information about fluorine-containing foaming agents, their manufacturers and labelling, properties, possible volumes of production and application on a global scale are given. It is shown that the use of fire-fighting foam to extinguish fires, as well as during training, leads to direct discharges of PFOS, PFOA and other fluorine-containing compounds into the environment. The results of studies carried out in various EU countries, Norway, the USA, Canada and Australia, which testify to high concentrations of PFOS, PFOA and other fluoride-containing compounds in groundwater and surface waters as well as in soils, are discussed. The highest levels of contamination are found in the sites where fluorine-containing foaming agents are used. The danger of fluoride-containing compounds entering the human body with contaminated drinking water and food products is shown.