Europium (III) recovery from nitrate solutions in a form of dodecyl sulfates using extraction methods was studied. Distribution and recovery coefficients as a function of equilibrium aqueous phase рН value were received. Conclusions on the effectiveness of presented method depending on the assigned task were drawn. The aims of this study were the development of rare-earth elements recovery and separation methods by using extraction with surfactant and distribution coefficients separation as well as recovery coefficient experimental validation with their subsequent introduction for poor mineral raw materials industrial processing. The authors study the rare-earth metals distribution and recovery coefficients during the extraction processes as a function of aqueous phase pH value with recovered compound form determination and thermodynamical justification.

This paper describes the results of experimental and theoretical studies that looked at ion exchange processes in liquid phase systems containing nonferrous metals, rare earth elements and a surfactant — i.e. sodium dodecylsulphate (NaDS). Ion flotation processes are considered in reciprocal systems containing Co+2 and Ni+2. There is a number of reasons for choosing the above salts: – The problem of removing cations of heavy metals (in particular, Co+2 and Ni+2) from water is of relevance; – At рН 7, these ions do not form hydroxides or hydroxide residue; – Co+2 and Ni+2 bond with NaDS to form easily soluble salts; – Quite a few low-cost analysis techniques are known that can detect these ions. Ion flotation processes were also examined in systems containing rare earth elements, NaCl and surfactants. The influence of Cl– ions on the distribution coefficient in Sm+3 and Eu+3 containing systems was studied by comparing instability constants typical of chlorine compounds and hydroxides. It was found that a rising concentration of NaCl is associated with a rising pH of cations of the rare earth elements of interest at the early stage of recovery and during the peak recovery. The paper considers an innovative technique to examine systems with rare earth elements and surfactants — i.e. solvent sublation. The authors examine the possibility of recovering ions of lanthanides (e.g. erbium) by solvent sublation using NaDS as a collector and isooctyl alcohol as an extractant. Many researchers believe the latter to be the best agent for such studies. The concentration of Er+3 in the standard test solutions was 0.001 mol/l. As the process develops, the concentration of extracted ions asymptotically approaches the value that is typical of a system approaching its steady state. It was established that in these conditions the maximum recovery for Er+3 is reached at рН of 8.0. This research study was funded through a scholarship granted by the President of the Russian Federation to young researchers and postgraduate students under the following project: SP-347.2019.1 “Ion flotation as an innovative and efficient technique to recover rare earth elements while concentrating dilute industrial solutions with possible identification of elements”.

Ion fl otation of lanthanum(III) and holmium(III) from nitrate and nitrate-chloride solutions with sodium dodecyl sulfate was studied. The distribution coeffi cients and their dependence on pH were determined.The development of modern technologies requires an even growing number of new materials. Rare earth metals (REMs) play an important role in metallurgy, glass and ceramic manufacturing, and other industries. Cerium lanthanides (lanthanum, cerium, and neodymium) and some yttrium lanthanides (holmium, samarium, and europium) are the most widely used individual REMs. Misch metal containing 50% cerium, 30% lanthanum, 15% neodymium, and 5% praseodymium is extensively used in steel treatment to remove free oxygen and sulfur and the impurities of lead and antimony. Lanthanum oxide is an important component of the optical glass used in the manufacture of laboratory glassware with high thermal stability and acid resistance. Holmium is a component of some magnetic alloys; its compounds have found limited application in the preparation of special glass, phosphors, and some materials for microelectronics.Individual REMs are most in demand in the global market. The diffi culties consist in separating the certain element from their sum and a small number of viable REM deposits. In Russia, the main source of rare metal raw is loparite ore of the Lovozerskoe deposit [1, 2]. Therefore, it is necessary to develop a technology for obtaining a wide assortment of individual rare earth elements. Ion fl otation, ensuring production of a concentrate containing 60-70% of REM oxides, is the promising technology.The removal of lanthanides with naphthenic acid on addition of chlorides to the concentration 0.1-0.15 M decreases the distribution coeffi cient due to the formation of nonextractable chloro complexes [3]. Because the chloro complexes have the different strengths, this decrease is different for each lanthanide, and, consequently, the factor of the Ce/Y separation increases from 1.5 to 14. In ion fl otation of REMs, the separation factors are low [4]. Therefore, it is of interest to study the effect of chloride ions on the ion fl otation process.The ion flotation was performed during 5 min on a 137 V-FL laboratory flotation machine with a chamber volume of 1.0 dm 3 . As model solutions were used 0.001 M solutions of lanthanum and holmium nitrates (both chemical purity grade). The volume of the solution was 200 ml. As surfactant served dry sodium dodecyl sulfate (SDS) whose concentration corresponded to the stoichiometry of the reactioni.e., it was 0.003 M (DS -is the dodecyl sulfate ion).To initial solution, sodium chloride was also added in amount corresponding to the concentrations 0.01 and 0.05 M. At 0.1 M NaCl the lanthanide fl otation is inhibited virtually completely. The resulting solution (foam product) and the solution remaining in the chamber (chamber residue) were separated and analyzed. The foam was disintegrated by addition of 1 M sulfuric acid. The concentration of REMs was determined photometrically with Arsenazo-...

The paper considers the current problem of improving the quality of atmospheric monitoring. The paper aimed at conducting a monitoring section of the existing situation in the studied territories in St. Petersburg. The following study methods were described: gravimetric, electrochemical, and chromatographic. The analysis of samples was carried out on the following laboratory facilities of the mobile environmental laboratory: PU-3E aspirator, ECO-LAB portable gas analyser, DUSTTRAK 8533 dust analyser, portable gas chromatograph FGKh-1, professional weather station. The study consisted of two parts and was carried out in two districts of the city: Novosmolenskaya Embankment of the Smolenka River (Vasileostrovsky District) and the banks of the Volkovka River (Frunzensky District). As a result of the study, the concentrations of nitrogen dioxide, carbon oxide, suspended solids and volatile organic compounds in the air of the studied districts were measured. The obtained values were compared with the maximal single limiting concentration (LMC m.s. ) and assumptions were made about the possible sources of pollution. In the territory of Novosmolenskaya Embankment, the concentration of nitrogen dioxide varied from 0.211 mg/m 3 to 0.472 mg/m 3 , which means the exceedance of LMC m.s. The maximum permissible concentration of the volatile organic compounds (VOC) content in air was exceeded by several orders of magnitude. No exceedance of LMC m.s. was detected for the content of carbon oxide and suspended solids in the air. The empirical data was used to build the air pollution content maps and to calculate the atmospheric pollution index in the studied territory.

This article describes properties of the catalytic conversion of methane to synthesis gas, makes a review of information on the chemical composition of catalysts and provides assumptions about the mechanism of their action. The facts and generalizations given in the article can be useful in determining ways to improve catalytic systems. The most active and most selective catalytic systems make it possible to optimize existing processes by cutting down energy consumption, cost, emissions and increasing the yield of a valuable product. Increasing the depth of conversion and the integrated use of raw materials, as well as ensuring the environmental cleanliness of the technological processes of processing is achieved by using highly efficient catalysts. With the help of highly efficient catalysts it is probable to increase the depth of conversion, the integrated use of raw materials as well as ensuring the environmental cleanliness of the technological processes of its processing.