Vol 57, No 6 (2023)

Hydrometallurgical methods remain among the most promising for lithium-ion battery recycling, and liquid–liquid extraction is the key step in separating the complex mixture of elements that make up the anode and cathode. The development and complication of the composition of batteries, in particular, the active production of lithium titanate anodes, requires additional research on extraction. The work studied in detail the extraction of Ti(IV) ions with the Aliquat 336–menthol hydrophobic deep eutectic solvent, which was previously successfully used to separate elements from leaching solutions of NMC-type cathodes (LiNiMnCoO2). Data were obtained on the extraction of titanium(IV) ions with varying acidity of the medium, concentration of chloride ions, and concentration of the extractant in the deep eutectic solvent. Based on these data, a mechanism for the extraction of titanium(IV) ions was proposed. Finally, a system for efficient extractant regeneration was proposed. The result of this work can be used to create an extraction
scheme for separating leaching solutions of lithium-ion batteries with a lithium titanate anode.

Hydrophilic deep eutectic solvents are actively positioned as efficient extractants for removing heterocyclic compounds from light hydrocarbon fractions. Of particular interest is the subclass of natural deep eutectic solvents (NaDESs), since they contain substances of exclusively natural origin. However, these processes have not been systematically studied to date in extraction equipment. To study the process of countercurrent extraction of pyridine, quinoline, and indole from a model solution of light hydrocarbon fractions
using commercial equipment, a series of NaDESs based on citric and malic acids, xylitol, and water was used for the first time in this work. The high extraction capacity of these NaDES was demonstrated in laboratory experiments, and the extraction mechanism was determined. A detailed study of the efficiency of extraction of heterocycles with varying process conditions allowed us to move on to studying the process using extractors
of the mixer–settler type. From the model solution of light hydrocarbon fractions, pyridine, quinoline, and indole were removed to concentrations <1 ppm by countercurrent extraction using a cascade of six mixer–settlers.

The effect of pressure on the coefficient of relative volatility of binary mixtures of different natures and ternary mixtures containing potential separating agents such as dimethylsulfoxide (DMSO) and butyl propionate is studied. A wide range of information is obtained based on the data on the vapor–liquid equilibrium, and effects of the pressure on the relative volatility of various nature and cause for a fixed composition of the initial mixture are determined. In the presence of points of intersection of the phase-equilibrium curves in the initial binary mixture and pseudobinary mixture (in the section with a constant concentration of the third high-boiling component), the concentration simplex is divided into regions in which the values of the coefficient of relative volatility decrease (increase) upon varying pressure. This fact makes it possible to improve the procedure of optimization of the process of separation at the stage of selection of the working pressure in the columns.

The effect of boric acid amino ester, which was obtained from triethanolamine, boric acid, and triethylene glycol, on the conditions of vapor–liquid equilibrium in the ethyl acetate–ethanol and ethyl acetate–isopropanol azeotropic binary mixtures and the ethyl acetate–ethanol–water ternary mixture was studied both by experimental methods of open evaporation with a Świętosławski ebulliometer, and by modeling using the UNIFAC method. Parameters of the interaction of the CCOO group (in ethyl acetate) with the
boron group B were determined, which are absent in the literature. A process for separating the ethyl acetate–ethanol–water azeotropic mixture by extractive distillation was proposed.

The efficiency of separate trapping of cesium oxide and molecular iodine formed during oxidative thermolysis of cesium iodide in the process of chemisorption on ceramic highly porous block-cellular contact elements is investigated. The dynamic sorption capacity of contact elements with an applied aluminosilicate sorption-active layer and with an active layer of silver nitrate for cesium and iodine, respectively, is determined. The developed contact elements are recommended for use in systems of local gas purification of hightemperature processing stages of recycling of spent nuclear fuel.

Literature analysis shows that the main method to model the equilibrium characteristics of reaction systems at elevated pressures, including processes under supercritical conditions, are equations of state describing the non-ideality of the vapor and liquid phases, while the law of mass action is applied to describe the kinetics of the elementary and chemical stages. The mentioned difference in the types of models used to describe the equilibrium and kinetic characteristics of the same experimental system under study violates the
second law of thermodynamics formulated by Clausius. The only theoretical method consistent with the second law of thermodynamics is the molecular theory based on the lattice gas model. In order to satisfy the second law of thermodynamics, molecular models must provide the self-consistent description of the rates of the chemical process at the equilibrium and elementary stages. This means that the molecular models must provide
a single mathematical apparatus to calculate the states of the system both outside and inside the equilibrium point. The molecular models can differ in both the effective parameters of the interparticle interaction and the methods of refining these models due to taking into account distinctions in sizes, contributions of the vibrational motions of the components, as well as the accuracy of description of the correlation effects. To ensure the self-consistent description of the equilibrium and kinetics, the models must at least reflect the effects of direct correlations. One-particle approximations (mean field, chaotic, density functional) do not correspond to the self-consistency condition and violate the second law of thermodynamics.