Том 66, № 5 (2024)

The paper analyzes the causes of the appearance of steps with plateaus of different lengths in sorption isotherms, based on experimental and literature data. Examples of step isotherms are given to illustrate each type of causes. It is shown that the following factors can cause the deviation of sorption isotherms from linearity and the appearance of steps: sorbent polyfunctionality, the presence of sorption sites with significantly different specificity to sorbate; sorbate heterogeneity, the presence of inert sorbable sorbate species; chemical transformation of sorbents in the course of sorption with the formation of new phases, including processes involving solution components; sequential change of sorption mechanisms.

A novel procedure was developed for preparing methyl 14-isocyano-3-methyltetradecanoate. It consists of 12 steps. “2+1_B” tricarbonyl complexes [^99mTc(CO)₃(N^N)CN(CH₂)₁₁CH(CH₃) CH₂COOMe]⁺, where N^N = 2,2’-bipyridine (bipy) or 1,10-phenanthroline (phen), were prepared by the reaction of [^99mTc(CO)₃(N^N)(H₂O,EtOH)]⁺ with methyl 14-isocyano-3-methyltetradecanoate in aqueous ethanol. The formation of technetium-99m complexes was confirmed by HPLC, and the partition coefficient (n-octanol/water) of these complexes was measured.

The extraction of U(VI), Th(IV), and lanthanide(III) ions with mixtures of diphenyl-N,N-dioctylcarbamoylmethylphosphine oxide (Ph₂Oct₂) and lithium bis[(trifluoromethyl)sulfonyl]imide (LiTf₂N) in dodecane containing 10% octanol was studied. A synergistic effect was discovered during the extraction of metal ions with such mixtures. When extracting Ln(III) from solutions of 3 mol/l HNO₃, the D_Ln values in the system with Ph₂Oct₂–LiTf₂N are more than three orders of magnitude higher than when extracting with a solution of Ph₂Oct₂. The stoichiometry of the extracted complexes was determined, and the effect of HNO₃ concentration on the extraction of metal ions was studied. It has been established that actinide and lanthanide(III) ions are extracted with a mixture of Ph₂Oct₂ and LiTf₂N from nitric acid solutions via a cation-exchange mechanism.

The sorption of neodymium, lanthanum, and thorium fluorides from a melt under dynamic conditions using AG-3 activated carbon at a temperature of 650°C was studied for the first time. The well-known eutectic mixture of alkali metal fluorides LiF–NaF–KF was used as the melt. To conduct the experiments, a special installation was developed and manufactured to study the sorption process under dynamic conditions as applied to melts. During the sorption of neodymium and lanthanum fluorides, three main zones are identified: the sorption front formation zone and the sorption and slip zones. It is shown that, under the conditions considered, it is possible to purify thorium fluoride to remove lanthanum fluoride. The maximum value of the sorption capacity for lanthanum fluoride reached more than 5 mg/g and depended on the melt flow rate through the activated carbon zone. Thorium fluoride was not sorbed with activated carbon under the studied conditions studied.

By the methods of thermodynamic modeling, sorption diagnostics, analysis of particle zeta-potential, and UV-Vis spectrometry the equilibrium conditions of sorption interaction of CrO₄ ^2– , MoO₄ ^2– , WO₄ ^2– , SeO₃ ^2– oxygen anions in the region of chemical stability of Al₂O₃||C composite have been analyzed. The anion sorption isotherms are shown to follow the Langmuir model for a monoenergetic sorbent. The Henry region is observed at concentrations less than 1 μmol/L. According to the established mechanism of surface complexation, the value of anions protonation constant (K₁) in the investigated pH range determines the sorption activity of the composite to these anions. This explains the correlation found between the ratio of parameters of acid–base sites {Al–O^–}, {Al–HO⁰}, and {Al–OH₂⁺} of composite K_M(1,2) and the protonation constant of anion K₁. It is shown that the Al₂O₃||C composite exhibits the properties of collective action sorbent, concentrating from dilute solutions both cations of d-, f-elements and oxygen anions of d-elements with the value of logK_d [mL/g] > 4.

The article presents the results of studies of the effect of heat and ionizing radiation on oil extraction from natural bitumen sands (BS) of Azerbaijan. The combined effect of heat (20–500°C) and ionizing radiation at dose rates of 1 and 470 Gy/s was studied. The reactions of radical products generated by ionizing radiation depend on the temperature and rate of their generation, determined by the radiation power. The ratio of the rates of thermal and radiation-thermal reactions is the most universal characteristic. This value is a function of temperature and dose rate. The temperature and dose rate intervals for radiation-thermal processing of oil bitumen sands are calculated. The results obtained allow us to estimate the possibility of obtaining oil products by the radiation-thermal (RT) method. The use of radiation technologies for the organization of industrial production of synthetic oil from natural bitumen sands and heavy oils will have a positive effect from the point of view of environmental protection, since materials that pollute the environment are used in the production of electricity.