Illarion Igorevich Dovhyi

Background: Antimony-119 ( ¹¹⁹ Sb, t _1/2 = 38.19 h) is an Auger electron emitting radionuclide of interest for radiopharmaceutical therapy. It can be directly produced by proton bombardment of tin-119 using low energy cyclotrons. The radiochemical separation methods available for recovering ¹¹⁹ Sb from the bulk Sn target material are lacking, particularly with respect to matrix suitability for further applications. Results: Eight new resins were successfully synthesized, evaluating combinations of two different resin support materials with three different chain lengths of ethers (dibutyl, dipentyl, dioctyl) as well as fluorinated alcohol as the impregnated extractant. All resins showed good stability, losing less than 1% of functional groups in HCl and water. Seven out of eight synthesized resins showed excellent capacity, retaining tens to hundreds of milligrams of Sb per gram of resin. Seven out of eight synthesized resins, as well as one of the resin supports showed good separation between Sb and Sn based on the distribution coefficient studies as well as dynamic elution studies. Conclusions: Our tested resins may be applied for the separation of radiotracer amounts of Sb from bulk Sn target material. We propose the dibutyl ether functionalized divinylbenzene copolymer resin support (DBE-300 resin) as the best candidate, based on the following characteristics: (1) quantitative, concentrated elution of Sn offering compatibility with recycling of enriched ¹¹⁹ Sn material; (2) near-quantitative (98%), concentrated recovery of ¹¹⁹ Sb in ethanol, providing a matrix resistant to hydrolysis, easy to convert by evaporation, as well as toxicologically insignificant pre-clinically and even clinically.

In our work, the photonuclear production of ^198,199Au isotopes for nuclear medicine purposes was studied, and a method for their recovery from irradiated mercury was developed. The yields of the corresponding nuclear reactions were determined, and a comparison of various methods of obtaining gold radioisotopes was provided. New sorbents based on benzo-15-crown-5, which selectively binds gold, were studied, and the optimal conditions for Au recovery with a high degree of purification from mercury were found. It was established that, for the fast and quantitative recovery of Au isotopes, it was necessary to add at least 0.1 mg of the carrier. As a result, the developed method can be regularly used to obtain ^198,199Au for the research of radiopharmaceuticals based on them.

Sorbents based on Fe(OH)₃ and aluminum oxide are widely used in oceanology for the recovery of cosmogenic radionuclides ⁷Be, ³²Si, ³²P, and ³³P from the seawater. It is also possible to use them for the recovery of the natural radionuclides ²¹⁰Pb, ²³⁴Th. A comparative study of the sorbents based on Fe(OH)₃ and acrylic fiber obtained through various impregnation methods was carried out, and their comparison with granulated aluminum oxide. The possibility of extracting trace amounts of phosphorus and beryllium under laboratory and field conditions with these sorbents was studied. The sorption of ⁷Be, ²¹⁰Pb, and ²³⁴Th on the natural content by the two-column method was investigated. It is shown that fiber samples obtained by oxidation with sodium ferrate and the “classical” method have the highest sorption characteristics.

The groundwaters of the southwestern region of Crimea are formed on the karst plateaus of the Crimean Mountains, and a significant amount of them is discharged into the Black Sea. The Crimean Peninsula is a water-deficient region; therefore, the study of its hydrogeology is an urgent task, since groundwater is a valuable freshwater resource. Through submarine groundwater discharge (SGD), the transfer of chemical compounds to the sea in the event of anthropogenic interference may also occur. In this work the fluxes of submarine groundwaters in the area of Cape Peleketo in different seasons, and also the fluxes of nutrients within them, are evaluated for the first time, as well as the factors determining their variability. During the study, hydrological (temperature, salinity (S), current velocity) and hydrochemical (concentration of biogenic elements) parameters, as well as the concentration of long-lived isotopes of ²²⁶Ra and ²²⁸Ra, were measured. The SGD fluxes were estimated through the mixing formula. As the endmember, we used groundwater concentrations of nutrients or radiotracers, defined by extrapolation of nutrients or radium concentrations to zero salinity. Significant differences in the studied region’s SGD flux values (from 4100 to 13,900 m³/day) are shown; maximum values are in winter and summer, and minimum values are in autumn and spring. The relationship between the seasonal variability of the discharge intensity and the amount of precipitation in the groundwater formation area is shown. The data obtained show that this source makes a significant contribution to the local supply of nutrients. Substantial amounts of nitrates come from the karst cavity, which can lead to eutrophication and limit the primary production of phosphorus in the local coastal sea region.

The review presents the general methodology of using sorption methods to solve problems of marine radiochemistry, including sampling, preconcentration and radiochemical preparation and methods for measuring the activity of radionuclides. The possible methodological errors at various stages of sampling and sample concentration are discussed. The most widely used artificial (⁹⁰Sr,¹³⁴Cs,¹³⁷Cs,²³⁹Pu,²⁴⁰Pu), natural (²¹⁰Pb,²¹⁰Po; radium quartet:²²³Ra,²²⁴Ra,²²⁶Ra,²²⁸Ra; thorium isotopes, mainly²³⁴Th) and cosmogenic (⁷Be,³²P,³³P) radiotracers are considered. The sorption of uranium from seawater is not addressed, since its concentration in seawater is usually calculated from the known dependence of uranium concentration on seawater salinity.The bibliography includes 200 references.