Search

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, mainly 234Th) 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.

This paper investigates the physical and chemical regularities (isotherm and kinetics) of the sorption of strontium and cesium ions from the seawater. Cesium ions were extracted by sorbents based on transition metal ferrocyanides (Anfezh, Niket, Uniket, FSS, FD-M, Termoxid 35, NKF-C), resorcinol–formaldehyde polymer (Axionit RCs), zirconium phosphate (Termoxid 3A), strontium ions—by sorbents based on manganese oxide (Modix, MDM, DMM, fiber impregnated with MnO2), phosphorus oxide (FD), zirconium hydroxide (Termoxid 3 K), barium silicate (SRM-Sr). The obtained dependences of the sorption parameters on time were described using the models of intraparticle diffusion, pseudo-first, pseudo-second-order, and Elvoich; the dependences of the sorption parameters on the equilibrium concentration of the metal in the solution were described using the Langmuir, Freundlich, and Dubinin-Radushkevich sorption isotherms.

The sorption of lead by an impregnated type sorbent based on the phosphorylpodand, 1,8-bis[2-(diphenylphosphorylmethyl)phenoxy]-3,6-dioxaoctane, was studied. Sorption isotherms were plotted, as well as the data on kinetics, selectivity, and dynamics of sorption were obtained. The phosphorylpodand-based sorbent attains the sorption equilibrium of lead extraction with a high rate. The maximum sorbent capacity was achieved when the equilibrium concentration of lead in solutions was more than 150 mg L−1. The 1,8-bis[2-(diphenyl-phosphorylmethyl)phenoxy]-3,6-dioxaoctane-based sorbent shows a high selectivity for lead sorption from neutral solutions. The output curve of lead sorption was plotted. The dynamic exchange capacity and total dynamic capacity of the obtained sorbent were determined.

The paper contains the results of determining the physical and chemical characteristics of lead sorption by impregnated sorbents based on Di-(tert-butylcyclohexano)-18-crown-6 and different diluents (1,1,7-trihydrododecafluoroheptanol, ionic liquid). The results of studying the influence of sorption time (kinetics) and lead concentration in the initial solution (isotherm) on the degree of lead extraction by the obtained sorbents, as well as the selectivity of lead sorption against other metals, were presented for the first time. These characteristics are important to justify the ratio of the solution to the sorbent for concentration and separation from related impurities, the rate of transmission of the solution through the sorbent, estimates of the amount of stable tracer to be inserted. The specific activity of 210Pb in the Black Sea was determined for the first time using the obtained sorbents. Samples for determining the specific activity of 210Pb in sea water were taken on cruise 101 of the R/V “Professor Vodyanitsky” (December 14–28, 2017).

Purpose. The purpose of the study is to investigate distribution of 137Cs in the coastal and deep-water part of the Black Sea. To achieve this goal, the following scientific problems has to be solved: choosing a method for concentrating 137Cs from seawater samples, seawater sampling and 137Cs concentrating, measurements of the obtained samples, discussion of the obtained results and their comparison with the available scientific literature data. Methods and Results. Distribution of 137Cs activity in the coastal and deep-water part of the Black Sea was studied. The in situ data on spatial-temporal variability of the 137Cs volumetric activity field in the Black Sea surface layer obtained in course of the 95th cruise of the R/V "Professor Vodyanitsky" in June, 14–July 7, 2017 were used. The data on the radionuclide vertical distribution in the sea active layer were obtained at a number of stations. 22 seawater samples were taken and processed at 11 stations. To separate 137Cs from seawater, a ferrocyanide sorbent of the FCC brand was first applied; it was intentionally developed for selective recovery and separation of 134Cs and 137Cs radionuclides from the technological processing solutions and radioactive waste water. Conclusions. According to the results, the volumetric activity of 137Cs varied spatially in the range 5.7–8.8 Bq/m3 and amounted on average 6.9 ± 0.2 Bq/m3. Within the active layer boundaries, vertical distribution of 137Cs was found to be uniform.

The paper presents the results of a study of the physical, chemical and sorption properties of a fibrous sorbent—polyacrylonitrile modified with a mixed phase of manganese oxide, in relation to the natural isotopes of radium in seawater. The paper contains methodical guidelines for synthesizing the material the most efficiency and hydromechanical stability. It is described using structural (diffractometry, IR spectroscopy) and physicochemical methods of analysis (thermal analysis, gas adsorption). The possibility of using this sorbent for the concentration of cosmogenic (7Be) and natural (226Ra, 228Ra, 234Th) radionuclides from seawater samples under field conditions was studied. The results of determination of the concentration of dissolved 226Ra, 228Ra, 234Th in seawater samples using this sorbent were compared with the published data. Evidence of sorption 7Be from seawater samples using this fiber was obtained by γ-spectrometric analysis.

Sorption of Sr(II) and Pb(II) onto impregnated sorbents based on di(tert-butylcyclohexano)-18-crown-6 and an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C4mim+Tf2N−), was studied. The influence of the crown ether concentration in the sorbent, kind and pretreatment of the support, and kind of the solvent used for impregnation on the sorption of Sr and Pb onto sorbents based on di(tert-butylcyclohexano)-18-crown-6 and C4mim+Tf2N− was analyzed. Sr(II) is taken up most efficiently from neutral and weakyl acidic (up to 0.01 M HNO3) media with the degree of sorption R > 90% and distribution coefficients Kd from 1410 to 706 cm3 g−1, respectively. The efficiency of the Sr(II) sorption is not affected by Na+ ions in the solution up to their concentration of 1 M. In the presence of calcium ions, as the Ca(II) concentration in the solution is increased from 0.02 to 0.16 M, Kd of Sr(II) decreases by a factor of 4. In sorption of 90Sr from seawater, Kd is 193 cm3 g−1; it increases by a factor of 1.05 and 1.25 upon dilution of seawater by a factor of 2 and 10, respectively. Lead(II) is quantitatively taken up from neutral media (R > 98%) and from 0.01–1.0 M HCl and 0.01–3.0 M HNO3 solutions (R > 87%). The sorbents prepared show promise for radioanalytical determination of Sr and Pb radionuclides in natural objects.

Synthetically convenient method for preparing phosphoryl podand 1,8-bis[2-(diphenylphosphorylmethyl)phenoxy]-3,6-dioxaoctane (L) has been developed. Recovery of Pb2+ with impregnated type sorbents was studied, the sorbents contain isodentate organic ligands—phosphoryl podand L and crown ether (4,4',(5')-di(tert-butyl)dicyclohexyl-18-crown-6)—as extractants. A sorbent based on the phosphoryl podand quantitatively extracts lead from neutral solutions (R = 98.4%) and does not recover it from acid solutions. On the contrary, the sorbents based on 4,4',(5')-di(tert-butyl)dicyclohexyl-18-crown-6 do not extract lead from neutral media and efficiently adsorb it from nitric and hydrochloric acid solutions (R = 90% from 3 M nitric acid solutions and R = 73.2% from 2 M hydrochloric acid solutions). Effect of diluent and support type, support pretreatment procedure, impregnation temperature and time, and solvent for support impregnation on lead sorption with sorbents based on 4,4',(5')-di(tert-butyl)dicyclohexyl-18-crown-6 have been studied.

Pupose. The study of submarine groundwater discharge is one of the most pressing issues of modern hydrogeology and oceanography. The purpose of the paper is to represent a comprehensive study of the submarine groundwater discharge focus at the Cape Ayia using the hydrological, hydrochemical and radiochemical methods, as well as to determine the flux of submarine groundwater including the nutrients. Methods and Results. The scientific investigations were carried out during the coastal expeditions nearby the Cape Ayia on March 24, 2019, and also on April 22–24, 2019 during the 106th cruise of the R/V “Professor Vodyanitsky” (April 18–May 13, 2019). The isotopes 226Ra, 228Ra were extracted using the proprietary MnO2-based fibers. After concentration, the sorbent was squeezed to remove excess water, dried and ashed. Then the ash was placed in the Petri dishes and poured with epoxy resin. Activity of the radionuclides was measured on a low-background semiconductor γ-spectrometer with a detector of high-purity germanium (GC3020) in 3 weeks after the resin casting. The activity of 226Ra was determined by the daughter radionuclide 214Pb with the energy 351.9 keV (qγ = 37.2%), and that of 228Ra – by the daughter 228Ac (T1/2 = 6.1 h, qγ = 27.7%) with the energy 911.6 keV. The basic elements of the main biogenic cycle were determined using the photo-colorimetric means: mineral phosphorus – by molybdenum blue, silicon – by silicon-molybdenum complex. Nitrates (reduced to nitrites) and nitrites were determined by azo dye; ammonium – by indophenol blue also by the photo-colorimetric method. Conclusions. Distribution of hydrophysical, hydrochemical and radiochemical parameters in the water area connected with the known focuses of the groundwater submarine discharge was studied. For the first time, the distribution of the 226Ra, 228Ra isotopes was studied. The data on salinity, volumetric activity of the 226Ra, 228Ra isotopes and the nutrients concentration permitted to determine the flows of submarine underground waters in the Cape Ayia area, which amounted to 8220 ± 1200 m3/day. The anthropogenic contribution to pollution of the groundwater forming the submarine sources is shown.

A series of sorbents based on benzo-15-crown-5, various supports (styrene-divinylbenzene LPS-500, hydrophobized silica gel), and diluents (octan-1-ol, nitrobenzene, 1,1,7-trihydrododecafluoroheptanol (FHA), ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (С4mim+Tf2N-)) and without diluents was obtained. The sorbents without diluents with the benzo-15-crown-5 content 20–30% have the maximum sorption characteristics (recovery of gold higher than 90%). The influence of the diluent and support nature, procedure of support pretreatment, impregnation time and temperature, and the solvent for impregnation on the sorption characteristics was studied. The maximum sorption characteristics were found for the sorbents based on the styrene-divinylbenzene support LPS-500. A high selectivity of the obtained sorbents toward gold was established, and the recovery of gold higher than 95% was achieved by the optimization of the synthesis procedure of the sorbents.

A number of sorbents based on di-(tert-butylbenzo)-18-crown-6, 1-octanol, and various supports (LPS-500, hydrophobized silica) was obtained. The effect of temperature, support impregnation time, and thiocyanate ion concentration on cobalt sorption was evaluated. A comparison of the sorbent efficiency of cobalt recovery from thiocyanate solutions was performed for sorbents obtained by impregnation with different solvents (methanol, chloroform). Sorption and kinetic characteristics (isotherm, sorption and desorption kinetics, selectivity) of the sorbents in relation to cobalt in thiocyanate solutions were obtained. The sorbent was shown to possess a high selectivity towards Co in the presence of foreign ions. Sorption and desorption of cobalt were investigated under dynamic conditions. The technique developed for determination of cobalt ions and the specific activity of 60Co radionuclide in aqueous environmental objects enabled quantitative recovery of 60Co against the prevailing background of 137Cs and 152Eu radionuclides accompanied by not less than 20-fold sample concentrating.

A number of sorbents based on di(tert-butyldicyclohexano)-18-crown-6, 1,1,7-trihydrododecafluoroheptanol, and various supports (Porolas-T, LPS-500, hydrophobized silica gel) were prepared. The effect of the supports on strontium sorption from nitric acid solutions was estimated. The physicochemical regularities of strontium sorption (isotherm, kinetics, and selectivity) were studied.

A number of impregnated sorbents based on di-(tert-butyldibenzo)-18-crown-6 (DTBDB18C6) and di-(tert-butylcyclohexano)-18-crown-6 (DTBDCH18C6) was obtained using different diluents for the crown ether and the styrene–divinylbenzene support. Sorption characteristics of the sorbents in relation to cobalt ions and 60Co radionuclide in thiocyanate solutions were determined within the range of pH of 1–7. It was found the DTBDB18C6-based sorbents were the most efficient for the sorption of cobalt macro quantities whereas the DTBDCH18C6-based ones for the sorption of 60Co radionuclide, using nitrobenzene as a diluent. A possibility was shown of the complete cobalt desorption by hydrochloric and nitric acid solutions with the concentration of 0.1–1.0 mol L–1.

A series of impregnated sorbents based on di-tert-butyldicyclohexyl-18-crown-6 (DTBDCH18C6), various diluents (1-octanol, nitrobenzene, telomeric alcohol n3), and supports (Porolas-Т, LPS-500, hydrophobized silica gel) for removing tracer and weighable amounts of Sr ions from nitric acid solutions were prepared. The distribution coefficient of tracer amounts of 90Sr on all the synthesized sorbents increases with an increase in the HNO3 concentration in the range 1–7 M. The most pronounced increase in the sorption occurs with an increase in the HNO3 concentration to 3 M. The maximal distribution coefficient of 90Sr (Kd = 158 cm3 g–1) is reached for the sorbent based on DTBDCH18C6 and 1-octanol in 7 M HNO3. Experiments on sorption of weighable amounts of Sr2+ ions show that the static capacity of all the prepared sorbents for Sr in nitric acid solutions amounts to 4.3, 9.2, and 8.4 mg g–1 for the sorbents based on 1-octanol, nitrobenzene, and telomeric alcohol n3, respectively. The synthesized sorbents are suitable for radioanalytical determination of Sr radionuclides in liquid radioactive waste and in radioactively contaminated natural objects.

The key approaches to the synthesis of crown ether-based sorbents, including immobilization both with and without covalent bonding, are reviewed. Examples of sorbent preparation using anodic oxidation, chemical modification of polymers, polycondensation reactions, chemical modification of inorganic supports and radiochemical synthesis for covalent bonding of crown ether moieties are considered. Immobilization methods without covalent bonding including support synthesis in the presence of crown ethers, impregnation of supports with a crown ether solution and the use of powdered crown ether as a sorbent are presented. The applications of sorbents for selective removal of strontium from solutions of radioactive waste and spent nuclear fuel, for radiochemical analysis (determination of strontium in water, soil and biological materials) and for separation of strontium and yttrium isotopes are discussed. The bibliography includes 114 references.

A set of new sorbent were obtained by impregnation different amounts of endoreceptor dibenzo-18-crown-6 in the styrene–divinylbenzene polymer matrix “Porolas-T”. Physical and chemical parameters of strontium sorption on a natural mixture of isotopes from nitric acid solutions were investigated, namely isotherm of sorption, dependence of the distribution coefficient on the concentration of nitric acid in a solution and concentration of crown ether in the sorbent, kinetics of sorption and desorption of strontium. The selectivity of strontium sorption was studied to the alkaline, alkaline-earth metals and cobalt. The sorption properties of sorbent were examined to extraction of radioactive 90Sr.