Оценка эффективности экстракции малорастворимых примесей из водных растворов сверхкритическими флюидам в динамическом проточном режиме хромато-масс-спектрометрическим методом

Supercritical fluid extraction (SFE) is actively used in the separation of valuable components or espe-cially toxic and radioactive substances from various natural sources, such as water systems. Despite the active study of this method, its possibilities have not yet been fully studied. In this study, two low-soluble substances, tributyl phosphate (TBP) and methanitrobenzotrifluoride (meta-nitro-trifluoromethyl-benzene, F-3), were used for the release of radionuclides during the reprocessing of spent nuclear fuel (SNF) were considered as model objects. The purpose of this study was the evaluation of the efficiency of the extraction purification of aqueous solutions containing TBP and F-3 under dynamic conditions based on the estimated calculation and the verifi-cation of its results in an experiment on a counter-current extraction column. The calculation was based on the data on the distribution of impurities between the water and fluid phases, which were obtained in static exper-iments. The concentrations of substances in the initial solutions (before extraction) were determined by gas chromatography with mass spectrometric detection (GC-MS) using a SHIMADZU GCMS-TQ8040 instru-ment. For chromatographic separation, a standard ZB-5MS capillary column (60 m × 0.25 mm × 0.25 μm) was used. The same method was applied for the determination of the residual concentrations of TPB and F-3 in aqueous solutions after extraction. Based on the extraction data under static conditions, the interfacial distri-bution coefficients (K) were determined for TBP and F-3 between the aqueous phase and supercritical (SC) fluids - CO2 and R-23 Freon (CHF3) at 50°C with a fluid density of about 0.4 g/cm3. It was shown that under these conditions SC CO2 is a more effective extractant for the isolation of TBP and F-3 from aqueous solutions. The obtained K values were used to evaluate the efficiency of the extraction purification of aqueous solutions from TBP and F-3 in various modes. The performance of such an evaluation has been demonstrated in exper-iments in a counter-current extraction column (PEC). It is shown that in all the studied pairs of "extractable component - extractant", the degree of purification in PEC can reach 0.995 with moderate consumption of the extractant