Separation of Silicon Isotopes by Chemical Exchange between Silicon Tetrafluoride and Its Complex Compounds with Aliphatic Alcohols

摘要

Silicon tetrafluoride SiF_4 reacted with aliphatic alcohols ROH to form liquid complex compounds SiF_4 ? 2ROH. The gas-liquid SiF_4_(g)-SiF_4 ? 2ROH_(l) systems can be used for separating silicon isotopes. The hydrodynamics and mass transfer of the separation of silicon isotopes in a countercurrent column were studied using SiF_4-SiF_4 ? 2ROH systems based on butanol-1, pentanol-1, and hexanol-1 at 293 K. Corrections were applied to the empirical coefficients in the equations of the dependence of the total holdup of a helical prismatic packing (HPP) and its specific pressure drop on a load in an isotope exchange column. The height equivalent to the theoretical plate (HETP) increased more than twofold in the butanol-1-hexanol-1 homologous series (the flow rate in the column was (3.4 ± 0.2) mmol SiF_4/(cm~2 min) for the working gas). It was shown using pentanol-1 as a complex-forming agent that the limiting stage of mass transfer during the separation of silicon isotopes was the isotope exchange between SiF_4 and the SiF_4 ? 2ROH complex.