Hydrogen-deuterium separation

Hydrogen-Deuterium Separation.—When an aqueous solution is electrolyzed, the hydrogen gas evolved always contains relatively more of the lighter isotope than does the electrolyte the difference is expressed as the separation factor (s) defined by... 

As a result of experimental studies it appears that the electrolytic hydrogen-deuterium separation factors fall into two distinct classes " in the first 8 has a value of about 6, viz.,... 

Erdey-Gruz and Volmer and Butler/ to whom we owe a rate expression for charge transfer processes. Later, Frumkin " took into account the potential distribution at the electrode-electrolyte interface and its influence upon the process of discharge of ions. Experimentally observable quantities other than the Tafel constants have also been employed since then in elucidating the mechanism. For example, experimental observations of and attempts of theoretical interpretation of the electrolytic hydrogen-deuterium separation factor were presented by Topley and Eyring, Horiuti, " and others, " as briefly reviewed elsewhere. ... 

Determination of the number of theoretical plates required in the hydrogen-deuterium separation requires the use of reliable equilibrium constants. Values for such constants at different temperatures and pressures have been correlated reasonably well by the following expression... 

The interaction of hydrogen (deuterium) molecules with a transition metal surface c an be conveniently described in terms of a Lennard--Jones potential energy diagram (Pig. 1). It cxxislsts of a shallcw molecular precursor well followed by a deep atomic chemisorption potential. Depending on their relative depths and positions the wells m or may not be separated by an activation energy barrier E as schematically Indicated by the dotted cur e in Fig. 1. 

Hydrogen-deuterium exchange Preparative separation of hydrogen isotopes. 

The inductive effect of the donating C—D bonds to the observed large inverse secondary deuterium isotope effect has not been given proper consideration but treated as a rather minor component superimposed on the important steric component caused by larger amplitudes of vibrations of C—H bonds than those of the C—D bonds. 14C KIE have not been studied in this reaction. The C2, C V. C3 , C3, endo hydrogens are separated only by 2.11 A, substantially less than van der Waals radii (2 x 1.2 A)404. 

Keywords nanoporous carbon, adsorption, gas storage, separation factor, hydrogen, deuterium... 

Also, there are theoretical simulations predicted a high adsorption selectivity (up to 100000 at 20 K) of heavy hydrogen isotopes (tritium, deuterium) from isotopes mixtures in nanotubes at low temperatures [7, 8], But there is no experimental information about adsorption isotherms (except natural isotopic composition hydrogen) and separation factors of the hydrogen isotopic modifications on nanoporous materials at cryogenic temperatures in the literature, and it obtaining has doubtless interest. 

Distribution Functions and Hydrogen-Deuterium Isotope Effects in Thermal Activation Systems. The isotope effects in thermal activation systems are determined to a large degree by the energy distribution function and kt and /(e) must be simultaneously considered. The equilibrium high-pressure effect is considerably different from the non-equilibrium low-pressure case, and they are discussed separately. 

Rechargeable metal hydrides have a number of potential applications in the "hydrogen economy" concept and in the present industrial sector. Because general surveys of hydride applications have been recently published(1,22,23), we will not try to review all the potential applications, but rather concentrate on a few that might be particularly applicable to the hydrogen industry storage containers, H2 compressors, H2 purification or separation, and deuterium separation. 

Deuterium Separation. Most hydrogen storage alloys show similar absorption/desorption properties for hydrogen and deuterium. Occasionally, however, the hydride and deuteride show... 

For a fixed temperature So.Do.p.Hs and the ortho-para separation factors Sp-D2.o Doy S0.H2.p-H2 are given by Equation 29 and are constants for a given surface. The dependence of the isotope separation factor on the gas phase ortho-para concentrations is shown in Figure 5. The maximum isotope separation factor is obtained when para-hydrogen is separated from para-deuterium. The minimum is obtained when ortho-hydrogen is separated from ortho-deuterium. 

The rewards of a workable nuclear fusion process would be great. Fusion produces neither the long-lived radioactive nuclides that accompany nuclear fission (although tritium requires care in handling) nor the environmental pollutants released by the burning of fossil fuels. Although deuterium is present in only 1/6000 of the abundance of ordinary hydrogen, its separation from the latter by the electrolysis of water is readily accomplished, and the oceans contain a virtually unlimited quantity of deuterium. 

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