Applications carrier distillation techniques

Measurements of binary vapor-liquid equilibria can be expressed in terms of activity coefficients, and then correlated by the Wilson or other suitable equation. Data on all possible pairs of components can be combined to represent the vapor-liquid behavior of the complete mixture. For exploratory purposes, several rapid experimental techniques are applicable. For example, differential ebulliometry can obtain data for several systems in one laboratory day, from which infinite dilution activity coefficients can be calculated and then used to evaluate the parameters of correlating equations. Chromatography also is a well-developed rapid technique for vapor-liquid equilibrium measurement of extractive distillation systems. The low-boiling solvent is deposited on an inert carrier to serve as the adsorbent. The mathematics is known from which the relative volatility of a pair of substances can be calculated from the effluent trace of the elutriated stream. Some of the literature of these two techniques is cited by Walas (1985, pp. 216-217). 

Adsorption Method Iodine separation by the platinum adsorption technique was first reported by Toth (1961) and Lin et al. (1963). Oak Ridge National Laboratory has adopted an adsorption procedure (Case and Acree, 1966) for the purification of I produced from fission by a distillation process. In 1966, in comparison with other methods of L Baker (1966) has concluded that the adsorption technique is the most efficient and economical method. In this method, a metallic Pt plate or felt is used to adsorb carrier-free iodine from an acidic solution containing target materials. The Pt plate or felt with iodine activity is then removed from the solution and thoroughly washed with water. The activity is then desorbed in a slightly basic solution. Application of electrical current could enhance the desorption process. Nearly quantitatively the adsorbed iodine activity can be desorbed from the Pt surfaces. 

Another technique involving distillative concentration of sample constituents is sweep co-dis-tillalhn. Here the sample is treated with a highly volatile solvent introduced with the aid of a stream of carrier gas. The solvent in turn transports soluble components of the sample to a cooled distillation receiver. The method is useful for such applications as the isolation of volatile pesticides from animal and plant fats [237], [238]. 

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