Patent GB-886979-A (GB)
Title: Method of and apparatus for fractionation of ionic liquids
IPC: B01D57/02
Filed: 1959-09-28
Abstract: 886,979. Electrodialysis. KOLLSMAN, P. Sept. 28, 1959 [Sept. 26, 1958], No. 32826/59. Addition to 858,076.. Class 41. In the process described in the parent Specification (in which constituents of a true solution are separated under the simultaneous influence of an electrical potential and a mechanical accelerating force by formation of liquid strata containing the fractions in different concentrations in an electrodialysis cell through which the solution flows, the cell comprising spaced electrodes and between the electrodes at least two spaced barriers of ion-exchange material transverse to the direction of the electric field whereby electrodialytic intermediate products, e.g. ionic concentrates and dilutes, are formed at the barrier surfaces which are acted upon by a mechanical accelerating force, e.g. gravity or centrifugal force, acting in a direction forming an angle with the normal, i.e. right-angular, direction to the barriers, and also forming an angle with the direction of flow of the solution through the cell, resulting in the formation of the strata which arrange themselves one above the other in planes substantially normal to the direction of the mechanical force) a diluting liquid is continuously introduced into the lower portion of the cell to carry ions from the concentrate accumulating therein to elevated zones within the cell whereby ions of lower ionic mobility are transferred to higher zones than ions of higher ionic mobility. The products may be continuously withdrawn from zones spaced from each other, said zones containing the constituents in different relative proportions. The donee liquid may be water. The ionic solution may be passed in a direction substantially opposite to the mechanical accelerating force, preferably upwards. As shown, apparatus consists of a housing 21, Fig. 1, divided into electrode chambers 24 and 25 and treatment chambers 32, 33, 34 and 35 by barriers 36 of ion-exchange material. In this apparatus all the barriers are of similar polarity. The liquid to be separated is introduced into the treatment chambers through ports 37<SP>1</SP> at the bottom and after separation the fractions are removed through ports 40, 41, 42 at the other end of each chamber. In an alternative form of apparatus the barriers are alternately of cation-exchange material and anion-exchange material. The chambers are thus alternately concentration chambers 61, Fig. 8, and deionization chambers 62. The mixture to be treated is supplied into the concentration chambers through ducts 237 ; the donee liquid is supplied to the deionization chambers through ducts 243 ; and the product fractions are withdrawn from the concentration chambers through ducts 240, 241 and 242. In this case the barriers except those between the end treatment chambers and the electrode chambers are perforated. The top portion of the deionization chambers contains an ionconductive filler 63. The apparatus may also be disposed vertically with the barriers horizontal or at an angle as shown in Fig. 11 so that the tilt of the barriers assists the separation of the fractions.