Patent GB-691355-A (GB)
Title: Improvements in or relating to the treatment of liquids to separate components therefrom
IPC: B01D15/02
Filed: 1949-10-12
Abstract: <PICT:0691355/IV (b)/1> In the separation of constituents from a liquid mixture containing or consisting of at least two constituents which are sorbed to almost the same extent by a sorbent and are separable by chromatography, a stream of the liquid is passed in countercurrent to a stream or moving column of sorbent and the relative flow of liquid and sorbent is adjusted so that at least one constituent is continuously removed from the liquid by the sorbent and thereby separated from at least one other constituent of similar affinity for the sorbent.  The liquid may be a simple mixture of constituents of the kind described or a solution of at least two such constituents in an inert solvent.  The relative rate of flow of liquid and sorbent is initially such that the sorption front of the constituent to be removed by the sorbent, or of the least-strongly sorbed where more than one constituent is to be removed by the sorbent, is allowed to form and move in the direction of flow of the liquid, and the rate of flow is then adjusted so that the sorption front is held stationary. Preferably the streams move in vertical directions, the sorbent being introduced at the top if it is of greater density than the liquid, and moving downwards.  Where three or more constituents are to be separated, two or more may be removed by the sorbent, which is then treated with an eluting solvent to separate the sorbed materials.  In any case, provision is preferably made for continuously washing the column of sorbent after it has passed the point of inlet of the liquid.  Thus in Fig. 3, where sorbent is moving downwards through a tube 1 to separate one of two constituents from a liquid introduced through tube 4, a solvent is introduced at a lower level through a tube 7 to wash away any traces of the less strongly sorbed constituent, the main portion of which flows out with the solvent through a tube 6 at the top of the apparatus, while the sorbent containing the more strongly sorbed constituent passes out through a trap 9 into a collecting tank 10 filled with solvent.  The tube 1 is provided with enlargements 3 to avoid or localize disturbances in the stream of sorbent.  When a compact column is required, less sorbent is drawn off initially than is supplied at the top, so that the sorbent gradually accumulates in the tube.  To facilitate the flow the tube may be vibrated, preferably axially.  Modified apparatus is also described, Figs. 4 and 5 (not shown), suitable for separating three materials and dissolved in a solvent.  The solution is introduced near the middle of the tube while sorbent is introduced at the top and solvent at one or more points near the bottom.  In each case solvent containing the least strongly sorbed material is withdrawn at the top and sorbent containing the most strongly sorbed material at the bottom, while the third constituent is withdrawn near the middle either with the solvent stream or with the sorbent stream, according to the conditions.  Examples are given of the extraction of (1) carotene, chlorophyll, and xanthophyll from a petroleum ether extract of dry grass using alumina as the sorbent and petroleum ether as the solvent, and (2) carotene from fatty oil using isobutanol as the solvent and powdered rubber as the sorbent.  Specification 661,374 is referred to.ALSO:<PICT:0691355/III/1> In the separation of constituents from a liquid mixture containing or consisting of at least two constituents which are sorbed to almost the same extent by a sorbent and are separable by chromotography, a stream of the liquid is passed in counter-current to a stream or moving column of sorbent and the relative flow of liquid and sorbent is adjusted so that at least one constituent is continuously removed from the liquid by the sorbent and thereby separated from at least one other constituent of similar affinity for the sorbent.  The liquid may be a simple mixture of constituents of the kind described or a solution of at least two such constituents in an inert solvent.  The relative rate of flow of liquid and sorbent is initially such that the sorption front of the constituent to be removed by the sorbent, or of the least-strongly sorbed where more than one constituent is to be removed by the sorbent, is allowed to form and move in the direction of flow of the liquid, and the rate of flow is then adjusted so that the sorption front is held stationary. Preferably the streams move in vertical directions, the sorbent being introduced at the top, if it is of greater density than the liquid, and moving downwards.  Where three or more constituents are to be separated, two or more may be removed by the sorbent, which is then treated with an eluting solvent to separate the sorbed materials.  In any case, provision is preferably made for continuously washing the column of sorbent after it has passed the point of inlet of the liquid.  Thus in Fig. 3, where sorbent is moving downwards through a tube 1 to separate one of two constituents from a liquid introduced through a tube 4, a solvent is introduced at a lower level through a tube 7 to wash away any traces of the less strongly sorbed constituent, the main portion of which flows out with the solvent through a tube 6 at the top of the apparatus, while the sorbent containing the more strongly sorbed constituent passes out through a trap 9 into a collecting tank 10 filled with solvent.  The tube 1 is provided with enlargements 3 to avoid or localize disturbances in the stream of sorbent.  When a compact column is required, less sorbent is drawn off initially than is supplied at the top, so that the sorbent gradually accumulates in the tube.  To facilitate flow the tube may be vibrated, preferably axially.  Modified apparatus is also described, Figs. 4 and 5, (not shown), suitable for separating three materials dissolved in a solvent.  The solution is introduced near the middle of the tube while sorbent is introduced at the top and solvent at one or more points near the bottom.  In each case solvent containing the least strongly sorbed material is withdrawn at the top and sorbent containing the most strongly sorbed material at the bottom, while the third constituent is withdrawn near the middle either with the solvent stream or with the sorbent stream, according to the conditions. Examples are given of the extraction of (1) carotene, chlorophyll, and xanthophyll from a petroleum ether extract of dry grass using alumina as the sorbent and petroleum ether as the solvent, (2) unsaturated and saturated constituents of whale oil using acetone as the solvent and powdered rubber as the sorbent, and (3) carotene from fatty oil using isobutanol as the solvent and powdered rubber as the sorbent.  The term "chromatograph" includes partition chromatography and ion-exchange chromatography. Specification 661,374 is referred to.