Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Patent
1997-04-18
1998-04-21
Therkorn, Ernest G.
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
210511, 422101, 436178, B01D 1104
Patent
active
057414238
DESCRIPTION:
BRIEF SUMMARY
The invention relates to extracting substances(s) of interest from a first or carrier liquid into a second or extraction liquid, conveniently referred to as liquid-liquid extraction.
Such liquid-liquid extraction is widely used in industry for isolation etc of the substance(s) of interest and/or analysis, purification etc of samples of carrier liquid(s). The procedural steps involved are generally carried out manually. A typical known procedure starts with adding carrier liquid containing substance of interest to a receptacle, often with (or after) desired or necessary adjustments, for example to concentration, pH value, salt content, etc. Extraction liquid immiscible with the carrier liquid and of lower density is then added. The mixture is agitated vigorously by any of a variety of different techniques, for example shaking, vortexing, sonication, etc. During agitation some of the substance of interest passes from the carrier liquid into the extraction liquid, to an extent determined by the so-called partition coefficient of such substance in the conditions concerned. The extraction liquid is then separated from the carrier liquid after a liquid settling step or period leaving the extraction liquid with transferred substance of interest above the denser carrier liquid. Centrifuging of the receptacle is known to speed this settling step. The substance of interest is isolated by drawing off and evaporating the extraction solvent, usually to leave the substance dry.
Commercial laboratories in the pharmaceutical, food, chemical, environmental etc industries may carry out such procedures individually for as many as 50 to 70 samples per person per day. Separate execution of steps required, involving several different physical environments (for liquid dispensing, agitation, centrifuging, evaporation, etc) and considerable rigour of technique required, can be very time-consuming as well as prone to human error.
It is an object of this invention to provide method and means permitting greater regularising of liquid-liquid extraction and leading to reduction of problems and time/plural handling etc associated with prior procedures.
According to one aspect of the invention, there is provided a method of extracting substance of interest from a first or carrier liquid into a second or extraction liquid, said liquids being immiscible and of different densities, said substance transferring from said first liquid to said second liquid at admixture of those liquids, the method comprising admixture and then separation of said liquids in a container followed by insertion into said container of a separator member cooperating with said container as a physical barrier resulting in only separated said second liquid together with said substance as acquired by transfer from said first liquid being at one side of said member.
The first liquid may be denser than the second liquid, and passed through the second liquid herein for transfer of substance(s) of interest and separation of the immiscible liquids. As a result, the less dense separated second liquid will be on top of the first liquid and contain a useful proportion of the substance(s) of interest originally in the first liquid. Further actual physical liquids separation is then by insertion of said member into said container to pass through the separated said second liquid into preferably effectively sealing contact with cooperating internal abutment of said container before reaching the separated said first liquid.
This is generally the case for aqueous-based first or carrier liquids (such as biological fluids, drinks, impure water itself, etc) and second or extraction liquids based on organic solvents (such as ethyl acetate, di-ethyl ether hexane, etc) for the substance(s) of interest. As is known, suitable solvents can act by preferred solubility for substance(s) of interest that dissolve in water, but are equally applicable to water-insoluble substance(s) of interest carried as an aqueous suspension or homogenate. In principle, of course, the second liquid needs only to h
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Bates John
Edwards John David
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