Patent GB-599854-A (GB)
Title: Separation of non-neutral electrolytes
IPC: B01D11/04
Filed: 1945-05-23
Abstract: A process for separating a mixture of pencillin and acids normally associated therewith in its manufacture, different members of the mixture having different dissociation constants, comprises introducing the pencillin mixture into an extraction zone and subjecting it therein to the action of two at least partially immiscible liquid, one being an ionizing medium, such as water (and preferably containing a buffer), and the other a solvent for the penicillin mixture, the two liquid flowing countercurrently to each other through the extraction zone, to produce two phases (an ionizing medium extract phase and a solvent extract phase) which are rich in different components of the penicillin mixture, introducing (between the points of introduction of the penicillin mixture and of the solvent and preferably near the point of introduction of the latter) into the zone a stripping electrolyte having the same tendency to change protons as the components of the mixture and having a higher dissociation constant, and separating the phases, the stripping electrolyte being soluble in the ionizing medium, having a low distribution coefficient into the solvent, and being preferably an aqueous solution of an inorganic acid.  Examples of ionizing media, solvents, stripping electrolytes and buffers are given. According to one example, an aqueous solution of penicillin contaminated with weaker acids and made neutral with sodium bicarbonate is extracted with 100 per cent by volume of methylisobutyl ketone in two theoretical stages to recover 98 per cent of penicillin, the stripping electrolyte (4 per cent phosphoric acid) being introduced (1) as part of the feed, (2) at a number of points between the feed inlet and rafinate outlet and (3) near the solvent inlet.  In another example, aqueous solutions of penicillin are extracted with equal volumes of methylisobutyl ketone, the aqueous solution and solvent being introduced at different ends of an extraction column while dilute acid is introduced in a different manner in extraction of each sample: (1) with the aqueous penicillin feed; (2) with the feed which was lightly buffered and (3) between the feed and solvent inlets. The resulting aqueous phases are separately acidified, solvent extracted, water washed and dried.ALSO:A process for separating a mixture of electrolytes having a tendency to change their number of protons in the same direction, different members of the mixture having different dissociation constants, comprises introducing the electrolyte mixture into an extraction zone and subjecting it therein to the action of two at least partially immiscible liquids, one being an ionizing medium, such as water (and preferably containing a buffer) and the other a solvent for the electrolyte mixture, the two liquids flowing countercurrently to each other through the extraction zone, to produce two phases, an ionizing medium extract phase and a solvent extract phase, which are rich in different components of the electrolyte mixture, introducing between the points of introduction of the electrolyte mixture and of the solvent and preferably near the point of introduction of the latter into the zone a stripping electrolyte having the same tendency to change protons as the components of the mixture and having a higher dissociation constant, and separating the phases, the stripping electrolyte being soluble in the ionizing medium, having a low distribution coefficient into the solvent, and being preferably an aqueous solution of an inorganic acid or base.  In a modification, the solvent extract phase is scrubbed with an ionizing medium phase and a scrubbed solvent extract phase, the phases being separated and the separated ionizing medium phase being introduced into the extraction zone.  Examples of ionizing media are: water, liquid anhydrous ammonia, anhydrous liquid sulphur dioxide, liquid carbon dioxide; water-soluble mono-and polyhydric alcohols, e.g. methyl-, ethyl-and iso - propyl alcohols, ethylchlorhydrin, ethylene-, propylene-, butylene-, diethylene-, triethylene- and higher polyethylene glycols, corresponding polypropylene and butylene glycols, glycerine, methyl glycerine and ethers of glycerine; acetone, diacetone alcohol; esters of low fatty acids with water-soluble alcohols, e.g. methyl- and ethyl formate, methyl and ethyl acetate; amines, e.g. ethyl-, dimethyl-and propylamine, ethylene diamine, mono-, di-and triethanolamines, propanolamines, aminopropane diols, diamino propanols, pyrazine, pyridine, urea; ethers, e.g. dioxane, morpholine; lower fatty acids, e.g. formic, acetic and lactic acids; amides, e.g. formamide, acetamide, N-methylformamide; nitriles, e.g. acetonitrile, propionitrile, lactonitrile; sulphones, e.g. dimethyl and diethyl sulphones, sulpholane and diethyl sulpholane. Solvents specified are organic liquids or mixtures thereof, e.g. propane, butane, pentanes, hexanes, heptanes, octanes, benzene, toluene, xylenes, cumene, tetrahydronaphthalene; gasoline, naphthas, kerosene; methyl chloride, chloroform, carbon tetrachloride, ethyl chloride, ethylene dichloride, trichlorethylene, tetrachlorethane, propyl chloride; n-butyl alcohol, amyl alcohols and hexyl alcohols; methyl butyrate, valerate, caproate; ethyl propionate, butyrate, valerate; propyl acetate, propionate, butyrate, valerate; butyl and amyl formates, acetates and higher esters; methyl ethyl ketone, diethyl ketone, methyl isopropyl ketone, di-isopropyl ketone, methyl isobutyl ketone, di-isobutyl ketone; ethers, amines and imines, which are substantially water-insoluble; and alkyl phenols.  The stripping electrolytes specified are the strong inorganic acids and bases, e.g. hydrochloric, hydrobromic, sulphuric, phosphoric and nitric acids, and the hydroxides of sodium, potassium and calcium. Buffers specified are caustic soda, caustic potash, trisodium citrate, disodium-hydrogen phosphate, sodium bisulphate and phosphoric acid. The process of the invention is applicable to the separation of the following mixtures: fatty acids, acids obtained by oxidation of hydrocarbon mixtures, halogenated fatty acids, phenols and thiophenols, mercaptans, acids resulting from certain fermentation processes, e.g. those obtained in the manufacture of penicillin (as given in the examples), amino acids obtained from proteins, fruit and vegetable juices containing various acids, certain inorganic acid-bases obtained in the ammonolysis of chlorinated hydrocarbons, petroleum bases, coal tar bases, alkaloids and certain inorganic bases.