GB707950A - Improved partition adsorbent and a method for its use - Google Patents

Abstract

In an example of the use of composite particles in partition adsorption (see Group III) a solution of penicillin acid in amyl acetate is passed through a column of particles consisting of quartz on the surface of which "Hyflo Super Cel" (Registered Trade Mark) particles are tightly held by means of a solution of potassium hydroxide, whereby penicillin is transferred to the aqueous phase in the adsorbent particles. It is stated that the adsorbent can hold extremely large quantities of penicillin. If in the extraction of penicillin from a solution thereof in amyl acetate it is desired to maintain a constant pH, the aqueous phase may contain, e.g., a phosphate buffer of pH 6.ALSO:<PICT:0707950/III/1> Solute is removed from bulk solvent by bringing said solvent into contact with another solvent immiscible therewith which is imbibed in the pores of partition adsorbent particles adhering to heavy and non - porous carrier particles on account of the attractive forces between the solvent imbibed in the partition adsorbent and a film of the same solvent on the surfaces of the carrier particles, the imbibed solvent having a greater, preferably a much greater, affinity than the bulk solvent for the solute. The composite partition adsorbent is claimed. It may consist of carrier particles of materials such as quartz, corundum, silicate minerals and gypsum covered with a hydrophilic adsorbent such as diatomaceous earth, various bleaching earths, Fuller's earth, Wyoming bentonite, silica gel, activated alumina, cellulose powder, ion echange resins, "Hyflo Super Cel" (Registered Trade Mark), "Filter Cel" (Registered Trade Mark) or hydrous precipitates such as silicic acid, aluminium hydroxide, ferric hydroxide, alginic acid, carboxymethyl cellulose, starch or regenerated cellulose (e.g. viscose) when a polar imbibed solvent such as water is to be used in conjunction with bulk solvents such as amyl acetate, benzene, methyl isobutyl ketone, chloroform, butanol and ethyl ether. In an example, penicillin acid dissolved in amyl acetate is extracted into a potassium hydroxide solution imbibed in a composite adsorbent prepared by adding 2g. of water to 30g. of 10-20 mesh quartz and blending therewith 1.4g. of "Hyflo Super Cel." Salicyclic, phenylacetic and acetic acids, and (by the use of an acid in place of the alkali) coal tar bases, alkaloids and antibiotics can be extracted similarly. Acid or alkali dissolved in a miscible organic solvent (e.g. butanol) or gaseous ammonia may be added to a solvent solution (e.g. amyl acetate) of an organic base or acid and the salt formed may then be extracted from the bulk phase by contact with a partition adsorbent having an imbibed aqueous phase. If desired, the partition adsorbent may contain precipitating, chelating or other agents having an affinity for the solvent to be extracted. In the case of partition adsorbents in which non-polar solvents, such as benzene, are to be imbibed, hydrophobic carrier particles such as synthetic resins (particularly hydrocarbons such as polystyrene and polythene) solid organic compounds such as fatty alcohols, or minerals such as silicates coated with substances such as flotation agents (e.g. laurylamine hydrochloride), silicones and other substances which render their surfaces hydrophobic may be used with adsorbents such as activated carbons, synthetic resins, natural and synthetic rubbers swollen with solvents, diatomaceous earth or porous ceramic materials treated with flotation agents or silicones. In an example 15g. quartz and 0.55g. "Filter Cel" were treated with 3 per cent. aqueous "Quilon" solution, and when shaken with 0.43 mls. benzene in water, complete adhesion took place. The composite particles may be prepared by wetting the carrier material on a vibrating tray with the solvent to be imbibed and mixing in the dry partition adsorbent, or by first emulsifying the partition adsorbent and its imbibed solvent with a second immiscible solvent in the presence of an emulsifying agent and then shaking with a suspension of carrier in the bulk solvent. Preferably, however, the carrier particles are agitated with sufficient bulk solvent to cover the particles in a tumbling device, then wetted with the solvent that is to produce the adhesion in the presence of the bulk solvent and finally mixed by tumbling with the partition adsorbent. The solute may be recovered by bringing the composite particles into contact with a second bulk solvent immiscible with the imbibed solvent, a further quantity of imbibed solvent or a stripping solvent which dissolves the imbibed solvent, a stripping solvent containing surface active agents or a stripping solvent at such a temperature as to vaporize the imbibed solvent. The invention may be employed in a static column, or in apparatus of the type shown in which the particles move in counter-current to the solution. Particles are fed to the hopper 8 through the feed pipe 7 and as they move down the column by rotation of the star valve 5 the solution is upwardly displaced. Further quantities of solution may if desired enter at 6 and after overflowing at the weir 8A, solvent deprived of solute is removed at 10.