Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Patent
1996-05-09
1997-11-04
Shippen, Michael L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C07C22738
Patent
active
056841906
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a method of recovering an amino acid such as L-lysine from a solution containing the amino acid and various impurities including potassium and magnesium ions, other cations, ammonia and other amino acids.
The amino acid L-lysine is normally produced by large-scale fermentation that results in an impure L-lysine-containing solution, known as "broth", at a concentration of between 80 and 110 g/l. L-lysine is generally produced in a stable and non-hygroscopic hydrochlorinated form, which has the chemical formula H.sub.2 N(CH.sub.2).sub.4 CHNH.sub.2 CO.sub.2 H.HCl. So-called "feed-grade" lysine is usually of a purity of not less than 98.5% by mass L-lysine.HCl with a moisture content of not more than 1% by mass.
The conventional L-lysine purification route begins with the fermentation broth which is passed over a cation exchange resin, either before or after biomass removal by filtration or centrifuging. The L-lysine is adsorbed onto the resin at a low pH and is then stripped from the resin at a high pH using an eluent such as ammonium hydroxide. The eluent containing L-lysine and ammonia, with impurities such as potassium and magnesium ions and other amino acids, is then concentrated by evaporation. At the same time the bulk of the ammonia is stripped from the solution. The solution is then acidified with hydrochloric acid, after which the L-lysine is crystallized as L-lysine.HCl.2H.sub.2 O, either by means of a batch cooling crystallizer or an evaporative crystallizer, in a process termed "crystallisation". The wet crystals of L-lysine are separated from the mother liquor using a centrifuge or filter and then dried, typically by means of a fluid bed drier. The mother liquor may be recycled and at least a portion needs to be purged as a waste stream, resulting in the loss of some lysine.
There is a need for an improved method for the recovery of amino acids such as L-lysine.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a method of recovering a desired amino acid from an aqueous solution containing the desired amino acid and impurities, which method includes the steps of: adsorb the desired amino acid onto the resin at a pH lower than the isoelectric point of the desired amino acid; having a pH higher than the isoelectric point of the desired amino acid to produce a first solution; adsorb one or more of the impurities and to produce a second solution leaving the resin; of a selected impurity to the desired amino acid reaches a chosen value to produce a third solution which contains a lower level of impurities than the first solution; and
The amino acid to be recovered may be any amino acid which is sufficiently water soluble, for example lysine, glycine, threonine, proline, arginine and methionine.
The preferred amino acid is L-lysine, in which case there is provided a method of recovering L-lysine from an aqueous solution containing the L-lysine and impurities, which method includes the steps of: adsorb the L-lysine onto a resin at a pH of between 1.5 and 4 inclusive; pH higher than 9.59 to produce a first solution; adsorb one or more of the impurities and to produce a second solution leaving the resin; of a selected impurity to L-lysine reaches a chosen value to produce a third solution which contains a lower level of impurities than the first solution; and
According to a second aspect of the invention there is provided a method for the recovery of a desired amino acid from a first solution produced by passing an aqueous solution containing the desired amino acid over a primary cation exchange resin to adsorb the desired amino acid onto the resin, and then eluting the desired amino acid from the resin using a suitable eluent having a pH higher than the isoelectric point of the desired amino acid, the first solution containing in addition impurities including for example potassium, calcium, sodium and magnesium ions and possibly other amino acids, which method includes the steps of: adsorb one or more of the i
REFERENCES:
patent: 2894026 (1959-07-01), Hause
patent: 4691054 (1987-09-01), Tosa
patent: 4714767 (1987-12-01), Tanaka
Dienst Jonathan Hugh
Fechter Wolfgang Ludwig
Le Patourel John Frank
AECI Limited
Shippen Michael L.
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