Liquid purification or separation – Processes – Treating by enzyme
Patent
1990-09-05
1992-08-18
Wyse, Thomas
Liquid purification or separation
Processes
Treating by enzyme
435176, 435288, 8142, 210663, D06L 110, C02F 128
Patent
active
051396742
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of removing contaminants, especially neutral lipid contaminants, from a solvent which has been used for dry cleaning, by using a lipase.
BACKGROUND ART
Solvents used for dry cleaning are commonly re-used after removal of contaminants by filtration and adsorption. However, non-polar neutral lipid contaminants are poorly adsorbed and are highly soluble in the solvent, and they are therefore difficult to remove.
It is the purpose of the present invention to provide a purification method that can readily remove contaminants containing non-polar neutral lipid from a solvent that has been used for dry cleaning.
STATEMENT OF THE INVENTION
The above-mentioned problem is solved by a purification method characterized by placing used solvent in contact with a lipase, which is stable and exhibits an activity in the solvent, or with an immobilized product of said lipase, and with an adsorbent
DETAILED DESCRIPTION OF THE INVENTION
Lipase produced by a microorganism belonging to the genus Candida, Humicola, Pseudomonas or Mucor or lipases produced by a transformant obtained by inserting the structural gene for said lipase into another microorganism can be used advantageously.
Generally, enzymes do not show their activities in organic solvents because they undergo denaturation. However, it was surprisingly found that some lipases show activity even in dry cleaning solvents For example, lipases derived from Candida antarctica, Humicola lanuoinosa and Pseudomonas fluorescens show activity even in dry cleaning solvents. The present invention is based on this discovery. Neutral lipid contaminants dissolved in solvents are decomposed by lipases and the resulting fatty acid and glyceride products are easily adsorbed on the adsorbents
The lipase can be added in the form of an aqueous solution to the solvents used for dry cleaning, but may possibly recontaminate the clothes to be cleaned Consequently, it is desirable to use the lipase in the form of immobilized lipase. Any known method can be used for the immobilization of the lipase. For example, the immobilization can be done by gel entrapment e.g. in polyacrylamide or alginate, by adsorption e.g. on silica or alumina, by crosslinking with glutaraldehyde, or by adsorption on ion exchange resin. (The details for the immobilization are described, for example, in "Immobilized enzymes" written by Dr. Ichiro Chibata, published in 1975 by Kodansha Ltd.).
The contact between immobilized lipase and solvent is conveniently effected by use of a cartridge wherein the immobilized lipase is retained, while the solvent is allowed to flow through. Optionally, the cartridge may contain an adsorbent together with the immobilized lipase. Filter paper, filter cloth or other porous sheet material may be used to retain the immobilized lipase. The cartridge may allow the solvent to be pumped through; e.g. it may be cylindrical and have an inner tube and an outer, annular speace for solvent inlet and outlet. Or the cartridge may consist of a bag of porous material containing the immobilized lipase (and, optionally adsorbent), suited for dropping into a solvent tank.
The lipase may be a lipase produced by the original microorganism, or it may be a lipase produced by a transformant produced by inserting the structural gene for a lipase into another microorganism. Said gene transformant can be produced by generally known methods. Details are described, for example, in Idenshi Kogaku (Genetic Engineering), Volume 8 of Biseibutsu-gaku Kiso Koza (Basic Microbiological Seminars), edited by Tadahiko Ando and Kenji Sakaguchi, published in 1987 by Kyoritsu Shuppan Co., Ltd. and in Idenshi Kenkyuho (Genetic Laboratory Methods) II, Volume 1 of ZokuSeikagaku Jikken Koza (Sequel of Biochemical Experiment Seminar), edited by Japan Society of Biochemistry, published in 1986 by K. K. Tokyo Kagaku Dojin.
Some lipases which can be used for the practice of the present invention are commercially available. Some examples of suitable lipases are listed bel
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patent: 4193765 (1980-03-01), Jackson
patent: 4312633 (1982-01-01), Kazama et al.
patent: 4645741 (1987-02-01), Inada
patent: 4855233 (1989-08-01), Gancet et al.
Lambiris Elias J.
Novo Nordisk A S
Wyse Thomas
Zelson Steve T.
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