US2408454A - Decolorizing oils and agents therefor - Google Patents

Description

Patented Oct. 1, 1946 DECOLORIZING OILS AND AGENTS THEREFOR Francis Michael Sullivan, North Bergen, N. J.

No Drawing. Application July 16, 1941,

Serial No. 402,696

Claims. (01. 210 -62) This invention relates to the decolorization and purification of organic compounds of animal and vegetable origin, nd particularly to the treatment of glyceride oils and related products and agents therefor.

The natural glyceride oils vary in character both with respect to the glyceride present and also with respect to the various dissolved ibodies contained therein designated herein by the term solutes. The glyceride oils are exemplary of natural esters, alcohols and acids which carry various bodies dissolved therein during the preparation of the material from the tissues in which they occur in nature. The variation in characteristics of the impurities and color lbodies present in such natural products has given rise to difiiculties in purification and decolorization, particularly due to variation in characteristics of the color bodies which are present in glyceride oils,

for example.

The most commonly used prior art method of refining fatty materials consists essentially of mixing the fatty material with an excess of alkali, usually a solution of sodium hydroxide, with removal of the precipitated material. This operation is frequently followed by removal of residual color by treatment with activated earth and carbon adsorptive materials. The chemical treatment involved in the use of alkali unfavorably affects flavor, taste and other desirable characteristics in food and medicinal products and also results in substantial losses of the glycerides which are being purified or treated. Furthermore, some of the natural glycerides are not susceptible to decolorization by such alkali treatment.

Among the objects of the present invention are included the treatment of natural products, particularly glycerides in the form of oils, etc., to remove undesirable solutes, particularly color bodies, therefrom.

Other objects include the purification of these materials without exposure to chemical action such as characterizes the caustic alkali process.

Other objects include the production of agents desirably employed in the purification of such natural products, particularly the glycerides, and methods of making such agents.

Still further objects and advantages of the present invention will appear from the more detailed description set forth below, it being understood, however, that this more detailed description is given by way of illustration and explanation only, and not by way of limitation, since various changes therein may be made by those skilled 2 in the art, without departing from the scope an spirit of the present invention.

In accordance with the present invention preformed soaps, particularly of hydrous character, are utilized for removal from natural products such as glycerides, of dissolved solutes contained therein which it is desired to eliminate and of which the color bodies are particularly exemplary. It has :been found that the color bodies present in such natural glycerides are collectively adsorbed by such preformed soaps so that they may be readily and economically removed from the natural products, such as glycerides, by such treatment; the use of preformed hydrous alkali metal soaps is particularly desirable for the adsorption of the color bodies and impurities in naturally occurrin fatty materials and that procedure and treatment will be used to exemplify the present invention.

In accordance with the present invention a hydrous soap desirably in concentrated suspension in a medium that is miscible with the material undergoing treatment, is mixed with such material to be treated and then separated from the latter. The hydrous soap is of such nature as tobe separable from the material undergoing treatment. While various types of soaps may be utilized, particularly important results are obtained by the use of the soaps in specially prepared condition and several examples are given immediately below of the preparation of such hydrous soap agents for use in accordance with the present invention.

Example I 5 parts (by weight) of stearic acid and 15 parts of oleic acid are added to parts of decolorized cottonseed oil and the mixture heated and stirred until the stearic acid dissolves. The temperature was adjusted to about 50 C. and 26 parts of a 13% solution (aqueous) of sodium hydroxide was added gradually with agitation.

The resulting product is very desirably employed in decolorizing glyceride oils.

Example II 20 parts of decolorized palm oil fatty acids were dissolved by heating with 60 parts of decolorized cottonseed oil. The temperature of the mixture was adjusted to 50 C. and 26 parts of a 13% solution of sodium hydroxide was added gradually with agitation.

This product also can be utilized in the treatment of glyceride oils for decolorization and removal of solutes from the. natural glyceride oils.

While a variety of soaps can be employed in accordance with the present invention, the alkali the ability to adsorb the color bodies or other deg sirable solutes to be removed from the glyceride The properties of the soaps which are thus most- 4 and is not limiting. But the presence of water is desirable although alcohol may be substituted at least in part, in the formation of the soaps.

The characteristics of the preformed soaps are also determined for use in the present invention by the medium in which they are prepared and desirably the soap adsorptive agents employed in .niation of curd-s or strands.

accordance with the present invention are pro duced in situ as a suspension in a desirable mejdium. Aqueous media alone are not so satisfactory for'the preformed soaps because of the for- Most desirably an oily medium is employed, particularly a medium desirable for carrying out the present treatment V are readily produced by the use of mixtures of fatty acids which should be convertedinto the segregability of the preformed soaps from the treated oils is readily controlled, since an increase in the content of solidacids increases the readiness of separation of the soaps from the oil. But theiuse of solid acids alone are not so satisfactory, anda substantial amount of liquidacid is, desirably emp-lcyed to give effective solvent action on A the coloredbodies. The. most preferred type of preformed hydrous soap composition is, therefore,

one which is produced from mixed fatty acids having the desired solid and liquid acid content, the solidv acid desirably being saturated and the liquid acid unsaturated, the proportions of the fatty acid mixture, as in Example I gives an ads-orptive agent which is practically ideal. -Other proportions may be employed and the ratios of fatty acids when mixed fatty acids are employed necessarily depend on the characteristics of the acids being used. When stearic acid isused for the solid acid component, it enables the lowest amounts of solid; acid to be employed. Other solid acids would generally beused inhigher quantity. A mixed acid containing 40%of stearic acid can be used satisfactorily. When the ratio of stearic to oleic reaches 50:50, the product is somewhat hard and not as satisfactory for adsorption purposes. The liquid acid present should as indicated above, desirably be unsaturated. and

generally should not be less than 30% depending on the type of solid acid employed. Various mixtures of acids can be'utilized as indicated and mixed solid acids and mixed liquid acids can'also be employed. Other exemplary compositions are 90% lauric acid with 10% oleic acid and 40% palmitic acid with 60% oleic acid, both of which produce satisfactory operation. Oleic acid alone may be employed at'temperatures of about C., but the use of individual acid is not so satisfactory. I

The soaps produced should desirably be of hydrous character and a sufficient amount of water should be present so that the soaps are not too hard. The 13% of aqueous caustic soda employed in Examples I and II is merely exemplary of the caustic soda concentration that may be employed preformed soaps. By the use of solid acids, -pa'r'-' ticularly of, saturated character, the separation-or "which is miscible with the oil in which event it sh-ouldnot dissolve the soap. By the production ,rof'the preformed soap in situ in the oily medium,

a concentrated suspension of the preformed soaps inthe form of small droplets in the oily medium is first obtained. On standing the droplets usually coalesce. In these forms the products are suitable of usein connection with the present invention. The soap stock is finely dispersed in the oil under treatment by violent agitation to providea maximum surface for adsorption of the color bodies. Glyceride oils, therefore, offer a very desirable medium for carrying the preformed soaps. It is not essential that the oily medium be decolorized since the Soaps themselves will serve to decolorize the medium during thetreatment; butv since the adsorpti've' capacity of the soap is most desirably employed for removal of the color bodies from the crude'glyceride oil's undergoing treatment; a decolorized oily me'd'iumi preferred. Other media that can be employed include fatty acids, fatty alcohols of the higher types, and various fatty acid esters "such as ethyl oleate, where the presence of such-media in the oil undergoing treatment is not-objectionable,Ias for example,

in the production of paint oils, etc. The amount of oily medium present should be sufficient to cover the soaps and the proportions given Example I arevery desirable. Other ratios, for example, would include 5 parts ste'aricjto 15 parts of oleic with 30 parts of the oil as given in Example I.

Des'lr'abl'y the" medium used to carry the by dreu's soap products or the" reaction between' the alkali and acid is usually the same or sim lar to the products resulting from the hydrous soap purification treatment in order to avoid the indeduction of ally undesirable material into the final'pioduct. This is particularly true in connection with the production of food products,

' suchas, salad oils. 'Where, the treated glycerides ar'eto'beused for purposes where the introduc tion of foreign oils is immaterial, then the medium may differ from that .of the oil resulting from theipurification treatment, To, avoid free alkalL'the hydroussoap' concentrate is prepared with an excess of, acid and such excess of acid, although small,is desirably present. A T

The following examples illustratethe u'tiliza tion'of such preformed scans in decolorization of glylceride oils. I e

' Example-III Crude cottonseed oil was washed with about 10% of its weight of water at about' ih" C." The water caused coagulation of a portion of the solutes: and the water and coagulated solutes were then separated from the oil using a centrifuge. 5.%'by weight of a hydrous soap concentrate prepared in accordance with Example I were intimately contacted with the oilat a temperature,

for example, of about 30C. by violent mixing and passage through a restricted opening under slight pressure. The soaps were removed from the oil by centrifugal separation. Corn, soya bean and peanut oils may be similarly treated.

The initial step of washing with water as given inthis example may be omitted and the process carried out otherwise as set forth in this examp18.

Example IV Crude cottonseed oil was heated rapidly to 310 C. without agitation and then cooled rapidly. A sludge resulted which was removed by centrifugal separation. 5% by weight of a hy drous soap concentrate prepared in accordance with Example I were put into contact with the oil at about 30 C. by violent mixing, and passage through a restricted orifice under slight pressure. The soaps were then removed from the oil by centrifugal separation.

Example V Crude palm oil was heated rapidly to 300 C. without agitation and then cooled rapidly. 5% by weight of a hydrous soap concentrate prepared in accordance with Example II was violently mixed with the oil at about 50 C. The soaps were then separated from the oil by centrifugal separation.

Example VI 5% of a hydrous soap concentrate prepared in accordance with Example I were violently mixed cation. Emulsification can generally be avoided by the use of acids that yield partially solid soaps under the operating conditions. This characteristic varies from acid to acid and depends in part upon the length of chain and extent of unsaturation.

The acids that may be employed vary widely since by blending acids, which by themselves would be inapplicable owing to the hardness of their hydrous soaps, with acids that yield a softer soap, a product can be obtained that is satisfactory. Thus certain acids such as lauric, myristic and iso-oleic can be used without admixture with other acids. Stearic acid cannot be used alone because its soaps are too hard for favorable adsorption of the color bodies. Linoleic acid alone yields soaps that are too softfor favorable separation from the oil. A mixture of the two acids, e. g. 30% stearic-70% linoleic, yields a hydrous soap that is effective. The temperature at which a hydrous soap is used, of course has a bearing on the softness of the soap and by working at substantially elevated temperatures, for example 80 C., stearic and palmitic acids which cannot be effectively used alone for applications at about 30 C. may be used alone or in admixture with each other. Correspondingly, by working at reduced temperature, acids can be used which would be too soft to be eifective at normal temperature. In addition to temperature and fatty acid composition, the water content of the soaphas an important influence on its plasticity and hence its effectiveness. By adjusting one or more of these variables, all of the 10 to carbon acyclic acids can be used in the preparation of a workable hydrous soap stock and most of them can be applied directly without blending but in practice blending is resorted to for optimum results. Owing to the great number of these acids, a limitless number of blends of varying formulations might be used to yield a desirable adsorptivegel type of soapstock. The soaps obtained from the mixtures of acids as they are found in nature in cocoanut, palm and other glycerides are applicable to the adsorption of color bodies. The governing principle in the choice of acid proportions using any combination of acids is to use suficient of the harder soap forming acid to provide just enough solids in the hydrous soap gel to allow it to be separable from the oil under treatment Without undue emulsification. The hydrous soap stock must contain sufficient solids to provide for the separation, on the other hand it must contain sufficient of the liquid hydrous soap component to adsorb the color bodies.

The utilization of preformed soaps in accordance with the present invention enables control of the character of soaps used in the treatment of the oil and by the use of soap adsorbents in accordance with the present invention, alkali is kept out of contact with the oil and in this way the undesirable effect of alkali, as for example, in isomerization of cottonseed and palm oils, is eliminated. Emulsification is also avoided which frequently takes place in connection with oils such as heat treated oils. Any free fatty acids present in the crude oil undergoing treatment, are not affected and may be recovered ultimately as such free fatty acids, for example, by distillation, in a refined condition. Treatment of the oil undergoing refinement by repeated contact and removal of fresh portions of the hydrous soaps provides a maximum of decolorization. The soaps used for the second contacting of an oil may be used again for a primary contact of a fresh oil prior to disposal.

Having thus set forth my invention, I claim:

1. The method of treating a glyceride oil containing its natural color bodies to decolorize the same which comprises intimately contacting said glyceride oil with a preformed hydrous alkali metal soap of saturated and unsaturated fat acids, the unsaturated fat acid constituting at least 30% of the soap forming acids, and the amount of saturated fat acid being Sllfi'lCieIlt to produce ready separability of the soap from the oil, the soap being dispersed through the oil in finely divided condition, the'soap being separable from the oil, and separating the soap carrying the color bodies from the treated oil.

2. The method of treating a glyceride oil containing its natural color bodies to decolorize the same which comprises intimately contacting said glyceride oil with preformed hydrous alkali metal soaps separable from the oil, the soaps being formed from saturated and unsaturated fat acids containing at least 25% of saturated and at least 30% of unsaturated acids, the soaps being dispersed through the oil in finely divided condition, and separating the soap carrying the color bodies from the treated oil.

3. The method of treating a lyceride oil containing its natural color bodies to decolorize the same which comprises homogenizing said glyceride oil with preformed hydrous alkali metal soaps of a saturated solid fat acid and an unsaturated liquid fat acid, the solid fat acid constituting at least 25% and the unsaturated liquid fat acid at least 30% of the soap forming acids, the soap being separable from the oil, and separating the soap carrying the color bodies from the treated oil.

4. A method as set forth in claim 3 in which the saturated acid is stearic acid and the unsaturated acid is oleic acid.

5. A method as set forth in claim 3 in which the saturated acid is lauric acid and the unsaturated acid is oleic acid.

6. A method as set forth in claim 3 in which the saturated acid is palmitic acid and the unsaturated acid is oleic acid.

7. A method as set forth in claim 3 in which the saturated acid is stearic acid and the unsaturated acid is oleic acid and the proportions are 5 parts of stearic to parts of oleic acid.

8. The method of treating a glyceride oil containing its natural color bodies to decolorize the same which comprises homogenizing said glyceride oil with a preformed hydrous alkali metal soap suspended in an oil of the same character as that undergoing treatment, the soap being separable from the oil, and separating the soap carrying the color bodies from the treated oil.

9. The method of treating a glyceride oil containing its natural color bodies to decolorize the same which comprises homogenizing said glyceride oil with a preformed hydrous alkali metal soap suspended in a glyceride oil difierent from that undergoing treatment, the soap being separable from the oil undergoing treatment, and separating the soap carrying the color bodie from the treated oil.

10. The method of treating a glyceride oil containing its natural color bodies to decolorize the same which comprises homogenizing said glyceride oil with a preformed hydrous alkali metal soap of saturated and unsaturated fat acids, the unsaturated fat acid constituting at least of the soap forming acids, and the amount of saturated fat acid being sufficient to produce ready separability of the soap from the oil, said soap being suspended in a glyceride oil different from that undergoing treatment, the soap being separable from the oil undergoing treatment, and separating the soap carrying the color bodies from the treated oil.

FRANCIS M. SULLIVAN.