US2221559A - Process for bleaching oils, fats and waxes - Google Patents

Description

, 55 bleaching as prior .to bleaching. Moreover, the j Anothersource of acid resides in'the hydrogen 5 Patented Nov. 12, 1940- g i f i I I UNITED STATES. PATENT orrica' 1,221,559

PROCESS Fort BLEACHING oins, FATS Am) waxes I Emil Scheller, Lorsbach in Taunus, Germany, assignor to Deutsche Gold nndsilber Scheldeanstalt, Frankfort-on-the-Main, Germany, a cor- Duration of Germany No Drawing. Application mm 20, 1937, Serial Not-170,073; In Germany March 5,1936

. Clai ms. (01. 260-423) This application relates to the bleaching of oils, waste water resulting from the treatment of the fats and waxes. In the improved process of wax is neutral in reaction, thus indicating no sub-' bleaching these substances it is proposed to utilize stantial decomposition of the wax. Beeswax bleaching agents, preferably bleaching agents of bleached in accordance with the'procedure outthe oxidizing type. More particularly, the imlined and more fully described in German patent proved process is concerned with the bleaching of 595,126 has been founghofmespecial value in in- 5 waxes such as commercial beeswax and other dustries such as the cos ,ic industry, wherein waxes in order that a light, colored product of a whiter but substantially unchanged product is especial value in the'cosmetic industry may be desired;

-secured. However, it has-been observed insome cases There are nowknown to the art various methods that. unsatisfactory bleaching is secured when for bleaching oils, fats and waxes. For the leils, fats and waxes, and more especially bees! bleaching of beeswax and other waxes of value in; wax, are subjected to bleaching processes of the industrial processes, bleaching by subjecting the general type outlined. 'At first it was believed 5 emulsified wax to the action of an oxidizing that the unsatisfactory bleaching was attributbleaching agent has already been disclosed. In able to .the' bleachingactivitymf the agents these processes the beeswax or otherwax being utilized in the process and to the difficulty of bleached is maintained at a temperature at which bleaching dark. colored organic substances such it is in the molten condition during theble'aching asthe usual commercial waxes and beeswaxes.-

process. An alkaline medium yielding active It has now been found, however that the un- 2 oxygen or active chlorine is usually utilized, the satisfactory bleaching results from the presence bleaching being carried out under conditions of small amounts of inorganic acids in the prodwherein the wax and medium form a more or less uct being treated in the subsequent bleaching step stable emulsion. However, bleaching with; the wherein. the product, in molten form, is subpermanganates as the active agents has also been jected to the action of hydrogen peroxide. The 25 employed for lightening the color of oils, fats presence of inorganic acids in the'wax or beesand waxes. I wax, or in the oil or fat, during the hydrogen In processes as now utilized in the art it is peroxide bleaching step seriously interferes with j customary, at the conclusion of the bleaching tep bleaching and impairs the character of the rewherein the oil, fat or wait in'emulsified to m is sultant product. I 30 treated with the bleaching agent, to brea the As previously pointed out, it is customary at the emulsionby the addition of an acid to the emulconclusionof the step wherein the oil, fator wax sifled mixture. This results in precipitation of. is'subjected, m1 emulsified form; to the action of the beeswax or other product being treated. The a bleaching agent, to recover the product from 3.5,. precipitated substance is then ordinarily washed the emulsion by the addition of an acid such as and subjected to a second bleaching operation sulfuric acid thereto. In present processes the in the molten or liquid condition. While'hydroproduct is then carefully washed several timesfor gen peroxide may frequently be used in the first the purpose of removing that acid, It has been step, that wherein the emulsified oil, fat or wax found that repeated remelting of. the product 40 is treated with the bleaching agent, it is also frewhenthat product is a solid and repeated washquently utilized as the bleaching agent in the ing with water doesnot remove the last traces latter step. A process of the general type de-, of the acid used for breaking theemulslon. scribed is given in full in German Patent 595,126. Moreover, in, practice clarification is only rarely Since the improved process utilizes relatively so completethat-very distinctsepar'ation between mildlchemical reagents it has found distinct favor the molten-wax'treated and the aqueoustreating 45 for industrial operations. When relatively mild agents utilizedvwill result. Depending primarily chemicals are utilized the wax retainsits desirupon the quality of the wax or other product able natural characteristics and is substantially treated and the apparatus employed, there are unchanged, except as to color, during the bleachusually formed intermediatelayers or more or less' mg operations. The absence of substantial heavy-appearance.- These layers are customarily 50 change in the character of the wax during bleachtreated together with the liquid wax in the em I .ing'in. accordance with the process described-is suing bleaching step or steps, thus introducing a evidenced by the fact that the wax constants into the wax small amounts of acids which matearesubstantially the same at the conclusion of rially interfere withbleaching;

peroxide itself which is employed for the final bleaching step. It must be remembered that commercial hydrogen peroxide contains acid, usually an inorganic acid such as sulfuric or phosphoric 5 acids, and that when commercial hydrogen peroxide is added to the product being treated and maintained in the molten state, in processes such as that described in German Patent 595,126, defim'te amounts of acid are introduced. This is clearly shown by experimental results for frequently when large amounts of hydrogen peroxide are employed in an attempt to secure improved bleaching results, amounts greater than those normally utilized, it is observed that the bleaching results are less favorable than when the smaller amounts of hydrogen peroxide were employed. This decrease in bleaching activity is attributable to the introduction into the process of larger amounts of acid with the larger amounts of hydrogenperoxide, the greater amount of acid present seriously interfering with bleaching.

I have now found that the second bleaching step of processes such as that described in German Patent 595,126, the step wherein the oil, fat

or wax in the liquid or molten state is treated with hydrogen peroxide, may be more successfully carried out with results of greater uniformity if care is taken to insure the substantial absence of free inorganic acids during this portion tion of the process. The substantial elimination of acids during, this bleaching operation may be accomplished in va'rious'ways, one of which is by neutralization of the acid present by the addition of materials which are alkaline in reaction.

It is possible to employ for the purpose alkaline agents such as ammonia, caustic soda, alkali metal salts, or alkaline. earth metal salts. Specific examples of salts suitable include sodium acetate, sodium carbonate, and lime. I have 40 found, however, that best results are obtained when magnesium oxide is utlized for neutralizing the free acid present. It is especially advantageous to. utilize for neutralizing the acid those alkaline agents which, upon neutralization,

do not form acid products with the acids that they neutralize. For this reason sodium acetate is not very suitable as an addition agent for neutralizing free acid present in the product being bleached for it forms acetic acid during the neutralization of the inorganic acid present. I prefer to .employ alkaline addition agents which form products whichare neutral or almost neutral in reaction with the acids that they neutralize. While a slight excess of the alkalining agent employed may not be injurious to the oil, fat or a wax, it is preferable to add but small amounts of these alkaline agents, amounts not exceeding those sufiicient to impart to the resulting mixture during the. bleaching operation a pH value between 7 and 8.5. The amount of alkaline agent added should not exceed that necessary to insure a substantially neutral medium, i. e., one having a pH value between 7 and 8.5, during the bleaching step.

5 "I have observed that best results are obtained when magnesium oxide is utilized as the agent for neutralz'ing the acids present in the oils, fats or waxes or present in the hydrogen peroxide duringthe step wherein the oil, fat or wax,

70 in liquid or molten form, is treated with hydrogen peroxide. This is probably because magnesium oxide is substantally completely neutral in reaction, and, moreover, yields with the acids neutralized, salts which are neither acid non basic 75 in reaction. Whilean excess of magnesium ox- 'solution slightly on the alkaline side.

-- agent.

ide is not injurious to the oil, fat or wax nor does it interfere with the bleaching process, it should, nevertheless, be avoided if possible. -I have found it advantageous to employ from 0.1 to 0.2% magnesium oxide, that amount being by weight based 5 upon the weight of the oil, fat or wax being treated.

As analternative way of accomplishing the same result, I have found it possible to utilize in the final, bleaching step hydrogen peroxide to 10 which, has been added an alkali metal peroxide in such quantity that the inorganic acid present in the substance being bleached is substantially neutralized. A slight excess of the alkali metal peroxide may be present if desired and enough 15 may be added to render the pH of the resulting Care should be taken, however, to have present only such amounts of alkali metal peroxide as will not raise the pH of the oil, fat or wax and the 20 hydrogen peroxide above about 8.5.

After completion of the bleaching step, the products resulting from neutralization of the acid may be removed by any suitable procedure. i They may be removed, for example, by washing 25 the oil, fat or wax with acid or with acidulated water. Ordinarily this does not involve a step additional to those now employed, for as pointed out in German Patent 595,126, these products i are customarily remelted or recovered over acidu- 30 lated water at the conclusion of the bleaching process.

Oils, fats or waxes bleached in accordance with the process described will be observed to have a lighter color than those bleached under similar 35 conditions but without the neutralization of free acid present by the addition of magnesium oxide or similar alkaline material. Moreover, it will be found that waxes, especially beeswax bleached in accordance with the procedure described, will 40 be more satisfactory in that their desirable natural characteristics are less changed during .the. bleaching. Moreover, my improved process makes. it possible to obtain-more satisfactory and more uniform results, especially with those types 45 of commercial waxes and beeswaxes which are exceedingly difficult to bleach to a satisfactory light color without substantially impairing their desired physical and chemical characteristics.

When bleaching substances which are more so easily bleached by chemical agents, such as the readily bleachable varieties of beeswax, it. has been found possible to eliminate the step of preliminary bleaching wherein the emulsified product is subjected to the action of an oxidizing When this step is eliminated the bleaching is carried out in a single operation, the material to be bleached is in the liquid or .in'the molten state during this operation and, in general, a greater amount of hydrogen peroxide will (50 be necessary than that necessary when the twostage method ,is utilized. During the step of bleaching the oil, fat or wax in a single operation, the inorganic acids present should, of course, be neutralized by the addition to the reaction mixture of some. material which' is alkaline in reaction, more especially some material, preferably magnesium oxide, which. meets the requisites previously given.

As examples of my improved process for the bleaching of oils,fats and waxes the following may be given:-

. 2 Example 1 A sample of Congo wax, a product especially 7;;

this step the sodium peroxide was first dissolved.

in about 20-times its volume of cold water and then gradually added to the wax emulsified in about twice its volume of hot water containing 1% of caustic soda. During this step the temperature was maintained sufliciently high to keep the wax in the molten condition. A temperature of 90-l00 C. was found suitable;

After completion of this bleaching step, the time in which the bleaching was complete being observed by determining that point at which the gsactive oxygen content of the bath became depleted, the emulsion was broken by the addition of a slight excess of dilute sulfuric acid. Thewax was then clarified to as reat an extent as possible by' the introduction of steam nd by permitting it to stand for a short period. The lower aqueous layer was then drawn oil, the wax being thus recovered.

Magnesium oxide in the amountof .0.1% based on the weight of the Congo wax, was then added. The max was maintained in the molten state, the temperature being maintained between 90-100 C., and treated with a 4% solution oi hydrogen peroxide (40%concentration). During this step the mixture was continuousl stirred. When bleaching was complete, determined by testing for residual oxygen, hot water was added to the wax and enough dilute sulfuric acid to dissolve the magnesiumcoxide. It was then allowed to stand for a period of time to effect clarification. The temperature was then lowered and the wax permitted to solidify. 4

The waxbleached in this manner had 'a considerably lighted color than samples of wax bleached in the same general process but with-' out the addition of magnesium oxide.

. Example 2 A sample of Congo wax was bleached in accordance with the same process described in Example 1 except that 0.1% or sodium bicarbonate (NaHCOs) was utilized in place or 0.1% magnesium oxide. The wax was clarified and light; ened in color to substantially the same degree as that obtained in accordance with the'process 0 Example 1.

- It should be understood that the various details oi the general process described are intended to be illustrative and not restrictive except insofar as necessitated by the appended claims. As various changes maybe made in the general procedurewhich I regard as my preferred embodiment without departing from the spirit and scope of my invention, the disclosure and description given herein, except as necessitated by the'appended claims, are to be regarded as illustrative and in no sense limiting.

I claim:

1. A process of bleaching oils, fats and waxes which comprises contacting the product to be bleached in the emulsified state with an oxidizing agent in order to efiect a partial bleach, adding an acid thereto in amount sufllcient to break said emulsion, adding to said product an alkaline agent in amount sufiicient'to neutralize the free inorganic acid present, said amount not being in excess of that amount necessary to impart thereto a pH of substantially 8.5, and then bleaching said product in the liquid or molten state with hydrogen peroxide under. conditions wherein the mixture of said product and hydrogen peroxide is substantially neutral in reaction.

2. A process as defined in claim 1 wherein the alkaline agent added for the purpose of neutralizing free inorganic acids present is magnesium oxide.

3. A- process as described in claim 1 wherein the alkaline agent addedis magnesium oxide in amounts ranging from 0.1 to 0.2% based on the weight of said oil, fat or wax. v

- 4. A process as defined in claim 1 wherein, at the conclusion of the hydrogen peroxide bleaching operation, the products formed by neutrali- "o zation of the inorganic acids present with said alkaline agent are removedby washing said oil, fat or wax with a dilute acid.

5. A process tor-bleaching oils, rats and waxes which comprisesv contacting the product to be bleachedin the emulsified state with an oxidizin agent inorder to effect a partial bleach, adding an acid thereto in amount sufiicient to break said emulsion, adding to said product an alkaline agent in amount suificient to neutralize the free I inorganic acid present therein but insufllcient to impart thereto a pH in excess of substantially 8.5, and then contactingsaid product in the liquid or molten state with hydrogen peroxide under conditions wherein the mixture or hydrogen'pe'roxide is substantially neutral in reaction andremains neutral through-- out said final bleaching stage.

Elm-SCHILLER.

said product and