US2250203A - Method for bleaching oils, fats, and waxes - Google Patents

Description

Patented July 22,1941

UNITED STATES PA-TENT,

OFFICE METHOD non nmscnmc oms, nus, AND waxrs Anna Noder, Munich, Germany, assignor to Buffaio' Electra-Chemical Company, Inc.; Bnflalo,

No Drawing. Application June 8, 1939, Serial No. 278,168. .In Germany September 6, 1937 1 Claim.

The invention refers to a method for bleaching oils, fats, and waxes. I

It has been proposed before now to bleach such products by pure hydrogen peroxide or by a mixture of hydrogen peroxide and other chemicals. It has also been tried to apply various organic andinorganic peroxides to this purpose. Withsome oils, fats, and waxes relatively easy to be bleached fairly good results have indeed been obtained with this method. But there are products where by the methods known up to now nobleaching or but insuiiicient bleaching has been achieved. For such cases the method of the present invention may mostly be applied success- I .fully. Thus with experiments of the applicant products could be bleached where any of the methods known hitherto had failed. Thenew method has the great advantage that the materials bleached take a white to yellow tinge, while the other methods frequently result in giving the very undesirable reddish tinge. Besides this 'method, when carried through entails an automatic clearing of the oils, fats, and waxes inasmuch as suspended dirt particles are deposited at the bottom of the reaction-vessel. The chemical constants of the oils, fats and waxes changed very inconsiderably in bleaching, consequently the typical properties of the respective substances are thus preserved.

The method consists in oils, fats, and waxes in liquid state being diluted with perpyro-phosphate, preferably sodium perpyro-phosphate,

perhaps in combination with hydrogen peroxide and other per-compounds. I

The way of procedure in carrying out this method is as follows: The fat, oil, or wax, after having been cleaned I preliminarily, if need be, in the known manner, is heated to a temperature of 50 to 100 (7., preferably Gil-80 C. Conveniently indirect heating is resorted to; direct heating e. g. by meahs of steam blown. in is unsuitable. The bleaching agent is added slowly whilst stirring to the heated fat, oil, or wax. After a few hours during which the mixture is stirred continuously and the tempei'ature kept constant, the bleaching is ended.

It is then allowed to settle-perhaps overnightand the bleached oil, fat. or wax is withdrawn. In case of need the. bleaching may be followed by a washing according to any of the known methods. It has been found that in some cases the intensity of the bleaching may even be, in-

. creased by using instead of perpyro-phosphate a mixture of perpyro-phosphate and hydrogen peroxide or other per-compounds e. g. benzoyl peroxide. Then one proceeds conveniently adding first the pemyro-phosphate-and subsequently the other per-compounds.

' I Example I showed the following values:

Raw Bleached Number of iodine 52.0 no Number of saponiflcation 212 214 Comparative tests with pure hydrogen peroxide and with bennoyl peromde plus hydrogen peroxide showed a considerably lesser bleaching action. With pure hydrogen peroxide bleaching a very undesirable reddish tint appeared. A

Example If (a) 100 kilos of cotton oil (cotton seed oil) were first of all cleaned preliminarily with 5% trinatrium phosphate solution at 80 C. Thereupon the goods were bleached with 2% sodium p'erpyrophosphate for three hours at -'75 C. whilst stirring.

(b) 100 kilos of cotton 011 (cotton seed oil) were treated preliminarily as described above. As

ableaching agent served 1% of perpyro-phosphate and 1% of hydrogen peroxide (30%). The goods were likewise bleached at IO- C. for three hours. The originally opaque, blackbrown coloured oil was completely clear in both cases and took a light-yellow tint. The numbers of analysis wer as follows:

Raw Bleached Numbe'roflodlne .l 103.0 103.0 Numbcrofsaponifleation 179.2 177,0

Example III v stirring with a mixture or 4% sodium perpyro-- phosphate and 3% hydrogen peroxide (30%).

Then the sample was allowed to settle overnight at '80? 0. Then it was washed with diluted sulphuric acid and water. After bleaching, the originally dark, yellow wax had acquired a white, slightly yellowish tinge. The bleaching tint could still be improved somewhat by using 4% of sodium perpyro-phosphate, 3% or hydrogen peroxide (30%) and 2% 01' benzoyl peroxide as a bleaching agent.

Comparative tests with an equal amount or active oxygen in the form or pure H2O: or H2O:

plus benzoyl .peroxide produced a worse result. 2

The numbers oi analysis'were as follows:

Raw Bleached Number oi saponifloation s2. 4 80. 9

What I claim is: a

The method of bleaching a material of the group consisting of oils, fats and waxes which comprises subjecting the material to indirect heating to raise the temperature thereof to 50 C.

to 100 C. and thereafter slowly adding to the