WO2019092017A1 - Method for extracting fatty acids from triglyceride oils - Google Patents

Abstract

The invention relates to an improved method for extracting fatty acids from triglyceride oils. According to the invention, the triglyceride oil is extracted using an aqueous solution that consists of alkaline (earth) metal hydrogen carbonates and specific carboxylic acid salts. The method according to the invention is characterized by a particularly efficient separation compared to conventional methods.

Description

 The invention relates to an improved process for the extraction of fatty acids from triglyceride oils. The extraction of the triglyceride oil is carried out with an aqueous solution comprising mixtures of (alkaline) alkali metal bicarbonates and certain carboxylic acid salts. The inventive method is characterized by the fact that a particularly efficient separation is achieved compared to conventional methods.

Background of the invention

Natural fats and oils have various undesirable components, such as metals, free fatty acids and phospholipids, and therefore need to be refined. In the refining of natural fats and oils is thereby between the physical and the chemical

Refining distinguished.

In chemical refining, which is mainly used for triglyceride oils with a low content of free fatty acids, the free fatty acids are separated by reaction with a base. This produces Soapstocks, an aqueous mixture of base, free fatty acids, the salts of free fatty acids and oil. These soapstocks are an undesirable by-product of chemical refining of low value and limited use.

In the physical refining, which is mainly used for triglyceride oils with a higher proportion of free fatty acids, the free fatty acids, however, are thermally separated. In this way, the formation of Soapstocks can be avoided, but at the same time high temperatures (up to 260 ° C) must be applied in order to remove the free fatty acids by distillation from the oil can. In addition to chemical and physical refining, other processes are described in the prior art with which free fatty acids can be separated off or soapstocks can be worked up. For example, liquid-liquid extraction techniques are used (C.E.C. Rodrigues, C. B. Gongalves, E. Batista, J.A. Meirelles, Recent Patents on Engineering 2007, 7, 95-102).

In addition, there is also the regeneration of fatty acids by means of ion exchangers, described in US 2,771,480. This is very expensive. WO 2015/185657 A1 describes a process for working up an organic oil, in which it is first degummed by adding water and / or acid and then combined with sodium bicarbonate and / or sodium acetate. WO 2012/035020 A1 and GB 1 520 523 A describe processes for the extraction of fatty acids from vegetable oils, in which polyols are used in combination with bases as extractants.

WO 2015/031857 A2 describes the workup of soap-containing solutions with CO2 at a temperature between 0 ° C and 50 ° C, whereby the soaps are converted into free fatty acids.

WO 2016/189114 A1, WO 2016/189115 A1 and WO 2016/189328 A1 describe the treatment of triglyceride oils with quaternary ammonium salts and their solutions for removing free fatty acids, metals and other undesired components.

WO 2016/149692 A1 describes the acidification of aqueous solutions consisting of

Saponification reactions are derived and contain lipids. The lipid-containing raw material is mixed with base (especially sodium or potassium hydroxide) and saponified. Subsequently, CO2 is pressed, this reacts with the reaction mixture and the aqueous phase is removed.

WO 2012/031 176 A1 describes the extraction of unrefined triglyceride oil with solutions of alkali metal carbonates.

It has now been found that the extraction of fatty acids from triglyceride oils is unsatisfactory in the process described in WO 2012/031 176 A1. In aqueous phase extractions with solutions of alkali metal carbonates and bicarbonates, the phases separate very slowly, or only incomplete phase separation is achieved, as indicated by clouding of the oil phase and emulsion formation in the aqueous phase after extraction. This is especially disadvantageous because it is precisely the use of alkali metal bicarbonates for the extraction of fatty acids is desirable.

The object of the present invention was therefore to provide a process for the extraction of fatty acids from triglyceride oils, which does not have the aforementioned disadvantages.

Detailed description of the invention

The invention accordingly relates to a process for the extraction of fatty acids from triglyceride oils, comprising the step (a), in which (a) a triglyceride oil Ti comprising fatty acids with an aqueous solution Wi comprising at least one salt S selected from the group consisting of

 Alkaline earth metal bicarbonate, alkali metal bicarbonate and at least one salt of a carboxylic acid wherein the carboxylic acid is saturated or unsaturated, has 1 to 8 carbon atoms and 1 to 3 carboxy functions and besides may have one or more OH functions, thereby forming a triglyceride oil phase T2 and an aqueous phase Wherein T2 has a content of fatty acids which is reduced compared to Ti and W2 has a content of fatty acids which is increased compared to W1.

This above-described step (a) is essential for the method according to the invention. The inventive method also comprises the step (b) with

(b) separating the triglyceride oil phase T2 from the aqueous phase W2. In the process according to the invention, step (b) is followed by step (c)

(c) addition of CO2 and optionally an organic solvent to the aqueous phase W2, whereby an aqueous phase W3, which has a lower content of fatty acids compared to W2, and a fatty acid-containing organic phase Fo are obtained. In a preferred embodiment of the method according to the invention, step (c) is followed by a step (d)

(d) separating the aqueous phase W3 from the fatty acid-containing organic phase Fo obtained in step (c).

In a more preferred embodiment of the method according to the invention, step (d) is followed by a step (e)

(e) contacting further triglyceride oil T3 comprising fatty acids with the aqueous phase, whereby a triglyceride oil phase T ₄ and an aqueous phase W ₄ are obtained, wherein T _{4 has} a reduced fatty acid content compared to T ₃ and W _{4 has} a fatty acid content increased compared to W ₂ , It has surprisingly been found that the problems occurring in the prior art in the separation of the aqueous phase can be avoided if a triglyceride oil comprising fatty acids instead of with the (alkaline) alkali metal bicarbonate according to

WO 2012/031 176 A1 with an aqueous solution Wi comprising at least one salt S

selected from the group consisting of alkaline earth metal bicarbonate,

Alkali metal bicarbonate and at least one salt of a carboxylic acid wherein the carboxylic acid is saturated or unsaturated, has 1 to 8 carbon atoms and 1 to 3 carboxy functions and besides one or more OH functions may have contacted.

If such a solution is used in step (a), this leads to a surprisingly rapid and efficient separation of the aqueous phases T2 and W2 obtained in this step.

The salt S is selected according to the invention from the group consisting of

Alkaline earth metal bicarbonate, alkali metal bicarbonate, and is preferably one

Alkali metal.

For the purposes of the invention calcium bicarbonate is the preferred

Erdalkalimetallhydrogencarbonat.

For the purposes of the invention, the alkali metal bicarbonate is preferably selected from the group consisting of sodium bicarbonate, potassium bicarbonate, and more preferably in the context of the invention in the alkali metal bicarbonate to

potassium

The most preferred salt S, which is selected from the group consisting of alkaline earth metal bicarbonate, alkali metal bicarbonate, is potassium bicarbonate.

According to the invention, the term "triglyceride oil" includes any oil or fat whose main constituent is> 50% by weight of triglycerides In addition to the main constituent of the triglycerides, the oil or fat may also comprise mono- and diglycerides.

The triglyceride oil is preferably of natural origin and more preferably of animal or vegetable origin. More preferably, the triglyceride oil is a fat or oil of vegetable origin.

As fats and oils of plant origin come in particular into consideration (where appropriate in brackets Latin terms indicate the plant species from which the oil is obtained): algae oil, apricot kernel oil (Prunus armeniaca), argan oil (Argania spinosa), avocado oil (Persea americana) , Babassu (Attalea speciosa), cottonseed oil (Gossypium), borage oil (Moringa oleifera), borage oil (Borago officinalis), nettle seed oil (Urtica pilulifera or Urtica dioica), beech oil (Fagus), cashew nut oil (Anacardium occidentale), oil from plants of the genus Citrus (for example lemon, orange, grapefruit, lime), cupuagu butter (Theobroma grandiflorum), thistle oil (Carthamus ), Peanut oil (Arachis hypogaea), rose hip seed oil (Rosa), hemp oil (cannabis), hazelnut oil (Corylus avellana), jatropha oil (Jatropha curcas), jojoba oil (Simmondsia chinensis), coffee bean oil (Coffea),

Cocoa butter (Theobroma cacao), camellia oil (Camellia), cabbage palm (Euterpe oleracea), coconut oil (Cocos nucifera), pumpkin seed oil (Cucurbita), camelina oil (Camelina sativa), linseed oil (Linum), corn oil (Zea mays), macadamia oil (Macadamia integrifolia, Macadamia tetraphylla), almond oil (Prunus dulcis), mango butter (Mangifera indica), corn oil (Zea mays), poppy seed oil (papaver),

Evening primrose oil (Oenothera biennis), olive oil (Olea europaea), palm oil (oil available from a plant of the genus Elaeis, especially Elaeis guineensis, Elaeis oleifera), papaya seed oil (Carica papaya), pecan nut oil (Carya illinoinensis), perilla oil (Perilla frutescens), pine nut oil (Plants of the genus Pinus), pistachio oil (Pistacia vera), rapeseed oil (Brassica napus), rice oil (Oryza sativa), castor oil (Ricinus communis), sea buckthorn seed kernel (kernels of Hippophae rhamnoides), sea buckthorn oil (pulp of Hippophae rhamnoides), black cumin oil (Nigella sativa), mustard oil (Brassica nigra), sesame oil (Sesamum indicum), shea butter (Vitellaria paradoxa), soybean oil (Glycine max), sunflower oil (Helianthus annuus), grape seed oil (Vitis vinifera), tung oil (Vernicia, Aleurites), walnut oil (Juglans regia ), Watermelon seed oil (Citrullus lanatus), wheat germ oil (Triticum). Preferably, the fats and oils of vegetable origin are selected from coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rice oil, soybean oil, sunflower oil, rapeseed oil,

Castor oil, thistle oil. Most preferably, the fat and oil of plant origin is palm oil.

As fats and oils of animal origin are in particular: marmot fat, butter fat, fish oil, oil available from crustaceans (for example krill), cod liver oil, milk fat, lard, duck lard, goose fat, beef tallow, wool wax.

For the purposes of the invention, "fatty acids" comprise saturated and monounsaturated or polyunsaturated fatty acids.Furthermore, this term according to the invention (unless otherwise specified in the specific case) always encompasses both the protonated and the deprotonated form of the respective fatty acid.

Examples of unsaturated fatty acids are myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linolelaidic acid, α-linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid and docosahexaenoic acid. Examples of saturated fatty acids are caprylic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid,

Palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachic acid, heneicosanoic acid, behenic acid, lignoceric acid and cerotic acid. "Palm oil" means an oil obtainable from a plant of the genus Elaeis (part of the palm family or palm trees Arecaceae or Palmae), in particular Elaeis guineensis, Elaeis oleifera or hybrids thereof, for example, the pulp of the pulp or the kernel of the plant.

The triglyceride oil Ti comprising fatty acids, in particular the palm oil used in step (a), may be unrefined or at least partially refined. Thus, Ti also includes fractionated triglyceride oil, for example fractionated palm oil, in particular stearic acid fractions or oleic acid fractions of palm oil.

According to the invention, "unrefined" triglyceride oil means triglyceride oil which does not belong to anyone

Refining step was subjected. For example, unrefined triglyceride oil has not undergone any of the following refining steps: degumming, deacidification, bleaching, depigmentation, deodorization, winterization.

"Refined" triglyceride oil has undergone at least one refining step, for example at least one of the following refining steps: degumming,

Deacidification, bleaching, depigmentation, deodorization, winterization. In step (a) of the process according to the invention, a triglyceride oil Ti comprising fatty acids with an aqueous solution W comprising at least one salt S selected from the group consisting of alkaline earth metal bicarbonate, alkali metal bicarbonate and at least one salt of a carboxylic acid, wherein the carboxylic acid is saturated or unsaturated, 1 to 8th

Having carbon atoms and 1 to 3 carboxy functions and besides one or more OH functions may have contacted.

"At least one salt of a carboxylic acid wherein the carboxylic acid is saturated or unsaturated, has 1 to 8 carbon atoms and 1 to 3 carboxy functions and may have one or more OH functions next to it" means according to the invention a carboxylic acid having not more than 8 carbon atoms takes into account the number of carboxy groups

Carboxylic acid also has hydroxy functions or not. Preferred carboxylic acids are selected from the group consisting of acetic acid, lactic acid, citric acid, more preferably acetic acid, lactic acid. Preferred salts of a carboxylic acid wherein the carboxylic acid is saturated or unsaturated, has 1 to 8 carbon atoms and 1 to 3 carboxy functions and besides may have one or more OH functions are alkaline earth metal salts and alkali metal salts, more preferably selected from potassium, sodium, calcium. Most preferably, sodium or potassium salts of the carboxylic acids are used, most preferably potassium salts. The carboxylic acid salts are preferably potassium acetate or potassium lactate, especially when selected as salt S from the group consisting of

Alkaline earth metal bicarbonate, alkali metal bicarbonate in Wi potassium bicarbonate is used.

The temperature in step (a) of the process according to the invention is not limited further. In particular, step (a) of the process according to the invention is carried out at a temperature of <100 ° C, preferably at a temperature of 25 ° C to 99 ° C, more preferably 40 ° C to 95 ° C, even more preferably 55 ° C to 90 ° C, more preferably at 70 ° C to 80 ° C.

The pressure in step (a) of the process according to the invention is likewise not limited further. In particular, step (a) of the process according to the invention is carried out at a pressure of from 1 bar to 100 bar, in particular at atmospheric pressure of 1 bar. The contacting of the triglyceride oil Ti comprising fatty acids with an aqueous solution Wi comprising at least one salt S selected from the group consisting of

Alkaline earth metal bicarbonate, alkali metal bicarbonate and at least one salt of a carboxylic acid wherein the carboxylic acid is saturated or unsaturated, has 1 to 8 carbon atoms and 1 to 3 carboxy functions and besides may have one or more OH functions can be carried out by methods known to those skilled in the art. The contacting may take place in a vessel in which Ti and Wi are mixed together. It goes without saying that the contacting should take place in such a way that as many fatty acids as possible pass from the triglyceride Ti into the aqueous phase Wi. For this purpose, for example, a mechanical mixer (such as a stirred tank, which can be operated non-continuously or continuously), an ultrasonic mixer or an electromagnetic mixer used. In the

Contacting one can blow an inert gas through the resulting mixture. Alternatively, one can mix Ti and Wi in a static mixer such as a Sulzer mixer or Kenics mixer. It is also possible to continuously countercurrently flow Ti and Wi e.g. in a column or in the

To mix direct current. The column may be a sieve tray column, a packed column or a stirred column, such as a Kühni column or a Scheibel column.

In the continuous process, for example in cocurrent Ti and Wi can be performed before contacting them by means of a pump through each tube, at the end they meet and mix, and then passed through a flow tube R.

In the continuous countercurrent process in a column, for example, the triglyceride oil Ti is introduced at or at least near the bottom of the column and the aqueous solution Wi is introduced at or near the top of the column. The aqueous phase W2, which has a higher fatty acid content than W1, is then removed at or near the bottom of the column, and a triglyceride oil phase T2, which has a reduced fatty acid content compared to T1, is then at or near the top Column dissipated.

Preferably, the column also has a sump region in which a secondary stream can be collected, and more preferably the triglyceride oil T1 is then fed directly above this sump region.

Of course, several such countercurrent column can be used, for example 2 to 6, or 3 to 5 or 4.

It is preferred that the column also has a packing, for example a pack of Raschig rings or "trays".

Other equipment options for mixing in DC provide mixer settler, which can be arranged in a countercurrent cascade. In addition, as described below, there are centrifugal extractors in which step (a) of the process according to the invention can be carried out.

Preferably, step (a) of the process according to the invention is carried out in which T1 and W1 are mixed in cocurrent, more preferably in at least one mixer-settler. The volume ratio of T1 and W1 in step (a) of the method according to the invention is not further limited. The ratio of the volume of the triglyceride oil T1 to the volume of the aqueous phase W1 is in particular in the range from 2: 1 to 1: 200, preferably 1: 2 to 1:20, more preferably 1: 2.3 to 1:10. The mixing as for For example, the contacting in the column in the case of continuous contacting can be adapted by the person skilled in the art such that as much as possible of the fatty acids is transferred from the triglyceride oil phase T1 into the aqueous phase W1. Accordingly, the contacting is carried out, for example, for 1 second to 2 hours, in particular 30 seconds to 1 hour, preferably 1 to 50 minutes, more preferably 5 to 40 minutes, most preferably 10 to 30 minutes.

The fatty acids comprised by the triglyceride oil T1 are neutralized in step (a) of the process according to the invention by the salts S selected from the aqueous phase W1 selected from the group consisting of alkaline earth metal hydrogencarbonate, alkali metal hydrogen carbonate.

In particular, the molar amount of all salts comprised by the aqueous phase W1 is S selected from the group consisting of alkaline earth metal bicarbonate, alkali metal bicarbonate at least equal to the molar amount of all fatty acids comprised of triglyceride oil Ti. Preferably, the ratio of the molar amount of all salts S included in the aqueous phase Wi is selected from the group consisting of

Alkaline earth metal bicarbonate, alkali metal bicarbonate to the molar amount of all fatty acids comprised of triglyceride oil Ti in the range 1: 1 to 200: 1, more preferably 5: 1 to 50: 1, even more preferably 15: 1 to 35: 1.

The proportion of fatty acids in the triglyceride oil can be determined by methods known to those skilled in the art, for example by titration with potassium hydroxide and a

 Phenolphthalein. After determining the proportions of fatty acids in the triglyceride oil Ti, the expert then also knows how large the desired molar amount of all of the aqueous phase Wi comprised salts S selected from the group consisting of alkaline earth metal bicarbonate, alkali metal bicarbonate must be, which he can then adjust accordingly.

In step (a), an aqueous phase Wi comprising at least one salt S selected from the group consisting of alkaline earth metal bicarbonate, alkali metal bicarbonate and at least one salt of a carboxylic acid wherein the carboxylic acid is saturated or unsaturated, has 1 to 8 carbon atoms and 1 to 3 carboxy functions, and besides one or more OH functions may have used. In addition to water, the aqueous solution may also comprise further solvents, for example acetone, ethyl acetate, alcohols, preferably methanol or ethanol. However, in addition to water, the aqueous phase Wi preferably comprises no further solvents, which according to the invention means that the weight fraction of the sum of all salts S is selected from the group consisting of alkaline earth metal bicarbonate,

Alkali metal bicarbonate and the water in Wi is at least 95% by weight, preferably at least 99% by weight, more preferably at least 99.9% by weight, and the remainder of Wi thereof are various chemical substances such as organic solvents.

The concentration of all salts S selected from the group consisting of

Alkaline earth metal hydrogencarbonate, alkali metal hydrogencarbonate in the aqueous phase Wi is not further limited and is preferably in the range of> 0.4 mol / L, more preferably 0.5 mol / L to 5.0 mol / L, even more preferably 0.5 mol / L to 4.0 mol / L, even more preferably 1.0 mol / L to 3.5 mol / L, much more preferably 2.0 mol / L to 3.0 mol / L. The ratio of all salts S selected from the group consisting of

 Alkaline earth metal hydrogencarbonate, alkali metal bicarbonate to the salts of the carboxylic acids within the aqueous solution Wi is also not limited, and is preferably such that in the aqueous solution Wi the ratio of molar amount of all salts of saturated or unsaturated, 1 to 8 carbon atoms and 1 to 3 carboxy functions having

Carboxylic acids, which besides one or more OH functions may have, to the molar amount of all salts S selected from the group consisting of

Alkaline earth metal bicarbonate, alkali metal bicarbonate in the range 9: 1 to 1: 9, more preferably 7: 3 to 3: 7, even more preferably 1.75: 1 to 1: 1.75, even more preferably 6: 4 to 4: 6, and most preferably 1: 1 ,

When a triglyceride oil Ti is contacted according to step (a) of the process according to the invention, the fatty acids from the triglyceride oil Ti at least partly pass into the aqueous phase Wi. Therefore, in step (a) of the process according to the invention, a triglyceride oil phase T ₂ and an aqueous phase W ₂ are obtained, wherein T _{2 has} a reduced content of fatty acids compared with Ti and W _{2 has} an increased content of fatty acids compared to W ₁ .

In the process according to the invention, then, following step (a), in step (b) of the process according to the invention, the triglyceride oil phase T _{2 is separated} from the aqueous phase W ₂

separated.

This separation can also be carried out by methods known to the person skilled in the art, for example by means of gravity in a seeding unit. In general, the

Trigylceridölphase T ₂ while the upper phase, while the aqueous phase W _{2 is} the lower phase. The separation of the triglyceride oil phase T ₂ from the aqueous phase W ₂ can alternatively also be carried out in a decanter, a hydrocyclone, an electrostatic coalescer, a centrifuge or a membrane filter press. Preference is given in step (b) of

According to the invention, the triglyceride oil phase T _{2 is separated} from the aqueous phase W ₂ in a settler or in a centrifuge, more preferably in a centrifuge.

If the salt S is selected from the group consisting of alkaline earth metal bicarbonate, alkali metal bicarbonate and / or the salt of the carboxylic acid in W ₁ during the

Contacting in step (a) at least partially precipitated and present in the triglyceride oil phase T ₂ as a solid, it can also be separated by centrifugation or filtration. Solvent or water may also be added to the triglyceride oil phase T ₂ containing the solid to solubilize the solid and separate the aqueous solution comprising the appropriate salt as described above. In a preferred embodiment of the present invention, the steps (a) and (b) of the method according to the invention, ie the contacting and separation, in one

Centrifugal separator, as described for example in US 4,959,158, US 5,571,070, US 5,591, 340, US 5,762,800, WO 99/12650 and WO 00/29120. In this case, Ti and W _{1 are} in particular supplied to the separator only as separate streams and in an annular Mixing zone mixed. The mixture is then passed to the deposition zone, where the phases are then separated by means of a centrifuge.

More preferably, one uses a series of centrifugal separators, for example 2 to 6, 3 to 5 or 4, and introduces the triglyceride oil Ti into the first separator of the series, and the aqueous

Phase Wi in the last separator of the series, so that triglyceride oil with decreasing content of fatty acids passes through the first to last separator in the series, while the aqueous phase with increasing content of fatty acids passes through the separator in the opposite direction. The aqueous phase W2 is then taken from the first separator, the triglyceride oil phase T2 from the last separator in the series.

In any case, the triglyceride oil phase T2 can also be fed to a coalescing filter in order to remove last drops of aqueous solution from the fat or oil phase. Such a coalescing filter is known to those skilled in the art and may comprise a filter material which is wetted by the aqueous phase rather than by the oil phase, for example a glass or cellulose filter material.

After separation of the triglyceride oil phase T2 from the aqueous phase W2 in step (b), the triglyceride oil phase T2 can then be sent for further processing. Such a step may include one or more of degumming,

Deacidification, winterization, bleaching, depigmentation, deodorization. These steps are known to the person skilled in the art and described, for example, in WO 2016/189114 A1.

It goes without saying that the triglyceride oil phase T2 after the separation in step (b) can be fed once more or several times, for example twice to ten times, to a contacting step (a) in which the triglyceride oil phase T2 is used as triglyceride oil T1 and each step comprising a new batch of aqueous phase W1 comprising at least one salt S selected from the group consisting of alkaline earth metal bicarbonate,

Alkali metal bicarbonate and at least one salt of a carboxylic acid wherein the carboxylic acid is saturated or unsaturated, has 1 to 8 carbon atoms and 1 to 3 carboxy functions and besides one or more OH functions may be contacted to the proportion of fatty acids in the triglyceride oil phase T2 yet lower further.

The aqueous phase W2 obtained in these additional steps is then in the process according to the invention (after separation of the aqueous phase) completely or partially

be fed to subsequent step (c), in which the aqueous phase is regenerated.

In this step (c) the addition of CO2 and optionally an organic

Solvent to the aqueous phase W2 instead, whereby a fatty acid-containing organic phase Fo and an aqueous phase W3, which has a lower content of fatty acids compared to W2 has to be obtained. The corresponding conditions are known to the person skilled in the art and are described, for example, in WO 2016/149692 A1.

According to the invention, "fatty acid-containing organic phase Fo" means the phase which forms the second phase comprising free fatty acids in addition to the aqueous phase W3.For this phase Fo, the content of fatty acids is increased compared to the content of fatty acids in W 2. The phase Fo is already alone therefore "organic" because it includes free fatty acids. It may contain, in addition to the free fatty acids, an organic solvent, if this is added in step (c) of the

However, it does not have to be added. Even without addition of an organic solvent in step (c) of the process according to the invention, the phase Fo is formed as a separate and separable in particular by centrifugation phase in addition to the aqueous phase W3, as shown in the inventive example E4.

The addition of an organic solvent in step (c) of the process according to the invention is preferred because it facilitates the separation of the fatty acid-containing phase from the aqueous phase W3.

The contacting of the aqueous phase W2 with CO2 and optionally an organic solvent can take place by methods known to the person skilled in the art. The contacting can take place in a gas-tight sealable pressure vessel in which W2 and CO2 and optionally an organic solvent are mixed together. For this purpose, CO2 can be introduced, for example, via a capillary or a gasatable stirrer. It goes without saying that the contacting should take place so that as much CO2 as possible is introduced into the aqueous phase W2. For this purpose, for example, a mechanical mixer or an electromagnetic mixer is used.

If an organic solvent is added in step (c) of the process according to the invention, then the volume ratio of W 2 and the organic solvent in step (c) of the process is not further limited. The ratio of the volume of W 2 to the volume of the organic solvent is then in particular in the range from 1: 100 to 100: 1, preferably 1: 5 to 5: 1, more preferably 1: 2 to 2: 1.

When an organic solvent is used in step (c), it is preferably diisopropyl ether, n-butyl acetate, ethyl acetate, hexane, 1-hexanol, more preferably n-butyl acetate.

The pressure and the temperature in step (c) of the method according to the invention are not limited further.

In particular, the pressure during the addition of the CO 2 is in a range of 0.1 to 55 bar, preferably 1 to 20 bar, more preferably 5 to 10 bar. The temperature is preferably in the range of 0 ° C to 120 ° C, more preferably 5 ° C to 100 ° C, even more preferably 10 ° C to 90 ° C, even more preferably 20 ° C to 80 ° C, even more preferably 40 ° C to 60 ° C, most preferably 50 ° C.

The CO2 used in step (c) may come from a combustion process or blast furnace process and may include other components such as N2O, SO2, H2S, NO2. These components can further acidify the aqueous phase W2, so that this further favors the formation of a fatty acid-containing organic phase Fo.

At the end of step (c) of the process according to the invention, a fatty acid-containing organic phase Fo and an aqueous phase W3 which has a lower content of fatty acids than W2 are then obtained. In the optional next step (d) of the process according to the invention, the aqueous phase W3 is separated off from the fatty acid-containing organic phase Fo obtained in step (c).

This can be done by methods familiar to the person skilled in the art, as well as for step (b) of the

described method to be carried out according to the invention, in particular per

Centrifugation.

After completion of the process according to the invention, a phase W3 is obtained which can be treated in a new cycle with a new batch of triglyceride oil. In a preferred embodiment of the process according to the invention, therefore, in a further step (e), at least a portion of the aqueous phase W3 is contacted with further triglyceride oil T3 comprising fatty acids, whereby a triglyceride oil phase T ₄ and an aqueous phase W ₄ are obtained, wherein T _{4 is} opposite T3 has reduced content of fatty acids and W _{4 has} an increased content of fatty acids compared to W3.

This further step (e) is preferably carried out as described for step (a). The process according to the invention is in fact suitable for recycling the aqueous phase W1 again and again and for use in a new extraction process.

The following examples are intended to illustrate the invention without limiting it. Inventive Examples E1 E4 and Comparative Examples V1

In each case 70 g of the salt solutions described in Table 1 were mixed with 30 g of palm oil (5.5% free fatty acids, determined by titration according to DGF method DGF-C-V 2, based on palmitic acid). added and stirred at 80 ° C for 1 hour.

The salt solutions in each experiment were as follows:

E1: aqueous salt solution in which the following concentration of the respective substance is present:

Potassium acetate with a concentration of 2 mol / L and KHCO3 with a concentration of 2 mol / L.

E2: aqueous salt solution in which the following concentration of the respective substance is present:

Potassium acetate with a concentration of 2.8 mol / L and KHCO3 with a concentration of 1.2 mol / L.

E3: aqueous salt solution in which the following concentration of the respective substance is present:

Potassium lactate with a concentration of 2 mol / L and KHCO3 with a concentration of 2 mol / L.

V1: 3.0 M KHCOs solution in water.

V2: aqueous salt solution in which the following concentration of the respective substance is present: K2HPO4 at a concentration of 2 mol / L and KHCO3 at a concentration of 2 mol / L.

V3: aqueous salt solution in which the following concentration of the respective substance is present: KCl at a concentration of 2 mol / L and KHCO3 at a concentration of 2 mol / L.

After the reaction, the reaction mixture was transferred to a separatory funnel and the time was determined until complete separation of the phases. The content of fatty acids in the obtained triglyceride phase was determined by titration (see Table 1, next page).

Experiment salt mixture conc, [mol] FFA content conversion separation time

 [%] [%]

 E1 KHCO3: potassium acetate

 4.0 5 min 1: 1 0.52 91.1

 E2 KHCO3: potassium acetate

 3.9 5 min 1.2: 2.8 0.40 92.4

 E3 KHCO3: potassium lactate

 4.0 5 min 1: 1 0.47 91.0

 V1 3.0 M KHCO3 (aq) 90 min, aqueous

 3.0

 Emulsion, turbid (saturated)

 0.34 94.1 palm oil phase

V2 KHCO3: K2HPO4 1: 1 5 min, cloudy

 4.0

 0.34 94.1 palm oil phase

V3 KHCO3: KCl 1: 1 4.0 0.23 96.0 120 min, emulsion

It was found, surprisingly, that a faster phase separation is possible with the combination of potassium hydrogen carbonate and potassium lactate or potassium acetate.

The subsequent experiment E4 was carried out in order to show that a separation of the phases in step (c) of the process according to the invention also without addition of an additional

500 g of an aqueous salt solution of potassium acetate and potassium bicarbonate, wherein the concentration of the respective substance is 2 mol / L, with 210 g of palm oil (5.5% free

Fatty acids, determined by titration according to DGF method DGF-C-V 2, based on palmitic acid), and stirred at 80 ° C for 1 hour. After the reaction, the reaction mixture was transferred to a separatory funnel and the organic palm oil phase separated from the aqueous salt solution. The content of fatty acids in the obtained triglyceride phase was determined by titration to 0.38 wt .-%. This corresponds to a conversion of free fatty acid of 94%. The

Triglyceride phase showed thereby the characteristic smell of the raw palm oil.

Subsequently, the aqueous salt solution was transferred to a reactor. After introduction of CO 2, this was stirred at 40 ° C. partial pressure of 25 bar for 1 hour. After cooling to room temperature, the CC pressure was released and the reaction solution was discharged into a glass. Here, a second almost solid phase was observed on the salt solution, which is free fatty acid.

Claims

claims A process for the extraction of fatty acids from triglyceride oils comprising the step (a) comprising (a) a triglyceride oil Ti comprising fatty acids with an aqueous solution Wi comprising at least one salt S selected from the group consisting of  Alkaline earth metal bicarbonate, alkali metal bicarbonate and at least one salt of a carboxylic acid wherein the carboxylic acid is saturated or unsaturated, has 1 to 8 carbon atoms and 1 to 3 carboxy functions and besides may have one or more OH functions, thereby forming a triglyceride oil phase T2 and an aqueous phase Where T2 has a reduced content of fatty acids compared to Ti and W2 has an increased content of fatty acids compared to W1; and further comprising step (b): (b) separating the triglyceride oil phase T2 from the aqueous phase W2; and further comprising step (c): (c) addition of CO2 and optionally an organic solvent to the aqueous phase W2, whereby an aqueous phase W3, which has a lower content of fatty acids compared to W2, and a fatty acid-containing organic phase Fo are obtained. 2. The method of claim 1, further comprising the step (d): (d) separating the aqueous phase W3 from the fatty acid-containing organic phase Fo obtained in step (c). 3. The method of claim 2, further comprising the step (e): (e) contacting further triglyceride oil T3 comprising fatty acids with the aqueous phase W3, whereby a triglyceride oil phase T ₄ and an aqueous phase W ₄ are obtained, wherein T _{4 has} a reduced fatty acid content compared to T3 and W _{4 has} an increased content compared to W2 Has fatty acids. 4. The method according to any one of claims 1 to 3, wherein step (a) is carried out at a temperature of <100 ° C. 5. The method according to any one of claims 1 to 4, wherein in step (a), the ratio of the volume of the triglyceride oil Ti to the volume of the aqueous phase Wi in the range of 2: 1 to 1: 200. 6. The method according to any one of claims 1 to 5, wherein in the aqueous solution Wi, the ratio of molar amount of all salts of saturated or unsaturated, 1 to 8 carbon atoms and 1 to 3 carboxy-containing carboxylic acids, which in addition have one or more OH functions can, to the molar amount of all salts S in the range 9: 1 to 1: 9. 7. The method according to any one of claims 1 to 6, wherein the salts S are selected in the aqueous solution Wi from potassium bicarbonate, sodium bicarbonate, Calcium bicarbonate. 8. The method according to any one of claims 1 to 7, wherein the salts of a carboxylic acid in the aqueous solution Wi are selected from salts of acetic acid, lactic acid, citric acid. A process according to claim 8 which is potassium salts of acetic acid, lactic acid, citric acid. 10. The method according to any one of claims 1 to 9, wherein in step (b) the triglyceride oil phase T2 is separated from the aqueous phase W2 in a centrifuge. 1 1. The method according to any one of claims 1 to 10, wherein the concentration of all salts S in the aqueous phase Wi in the range> 0.4 mol / L is. 12. The method according to any one of claims 1 to 1 1, wherein in step (c) an organic Solvent is added to the aqueous phase W2. 13. The method of claim 12, wherein the ratio of the volume of W2 to the volume of the organic solvent is in the range of 1: 100 to 100: 1.