WO1991011242A1

WO1991011242A1 - Process for separating oil-water emulsions

Info

Publication number: WO1991011242A1
Application number: PCT/EP1991/000105
Authority: WO
Inventors: Claus-Peter Herold; Uwe Ploog; Günter Uphues; Brigitte Spei; Volker Wehle
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1990-01-29
Filing date: 1991-01-21
Publication date: 1991-08-08
Also published as: DE4002472A1; EP0513070A1

Abstract

The invention concerns a process for separating oil-water emulsions using organic emulsion separators. These are obtained by the reaction of primary, secondary and/or tertiary alkyl amines with propylene oxide and/or ethylene oxide in the presence of inorganic and/or organic acids. The compounds thus obtained, of the general formula (I), are used in concentrations of 0,01 to 10 vol. % to separate oil-water emulsions.

Description

Process for splitting oil / water emulsions

The invention relates to a process for splitting oil / water emulsions using organic emulsion splitters.

Oil-in-water emulsions (O / W emulsions) used very often in the processing of metallic materials, such as cooling lubricant, deep-drawing, cutting or drilling emulsions, the oil phase of which is predominantly natural or synthetic Oils of different chemical composition and origin are not only subject to wear when used, but are also contaminated by the entry of foreign substances. They must therefore be disposed of regularly. The most important step in the disposal, which may run continuously, is the cleavage of the processed emulsions; This means that the oil phase must be separated as much as possible from the water phase in order either to be able to work up and reuse the separated oil phase or to be able to dispose of it and the likewise separated water phase in an ecologically harmless manner to the usual disposal methods.

O / W emulsions are also obtained to a considerable extent in the extraction and extraction of petroleum. These are O / W emulsions, which are often stabilized by finely divided clay components. O / W emulsions also fall in the field of petroleum transportes and further processing in the refinery area. All these emulsions have in common that they have to be split up for disposal or further use of the water phase and for further processing of the oil phase.

The majority of all emulsions are stabilized either naturally or on the basis of special formulations with anionic surfactants. Accordingly, the cleavage agents used in practice are all of a cationic charge character, i.e. corresponding to cationic surfactants. Emulsion splitters of the cationic type based on copolymers of dimethylamine and epichlorohydrin - or other comparable polyamines correspond to the prior art. The influences that make the effectiveness of a cationic surfactant suitable as an emulsion splitter are not known. However, it has been shown in the past that only relatively narrowly limited classes of cationic surfactants are suitable for cleavage. Classic quaternary ammonium compounds, e.g. Cetyltrimethylam onium chloride absolutely unsuitable as a splitting agent.

The splitting of such emulsions by mineral salts or acids, which was customary in the past, was successively replaced by splitting processes in which organic splitters, generally surface-active substances, are used for splitting the emulsion because of the ecological disadvantages and the large amount of splitter required for complete splitting . Their advantage can be seen in the fact that the use concentrations required for complete cleavage are very low, for example in the range from 0.01 to 10% of the amount of emulsion, and the cleavers do not dispose of the oil phase, for example during combustion affect. In addition, they do not lead to any significant contamination of the aqueous phase with foreign substances. Complete emulsion splitting is only possible in a relatively narrow range of dosage of the splitting substances. Below this range, the emulsion splitting is incomplete, which is reflected in an undesirably high oil content in the water phase; Above this range, the overdose of the splitter and the associated re-emulsification likewise lead to an increase in the oil content in the water phase, which is of course also undesirable. An additional difficulty is to be seen in the fact that the oil-in-water emulsions which occur in practice can be subject to strong fluctuations with regard to composition, concentration of the constituents, pH, temperature and other parameters. These disadvantages mean that when empirically using surface-active substances as an emulsion splitter, constant empirical checks of the type of splitting agent and the amount of splitting agent are necessary in order to determine the optimum metering range for the organic splitter for each application problem.

In practice, the optimal dosing range is usually determined by visual observation of the gap course in the emulsion splitting. This determination of the optimal dosing range for the splitter, i.e. of the end point for the addition of the surface-active compound used as a splitter, is generally carried out in such a way that splitter was added until a doping oil sludge flake forms. In order to avoid overdosing, this has to be done with the addition of small amounts of breaker, which is why the splitting of oil / water emulsions takes a period of several hours when the end point is determined visually.

In the prior art, cationic polymers are preferably used as splitters (demulsifiers). These usually indicate

Molecular weight in the range of 50,000 to 500,000. In the In practice, even small demulsifier concentrations, compounds based on polyamines, polyamide amines, polyimines, condensation products of o-toluidine and formaldehyde, quaternary ammonium compounds and ionic surfactants are used. Of these, polyamines with an average molecular weight in the range from 75,000 to 200,000 or condensation products of o-toluidine and formaldehyde are particularly preferred due to the good splitting results even at low splitter concentrations.

Quaternary ammonium salts are known from EP-PS 0 098 802, which are produced from tertiary amines and ethylene oxide. These are particularly suitable for use in hair cosmetics, such as hair conditioners.

Corresponding compounds are known from European patent specification 213 601, which are produced from tertiary amines and ethylene oxide and / or propylene oxide.

Surprisingly, it has now been found that certain reaction products of amines and alkylene oxides or their salts are outstandingly suitable as emulsion splitters for cleaving the above-mentioned emulsions. These are quaternary ammonium bases obtained by reacting primary, secondary or tertiary amines with propylene oxide and / or ethylene oxide. Processes for the production of the substances mentioned are described in European patents 0098802 and 0213601.

The invention thus relates to a process for splitting oil / water emulsions, which is characterized in that compounds of the general formula (I) are used:

in which

R represents a straight-chain or branched-chain alkyl radical having 12 to 18 carbon atoms, R and R each independently of one another

Alkyl radical having 1 to 4 carbon atoms or a hydroxyalkyl radical having 1 to 4 carbon atoms, R ^{3 is} H or CH3, n is an integer in the range from 1 to 6 and X is an anion which is selected from the acids hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid or nitric acid or low molecular weight organic mono-, di- or tricarboxylic acids, with the proviso that the ratio of R ³ = CH3 to R3 = H is at least 3: 1.

The compounds to be used are obtained by processes known per se in the prior art by reacting primary, secondary or tertiary amines with ethylene oxide and / or propylene oxide in the presence of the desired acid. Corresponding methods are known in particular from European patent specification 0098802 and European patent specification 0213601.

Primary, secondary or tertiary alkylamines in which the radicals R- and R ^ are identical are particularly preferred as starting materials. Accordingly, a particular embodiment of the present invention consists in starting with dimethylalkylamines in the preparation of the compounds to be used according to the invention. For the purposes of the invention, those compounds of the formula (I) are therefore used in which R and R2 represent a methyl radical.

The abovementioned amines can either be reacted directly with ethylene oxide and / or propylene oxide or can be obtained as random or block polymers from ethylene oxide and propylene oxide by processes known per se. This is also a method known per se in the prior art.

Compounds to be used according to the invention in which the ratio of R ³ = CH ³ to R ³ = H is less than 3: 1 are too hydrophilic for the splitting of oil / water emulsions, so that they are less so for the present invention are suitable. Accordingly, it is preferred to use the largest possible ratio of propylene oxide to ethylene oxide units. It is therefore particularly preferred that the radical R ^{3 is} exclusively CH3, that is to say the compounds to be used according to the invention are propoxylates of quaternary ammonium compounds.

In a further preferred embodiment of the present invention, the number of propylene oxide and / or ethylene oxide units is adjusted such that only one or two of these units are present in the molecule. Accordingly, n stands for 1 or 2.

As indicated in EP-PS 0 098802, in particular in Example 1, the alkylamines are neutralized and heated with an inorganic acid or a low molecular weight organic mono-, di- or tricarboxylic acid. Then ethylene oxide and / or propylene oxide is passed through the reaction mixture. In a preferred embodiment of the present invention, the mono-, di- or tricarboxylic acids are selected from formic acid, acetic acid, propionic acid, glycolic acid, lactic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, malic acid, Tartaric acid, citric acid and / or aconitic acid. According to the invention, the salts of lactic acid to be used, ie the lactates, are of particular importance.

The emulsions to be cleaved by the process according to the invention are, without exception, oil-in-water emulsions, as are obtained, for example, when processing metallic materials. These emulsions serve to cool the workpieces and tools in metal cutting, for example when cutting, drilling and turning, or to improve the sliding and separating behavior in metal cutting, for example in deep drawing. In this sense, emulsions are processed or, for experimental purposes, synthetically produced cooling lubricant, deep-drawing, cutting and / or drilling emulsions, emulsion mixtures also falling under the term mentioned. The oil-in-water emulsions described are aqueous systems which can contain up to 10% extraneous oil fractions: However, emulsions in the abovementioned sense also mean the classic alkaline, neutral or acidic degreasing and cleaning baths which: for example in the automotive industry when degreasing or cleaning metal sheets.

The amounts of the compounds of the general formula (I) to be used for the cleavage of oil / water emulsions are less critical. In particular when the method is carried out in accordance with the automatic control in accordance with DE-OS 36 27 199, the concentration to be used results automatically from the method. Preferred in the sense of the present invention, in particular with regard to the introduction of the substances into the environment, is a concentration of the compounds to be used according to the invention of 0.01 to 10% by volume, based on the emulsion to be split.

In this sense, it is particularly preferred to carry out the process for splitting oil / water emulsions, the compounds of the general formula (I) being present in a concentration of 0.05 to 2% by volume, based on the emulsion to be split , starts.

The method according to the invention can in principle be carried out in any temperature range; in which it is possible to mix the compounds of the general formula (I) with the oil-water emulsion. The splitting of the emulsion according to the invention can thus be carried out between the pour point of the emulsion and the boiling point. For the purposes of the present invention, the process is preferably carried out in the range between room temperature and 80 ° C.

Particularly good results are obtained if the cleavage control is carried out automatically in accordance with the method according to DE-OS 36 27 199.

During the splitting of both fresh oil / water emulsions, ie those produced for experimental purposes, and the oil / water emulsions which are produced in practice, an increase in the turbidity of the emulsion occurs when an organic splitter is added. The increase in turbidity is due to the fact that aggregates form between the organic anions of the emulsifier and the preferably cationic polymer ions of the splitter or demulsifier in the split water phase. With further addition of organic cleavage agents, the turbidity rapidly decreases. This is based on coalescing of the oil droplets which are now no longer emulsified in the aqueous phase and the associated decrease in the total number of oil particles.

In a preferred embodiment of the method according to the invention, the result calculated from the ratio of the two measurement signals of two detectors in accordance with DE-OS 3627 199 is used to automatically interrupt the addition of organic splitter. According to the invention, this occurs when the turbidity, which is based on the formation of the aggregates between the emulsifier anion and demulsifier cation, is overlaid by the decrease in the turbidity which is caused by the coalescing of the oil droplets which are no longer emulsified. As a result of the superimposition of the increase in turbidity and the decrease in turbidity, a maximum of turbidity results in practice, which is followed by a first minimum of turbidity when organic splitter is further added. This minimum of turbidity results from the fact that the decrease in turbidity in the emulsion is overlaid by a renewed increase in the turbidity which results from the coalesced oil droplets being re-emulsified, and consequently the number of particles and thus also the measured turbidity increase. Since re-emulsification of the oil droplets is not desired, the addition of the organic splitter must be done before the re-emulsification, i.e. interrupted at the first minimum of the turbidity curve. The amount of splitter added at the time of the measured minimum of turbidity corresponds exactly to the amount of organic splitter required for complete splitting of the emulsion, since at this point the amount of splitter added corresponds to the amount of emulsifier originally present in the emulsion and thus an almost complete splitting of the Emulsion can be achieved.

As stated above, either the ratio of the measurement signals obtained from transmitted light and scattered light can be directly related to this be used to interrupt the addition of organic splitter when the turbidity has reached a first minimum after the maximum.

In a further embodiment of the invention, however, it is also possible to manually interrupt the amount of organic splitter added when the curve written down with the aid of a pen, which shows the course of turbidity as a function of the amount of splitter added, shows a first minimum after the turbidity maximum reached.

The invention is illustrated by the following examples.

The residual oil content in the split water phase served as a guideline for the result of the emulsion splitting achieved. According to DIN 38409 H 17 / H 18, the petroleum-extractable substances (PE) contained in the split water phase were determined. The experimental setup was the following:

A 1 liter beaker was filled with 600 ml of the emulsion to be split and stirred continuously at 500 rpm using a magnetic stirrer. The length of the stir bar was 50 mm.

An immersion concentration meter, model 25/34, from Monitek, was used as the measuring device for measuring the turbidity.

The sensor, type 25 (immersion probe), was attached to a tripod. The immersion depth of the probe was adjusted, ie all measurements were carried out at the same immersion depth of the immersion probe. The opacimeter was connected to a recorder to record the measured values (opacity versus added amount of splitter). With a constant stirring speed of the magnetic stirrer, the respective organic splitter was added dropwise at predetermined time intervals or in a continuous, slow flow.

Samples were taken from the untreated, that is to say not yet split, emulsion and for checking the individual split water phases. In the split water phases, the petroleum ether-soluble fractions (PE) were determined after each 30 min standing time in accordance with the DIN specification given above.

example 1

A mineral oil-containing, water-miscible cooling lubricant emulsion P-3 ultan 94 from the collection container of an automobile factory, which essentially contains mineral oil, corrosion inhibitor, wetting agent, anionic and nonionic surfactants, was split using the test arrangement described above. A compound of the general formula

CH ₃ CH ₃

R- -N - ((CCH ₂ -CH-0) ₂ -H. Lactate "CH ₃

with R = 012/18 - ^^, used.

The data obtained for the cleavage of the oil / water emulsion can be found in Table 1.

Comparative Example 1

In the same way as in Example 1, a mineral oil-containing, water-miscible cooling lubricant emulsion was split with an organic splitter.

Here, a copolymer of dimethylamine and epichlorohydrin with a molecular weight of 0.15. 10 * 5 used, as it is available from the applicant under the name "Ferolin ^R 8686".

The results obtained are shown in Table 1. Comparative Example 2

A mineral oil-containing, water-miscible cooling lubricant emulsion was split using the test arrangement described above in accordance with Example 1. "A copolymer of dimethylamine and epichlorohydrin with a molecular weight of 0.5.10 - was used as the splitter, which is called" Ferolin ^R 18687 "is manufactured by the applicant.

The results obtained are shown in Table 1.

* _ = after 1 h of idle time

Thus, the quality of the split water has been significantly improved when using this splitter, the oil phase is less water than in the comparison.

Example 2

* Comparative measurement of the agent against two organic splitters based on polyamine currently used in the market was carried out on freshly prepared emulsions of commercially available cooling lubricants based on mineral oil. It should be mentioned that fresh emulsions are fundamentally more difficult to split than processed ones. The cleavage was carried out on samples of 1 1 volume at room temperature. The dosing end point was determined automatically in accordance with DE-OS 3627 199.

Table 2

Ex. Dosage KW content of the * assessment (vol.) Cracked water

1 1.50 10 large, rapidly flocculating flake, approx. 20% flotate, slightly clear, approx. 10% flotate divided into 2 phases: upper transparent oil layer, solid, but not tough.

See l 1.50 65 The stirrer speed had to be reduced from 730 rpm to 580 rpm. Chewing gum-like mass stuck to the stirrer and fine, rapidly floating flakes, flotate content <5%, sp. Almost clear, flotate as tough as chewing gum, a stretching mass, almost clear.

See 2 1.50 73 Tough, greasy, very rapidly floating mass, at the dosing point the agitator cone became significantly larger, slightly milky, flotate content approx. 15%, greasy flotate, similar to chewing gum, partly slightly cloudy .

* = KW values minus surfactant content So that the cleavage with the novel agent leads to a broken water phase with very low Mineralölgeh ^'old, who gave the Vor¬ reach sewage limits.

Claims

Patent claims

1. Process for the cleavage of Ö water emulsions, characterized in that one

Compounds of the general formula (I) are used:

in which

R represents a straight-chain or branched-chain alkyl radical having 12 to 18 carbon atoms,

R and R ₂ each independently for one

Are alkyl with 1 to 4 carbon atoms or a hydroxyalkyl with 1 to 4 carbon atoms,

R ^{3 is} H or CH3, n is an integer in the range from 1 to 6 and

X stands for an anion which is selected from the acids hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid or nitric acid or low molecular weight organic mono-, di- or tricarboxylic acids, with the proviso that the ratio of R ³ = CH3 to R ³ = H is at least 3: 1.

2. The method according to claim 1, characterized in that R- and R2 are the same.

3. The method according to claim 2, characterized in that R ¹ and R ^{2 are} CH3.

4. The method according to claims 1 to 3, characterized in that the grouping R ³ for a random or block polymer

- (CH -CH-0) _n sat from ethylene oxide and propylene oxide.

5. Process according to Claims 1 to 4, characterized in that R ^{3 stands} exclusively for CH3.

6. The method according to claims 1 to 5, characterized in that n stands for 1 or 2.

7. The method according to claims 1 to 6, characterized in that X represents an anion from the low molecular weight organic mono-, di- or tricarboxylic acids which are selected from formic acid, acetic acid, propionic acid, glycolic acid, lactic acid, oxalic acid, malonic acid, Succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, malic acid, tartaric acid, citric acid and / or aconitic acid.

8. Process according to Claims 1 to 7, characterized in that the compounds of the general formula (I) are used in a concentration of 0.01 to 10% by volume, based on the emulsion to be split.

9. The method according to claim 8, characterized in that one uses the compounds of general formula (I) in a concentration of 0.05 to 2 vol .-%, based on the emulsion to be split.

10. The method according to claims 1 to 9, characterized in that one carries out the cleavage of the emulsions in the range between room temperature and 80 ° C.