EP0699098A1

EP0699098A1 - Method of removing water from waste oil using surface-active compounds

Info

Publication number: EP0699098A1
Application number: EP94916960A
Authority: EP
Inventors: Brigitte Spei; Hermann Jonke
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1993-05-21
Filing date: 1994-05-13
Publication date: 1996-03-06
Also published as: DE4317046A1; CZ306595A3; PL311699A1; WO1994027701A1

Abstract

Described is a method of removing water from waste oil consisting of either an oil-in-water or a water-in-oil emulsion using compounds selected from (A) the group comprising alkoxylation products of fatty alcohols and corresponding amines with 8 to 22 C-atoms and/or (B) the group comprising aliphatic monoalkylsulphates and monoalkylsulphonates with 8 to 22 C-atoms and subsequently separating the two phases.

Description

"Process for the drainage of waste oil using surface-active compounds

The invention relates to a process for the dewatering of technical waste oil, which is either an oil-in-water emulsion or a water-in-oil emulsion and which in each case consists of at least 15% oil. Such emulsions are obtained in the processing of technical oil-in-water emulsions, for example by creaming in a mechanical separator, by enrichment using membrane filtration processes or as a result of primary cleavage.

Used and disposed oil-in-water emulsions occur in large quantities in the metalworking industry. One source of this are cooling lubricant emulsions, which are used in metal cutting and which have an oil content of about 2 - 5%. Even if such emulsions can be used for a long time - up to several months - they are finally used up and must be disposed of. Another source of waste emulsions are, for example, technical degreasing and cleaning baths, which build up an oil content of about 1 - 5% due to the oil they enter and which have to be continuously de-oiled and / or discarded at the end of their useful life. Waste emulsions of mentioned type are oil-in-water emulsions. The processing and disposal generally begins by carrying out a concentration or primary cleavage into a water-rich and an oil-rich phase.

Such phase separation takes place, for example, in mechanical separators of sewage plants by the action of gravity, an "old oil" in the form of an oil-rich oil-in-water emulsion with an oil content of more than 15% by weight. A further possibility of a primary separation consists in subjecting the emulsion to membrane filtration, for example micro- or ultrafiltration, and splitting it into an oil-rich retentate with an oil content of more than 15% by weight and into a practically oil-free permeate. In both of these cases, an oil-rich oil-in-water emulsion is present after the first separation step.

The primary fission can, as described in DE-A-41 26 914, be carried out by an electrolytic charge neutralization of the oil droplets. Thermal splitting by heating the waste emulsion is also possible, but is not very common due to the high energy requirement. The processing of waste emulsions often begins by subjecting the emulsion to primary splitting with chemical emulsion splitters. Either strong acids, inorganic salts and / or organic emulsion breakers can be considered for chemical emulsion breakdown. The organic emulsion breakers, which often consist of cationic polymers, have the great advantage that they remain in the oil phase during the breakdown and therefore do not contribute to further contamination of the water phase and do not produce any additional sludge. Emulsion splitters for such primary cleavage are known in large numbers in the prior art, for example DE-A-40 09 760 mentions synthetic polymers based on polyimines, polyether polyamines, polyamines and polyamide amines or quaternized polyamines and quaternized polyamide amines, furthermore cationic copolymers of acrylamide and different proportions of cationic monomers or oligomers and homopolymers of dimethyldiallylammonium chloride. Organic cationic emulsion breakers based on polyamines, polyimines, polyether polyamines and polyamide amines have proven particularly useful.

DE-A-40 09 760 describes a two-stage process for the primary splitting of an oil-in-water emulsion using both inorganic and organic emulsion splitters. The emulsions to be split primarily are mixed with an organic cationic emulsion splitter of the type mentioned above and then with an inorganic emulsion splitter based on salts of polyvalent metals, in particular aluminum, iron and calcium. After the creaming oil phase has been separated off, the water phase, which still has a low residual hydrocarbon content, is subjected to a second cleavage step with a further inorganic emulsion splitter followed by an organic anionic emulsion splitter.

The oil phase separated in a chemical primary fission is usually in the form of a water-in-oil emulsion with an oil content of more than 15% by weight. If you want to process, deposit or incinerate this water-in-oil emulsion that arises during the primary splitting, the residual water content proves to be a hindrance or at least to drive costs. It is therefore generally advantageous to further rid this emulsion of water by secondary cleavage. The task this poses further dewatering is related to the problem of dewatering crude oil emulsions that occur during oil production either directly or as a result of tenside-assisted tertiary production. As DE-A-40 40 022 explains, the secondary splitting of technical waste oil to be carried out according to the task cannot be compared with the splitting of a crude oil emulsion. This is due to the fact that the stabilizers of the emulsions show very large differences in the two cases. Findings from the splitting of crude oil emulsions can therefore only be applied to a very limited extent to the splitting of technical waste oil emulsions. According to the proposal of DE-A-40 40 022, technical water-in-oil emulsions, which are the oil phase of a primarily split oil-in-water emulsion, are dewatered by using polymers and / or oligomers from ethylene oxide and / or 1,2-propylene oxide, oxalkylated phenolic resins, block or mixed polymers of ethylene and 1,2-propylene oxide, polyether urethanes and / or alkylbenzenesulfonic acid salts crosslinked with diisocyanates, dicarboxylic acids, formaldehyde and / or diglycidyl ether, are used as splitters. This teaching is limited to the splitting of water-in-oil emulsions. There are no indications that the secondary splitters mentioned can also be used for dewatering oil-rich oil-in-water emulsions with oil contents of more than 15% by weight, such as those in the form of "waste oils" or as Retentates from membrane filtration processes may arise.

On the one hand, since the water-in-oil emulsions that occur during primary splitting are generally stabilized by very different stabilizer systems and, on the other hand, there is also the task of further dewatering concentrated oil-in-water emulsions, there is a need for more widely applicable ones Dewatering agents that are suitable for different stabilizer systems and both for water-in-oil emulsions and for oil-in Water emulsions with oil contents of more than 15% by weight are suitable. It is the object of the present invention to provide such broadly applicable drainage agents.

According to the invention, this object is achieved by a

Process for the dewatering of waste oils which are water-in-oil emulsions or oil-in-water emulsions with an oil content of more than 15% by weight, characterized in that one or more surface-active compounds from the groups

A) alkoxylation products of fatty alcohols or fatty amines with 8 to 22 carbon atoms,

B) Aliphatic monoalkyl sulfates or sulfonates with 8 to 22 carbon atoms, distributed in the emulsion and phase separation.

The product groups mentioned under A) and B) are known as such. In preferred embodiments, the invention relates

Processes in which the compounds from group A) are selected from ethoxylation products of fatty amines or fatty alcohols with 10 to 18, preferably 12 to 16 carbon atoms with 5 to 29 moles of ethylene oxide and from ethoxylation / propoxylation products of fatty amines or fatty alcohols with 10 to 18, preferably 10 to 16 carbon atoms with 4 to 10 moles of ethylene oxide followed by 1 to 4 moles of propylene oxide, the fatty alcohols or fatty amines preferably being saturated compounds and product mixtures obtained from natural fats and oils are, and the alkylene oxide chains are available with conventional or with narrow homolog distribution, and

Processes in which the compounds from group B) are selected from saturated alkyl sulfates or sulfonates, preferably alkyl sulfates, having 10 to 16 carbon atoms, these in the form of their alkali metal, ammonium, alkylammonium or alkanolammonium salts, preferably as lithium -, Sodium, ammonium and / or triethanolammonium salts can be used. Lithium and / or triethanolammonium salts are particularly preferred.

The most suitable drainage agent or its combinations for a given drainage task, as well as their optimal concentrations, must be determined on a sample-specific basis. They depend on the water content of the samples, the degree of distribution of the emulsion, and the type and amount of the stabilizers present. In general, amounts between 5 ppm and 60,000 ppm, based on the total amount of the liquid to be dewatered, are effective. It is preferred to work in the concentration range between 100 ppm and 30,000 ppm. The dosing end point for the dewatering agents can be recognized in favorable cases by a change in the optical appearance of the emulsion to be dewatered. The power consumption of the agitator, which has a minimum with the optimal dosing, can also provide an indication of reaching the dosing end point. In the general case, however, it is preferable to determine the end point of the dosage by viscosity measurements. The viscosity of the emulsion to be dewatered indicates the optimal dosing of the dewatering agent Minimum on. It does not matter which of the known methods is used to determine the viscosity. For reasons of easy handling, the Brookfield viscosity determination is preferably used.

In special cases, it may be advantageous to combine the dewatering agents according to the invention with further dewatering agents, the dewatering agents from the individual groups being added to the emulsion to be dewatered simultaneously or preferably in succession. For example, the drainage agents from group A) can be combined with N-alkylpyridinium salts with an alkyl substituent with 10 to 16 C atoms, trimethylalkylammonium salts with an alkyl radical with 10 to 18 C atoms, dimethylbenzylalkylammonium salts with an alkyl radical with 10 to 16 C atoms, Dimethyldialkylammonium salts with two identical or different alkyl radicals, each with 6 to 12 C atoms, and dimethylalkylammonium betaines with an alkyl radical with 8 to 18 C atoms, and / or with polymers with the assemblies

and or

where X ^{n- is} a single, double or triple negatively charged preferably inorganic anion, in particular Cl, hydrogen sulfate, sulfate, phosphate or mono- or dihydrogen phosphate.

Furthermore, the drainage agents of group (s) A) and / or B) can be combined with the agents described in DE-A-4040022: polymers and / or oligomers of ethylene oxide and / or 1,2-propylene oxide, oxyalkylated phenolic resins, with Diisocyanates, dicarboxylic acids, formaldehyde and / or diglycidyl ether crosslinked block or mixed polymers of ethylene and 1,2-propylene oxide, polyether urethanes and / or alkylbenzenesulfonic acid salts.

On the one hand, the temperature of the emulsion to be dewatered is chosen to be as close as possible to room temperature for energy-saving reasons, on the other hand, one is dependent on a sufficiently low viscosity. In general, dewatering will be carried out at temperatures between 15 and 95 ° C, preferably between 20 and 80 ° C.

To carry out the process, the dewatering agents are uniformly distributed in the emulsion by methods well known to the person skilled in the art, for example by stirring. The separation of the Emulsion in a water-rich phase and in a dewatered oil phase can take place under the influence of natural gravity in suitable sedimentation containers. The efficiency of phase separation can be increased by using a continuous or batch centrifuge. If the emulsion to be dewatered still contains sedimentable solids, it is advisable to separate it before carrying out the dewatering, for example by sedimentation, filtration or by centrifugation.

Examples

Execution examples

The dewatering effect of the products according to the invention according to Table 1 and of comparison substances according to Table 2 was checked on mixed emulsions from used cooling lubricant emulsions and used cleaning and degreasing baths in the automotive industry. The exact composition of these mixed emulsions from manufacturing practice was not known. It is essential to the invention that after the primary separation they had an oil content> 15% by weight. The primary separation of the emulsions was carried out either by chemical emulsion splitting or by ultrafiltration. The flotates or retentates obtained in this way were used for the tests according to Tables 3 and 4. Flotates I to III were obtained by primary cleavage with polydiallyldimethylammonium chloride, Flotate IV and V by primary cleavage with a cationically modified polyamine. Retentate I was obtained during the ultrafiltration of the primary mixed emulsions through polyvinylidene difluoride membranes. Waste oils were obtained by mechanical separation of the mixed emulsions in oil separators.

The waste oils or comparative substances according to Tables 3 and 4 were added to the waste oils, flotates and retentates. For this purpose, the samples were stirred with a grid stirrer, the dewatering products were added and, after the product had been added, stirring was continued for 5 minutes. The end point of the product addition was determined either via the current consumption of the stirrer, a viscosity measurement or after the optical change of the samples. After stirring in the dewatering agents, the samples were either left to stand for 24 hours or with a laboratory centrifuge for one Centrifuged for 5 minutes at a speed of 4000 revolutions per minute. The volume fraction of the oil phase separating hereby was determined. It is included in Table 3. The oil phase was generally subordinate to a mixed phase and / or a water phase, which in practical cases may have to be subjected to further workup, for example by recycling to the primary cleavage or to the membrane filtration. Before the dewatering step, the water content of the samples was determined. The water content of the oil phase obtained after dewatering was also determined. The water contents were determined by evaporating a 10 g sample of the samples to constant weight by the action of microwaves.

For comparison, all samples were treated physically without the addition of dewatering agents in accordance with Table 3, ie left to stand at the specified temperatures or centrifuged. In no case was an oil-rich upper phase separated by more than 5%.

Table 1: Dewatering agents according to the invention

Group A

a) C ₈ -C ₁₈ alkylamine (= cocoalkylamine) + 10 E0

b) C ₈ -C ₁₈ alkylamine (= cocoalkylamine) + 12 E0

c) C ₈ -C ₁₈ alkylamine (= cocoalkylamine) + 25 E0

d) C ₁₀ -C ₁₄ fatty alcohol + 6.4 E0 + 1.2 P0

e) C ₁₀ -C ₁₄ fatty alcohol + 5 E0 + 4 P0

Group B

k) lithium lauryl sulfate

l) triethanolammonium lauryl sulfate

Table 2: Vero calibration substances

No substance vol. With

V1 C ₈ -C ₁₈ alkylamine (= cocoalkylamine) + 2 E0 a, b

V2 C ₁₂ -C ₁₄ fatty alcohol + 3 E0 + 6 P0 d, e

V3 C ₁₂ -C ₁₄ fatty alcohol + 2.5 E0 d, e

V4 Na-p-toluenesulfonate k

1) Sample first mixed with 400 ppm alkaline gluconate solution, then with drainage agent a

2) First add 1000 ppm of agent o to the sample, centrifuge, then add agent a and let it stand for 24 h

Medium o: polymer with assemblies according to formula (II), X = Cl, molar mass 200000, 20% by weight solution in

water

Claims

1. Process for the dewatering of waste oils which are water-in-oil emulsions or oil-in-water emulsions with an oil content of more than 15% by weight, characterized in that one or more surface-active compounds from the groups

B) Aliphatic monoalkyl sulfates or sulfonates with 8 to 22 carbon atoms distributed in the emulsion and phase separation.

2. The method according to claim 1, characterized in that the compounds from group A) are selected from ethoxylation products of fatty amines or fatty alcohols with 10 to 18, preferably 12 to 16 carbon atoms with 5 to 29 moles of ethylene oxide and from ethoxylation / propoxylation products of fatty amines or fatty alcohols with 10 to 18, preferably 10 to 16, carbon atoms with 4 to 10 moles of ethylene oxide followed by 1 to 4 moles of propylene oxide, the fatty alcohols or fatty amines preferably being saturated compounds and product mixtures as described in natural fats and oils are obtained, and the alkylene oxide chains are present with conventional or with narrowed homolog distribution.

3. The method according to one or both of claims 1 and 2, characterized in that the compounds from group B) are selected from saturated alkyl sulfates or sulfonates, preferably alkyl sulfates, having 10 to 16 carbon atoms and in the form their alkali, ammonium, alkylammonium or alkanolammonium salts, preferably as lithium, sodium, ammonium and / or triethanolammonium salts and in particular as lithium and / or triethanolammonium salts.

4. The method according to one or more of claims 1 to 3, characterized in that the dewatering agents from group A) combined with N-alkylpyridinium salts with an alkyl substituent with 10 to 16 carbon atoms, trimethylalkylammonium salts with an alkyl radical with 10 to 18 C. -Atoms, dimethylbenzylalkylammonium salts with an alkyl radical with 10 to 16 carbon atoms, dimethyldialkylammonium salts with two identical or different alkyl radicals with 6 to 12 carbon atoms each, and dimethylalkylammonium betaines with an alkyl radical with 8 to 18 carbon atoms.

5. The method according to one or more of claims 1 to 4, characterized in that the drainage agents from group A) combined with polymers with the assemblies

and or

6. The method according to one or more of claims 1 to 3, characterized in that the dewatering agents from groups A) and / or B) combined with agents from the group of polymers and / or oligomers of ethylene oxide and / or 1,2 - Propylene oxide, oxyalkylated phenolic resins, block or mixed polymers of ethylene and 1,2-propylene oxide, polyether urethanes and / or alkylbenzenesulfonic acid salts crosslinked with diisocyanates, dicarboxylic acids, formaldehyde and / or diglycidyl ether.

7. The method according to one or more of claims 1 to 6, characterized in that the dewatering agent is used in total concentrations between 5 ppm and 60,000 ppm, preferably between 100 ppm and 30,000 ppm, based on the total amount of the liquid to be dewatered.

8. The method according to one or more of claims 1 to 7, characterized in that the dewatering at temperatures between 15 and 95 ° C, preferably between 20 and 80 ° C.

9. The method according to one or more of claims 1 to 8, characterized in that the waste oil to be dewatered is a water-in-oil emulsion which was obtained by primary cleavage of an oil-in-water emulsion.

10. The method according to one or more of claims 1 to 8, characterized in that it is an oil-in-water emulsion in the waste oil to be dewatered.

11. The method according to claim 9 or 10, characterized in that one carries out a phase separation by centrifugation after mixing the dewatering agent with the emulsion.