WO1994027702A1

WO1994027702A1 - Method of removing water from enriched oil-in-water emulsions using polyethers

Info

Publication number: WO1994027702A1
Application number: PCT/EP1994/001555
Authority: WO
Inventors: Brigitte Spei; Hermann Jonke
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1993-05-21
Filing date: 1994-05-13
Publication date: 1994-12-08
Also published as: CZ304895A3; EP0699099A1; DE4317045A1; PL311700A1

Abstract

Described is a method of removing water from industrial waste oil in the form of an oil-in-water emulsion containing at least 15 % by wt. of oil using de-emulsifying agents selected from the group comprising polymers of ethylene oxide and/or 1,2-propylene oxide and obtained by the ethoxylation and/or propoxylation of alcohols or amines having up to 10 carbon atoms in the molecule.

Description

"Process for Dewatering Enriched Oil-in-Water Emulsions Using Polyether Compounds"

The invention relates to a method for dewatering technical waste oil, which is an oil-in-water emulsion which consists of at least 15% by weight of oil. Such emulsions are obtained when working up used technical oil-in-water emulsions, for example by creaming in a mechanical separator or by enrichment using membrane filtration processes.

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 approx. 1 - 5% due to the oil they enter during operation and which have to be continuously de-oiled and / or discarded at the end of their useful life. Waste emulsions of the type mentioned are oil-in-water emulsions. The processing and disposal can begin by concentrating into a water-rich and an oil-rich phase.

Such a phase separation takes place, for example, in mechanical separation devices 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. The processing of waste emulsions often also begins by subjecting the emulsion to primary cleavage with chemical emulsion splitters. Either strong acids, inorganic salts and / or organic emulsion breakers come into consideration for chemical emulsion splitting. The oil phase separated during chemical primary splitting is generally present as a water-in-oil emulsion. The further dewatering of water-in-oil emulsions is not the subject of this invention.

In cases of physical pre-splitting by gravitation or membrane filtration, an oil-rich oil-in-water emulsion is present. If you want to work up, deposit or burn this emulsion, the residual water content proves to be a hindrance or at least a cost driver. It is therefore generally advantageous to further free this emulsion from water by secondary cleavage. Emulsion splitters (= demulsifiers) are known in large numbers in the prior art. Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume 9, states on pp. 311/312: "The number of emulsion-splitting substances ... is approximately the same as the number of emulsifiers ... ... adding one cationic compound to an emulsion stabilized with an anionic emulsifier usually causes rapid cleavage. "

DE-A-32 14 145, which describes special polyalkyloxyamines as demulsifiers, teaches: "The demulsifiers according to the prior art largely consist of mixtures of ionic and non-ionic surface-active agents which, after addition to an emulsion, contain their hydrophilic-lipophilic agents Change equilibrium (HLB), and the correct setting of this parameter usually leads to demulsification. "

Since emulsions are generally stabilized in very different ways, the most suitable emulsifiers are to be selected from a large number of possible agents. The present invention is specifically concerned with the further dewatering of oil-rich (oil content> 15%) oil-in-water emulsions which were obtained by preconcentration of more dilute technical waste emulsions of the type mentioned at the beginning, which were brought about by physical means.

US-A-4 029 708 mentions reagents which are suitable for cleaving both oil-in-water and water-in-oil emulsions. These are polymers which are formed by reacting a substituted amine with a bifunctional reactant. The substituted amines are alkoxylation products of organic di- or triamines or reaction products of these amines with epichlorohydrin or with alkyl or aryl chlorides. The bifunctional reactants include glycol adducts of epichlorohydrin, epichlorohydrin itself, ethylene dichloride, dichlorobutene, diepoxides, maleic anhydride, maleic acid, acrylic acid and alkyl chloride. According to the proposal of DE-A-40 40 022, technical water-in-oil emulsions are dewatered, which are the oil phase of a primarily split oil-in-water emulsion, in that

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 diols crosslinked with diisocyanates, dicarboxylic acids, formaldehyde and / or diglycidyl ether / or uses alkylbenzenesulfonic acid salts 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 the dewatering of 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 of Membrane filtration processes may arise.

Since emulsions are generally stabilized by very different stabilizer systems and, in particular, the task of further dewatering technical oil-in-water emulsions concentrated with physical means arises, there is a need for more widely applicable dewatering agents which can be used suitable for oil-in-water emulsions with oil contents of more than 15% by weight. It is the object of the present invention to provide such drainage means.

According to the invention, this object is achieved by a

Process for dewatering technical waste oils which are oil-in-water emulsions with an oil content of greater than 15% by weight, characterized in that one or more polyether compounds from the group Polymers made from ethylene oxide and / or 1,2-propylene oxide, obtainable by ethoxylation and / or propoxylation of alcohols or amines, each having up to 10 carbon atoms in the molecule

distributed in the emulsion and phase separation.

The product groups mentioned are known as such, for example from DE-A-4040022.

Polymers of ethylene and / or 1,2-propylene oxide suitable for the process according to the invention can be obtained, for example, by polyalkoxylation of lower alcohols, such as methanol, ethanol, propanols, butanols, pentanols or hexanols, with ethylene and / or 1,2-propylene oxide receive. Suitable alcohols here are also diols and polyols, e.g. B. propanediols, butanediols, neopentyl glycol, other pentanediols, adipol, hexanediols, cyclohexanediols, 1,4-dihydroxyethylcyclohexane, perhydrobisphenol A, glycerol, trimethylolethane, triethylolpropane, other hexanetriols and pentaerythritol. Lower amines, e.g. B. Ethylene diamine and diethylene triamine can be polyoxyalkylated with ethylene oxide and / or 1,2-propylene oxide to obtain polymers suitable for the present invention. Both block polymers and polymers with a static distribution of different oxyalkyl groups, so-called mixed polymers, or else mixed forms of these two possibilities can be used according to the invention.

In preferred embodiments, the invention includes

Process, characterized in that the polyether compounds are selected from alkoxylation products containing on average 20 to 100 mol of ethylene oxide or propylene oxide or 10 to 40 mol of ethylene oxide and 20 to 50 mol of propylene oxide, Process, characterized in that the polyether compounds are selected from alkoxylation products with first 10 to 40 mol ethylene oxide and then with 20 to 50 mol propylene oxide, the number of propylene oxide groups preferably exceeding the number of ethylene oxide groups,

Process, characterized in that the polyether compounds are selected from alkoxylation products of alcohols and / or amines with one to 5 carbon atoms and with one to four amino or hydroxyl groups, each carbon atom carrying at most one hydroxyl or amino group,

Process, characterized in that the polyether compounds are selected from alkoxylation products of alcohols having one to 4 carbon atoms and with one or two hydroxyl groups, preferably alkoxylation products of propylene glycol.

The ethoxylation and / or propoxylation products can be present with normal or with a so-called "narrowed" homolog distribution.

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, on the degree of distribution of the emulsion and on the type and amount of 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 in favorable cases, the dewatering means can be recognized by a change in the optical appearance of the emulsion to be dewatered. The power consumption of the agitator, which has a minimum in the optimal metering, can also provide an indication of reaching the metering end point. In the general case, however, it is preferable to determine the end point of the metering by means of viscosity measurements. The viscosity of the emulsion to be dewatered is at a minimum when the dosing agent is optimally dosed. 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.

The temperature of the emulsion to be dewatered will, on the one hand, be chosen to be as close as possible to room temperature for reasons of energy saving, and on the other hand it 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 into a water-rich phase and into 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 and of comparison substances was checked on mixed emulsions from used cooling lubricant emulsions and used cleaning and degreasing baths of the automotive industry. The exact composition of these mixing emulsions originating 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 by ultrafiltration through polyvinylidene difluoride chemicals (retentates I and II). "Waste oils" I and II were obtained by mechanical separation of the mixed emulsions in oil separators.

The waste oils or reference substances according to Table 1 were added to the waste oils or 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 the dewatering agents had been stirred in, the samples were either left to stand for 24 hours or centrifuged with a laboratory centrifuge 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 1. The oil phase was generally subordinate to a mixed phase and / or a water phase, which in practical cases may have to be processed further, for example by returning it to the oil separator or to the membrane filtration. Before draining 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 1, ie left to stand or centrifuged at the temperatures indicated. In no case was an oil-rich upper phase separated by more than 5%.

Table 1: Drainage results

Example water sample, dosing, temperature, phase separation, water content. Oil phase

No. Content serum quantity ( ^β C)% oil phase after (wt .-% after

(% By weight) medium ¹ ) (ppm) are centrifuged for 24 h. 24 are centrifuged.

1 retentate I 69 a 24000 20 25 22

2 retentate I 69 a2) 21000 20 35 35 6.4 9.6

3 Retentate II 44 a 12000 60 55 4.9

4 "waste oil" I 19 b 40,000 80 35 3.7

5 "waste oil" II 27 a 15000 80 40 0.6 2.6

Cf. l retentate I 69 c 50000 20 none 1 - 2 - not best.

See 2 "used oil" I 19 d 50000 80 5 12

!) a) Propylene glycol + 19 ethylene oxide + 35 propylene oxide b) Propylene glycol + 36 ethylene oxide + 40 propylene oxide c) Comparative product: propylene glycol + 7 ethylene oxide + 12 propylene oxide d) Comparative product: propylene glycol + 15 ethylene oxide + 17 propylene oxide

2) first mixed with 2000 ppm of a quaternary polyamine of the formula [CH2 - CH (OH) - CH2 - N (CH3) 2] $ (Cl-) _y , average molecular weight 200,000, then with dehydrating agent a.

Claims

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

Polymers made from ethylene oxide and / or 1,2-propylene oxide, obtainable by ethoxylation and / or propoxylation of alcohols or amines each having up to 10 carbon atoms in the molecule

distributed in the emulsion and phase separation.

2. The method according to claim 1, characterized in that the polyether compounds are selected from alkoxylation products containing on average 20 to 100 mol of ethylene oxide or propylene oxide or 10 to 40 mol of ethylene oxide and 20 to 50 mol of propylene oxide.

3. The method according to claim 2, characterized in that the polyether compounds are selected from alkoxylation products with first 10 to 40 mol of ethylene oxide and then with 20 to 50 mol of propylene oxide, the number of propylene oxide groups preferably exceeding the number of ethylene oxide groups.

4. The method according to one or more of claims 1 to 3, da¬ characterized in that the polyether compounds are selected from alkoxylation products of alcohols and / or amines with one to 5 carbon atoms and with one to four amino or hydroxyl groups, each carbon atom carrying at most one hydroxyl or amino group.

5. The method according to claim 4, characterized in that the polyether compounds are selected from alkoxylation products of alcohols having one to 4 carbon atoms and with one or two hydroxyl groups, preferably alkoxylation products of propylene glycol.

6. The method according to one or more of claims 1 to 5, characterized in that the industrial waste oils are retentates from a micro- or ultrafiltration.

7. The method according to one or more of claims 1 to 5, characterized in that the technical waste oils are used oils which were obtained by creaming in a mechanical separating device.

8. The method according to one or more of claims 1 to 7, characterized in that after mixing the drainage agent with the emulsion, a phase separation is carried out by centrifugation.