DK156543B - MATERIALS CONTAINING SURFACE ACTIVE SUBSTANCE AND SOLVENTS FOR DISPERSING OIL PLATES - Google Patents

Description

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DK 156543 B

The invention relates to a material containing surfactant and a solvent for dispersing oil stains.

5 Contamination of seawater by oils (crude oil or fractions of crude oil) caused by accidents, drilling in the seabed, emptying of ballast water or discharges from oil tankers, results in the formation of a continuous oil membrane or stain which is said to spread evenly . This oil membrane is indispensable because it presents a barrier to the transport of air and light from the atmosphere which is indispensable for the maintenance of marine life.

One method of eliminating such contamination consists in the use of oil-collecting preparations. They are poured on the edge of the oil stain and repel the oil, which is thus collected in a smaller area and can be removed by conventional mechanical means. However, this contraction of an oil stain is only possible in the case of a relatively calm SO. Furthermore, the 20 preparations are effective only for a very short time due to their solubility in the oil.

Another method consists in the use of surfactants which probe the cohesive oily membrane into small droplets which are dispersed in the water in the form of a several meters deep water column below the surface. The membrane is thus broken and transport of air again. and light from the atmosphere.

Some surfactants are highly effective in dispersing oil stains, but their use has caused serious damage to marine life because they are too toxic to aquatic flora and fauna. Other less toxic surfactants are often ineffective as oil dispersants in the high seas. Namely, the water 35 leaches them too quickly from the oil stain on which they are sprayed, so that the oil droplets stick together or react - 2 -

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glomers and again forms an oil stain.

For this reason, surfactants are usually used in conjunction with a solvent, especially a low-toxicity solvent such as paraffinic and cycloparaffinic hydrocarbons and lower alcohols. The use of a solvent provides many advantages: The solvent lowers the flow point of the composition. It reduces the viscosity of the oil in the oil stain, it acts as a diluent 10 for the surfactant which is distributed more easily and more uniformly in the oil stain, and it reduces the time required for mixing the dispersant with the oil.

Another problem that arises from the use of surfactants as dispersants for oil spills is their water solubility. Some of these agents dissolve too quickly in water and thus do not penetrate the oil stain. For this reason, it has been proposed to use dispersants containing at least two surfactants. 20 better dispersion is obtained by the use of surfactant mixtures, the proportions of which are chosen such that the hydrophilic-lipophilic balance (HLB) fades between certain boundaries.

Therefore, the trend is towards using surfactant mixtures in admixture with a solvent. British Patent No. 1,404,684 discloses such a composition wherein the oil dispersant comprises a mixture of fatty acids and polyoxyalkylene glycol esters and fatty acids and sorbitan esters (HLB of the mixture: 9-10.5) dissolved in a hydrocarbon solvent. containing less than 3% by weight of aromatic compounds. The solution may contain 5-50% by weight of the surfactant mixture, with an amount of 8-10% by weight being particularly preferred. André 35 patents disclose the use of compositions containing a monoester between a fatty acid and sorbitan and a polyalkylene oxide adduct of a monoester of a fatty acid and sorbitan - 3 -

DK 156543 B

(U.S. Patent No. 1,255,394) or containing these compounds in admixture with 25-35% by volume (excluding the solvent) of a 75% aqueous solution of dialkylsulfosuccinate salt (U.S. Pat.

5 3,793,218). Reference must also be made to German Patent Specification 20 18 798, German Patent Specification 21 60 698, which discloses the use of 50-95% by weight of hydrocarbons together with the surfactants, while according to GB patent 1,557,182 more concentrated materials containing 40-80% by weight of dispersant and ethers instead of hydrocarbon. The best results in dispersing oil stains are obtained by preparations containing approx. 40% of a mixture of surfactants and approx. 60% of an isoparaffinic hydrocarbon solvent.

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The use of a solvent presents the above-mentioned advantages, but some problems may arise when diluent mixtures are diluted with large amounts of solvent. Storage of preparations containing volatile solvents may increase the risk of fire and lead to explosions.

The presence of a large amount of solvent in a composition means that there is a smaller amount of surfactant available to disperse the oil stain. In addition, some volatile constituents of the solvent 25 may be lost by evaporation when the composition is used for spraying on the oil stain, particularly when the composition is applied from an airplane or from a large distance boat, and the advantages of incorporating a solvent into the composition are lost. lost.

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To be effective in dispersing oil stains, a material in the form of a solution of surfactants must meet the following conditions: it must have a high content of active substances, 35 - it must have a sufficient and long-lasting dispersion effect, it must be manageable at low temperatures and high - 4 -

DK 156543 B

an appropriate viscosity which allows the preparation to be sprayed from either the boat or from the fly ash without any increase in viscosity due to evaporation of volatile solvent under the feed, it must be a homogeneous and clear liquid which is free of insoluble material and of cloudiness, it must have a flash point above 61 ° C so that it complies with the regulations on the handling of chemicals, it must be non-toxic and biodegradable, and it must be light and inexpensive to manufacture.

The object of the present invention is to provide a material which meets the above conditions.

This is achieved according to the invention in that the material is composed as defined in claim 11 s.

Advantageous embodiments are given in claims 2-10.

The sorbitan monoester of a fatty acid is usually an ester of an aliphatic monocarboxylic acid containing 10-20 carbon atoms such as oleic acid, lauric acid, palmitic acid or stearic acid or a mixture of these acids.

The polyalkylene oxide adduct is obtained by reacting a sorbitan monester of a fatty acid with ethylene oxide and / or propylene oxide. Usually, the adduct contains 12-15 oxyethylene units 30 or 6-12 oxypropylene units per unit. molecule.

The selection of these surfactants depends on their availability, price and purity. Usually, the preferred substances are sorbitan monooleate and its polyethylene oxide product containing an average of approx. 20 oxyethylene units per

molecule.

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DK 156543 B

The third component of the surfactant mixture is an alkali metal salt of a dialkyl sulfosuccinate, in particular the sodium salt of di- (2-ethylhexyl) sulfosuccinate, which is usually commercially available in the form of a 75% by weight aqueous solution.

The mixture of these surfactants has a HLB value of 9-10.5, especially 9.4-10.5.

The solvent for the surfactant mixture is a mixture of water and a monoalkyl glycol ether wherein the alkyl group contains 1-4 carbon atoms. Suitable glycol ethers are ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether and dipropylene glycol monomethyl ether.

It has been found that dispersing materials containing 65-75% by weight of a mixture of the above surfactants, while the remainder consists of the solvent mixture, have particularly advantageous properties when the mixture (as a mixture) contains 35-40% by weight of succi night and the composition contains at least 20% water based on the total weight of the preparation. The total amount of water in the preparation should not exceed approx. 27.5%.

When a hydrocarbon solvent is used in place of the aqueous solvent mixture or mixed with the aqueous solvent, the resultant composition is usually unclear and exhibits poorer oil dispersion efficiency.

The material of the invention may also contain a number of optional ingredients such as nutrients, corrosion preventants and other normal additives. Eg. it may be advantageous to add a floating point reducing agent such as diethylene glycol in an amount which normally does not exceed 5% of the total weight of the composition.

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The effectiveness of the dispersants has been investigated using the method of the Warren Spring Laboratory (Department of Trade and Industry, Stevenage, Herfordshire). In this test, the material is added dropwise 5 to a metered amount of oil which floats on the surface of a column of seawater in a separating funnel. The funnel is then shaken to disperse the oil. The amount of oil which has been dispersed in the water column is determined after leaving the water column for a certain period of time. The efficiency of a material is expressed by the percentage of the oil which has been dispersed in the aqueous phase.

The test results in the following examples illustrate the compositions of the invention. Unless otherwise indicated, 15 percent is expressed as weight percent.

The following abbreviations are used in the examples: DOSS = sodium salt of di- (2-ethylhexyl) sulfosuccinate EGBE = ethylene glycol monobutyl ether 20 SMO = sorbitan monooleate SMOE = ethoxylated sorbitan monooleate (about 20 moles ethylene oxide) DEG = diethylene glycol.

Example 1

A mixture of surfactants is prepared from SMO, SMOE and 75% aqueous solution of DOSS. The weight percentages of these constituents (based on dry constituents) are 30 and 34.5 for SMO, 28.3 for SMOE and 37.2 for DOSS, respectively. The HLB value of this mixture is 9.44.

A solvent mixture is prepared from water (48.2%) and EGBE (51.8%).

A composition containing 70.1% of this mixture of surfactants and 29.9% of this 35 - 7 -

DK 156543 B

solvent mixture has an efficiency of 79.0%.

The total water content of the material (water in the aqueous solution of DOSS plus water in the solvent) is 22.15%, 5 on the basis of the weight of the material.

For comparison purposes, the following materials are also manufactured:

10 Comparative Material A

64% of the above surfactant mixture is dissolved in 36% of the above solvent mixture. The efficiency of Comparative Material A is only 71.3%.

This comparison shows that a material containing less than 65% of the surfactant mixture is less effective. This means that the mixture according to the invention does not require a large amount of aqueous solvent according to the invention for easy penetration into and dispersion of the oil stain.

Comparative material B

This material is prepared by mixing 74.25% of a mixture containing 38.5% SMO, 31.5% SMOE and 30% DOSS with 25.75% of the solvent mixture described above.

The efficiency of comparator B is only 53.4%.

This comparison shows that a material made from a mixture of surfactants containing 30 less than 35% DOSS is less effective.

Comparative material C

This material is prepared by mixing 75% of a mixture containing 32.5% SMO, 26.6% SMOE and 40.0% DOSS

with 25% of a solvent mixture containing 37.5% water and 62.5% EGBE. The total amount of water in this

DK 156543 B

- 8 - material is less than 20% on the basis of the total weight of the material. The efficiency of comparator C is only 41.3%.

Example 2

This example also illustrates the unexpected benefit obtained by using a material containing at least 20% water based on the total weight of the material.

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A material is prepared from the following ingredients: SMO: 23.1% SMOE: 18.9% DOSS (75% rs aqueous solution): 32.15% (24.11% of tort DOSS + 8.04% H2 O) H 2 O: 12.85% EGBE: 13.0% 20 The HLB value of this material is 9.44. The percentage of tort DOSS in the surfactant mixture is 36.46% and the total water content of the entire material is 20.89%. To this mixture is added 3% DEG. The material is clear and its cloud point is -22 ° C.

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By comparison, the same material is made, but with the difference that the amount of water based on the total weight of the preparation is only 16%. Despite the addition of DEG, the material is cloudy at 20 ° C.

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Example 3

The following materials (see table) are prepared and their main properties determined.

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DK 156543 B

- 9 -Table

Ingredients Material 1 2 3 5 SMO 20.9 18.0 15.2 SMOE 17.1 '· 20.0 22.8 DOSS (75% aqueous solution) 30.0 30.0 30.0 H 2 O 14.0 14.0 14.0 EGBE 15.0 15.0 15.0 10 DEG 3.0 3.0 3.0

Appearance at 20 ° C clear clear clear

Efficiency: 78.0 77.4 75.3

Viscosity (centistoke at -10 ° C) 519 527 559 15 Cloudiness point (° C) -21 -23 -28

Flow point (° C) -33 .35 <_4o HLB _9.44 9.96 10.45 In these materials, the total amount of SMO + SMOE on is kept constant, but the ratio of SMO to SMOE is 55:45, 47.4, respectively. : 52.6 and 40:60.

For comparison, a similar material is produced, but with the difference that the ratio of SMO to SMOE is ^ 70:30. The efficiency of this material is only 18.1%.

Example 4

Two materials are prepared similar to material 1 in Example 3, but with the difference that diethylene glycol monobutyl ether and diethylene glycol monomethyl ether are used instead of EGBE. The efficiency of these materials is 76.1% and 77.2%, respectively.

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Example 5

A material of the following components is prepared: SMO: 20.9% SMOE: 17.1% DOSS (75% aqueous solution): 30.0% H2O: 17.0% EGBE: 15.0% 10

This material is a clear liquid which remains stable without the formation of crystals or other deposits upon storage.

In comparison, a similar material is prepared but with the difference that an isoparaffinic hydrocarbon solvent is used instead of the mixture of H 2 O and EGBE. This last material is unclear and crystals form after 24 hours at 20 ° C.

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A further comparative example is carried out with a material containing the above surfactants, but without any solvent. The efficiency of this material is less than 10%.

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The results of the above experiments, made with materials according to the invention and with comparative materials, show that the mixture of surfactants must be dissolved in a solvent in order to be effective in dispersing an oil stain. It has also been found that a solvent consisting of a mixture of water and a glycol ether in the stated ratio gives unexpected results in terms of efficiency, stability, flow point and cloud point.

The synergistic effect between the mixture of surface 35

DK 156543 B

- II - active agent and hydrocarbon-free solvent occur only, 1) when the surfactant mixture constitutes 65-75% by weight of the total mixture, 5 2) when the surfactant mixture contains 35-40% of an alkali metal salt of dialkyl sulfosuccinate ) on the basis of the weight of dry mixture, and 3) when the solvent mixture, consisting of water and a glycol monoether, contains water in such an amount that the total water content of the total composition is at least 20% by weight.

Particularly advantageous materials contain 70-75% of the surfactant mixture and 3 (0-25% of the aqueous solvent mixture. A preferred surfactant mixture contains sorbitan monooleate and its polyoxyethylene adduct in a weight ratio of about 55:45.

These materials are easily applied to an oil stain as a fine spray, even at low temperatures. The oil is quickly dispersed under the influence of the ocean effect. In some cases, it may be advantageous to use mechanical movement to improve dispersion.

The materials are free of volatiles and the viscosity of the materials does not increase during spraying. The viscosity of the materials of the invention is of the order of 475-575 centistokes at -10 ° C. These materials are easily applied to oil stains by ejecting from an airplane or from a boat, even at low temperatures, without any increase in viscosity during spraying.

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Claims (10)

A surfactant-containing material and solvent for dispersing oil stains, characterized in that the surfactant constituting 65-75% by weight of the material is a mixture of a fatty acid sorbitan monoester, a polyalkylene oxide adduct of a fatty acid sorbitan monoester, and dissolving an alkali salt of a dialkyl sulfosuccinate, whereby the weight percent of the salt, calculated as the dry salt and of the dry mixture, amounts to 35-40%, and the weight ratio of fatty acid sorbitan monoester to polyalkylene oxide adduct is from 60:40 to 40:60, and constituting 35-25% by weight of the material is a hydrocarbon-free mixture of water and a glycol monoether, whereby the weight ratio of water to the ether in the mixture is from 60:40 to 40:60 and the total amount of water in the material is at least 20% based on the total weight of the material. 20 Material according to claim 1, characterized in that the fatty acid is an aliphatic monocarboxylic acid containing 10-20 carbon atoms, preferably oleic acid. Material according to claim 1 or 2, characterized in that the dialkyl sulfosuccinate salt is the sodium salt of di- (ethylhexyl) sulfosuccinate. Material according to claims 1, 2 or 3, 30, characterized in that the glycol monoether is a monoalkyl ether of a glycol selected from monoethylene glycol, diethylene glycol, monopropylene glycol and dipropylene glycol, wherein the alkyl group contains 1-4 carbon atoms and is preferably a methyl group. or butyl group, especially monoethylene glycol monobutyl ether, diethylene glycol monobutyl ether or diethylene glycol monobethyl ether. DK 156543 B - 13 - Material according to claim 1, characterized in that it contains 70-75% by weight of a mixture of an oleic acid sorbitan monoester, a polyethylene oxide adduct of oleic acid sorbitan monoester and a 75% by weight aqueous solution of di- (ethylhexyl) sulfosuccinate sodium salt, between oleic acid sorbitan monoester and its polyethylene oxide adduct is 55:45 and 30-25% by weight of a solvent mixture of water and a monoalkyl ether of monoethylene glycol, diethylene glycol, monopropylene glycol or dipropylene glycol, wherein the alkyl group contains 1-4 carbon atoms. Material according to claim 5, characterized in that the alkyl group is a methyl group or a butyl group. 15 Material according to claim 5, characterized in that the glycol mono ether is monoethylene glycol monobutyl ether, diethylene glycol monobutyl ether or diethylene glycol monomethyl ether. 20 Material according to claims 1-7, characterized in that the water content of the entire material is in the range of 20 to 27.5% by weight. Material according to claims 1-8, characterized in that the mixture of the surfactants has an HLB value in the range of 9 to 10.5, preferably from 9.4 to 10.5. Material according to claims 5-9, characterized in that the material has a viscosity in the range of 475 to 575 cST at -10 ° C. 35