Demulsifying

This invention relates to demulsifying mixtures of oil and water and in particular demulsification of tramp oils in cutting fluid oils and greases in commercial laundry effluent.

In the past, little care was given to effluent waste streams. The consequences of ignoring waste streams lead not only to environmental catastrophy, but also to the loss of valuable resources which could be reclaimed from the effluent stream. In particular, it has become apparent that greases and oils from waste streams may be recovered and sold for industrial purposes. Alternatively, certain oils may be recycled into the process from which they were originally effluted.

It has recently become important, particularly to commercial laundries, that effluent treatment must be accomplished to meet rigid Environmental Protection Agency Standards in the United States. Of course, regulations either exist or are being promulgated in several foreign countries dealing with waste treatment. The current standards for removal of grease and oils from waste water require that a commercial laundry discharge no more than 250 ppm of oils and grease to sewage treatment facilities. While large commercial laundries are capable of meeting the requirements through their greater economic advantage, smaller laundries are indeed suffering in attempting to comply with the rigid standards. It is thus an aspect of the present invention to deal with small commercial laundries and to provide an effective method for meeting EPA grease and oil discharge limits.

It is known from U.S. Pat. No. 4,104,164 issued Aug. 1, 1978 to Chelton, that a system for recovery of large particulate matter may be accomplished through centrifugal separation. The chelton patent does not deal with any particular chemical means for enhancing the separation of oils and grease from the waste water. U.S. Pat. No. 4,546,511 issued to Kaufmann on Oct. 15, 1985, describes a continuous flow laundry system incorporating a method of fluid flow control. The Kaufmann system requires many tanks and recirculates effluent water to transfer heat to fresh water.

U.S. Pat. No. 4,797,214, issued Jan. 10, 1989, to Sevier, describes a process for treating an emulsion or solution of water and oil by contacting the same with an inorganic salt and a polyelectrolyte flocculant. The Sevier patent describes chemical means which eventually contaminates the water employed with a salt such as sodium chloride and further uses as a demulsifying agent, sulfuric acid. It can be seen that the Sevier method of demulsification has certain inherent difficulties. Meffert et al, in U.S. Pat. No. 4,773,939 issued Sep. 27, 1988, describes a process of regenerating a soil-laden detergent solution comprising contacting the solution with a soil collector utilizing a polyfunctional quaternary ammonium compound. The difficulty in utilizing any quaternary compound is that any of the material which is discharged is deliterious to bacteria utilized in sewage treatment processes.

U.S. Pat. No. 4,846,976 issued Jul. 11, 1989 to Ford describes a filtration system for treating an emulsion containing water, an oil or a fat, an emulsifying agent and insoluble solid materials such as are present from a maritime oil emulsion containing an anionic detergent and solid greasy calcium salt of the detergent. The Ford patent describes a mechanical means utilizing microfilters for separating the oil or fat from the solid-free emulsion. A sludge and slime separating and settling device are described in U.S. Pat. No. 4,132,643 issued Jan. 2, 1979 to Hellqvist. The Hellqvist patent states that sludge and slime may be separated from various waste-water sources from laundries, industrial, agricultural, or other sources. U.S. Pat. No. 4,427,409 issued Jan. 24, 1984 to Gregorian et al describes effluent streams obtained from desizing, scouring and/or bleaching or mercerizing textile fabrics. Various surfactants are described by Gregorian et al for use in the process described therein. Gregorian et al makes further disclosures of compositions for treating textiles in U.S. Pat. Nos. 4,118,526 and 4,347,145 which were issued respectively on Jun. 6, 1975, and Aug. 31, 1982.

U.S. Pat. No. 4,420,578 issued Dec. 13, 1983 to Hagens et al describes methods for cleaning beverage bottles through the use of siloxane compositions. The glass bottle recycling industry generates tremendous volumes of industrial waste containing various organic components including greases. Weinberger in U.S. Pat. No. 4,390,466 issued Jun. 28, 1983 describes various acqueous liquid detergents useful for laundering compositions. Various nonionic surfactants are described in U.S. Pat. No. 4,391,719 issued to Meister on Jul. 5, 1983.

Lancz in U.S. Pat. No. 4,784,788 issued Nov. 15, 1988 describes hard surface viscous cleaning compositions containing various solvents and nonionic surfactants which form a non-flowable gelled composition. The compositions of Lancz also contain water soluble particulate builder-abrasive materials. Wixon in U.S. Pat. No. 4,790,856, issued Dec. 13, 1988 describes nonionic surfactant-cationic fabric softener/anti-static agents containing sulfosuccinamate.

Various iminodipropionate compounds are described in an Industrial Product Directory labeled 12-1282. Similar disclosures are made in an document entitled "Cospha/CD" dated Dec. 18, 1986. A further disclosure of diproplonates is found in a bulletin of Alkaril Chemicals, Inc. bulletin 1028-255 A Feb. 1987. Further disclosures of amphoteric materials are made in a brochure entitled "Properties and Formulations of Deriphat Amphoteric Surfactants" pages 1-37. Disclosures of Alkyl diproplonates are made in DeForest Enterprises, Inc. bulletin Number 720 REV.2/89. Certain nonionic surfactants are described in bulletin number 110 of DeForest Enterprises, Inc., entitled "DeIONIC LF-EP-16." REV. 12/87. A further disclosure of polyalkoxylated surfactants is found in DeForest Enterprises, Inc. bulletin Number 109, entitled DeIonic LT-EP15, dated 11/89. Further disclosures of amphoteric surfactants are found in DeForest Enterprises, Inc. bulletin 1350, dated 12/89 and entitled "Surfactant AN 5080 S-DF"

The various publications described above disclose the problem of treating waste water effectively to remove fats and greases. Yet none of the references taken singly teach the effective method found herein in rapidly demulsifying effluent obtained from sources such as tramp oils or commercial laundries.

The present invention deals with an effective composition which will demulsify effluent containing grease and oils. It is also desired to obtain a demulsifying system which does not lessen the cleaning benefits and which may be utilized to enhance cleaning. Furthermore, it is desirable to have a chemical system for demulsification which may be added either to the wash liquor or which may be used to treat a tank of effluent to bring about rapid demulsification.

Throughout the specific and claims, percentages and ratios are by weight, temperatures are given in degrees Celsius and pressures are given in KPa gauge unless otherwise indicated. To the extent that any references cited herein are applicable to the present invention, they are hereby specifically incorporated by reference.

This invention describes a composition of matter comprising:

(A) the reaction product of an alpha-beta unsaturated acid and a short chain amine; and

(B) at least one member selected from the group consisting of:

(i) an alkoxylated alcohol of the formula:

where R contains from 6 to 14 carbon atoms; a,b,c, and d all have values of one or greater; and EO and PO are ethylene and propylene oxide residues respectively;

(ii) a short chain alkyl sulfate;

(iii) a short chain alkyl sulfonate; and,

(iv) a phosphate ester having as the anion thereof

wherein AO is an alkylene oxide residue and x has a value of from 1 to 10, and R' is a hydrocarbyl residue having from 12 to 24 carbon atoms.

This invention also describes a method for demulsifying oil from water including the steps of contacting a mixture of oil and water with a mixture comprising:

(A) the reaction product of an alpha-beta unsaturated acid and a short chain amine; and

(B) at least one member selected from the group consisting of:

(i) an alkoxylated alcohol of the formula:

where R contains from 6 to 14 carbon atoms; a,b,c, and d all have values of one or greater; and EO and PO are ethylene and propylene oxide residues respectively;

(ii) a short chain alkyl sulfate;

(iii) a short chain alkyl sulfonate; and,

(iv) a phosphate ester having as the anion thereof

wherein AO is an alkylene oxide residue, x has a value of from 1 to 10, and R' is a hydrocarbyl residue having from 12 to 24 carbon atoms, for a sufficient time to effect substantial separation of the oil from the water.

The first aspect of the present invention to be discussed is the amphoteric compound denoted as component (A). The amphoteric is typically made by reacting an alpha-beta unsaturated acid and a short chain amine. The reaction product is a beta-amino diproplonate.

The structural formula of the beta-amino dipropionic acid is conveniently written as RN(CH.sub.2 CH.sub.2 COOH).sub.2. As the compounds are amphoteric materials the charge balance varies and the nitrogen may take one of the hydrogen atoms to become a quarternary leaving a negatively charged carboxyl group. Several forms of the foregoing compounds are possible including the disodium or other metallic salts, partial salts and the like. The effectiveness of the present invention is due in part to the fact of the amphoteric nature whereby the claimed compositions may be used over a wide pH range.

As previously stated the beta-amino dipropionate compounds are typically obtained from reacting acrylic acid with a short chain amine compound. The short chain amine in the present invention typically contains between seven and nine carbon atoms. The amine is preferably one corresponding to eight carbons or a normal octyl group. The fatty amine portion of the molecule is preferably one which is saturated.

Suitable amphoterics for use in the present invention are available from DeForest Enterprises, Inc. of 1215 Executive Drive West, of Richardson, Tex. 75081. A preferred product for use as the amphoteric in the present invention is DeTERIC ODP-LF.

The second component of the present invention referred to hereinafter as (Bi) is an alkoxylated alchohol of the formula R(EO).sub.a (PO).sub.b (EO).sub.c (PO).sub.d H wherein R contains from 8-14 carbon atoms; a,b,c,d all have values of one or greater and EO and PO are ethylene and propylene oxide residues respectively.

Component (Bi) is conveniently obtained by reacting an alcohol corresponding to 8-14 carbon atoms, preferably 9-13 carbon atoms, derived from a linear or branched saturated alcohol and the corresponding alkylene oxide. That is, the alcohol portion of the molecule is first reacted with ethylene oxide, followed by reaction with propylene oxide, again by ethylene oxide, and finally by propylene oxide. As the manner of reacting alcohols with an alkylene oxide is well known in the art no particular description is given of this feature of the invention. It is noted that a-d typically have values from 1 to 4, typically 2 or 3.

Components (Bii) and (Biii) are discussed together. These components are short chain sulfur containing anionic surfactants. The form of the surfactants is typically that the short chain organic material is one which contains from 7-9 carbon atoms which is reacted to obtain the corresponding sulfate or sulfonate. The cation of these surfactants is typically sodium, potassium, calcium or magnesium. If desired the ammonium cation may be utilized provided the circumstances are such that ammonia is either not liberated or may be vented during processing or use of the compositions.

Components (Bii) and (Biii) are typically obtained from the corresponding short chain saturated hydrocarbons or the corresponding alcohol. Obtaining the sulfate and the sulfonate follows the general procedures described in the art and no particular further discussion is given here.

Component (Biv) is also an anionic surfactant. This material is a phosphate ester of an alkoxylated alcohol. Typically the phosphate ester is obtained through the reaction of an alcohol with an alkylene oxide component and is then capped with the phosphate group which may be obtained from P.sub.2 O.sub.5 or from a phosphoric acid such as any of the "mainline" polyphosphoric acids.

A preferred phosphate ester for use in the present invention is one obtained from an alkyl phenol which has been reacted with from one to ten moles of ethylene oxide, typically from one to six moles of ethylene oxide. Also suitable as the precursor of the phosphate ester is a long chain alcohol containing from 12 to 24, preferably 14 to 18 carbon atoms. Typical alcohols which may be utilized herein include any of the odd or even numbered carbon alcohols within the foregoing description. Typically, stearyl or oleyl alcohols may be reacted from one to ten moles of ethylene oxide, typically one to six moles of ethylene oxide and used as the base for the phosphate ester. The phosphate ester as the anion has the formula R'O(AO).sub.x PO.sub.4 where R' is the alcohol residue, AO is the alklyene oxide residue and x is the degree of alkoxylation.

The cation of the phosphate ester may be any of the typically used detergent cations such as sodium, potassium, calcium, magnesium, or amines. Where highly acidic cleaners are employed it is possible to use the phosphate ester in its acid form.

A further version of the phosphate esters utilized in the present invention is the 2-ethylhexanol-triethanolamine phosphate ester obtained from the alkylene oxide condensate of 2-ethylhexanol which is then reacted to give the phosphate which is neutralized with the triethanolamine.

Generally speaking, component A may be compounded with any one of components Bi-iv in any desired amount. There are, however, certain preferred ratios depending on the usages of the combination of component A with any particular component B.

Generally speaking, component A is combined with component (Bi) the alkoxylated alcohol at a weight ratio of 10:1 to 1:10: preferably 5:1 to 1:5.

When combining component A with component (Bii) or (Biii) it is preferable to obtain a 9:1 to 1:1, preferably 8:1 to 2:1 weight ratio of the amphoteric to the anionic. Of course, it must be recognized in using the components of the present invention for demulsification that any extraneous anionic surfactant introduced to the system may vary the amount of the anionic required once such is added in a mixture with the amphoteric. Conveniently, in the scope of the present invention, the amphoteric (A) and component (B) may be sold separately to facilitate mixing to obtain the correct ratios. Stated otherwise, if it is determined in practice that optimum demulsification is not being obtained, it may be because there is too much of one component or the other in the wash liquor. Accordingly, the amount added for demulsification should be adjusted.

The ratio of the amphoteric to the alcohol alkoxylate phosphate is typically based on a weight ratio of 10:1 to about 1:10, more preferably about 9:1 to about 1:1.

Depending upon the use of the compositions in the present invention, all manner of ingredients found in such compositions may be used herein. Typically, a laundry detergent will contain alkali metal silicates having a SiO.sub.2 :Na.sub.2 O weight ratio of from 3:1 to 1:1. Additional ingredients in laundry compositions include all manner of organic and inorganic detergent builders. Such detergent builders include aluminoslicates, pyrophosphates, and tripolyphosphates and the like. Where the product is utilized for demulsification and is added to the waste wash liquor it is not necessary to utilize such additional ingredients. If desired, it may be useful to place in the composition of the invention, caustic in such an amount to bring the pH of the resulting solution to the desired level.

Where the compositions of the present invention are used in synthetic coolants or cutting fluids, or to demulsify a tramp oil it may be desirable to add additional ingredients such as are found in such compositions including bacteriocides and other stabilizing ingredients.

The compositions described herein may be used to demulsify various waste water streams and tramp oils. It is merely necessary to obtain the mixture of components through separate addition or by using a mixture of the components such as in a cleaning formulation.

The amphoteric (A) and component (B) are used at a level of 0.01% to 2% by weight of the water in the waste stream. The demulsification proceeds effectively in ten minutes or less at temperatures of 25 C. to 75 C. Cleaning compositions typically utilize the mixture of (A) and (B) at 0.05% to 5% by weight of the water.

What follows are examples of the use of the compositions of the present invention.

A laundry detergent is prepared by combining n-octyl beta-aminodypropionate at 7 parts active with 7 parts of the reaction product of isodecyl alcohol with alkylene oxides such as the isodecyl alcohol makes up 24.8% of the molecule such that the first alkylene oxide reactant is ethylene oxide to a total of 26% of the eventual molecule, followed by the addition of propylene oxide to make up the final product of 7.6% propylene oxide; followed by an additional 32.7% of ethylene oxide the total molecule and the remaining 8.7% of the molecule as propylene oxide. The last amount of the propylene oxide may be added incrementally to obtain the desired cloud point of 56 C. to 63 C. as measured at 1% by weight in distilled water.

The n-octyl beta-aminodipropionate product (component A) may be used to demulsify the waste wash liquor from a commercial laundry by adding 0.2-0.5 parts of the above combination to the waste wash liquor at 99.8-99.5 parts.

The waste wash liquor is allowed to demulsify to recover the oils, greases and fat from the waste wash liquor while allowing the cleaned wash liquor to be passed on for sewage treatment.

A formulation is prepared as Example I with regard to component A. This composition is separated into two parts, one of which is combined at 7 parts of component A to 1 part of a sodium octyl sulfonate. This mixture is utilized to demulsify a waste wash liquor rapidly and to remove substantially all of the grease from the waste wash liquor prior to passing it on to treatment.

The foregoing procedure is carried out a second time using sodium octyl sulfate in place of the sodium octyl sulfonate. Substantially similar results are obtained.

Each of the foregoing compositions is utilized as a detergent system for cleaning the contaminated surfaces of a food plant. The various animal fats and oils are rapidly separated upon placing the spent detergent and water in a holding tank. A rapid separation of the fat and oils is observed.

A tramp oil in a synthetic coolant or cleaning fluid is demulsified by combining 5 parts of component A from Example I with 5 parts of a nonylphenol with six moles of ethylene oxide followed by reaction of the resulting nonylphenol alkoxylate with one mole of P.sub.2 O.sub.5.

The foregoing product is observed to rapidly demulsify the tramp oil at a temperature of 25.degree. C.

Substantially similar results are obtained by substituting the foregoing phosphate ester with one obtained from oleyl alcohol which has been condensed with 4 moles of ethylene oxide following reaction with P.sub.2 O.sub.5.

Further similar results may be obtained by substituting in the above example a 2-ethylhexanol-triethanolamine salt with component A as described above.

Substantially similar benefits are obtained with synthetic coolants which require demulsification.