AU646733B2 - Cationic polyelectrolyte demulsifier and coagulator - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): W. R. Grace Co.-Conn.

ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

INVENTION TITLE: Cationic polyelectrolyte demulsifier and coagulator The following statement is a full description of this invention, including the best method of performing it known to me/us:- OB I* -2- FIELD OF THE INVENTION This invention relates to a composition and method for treating various waste streams to separate oil from water and more specifically to novel cationic polyelectrolyte blends which exhibit surprising and unexpected demulsifying and coagulating effects on oil in water emulsions.

BACKGROUND OF THE INVENTION 10 In water chemistry, there are basically two types of e emulsions that are commonly found, oily waste water and waste oil emulsions. An oily waste water emulsion (oil in water emulsion) is comprised of a continuous water phase and a dispersed oil phase, and may contain a variety of oil types in a wide range of concentrations, and may also contain other contaminants such as emulsifiers, detergents, cleaners, solvents, etc. as well as suspended solids, such as silicates, metal hydroxides and the like. The treatment of oily wastewater is 20 normally divided into two steps: 1) coagulation where the emulsifying properties of the oil droplet is destroyed, and 2) flocculation where the neutralized oil droplets are agglomerated into large separate globules.

It is well known in the art that the demulsification and separation of oil in water emulsions has been very difficult. The coagulation of oil in water emulsions involves the neutralization of the stabilizing factors to allow the emulsified oil droplets to coalesce. Since the emulsified oil droplets are negatively charged (anionic), chemical demulsifiers are generally positively charged (cationic). Various inorganic emulsion breakers are known including polyvalent metal salts such as alum (Al,(S0 4 3 A1C1 3 FeCl 3 Fe 2

(SO

4 3 Na 2 Al204 or NaAIO 2 calcium hydroxide; mineral acids such as H 2

SO

4 HC1, HNO 3 and adsorbents such as pulverized clay and lime. In addition, various organic emulsion breakers have been used for breaking oil in water emulsions which include polyamines, polyacrylates, their substituted copolymers, cationic starches, and the like.

However, due to the complexity of the various types of oil in water emulsions, the above inorganic and organic emulsion breakers are not always successful. It S 10 has now been discovered that certain blends of these emulsion breakers not only aid in coagulation, but noticeably speed the coagulating reaction.

•SUMMARY OF THE INVENTION It is an object of this invention to provide a composition for coagulating oil in water emulsions.

It is another object of this invention to provide a composition for treating waste streams containing oil in water emulsions to break the emulsion and thereby 20 separate the oil from the water.

In accordance with the present invention there have been provided certain novel compositions comprising a mixture of three cationic polyelectrolytes wherein the three polyelectrolytes include a) an inorganic polyelectrolyte selected from the group consisting of polyaluminum chloride, alum, calcium hydroxide and mixtures thereof, b) a cationically modified starch, and c) p n The above three component blends of cationic polvelectrolytes exhibit surprising and unexpected synergy in demulsifying and coagulating oil in water emulsions.

Also in accordance with the present invention, there has been provided a method of treating waste streams containing oil in water emulsions which method comprises -4adding to the waste stream a mixture of three cationic polyelectrolytes wherein the three polyelectrolytes include a) an inorganic polyelectrolyte selected from the group consisting of polyaluminum chloride, alum, calcium hydroxide and mixtures thereof, b) a cationically a ye\ o c.\b oern r\.

modified starch, and in an amount effective to break the oil in water emulsions.

DETAILED DESCRIPTION 10 This invention is directed to a composition useful for demuls.fying and coagulating oil in water emulsions.

More specifically, the invention is directed to a three component mixture comprising certain cationic polyelectrolytes comprising a) an inorganic polyelectroly e, b) a cationically modified starch and c) la The relative proportions of a:b:c supra, are generally in the range and are preferably in the range Suitable inorganic polyelectrolytes for use in 20 this invention include those selected from the group consisting of polyaluminum chloride, alum, calcium hydroxide, and mixtures thereof. The inorganic polyelectrolyte preferably contains aluminum ion, and is most preferably polyaluminum chloride because it is amphoteric and has a branched polymeric structure. It appears that these particular characteristics aid in precipitation.

Suitable cationically modified starches for use in this invention include the quaternary ammonium alkyl ether type as disclosed in U.S. Patent No. 4,088,600 which is hereby incorporated by reference in its entirety. The preparation of these cationic starch quaternary ammonium ethers is well known to those skilled in the art. They are prepared by reacting a starch and, e.g. a quaternary halohydrin salt with an alkali. See "Starch: Chemistry and Technology", Whistler, and Paschall, eds. Chapter 16, Production and Uses of Cationic Starches, by Paschall, C.F. (1967).

The cationically modified starches may also comprise cationic quaternary ammonium modified blends of a starch and a natural gum in accordance with USSN 499,939 which is hereby incorporated by reference in its entirety. As disclosed therein, the cationically modified blends are 0 prepared by reacting a mixture of a starch and a natural gum with a quaternary ammonium compound in the presence of an alkali catalyst at a pH in the range 12-13.

S• Suitable gums include carboxymethyl cellulose, guar, locust bean, karaya, alginate and xanthum gum, and is preferably guar, carboxymethyl cellulose or alginate gum.

Examples of starches which are suitable for use in :this invention include corn, potato, tapioca, sago, rice, wheat, waxy maize, grain sorghum, grain starches in raw or modified forms, and the like.

20 The quaternary ammonium compound can be expressed by the following formula: X- X Y N -R

'R

3 wherein X is any monovalent anion including, for example, chloride, bromide, iodide, methyl sulfate, and the like; Y is selected from the group consisting of 2, 3 epoxy propyl, 3-halo-2 hydroxy propyl, 2 haloethyl, o, m, or p (a hydroxy haloethyl) benzyl; Ri, R 2 and R 3 are independently selected from the group consisting of hydrogen, hydroxyl, alkyl, substituted alkyl, aryl and aralkyl, and in which two of the R's may be joined to form a heterocyclic or homocyclic ring compound, further in which the total number of carbon atoms in all three of RI, R, ;nd R 3 should not exceed 14 carbons. If all three of Ri, R 2 and Rj are different and R 3 contains more than 3 carbon atoms, but not more than 12, then Ri and R 2 should preferably be from the group consisting of methyl and ethyl; and if R, and R 2 are joined to form a ring compound, R 3 should preferably not be greater than ethyl.

10 The cationically modified starches generally have a charge density in the range 0.2 to 4.0 meq/g and preferably have a charge density in the range 0.7 to meq/g. The cationically modified starches generally have a molecular weight in the range from 25,000 to 750,000 and a e, referb between 50,000 to 500,000.

E e suitable for use in this invention are disclosed in U.S. Patent No. 3,738,945 which is hereby incorporated by,reference in its 1 \o o nn entirety. The is preferably dimethylamine 20 epichlorohydrin having a charge density of +7.5 meq/g and a molecular weight in the range 50,000 to 100,000, preferably about 75,000.

In general, the cationic polyelectrolyte demulsifiers of the instant invention may be added directly to the waste stream containing the oil in water emulsion in an amount effective to break the oil in water emulsion, generally at a dosage concentration in the range 10 ppm to 5000 ppm, depending of course, on the concentration of oil in the waste stream, and is preferably added at a dosage concentration of between 500 to 3000 ppi. The cationic polyelectrolyte demulsifiers may optionally be diluted with a suitable solvent, typically water, prior to adding them to the waste stream.

-7- Without further elaboration, it is believed that one of ordinary skill in the art, using the preceding detailed description can utilize the present invention to its fullest extent.

The following examples are provided to illustrate the invention in accordance with the principles of this invention, but are not to be construed as limiting the invention in any way except as indicated in the appended claims. All parts and percentages are by weight unless otherwise indicated.

io..

oleo Example 1 This example illustrates the surprising synergy exhibited by the claimed invention when tested on two separate oil in water emulsions which resulted from waste water streams from two separate nylon extruding processes .each of which utilized various distinct lubricants, and additionally, a third oil in water emulsion was obtained hereinafter indicated as Emulsion A and Emulsion B from the waste oil stream of a locomotive degreasing process.

The two emulsions from the nylon extrusion waste stream were diluted to 1% concentrations. The efficacy of the three component blended formulations were evaluated on their ability to break these emulsions when compared to efficacy of the individual components. The formulation dosages screened upon Emulsion A (Table 2) ranged from 2500 ppm to 5000 ppm. The formulation dosages screened upon Emulsion B (Table 3) ranged from 1000 ppm to 5000 ppm. The treated emulsions were mixed for approximately 5 minutes and allowed to stand, without mixing, for thirty minutes. The subnatant was sampled and transferred to a colorimeter and the percent transmittance was recorded. The higher the %T translated to a more effective demulsifier.

Table 1 describes the nature and relative proportions of the components in the various formulations screened against these emulsions. Tables 2 and 3 indicate that the three-component formulations provided a more effective treatment than any of the individual components and were in fact more effective than would have been expected from the combination of the individual components. In particular, it should be noted that the formulations designated A and C not only outperformed all 10 of the individual components, but two of the components; DMA-EPI and PAC failed to break the emulsion at all.

Table 1 INITIAL STARCH COAGULANT BLENDS FORMULATION ACTIVES FORMULATION STARCH PAC DMA-EPI A 2-61 8-14 1-6 B 2-62 8-14 1-6 C 2-63 8-14 1-6 20 'Corn starch with a molecular weight 50-200,000 and charge *O density 2-4.0 meq/g.

2Corn starch with a molecular weight 25-150,000 and charge density 0.5 to 2.0 meq/g.

3 Corn starch-guar gum with a molecular weight 200-750,000 and charge density 0.2 to 2 meq/g.

FOMLTO SCENN UPON* NYLON EXTRUSION EMULSION A CONCENTRATION) PRODUCT CONCENTRATION SAMPLE I.D. 2500 3000 3500 4000 4500 5000 Formulation A 0 16 65 16 26 2 Formulation C 0 29 56 1 0 0 Formulation B 0 54 5 3 0 0 Cationic Modified 0 0 0 0 0 29 Starch C.M.S. in Formulation A 0 2 0 11 0 C.M.S. in Formulation B 0 0 0 0 0 0 C.M.S. in Formulation C 0 0 0 0 0 0 PAC in Formulations A-C 0 0 0 0 0 0 DMA-EPI in Formulations 0 0 0 0 0 0

A-C

Note Numbers in Table are Transmittance.

OMLTO SCENN UPON*.. NYLON FRSI TO N USCREENINGUONETAIN PRODUCT CONCENTRATION (PPM) SAMPLE I.D. 1000 2000 3000 4000 5000 Formulation A 6 64 73 3 6 Formulaion C 6 67 79 4 6 Formulation B 10 65 68 3 6 C.M.S. in Formulation C 10 2 2 2 12 C.M.S. in Formulation A 3 1 10 22 78 C.H.S. in Formulation B 7 9 3 4 41 Cation.'c Modified Starch 9 2 51 26 66 DMA-EPI in Formulations 19 45 37 24

A-C,

PAC in Formulations A-C 3 11 7 3 9 Note Numbers in Table ars Transmittance.

-11- Example 2 This example contrasts the performance of the C.M.S.

in Formation C and the three most effective formulations of this invention for breaking an oil in water emulsion obtained from the waste stream of a locomotive degreasing process. The results are reported as turbidities (NTU) and accordingly, a lower number reflects a more effective treatment. All of the products were screened at the optimum dosage for the C.M.S. in Formulation C, which was the most effective individual modified starch. As indicated in Tcble 4, all three formulations provided superior performance to the C.M.S. (in Formulation C) by itself. Of these, the sample treated with Formulation C was the most effective as evidenced by a relative 15 decrease in turbidity of 49 NTU less than the C.M.S. used in Formulation C. This was surprising and unexpected since the PAC and DMA-EPI which are present in Formulations A-C failed to break the emulsion at all.

That is, it would have been expected that a blend of these ineffective components would have negatively affected the performance of the C.M.S. used in Formulation C.

Table 4 25 FIELD TESTING AT UNION PACIFIC RAILROAD PLATTE) POLYME CONCENTRATION TURBIDITY (PPM) (NTU) Cationic starch in 120 68 Formulation C* Formulation C 120 19 Formulation B 120 28 Formulation A 120 22 Most effective cationic modified starch when tested by itself upon the above emulsion.

11a Throughout this specification and the dlaiis which follow, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "1ccmprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

a a.

a a a a a a a a a a a a a

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Claims (7)

1. A composition for use in demulsifying and coagulating oil in water emulsions comprising a mixture of three cationic polyelectrolytes wherein the polyelectrolytes include an inorganic polyelectrolyte selected from the group consisting of polyaluminum chloride, alum, calcium hydroxide and mixtures thereof, a cationically modified starch, and a polyepihalohydrin.

2. A composition according to Claim 1 wherein the ratio of the cationic polyelectrolytes a:b:c is in the range

3. A composition according to Claim 2 wherein the ratio of the cationic polyelectrolytes a:b:c is in the range

4. A composition according to any one of Claims 1 to 3 wherein the inorganic polyelectrolyte is polyaluminum chloride, the cationic starch is a cationic quaternary ammonium modified blend of a starch and a natural gum, and the epihalohydrin is dimethylamine polyepichlorohydrin.

5. A composition according to any one of Claims 1 to 4 wherein the cationic starch has a charge density in the range 0.2 to 4.0 meq/g and a molecular weight of at least 25,000 end less than 750,000.

6. A composition according to any one of Claims 1 to 4 wherein the cationic starch has a charge density in the range 0.7 to 3.5 meq/g and a molecular weight in the range 50,000 to 500,000. o So 931231,p:\oper\ee,15143gra.spe,12 -13- 1 7. A method for demulsifying and coagulating oil in water emulsions comprising contacting the emulsion 3 with the composition according to Claims 1 to 1 8. A method according to Claim 7 wherein the effective amount is a dosage concentration in the range 3 of from 10 ppm to 5000 ppm. 1 9. A method according to Claim 8 wherein the dosage concentration is in the range of from 500 ppm to 3 3000 ppm. 4 S c e *o *oo *J -14- A composition and/or method for demulsifying and coagulating oil substantially as hereinbefore described with reference to the Examples.

11. The steps, features, compositions and comn-nds disclosed herein or referred to or id .od in the specification and/or clai this application, individually or ectively, and any and all combinations S of a o or more of said steps or features. S of DATED this TWENTY SEVENTH day of APRIL 1992 W. R. Grace Co.-Conn. by DAVIES COLLISON CAVE Patent Attorneys for the applicant(s) I 1, ABSTRACT OF THE INVENTION A cationic polyelectrolyte demulsifier and coagulator for use in demulsifying and coagulating oil in water emulsions comprising a mixture of three cationic polyelectrolytes wherein the polyelectrolytes comprise an inorganic polyelectrolyte, a cationically modified starch and an epihalohydrin. The inorganic polyelectrolyte component is selected from the group consisting of polyaluminum chloride, alum, calcium hydroxide, and mixtures thereof. *fool *so