CA1272191A - Method of clarifying sugar liquors using a cationic polyelectrolyte treatment - Google Patents
Method of clarifying sugar liquors using a cationic polyelectrolyte treatmentInfo
- Publication number
- CA1272191A CA1272191A CA000512485A CA512485A CA1272191A CA 1272191 A CA1272191 A CA 1272191A CA 000512485 A CA000512485 A CA 000512485A CA 512485 A CA512485 A CA 512485A CA 1272191 A CA1272191 A CA 1272191A
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- Prior art keywords
- oil
- sugar
- cationic
- acrylamide
- water emulsion
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C13—SUGAR INDUSTRY
- C13B—PRODUCTION OF SUCROSE; APPARATUS SPECIALLY ADAPTED THEREFOR
- C13B20/00—Purification of sugar juices
- C13B20/14—Purification of sugar juices using ion-exchange materials
- C13B20/144—Purification of sugar juices using ion-exchange materials using only cationic ion-exchange material
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biochemistry (AREA)
- Organic Chemistry (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An improved method whereby various flocs obtained in the refining of sugar may be removed is described. In this method, at least one cationic polyelectrolyte, optionally together with an anionic acrylamide copolymer, is added to a sugar liquor. In addition to giving more easily removed flocs, these materials also act to remove colored substances from the sugar liquors.
Case 85-02
An improved method whereby various flocs obtained in the refining of sugar may be removed is described. In this method, at least one cationic polyelectrolyte, optionally together with an anionic acrylamide copolymer, is added to a sugar liquor. In addition to giving more easily removed flocs, these materials also act to remove colored substances from the sugar liquors.
Case 85-02
Description
,3 ~7;; ~ 530-3~38 b, ,. ~L
This invention i5 concernec~ with improvements in methods of processing various o-f the sugar solutions, known and described hereafter as "sugar liquors", which occur in a sugar refinery.
The various forms in which sugar, or, to be more pre-cise, sucrose, is sold are derived essentially from two sources:
sugar beet and sugar cane. Whilst the initial processing steps used to obtain raw sugar from these source materials differs, the manner in which raw sugar is refined is essentially independant of the original source. Raw sugar, as generally handled in bulk, is a crystalline solid which contains usually at least 97~ by weight sucrose, together with small amounts of water, other sugars, other organic substances, and some inorganic materials. Apart from the water, these other substances in ~he main represent materials of a biological origin derived from the original cane or beet, together with some colored substances resulting from degradation or cara-melization of the raw sugar.
The chief aim of the refining process is to obtain a vendible sugar product substantially free of all contaminating substances except for a small, and carefully controlled, amount of water. Since the refining process involves both various recycle loops and a sugar liquor both of increasing colour density, and of increasing impurity level, leading eventually to molasses, it is necessary to take steps at various points either to remove these contaminants or at least to decrease the amounts present. Whilst the actual process steps used differ both between refineries and between different points in the same refinery, the technique generally used to remove impurities is to convert them into a ,,, ., /, r.~
~ ~7~
precipitated form which adsorbs the impurities, and which can t~en be removed. These precipitates generally do not form spontaneous-ly, and hence they are obtained by adding suitable reayents to the sugar liquor. The reagent then reacts or combines with at least some of the impurities forming a precipitate that can be removed.
Such a reagent, to be both useful and useable, must meet a number of important criteria, particularly the following:
(a) it should provide a precipitate which can easily be removed quantitatively, to provide a clear, non-hazy, sugar liquor.
(b) it should act efficiently,that is to say it should remove as high a proportion of the impurities as possible with as low an addition of reagent as possible.
(c) it should not be selective between different impur-ities.
(d) it should not leave any reagent residues in the sugar liquor since first such residues may cause problems when the sugar is used in comestibles, and second their presence may require addition of another purification step to remove them.
(e) it should be e-ffective to remove impurities which are present in very low concentrations: for example a 50% solution in water of raw sugar generally contains less than 1~ of total impur-ities.
These desiderata place significant constraints on the choice of reagen-ts that can be used. Additionally, these criteria tend to create the situation that a reagent useful at one point in the overall refinery sugar liquor circuit may not be of any use elsewhere in the sys-tem. Clearly, a level of convenience and economy can be achieved if -the same reagent can be used success-fully at several different points in the sugar liquor circuit.
In the initial clarification step applied to the raw sugar liquor the procedure generally adopted is to add, to a hot liquor containing about 65~ by weight of sugar, in sequence both phosphoric acid (H3P04) and milk of lime. This provides a calcium phosphate precipitate which carries down with it bo-th some of the impurities and some of the colored substances. But this precipi-tate is no-t easy to remove. It is known to add, to the hot liquor, a flocculating agent to assist in the removal step. One reagent used for this purpose is sold under the trade mark "Talofloc". It is alleged to contain a cationic quaternary ammonium compound of the formula:
CH2--( CH2 ) 16--CH3 CH3 - N - CH3 Cl-CH2 - (CH2)16-CH3_ This material is generally supplied as a gel in isopropanol, which contains about 70% of the active compound. It is referred to as a surfactant; the isopropanol also presents, to some degree a cer-tain fire risk.
This material is also often used in conjunction with another coagulant, which is sold under the trade mark "Taloflote".
It is alleged to be an anionic polymer, which is a copolymer of acrylic acid and acrylamide. Various grades are available con-taining various relative amounts of acrylic acid and acryla-mide units. However, it appears that this polymeric material is anion-ic and always contains more acrylamide units than acry~ic aci~
units, the maximum amount of acrylic acid units apparently being about 30%. It is generally supplied as a dry yranular material, which has to be dissolved in water before it can be added to -the sugar liquor. The maximum practical solubility, if viscous or partially ~elled materials are to be avoided, is about 0.1% by weight. This added water then has to be removed, at some later stage, by evaporation.
Whilst these reagents are effective, and indeed are commercially used, it is still true to say that this initial clar-ifying step, and other similar steps in the complete refinery sugar circuit, could be improved, especially the coagulation of the calcium phosphate precipitates discussed above.
We have now discovered that these various precipitate removal steps can be significantly improved by the use therein of a water soluble cationic homopolymer or copolymer polyelectrolyte.
This water soluble cationic polyelectrolyte additive has been ~n found to provide an easily handled floating floc, especially calcium phosphate flocs, and which also appears to remove undesir-able impurities, especially colored substances, better than the additives currently used to assist in calcium phosphate floc removal.
Further, it has also been found that the use of a water soluble cationic polyelectrolyte with an anionic acrylic-type polymer, which may be a homopolymer or a copolymer, further ~2,7~
enhances the process. Thus a cationic polyelectrolyte can be used to enhance coagulation of an initial calcium phosphate precipitate to a small-sized floc, and this in turn can be flocculated into a larger, and easily removed, floc by the use of a second acrylic-type anionic polyelectrolyte. These large flocs can then be easily removed from the sugar liquor. In this two-stage procedure the cationic polyelectrolyte generally will contain a quaternary ammonium group, such as a homopolymer containing dimethylamino ethyl methacrylate units. A suitable anionic polyelectrolyte generally will contain carboxyl groups, such as a polymer contain-ing acrylamide units and sodium acrylate units.
Thus in its broadest aspect -this invention provides a method for improving the removal of floc precipitates consisting mainly of calcium phosphate obtained in sugar liquors during the refining thereof which comprises adding to the sugar liquor a small but effective amount of a cationic water soluble polyelec-trolyte homopolymer or copolymer.
In a second broad aspect this invention provides a method for improving the removal of floc precipita~es consisting mainly of calcium phosphate obtained in sugar liquors during the refining thereof which comprises adding -to the sugar liquor in sequence a small but effective amount of a cationic water soluble polyelectrolyte homopolymer or copolymer, and of a small but effective amount of an oil-in-water emulsion of at least one anionic acrylamide copolymer polyelectrolyte.
It is noted that the anionic acrylic-type polymer is added as an oil-in-water emulsion. This is obtained by inverting a water-in-oil emulsion of -the polymer, preferably one which will spontaneously inver-t on addikion to water. The oil-in-water emul-sion can contain up to about 1% by weight of active polymer.
Preferably, an oil-in-water emulsion containing from about 0.3% to about 0.7% active polymer i5 used, as such solutions are conveni-ent to handle.
The oil carrier, together with at least some of the surfactant, in the emulsion is coagulated into the calcium phos-phate floc in the presence of the water soluble cationic polyelec-trolyte.
Typically the acrylamide copolymer water-in-oil emul-sions used in this invention contain approximately equal parts of copolymer, mineral oil, and water, together with suitable surfac-tants and stabilizers. Such emulsions are well known in the art.
In this application it is also highly desirable that the mineral oil used be essentially free of aromatics: an oil that is sub-stantially transparent to ultraviolet light in the wave band 280 to 350 m~ is suitable.
The acrylamide copolymers used herein are also well ~0 known in the art. Typical prepara~ion procedures are to be found in Canadian Patent 960,791 and in other similar sources. It is also known -that some of the polymers used herein can be prepared in a variety of ways: for example an acrylamide-acrylic acid copolymer can be obtained either by polymerizing a mixture of monomers, or by hydrolyzing an acrylamide homopolymer under suit-ably controlled conditions. It is also known that the molecular weights of these polymers can be controlled, to a degree, during their preparation. For the purposes of this invention, rnolecular weights of from 25,000 up to 100 million have been used success-fully. Where both a cationic and an anionic polyelectrolyte are used in sequence, it is preferred that the anionic polyelectrolyte have a molecular weight that i5 relatively high, being at least about 10 million and preferably about 15 million. On -the other hand, a cationic polyelectrolyte can have a relatively low molecu-lar weight, of the order of 25,000 -to 250,000, but higher molecu-lar weights are also usable.
The cationic polyelectrolytes used herein may be either homopolymers, such as polydimethyldiallylammonium chloride, or acrylic-type copolymers, such as a methacrylaminopropyl trimethyl-ammonium chloride, or a copolymer containing acrylamide, acrylic acid, and N-(dimethylaminomethyl)acrylamide units. Further usable cationic polymers are a polyethyleneamine mixture, and a polyamine condensation product of epichlorhydrin with dimethylamine.
The invention will now be described by way of the following examples. In all of these examples plant conditions were simulated on a laboratory scale. The sugar liquor bulk sample was treated with lime and phosphoric acid, sufficient phos-phonic acid is added to lower the pH to about 5, and lime is then added to raise the pH to about 8. Then 100 ml aliquot samples are taken from the treated bulk sample. Each aliquot, in a stoppered graduated cylinder, was then processed in the same way. Each cylinder was maintained at 88C in a water bath. To each cylinder was then added a color reducing reagent, and the contents mixed by inverting 5 times. The flotation reagent was then added, and the d~
cylinder shaken violently for 30 ~econds, partly to mix the con-tents thoroughly, and partly to mix air into the liquor, since an aeration step is used in a sugar refinery at this point. After standing -for 1 hour in the bath, samples were then withdrawn from the subnatent sugar liquor below the floating floccula-ted precipi-tate tby means of a syringe) for measurement purposes.
Each of the thus obtained subnatent solutions was then measured -Eor color and optical clarity on the Brinkman Scale. In this test, light is passed through a sample, and the amount of light absorbed is determined. An arbitrary scale of zero to 2,000 is used, in which ~ero corresponds to distilled water. If neces-sary a test sample may be diluted in order to obtain an observable value, which is then extrapolated to allow for the dilution. Two readings were applied to the subnatent sugar liquor samples: one reading was taken on the sample as removed, and the second after passing the sample through a membrane filter. The second reading gives an indication of color, whilst the difference between the readings gives an indication of turbidity in the sample, and thus indicates the efficiency of the flotation reagent used.
In the following examples the sugar liquor used is iden-tified as follows:
W.S.L. : a washed sugar liquor.
C.W.S.L. : a clarified washed sugar liquor.
~ew liquor ~ a C.W.S.L. further treated by passage through an activated carbon/bone char mixture~
Other sugar solutions are also used and identified.
Example 1 Clarification of W.S.L.
Four series of determinations were run, in which four cationic polymers are compared when used com'oined with the com-mercially available ma-terial Taloflote A-100, which was used as a precipitate coagulant. All polymers were allowed a contact time of 15 minutes prior to coagulation and subnatent examina~ion.
The W.S.L. used had a colour reading of 1163 and a turbidity of
This invention i5 concernec~ with improvements in methods of processing various o-f the sugar solutions, known and described hereafter as "sugar liquors", which occur in a sugar refinery.
The various forms in which sugar, or, to be more pre-cise, sucrose, is sold are derived essentially from two sources:
sugar beet and sugar cane. Whilst the initial processing steps used to obtain raw sugar from these source materials differs, the manner in which raw sugar is refined is essentially independant of the original source. Raw sugar, as generally handled in bulk, is a crystalline solid which contains usually at least 97~ by weight sucrose, together with small amounts of water, other sugars, other organic substances, and some inorganic materials. Apart from the water, these other substances in ~he main represent materials of a biological origin derived from the original cane or beet, together with some colored substances resulting from degradation or cara-melization of the raw sugar.
The chief aim of the refining process is to obtain a vendible sugar product substantially free of all contaminating substances except for a small, and carefully controlled, amount of water. Since the refining process involves both various recycle loops and a sugar liquor both of increasing colour density, and of increasing impurity level, leading eventually to molasses, it is necessary to take steps at various points either to remove these contaminants or at least to decrease the amounts present. Whilst the actual process steps used differ both between refineries and between different points in the same refinery, the technique generally used to remove impurities is to convert them into a ,,, ., /, r.~
~ ~7~
precipitated form which adsorbs the impurities, and which can t~en be removed. These precipitates generally do not form spontaneous-ly, and hence they are obtained by adding suitable reayents to the sugar liquor. The reagent then reacts or combines with at least some of the impurities forming a precipitate that can be removed.
Such a reagent, to be both useful and useable, must meet a number of important criteria, particularly the following:
(a) it should provide a precipitate which can easily be removed quantitatively, to provide a clear, non-hazy, sugar liquor.
(b) it should act efficiently,that is to say it should remove as high a proportion of the impurities as possible with as low an addition of reagent as possible.
(c) it should not be selective between different impur-ities.
(d) it should not leave any reagent residues in the sugar liquor since first such residues may cause problems when the sugar is used in comestibles, and second their presence may require addition of another purification step to remove them.
(e) it should be e-ffective to remove impurities which are present in very low concentrations: for example a 50% solution in water of raw sugar generally contains less than 1~ of total impur-ities.
These desiderata place significant constraints on the choice of reagen-ts that can be used. Additionally, these criteria tend to create the situation that a reagent useful at one point in the overall refinery sugar liquor circuit may not be of any use elsewhere in the sys-tem. Clearly, a level of convenience and economy can be achieved if -the same reagent can be used success-fully at several different points in the sugar liquor circuit.
In the initial clarification step applied to the raw sugar liquor the procedure generally adopted is to add, to a hot liquor containing about 65~ by weight of sugar, in sequence both phosphoric acid (H3P04) and milk of lime. This provides a calcium phosphate precipitate which carries down with it bo-th some of the impurities and some of the colored substances. But this precipi-tate is no-t easy to remove. It is known to add, to the hot liquor, a flocculating agent to assist in the removal step. One reagent used for this purpose is sold under the trade mark "Talofloc". It is alleged to contain a cationic quaternary ammonium compound of the formula:
CH2--( CH2 ) 16--CH3 CH3 - N - CH3 Cl-CH2 - (CH2)16-CH3_ This material is generally supplied as a gel in isopropanol, which contains about 70% of the active compound. It is referred to as a surfactant; the isopropanol also presents, to some degree a cer-tain fire risk.
This material is also often used in conjunction with another coagulant, which is sold under the trade mark "Taloflote".
It is alleged to be an anionic polymer, which is a copolymer of acrylic acid and acrylamide. Various grades are available con-taining various relative amounts of acrylic acid and acryla-mide units. However, it appears that this polymeric material is anion-ic and always contains more acrylamide units than acry~ic aci~
units, the maximum amount of acrylic acid units apparently being about 30%. It is generally supplied as a dry yranular material, which has to be dissolved in water before it can be added to -the sugar liquor. The maximum practical solubility, if viscous or partially ~elled materials are to be avoided, is about 0.1% by weight. This added water then has to be removed, at some later stage, by evaporation.
Whilst these reagents are effective, and indeed are commercially used, it is still true to say that this initial clar-ifying step, and other similar steps in the complete refinery sugar circuit, could be improved, especially the coagulation of the calcium phosphate precipitates discussed above.
We have now discovered that these various precipitate removal steps can be significantly improved by the use therein of a water soluble cationic homopolymer or copolymer polyelectrolyte.
This water soluble cationic polyelectrolyte additive has been ~n found to provide an easily handled floating floc, especially calcium phosphate flocs, and which also appears to remove undesir-able impurities, especially colored substances, better than the additives currently used to assist in calcium phosphate floc removal.
Further, it has also been found that the use of a water soluble cationic polyelectrolyte with an anionic acrylic-type polymer, which may be a homopolymer or a copolymer, further ~2,7~
enhances the process. Thus a cationic polyelectrolyte can be used to enhance coagulation of an initial calcium phosphate precipitate to a small-sized floc, and this in turn can be flocculated into a larger, and easily removed, floc by the use of a second acrylic-type anionic polyelectrolyte. These large flocs can then be easily removed from the sugar liquor. In this two-stage procedure the cationic polyelectrolyte generally will contain a quaternary ammonium group, such as a homopolymer containing dimethylamino ethyl methacrylate units. A suitable anionic polyelectrolyte generally will contain carboxyl groups, such as a polymer contain-ing acrylamide units and sodium acrylate units.
Thus in its broadest aspect -this invention provides a method for improving the removal of floc precipitates consisting mainly of calcium phosphate obtained in sugar liquors during the refining thereof which comprises adding to the sugar liquor a small but effective amount of a cationic water soluble polyelec-trolyte homopolymer or copolymer.
In a second broad aspect this invention provides a method for improving the removal of floc precipita~es consisting mainly of calcium phosphate obtained in sugar liquors during the refining thereof which comprises adding -to the sugar liquor in sequence a small but effective amount of a cationic water soluble polyelectrolyte homopolymer or copolymer, and of a small but effective amount of an oil-in-water emulsion of at least one anionic acrylamide copolymer polyelectrolyte.
It is noted that the anionic acrylic-type polymer is added as an oil-in-water emulsion. This is obtained by inverting a water-in-oil emulsion of -the polymer, preferably one which will spontaneously inver-t on addikion to water. The oil-in-water emul-sion can contain up to about 1% by weight of active polymer.
Preferably, an oil-in-water emulsion containing from about 0.3% to about 0.7% active polymer i5 used, as such solutions are conveni-ent to handle.
The oil carrier, together with at least some of the surfactant, in the emulsion is coagulated into the calcium phos-phate floc in the presence of the water soluble cationic polyelec-trolyte.
Typically the acrylamide copolymer water-in-oil emul-sions used in this invention contain approximately equal parts of copolymer, mineral oil, and water, together with suitable surfac-tants and stabilizers. Such emulsions are well known in the art.
In this application it is also highly desirable that the mineral oil used be essentially free of aromatics: an oil that is sub-stantially transparent to ultraviolet light in the wave band 280 to 350 m~ is suitable.
The acrylamide copolymers used herein are also well ~0 known in the art. Typical prepara~ion procedures are to be found in Canadian Patent 960,791 and in other similar sources. It is also known -that some of the polymers used herein can be prepared in a variety of ways: for example an acrylamide-acrylic acid copolymer can be obtained either by polymerizing a mixture of monomers, or by hydrolyzing an acrylamide homopolymer under suit-ably controlled conditions. It is also known that the molecular weights of these polymers can be controlled, to a degree, during their preparation. For the purposes of this invention, rnolecular weights of from 25,000 up to 100 million have been used success-fully. Where both a cationic and an anionic polyelectrolyte are used in sequence, it is preferred that the anionic polyelectrolyte have a molecular weight that i5 relatively high, being at least about 10 million and preferably about 15 million. On -the other hand, a cationic polyelectrolyte can have a relatively low molecu-lar weight, of the order of 25,000 -to 250,000, but higher molecu-lar weights are also usable.
The cationic polyelectrolytes used herein may be either homopolymers, such as polydimethyldiallylammonium chloride, or acrylic-type copolymers, such as a methacrylaminopropyl trimethyl-ammonium chloride, or a copolymer containing acrylamide, acrylic acid, and N-(dimethylaminomethyl)acrylamide units. Further usable cationic polymers are a polyethyleneamine mixture, and a polyamine condensation product of epichlorhydrin with dimethylamine.
The invention will now be described by way of the following examples. In all of these examples plant conditions were simulated on a laboratory scale. The sugar liquor bulk sample was treated with lime and phosphoric acid, sufficient phos-phonic acid is added to lower the pH to about 5, and lime is then added to raise the pH to about 8. Then 100 ml aliquot samples are taken from the treated bulk sample. Each aliquot, in a stoppered graduated cylinder, was then processed in the same way. Each cylinder was maintained at 88C in a water bath. To each cylinder was then added a color reducing reagent, and the contents mixed by inverting 5 times. The flotation reagent was then added, and the d~
cylinder shaken violently for 30 ~econds, partly to mix the con-tents thoroughly, and partly to mix air into the liquor, since an aeration step is used in a sugar refinery at this point. After standing -for 1 hour in the bath, samples were then withdrawn from the subnatent sugar liquor below the floating floccula-ted precipi-tate tby means of a syringe) for measurement purposes.
Each of the thus obtained subnatent solutions was then measured -Eor color and optical clarity on the Brinkman Scale. In this test, light is passed through a sample, and the amount of light absorbed is determined. An arbitrary scale of zero to 2,000 is used, in which ~ero corresponds to distilled water. If neces-sary a test sample may be diluted in order to obtain an observable value, which is then extrapolated to allow for the dilution. Two readings were applied to the subnatent sugar liquor samples: one reading was taken on the sample as removed, and the second after passing the sample through a membrane filter. The second reading gives an indication of color, whilst the difference between the readings gives an indication of turbidity in the sample, and thus indicates the efficiency of the flotation reagent used.
In the following examples the sugar liquor used is iden-tified as follows:
W.S.L. : a washed sugar liquor.
C.W.S.L. : a clarified washed sugar liquor.
~ew liquor ~ a C.W.S.L. further treated by passage through an activated carbon/bone char mixture~
Other sugar solutions are also used and identified.
Example 1 Clarification of W.S.L.
Four series of determinations were run, in which four cationic polymers are compared when used com'oined with the com-mercially available ma-terial Taloflote A-100, which was used as a precipitate coagulant. All polymers were allowed a contact time of 15 minutes prior to coagulation and subnatent examina~ion.
The W.S.L. used had a colour reading of 1163 and a turbidity of
2~9 before treatment. The four materials used were:
(1): A copolymer containing acrylamide, acrylic acid, and ~-(dimethylaminomethyl)acrylamide units, with a molecular weight 20,000 to 100,000.
(2) and (3): Two samples of polydimethylammonium chloride of differing molecular weights in the range 25,000 to 250,000.
(4): The commercially available material Talofloc.
(a) Turbidity When tested at additive levels of 100 ppm up to 500 ppm each of nos. 1, 2 and 3 reduced the turbid-ity to ~ero. The Taloflote at the same levels showed a minimum turbidity reading of 19 at 200 ppm loading; however, at loading ~0 levels giving adequate color removal of 300-500 ppm the turbidity was from 35 to 44.
(b) Color Removal The data is shown in the Eol-lowing table, which gives the observed color level for each addi-tive at the specified loading level, in ppm.
~ ~d~
T A B L E
Loading (1) (2) (3) (4) 200 828 757 7~9 894 300 788 687 6g4 835 350 793 679 6~2 786 400 787 667 667 7~3 500 7~7 648 648 651 Thus it is apparent that whilst all four additives pro-vide an acceptable reduction in colour at a comparitive 1O2ding level (e.g. a colour in the range 650-750 a~ loadings approaching 500 ppm) the Talofloc of additive no. 4 leaves significant turbid-ity whilst additives 1, 2, and 3 give æero turbidities.
Exam~le 2 In this Example a direct comparison is made between Additive (3) of Example 1 and Talofloc. In each case, Taloflote A-100 is used at a loading of 100 ppm as a flocculant.
Loading, Additive (3) Talofloc ppm. Colour Turbidity Colour Turbidity The original W.S.L. used showed: Colour 1135; Turbidity 205.
From this it can be seen that Additive (3) gives a consistently lower colour value, and, not until relatively a high loading is reached does any turbidity develop.
Example 3 In this Example a comparison is made using three differ-ent anionic polymers as coagulating agents in the presence of Additive (3) from Example 1, at a loading of 400 ppm, as colour reducing agent. The tests were applied to -three different sugar liquors with the following colours and turbidities:
~.S.L. Remelt feed Soft Sugar feed Colour 1260 5,063 7,260 Turbidity 362 `1,495 4,692 Additive (3) is as used in Example 1 above.
(A) W.S.L. feed~
(i) Additive (3) plus Taloflote A-100 Colour: 663; -turbidity: 9.
(ii) Additive (5) plus Additive (1) Colour: 618; turbidity: 0.
(iii) Taloflote A-100 plus Talofloc Colour: 817; turbidity: 42.
Additive (5) is a sodium acrylate-acrylamide copolymer having a molecular weight of about 15 million.
20(B) Remelt feed.
(i) Additive (1) plus Taloflote A-120 Colour: 2119; turbidity: 48 (ii) Additive (5) plus Additive (1) Colour: 2232; turbidity: 41.
(iii) Taloflote A-100 plus Talofloc Colour: 2259; turbidity: 62.
~ ~7~
(C) Soft Sugar feed.
(i) Taloflote 120 above.
Colour: 15,525; ~urbidity: 592.
(ii) Additive (5) above Colour: 16,376; -turbidity: 606.
Example 4 In a similar experiment to Example 3 a comparison was made between the commercially-used Taloflote/Talofloc combination and Additives ~1) and (5) combined, which represent a cationic ancl an anionic polymer, respectively. Again, W.S.L., Remel~, and Soft Sugar liquors were tested. In the following Table, colour and turbidities are given as a/b.
W.S.L. RemeltSoft SugarL.
Feed 822/723 1128/31012172/912 Talofloc + Taloflote A-100 679/8 523/09309/308 Additives (1) and (5) 604/8 614/910200/374 In each of these Experiments Additives (1) - (3) and ~5) were used as a water-in-oil emulsion containing typically about 35-40% polymex, 20-25~ mineral oil, and 35-40~ water, together with about 2-3% of suitable surfactants, and stabilizers. For all of these additives the mineral oil is substantially transparent at 280 to 350 m~, indicating no aromatic compounds are present.
Before addition to the sugar liquors, these water-in-oil emulsions were inverted to oil-in-water emulsion containing about 0.1 active polymers.
(1): A copolymer containing acrylamide, acrylic acid, and ~-(dimethylaminomethyl)acrylamide units, with a molecular weight 20,000 to 100,000.
(2) and (3): Two samples of polydimethylammonium chloride of differing molecular weights in the range 25,000 to 250,000.
(4): The commercially available material Talofloc.
(a) Turbidity When tested at additive levels of 100 ppm up to 500 ppm each of nos. 1, 2 and 3 reduced the turbid-ity to ~ero. The Taloflote at the same levels showed a minimum turbidity reading of 19 at 200 ppm loading; however, at loading ~0 levels giving adequate color removal of 300-500 ppm the turbidity was from 35 to 44.
(b) Color Removal The data is shown in the Eol-lowing table, which gives the observed color level for each addi-tive at the specified loading level, in ppm.
~ ~d~
T A B L E
Loading (1) (2) (3) (4) 200 828 757 7~9 894 300 788 687 6g4 835 350 793 679 6~2 786 400 787 667 667 7~3 500 7~7 648 648 651 Thus it is apparent that whilst all four additives pro-vide an acceptable reduction in colour at a comparitive 1O2ding level (e.g. a colour in the range 650-750 a~ loadings approaching 500 ppm) the Talofloc of additive no. 4 leaves significant turbid-ity whilst additives 1, 2, and 3 give æero turbidities.
Exam~le 2 In this Example a direct comparison is made between Additive (3) of Example 1 and Talofloc. In each case, Taloflote A-100 is used at a loading of 100 ppm as a flocculant.
Loading, Additive (3) Talofloc ppm. Colour Turbidity Colour Turbidity The original W.S.L. used showed: Colour 1135; Turbidity 205.
From this it can be seen that Additive (3) gives a consistently lower colour value, and, not until relatively a high loading is reached does any turbidity develop.
Example 3 In this Example a comparison is made using three differ-ent anionic polymers as coagulating agents in the presence of Additive (3) from Example 1, at a loading of 400 ppm, as colour reducing agent. The tests were applied to -three different sugar liquors with the following colours and turbidities:
~.S.L. Remelt feed Soft Sugar feed Colour 1260 5,063 7,260 Turbidity 362 `1,495 4,692 Additive (3) is as used in Example 1 above.
(A) W.S.L. feed~
(i) Additive (3) plus Taloflote A-100 Colour: 663; -turbidity: 9.
(ii) Additive (5) plus Additive (1) Colour: 618; turbidity: 0.
(iii) Taloflote A-100 plus Talofloc Colour: 817; turbidity: 42.
Additive (5) is a sodium acrylate-acrylamide copolymer having a molecular weight of about 15 million.
20(B) Remelt feed.
(i) Additive (1) plus Taloflote A-120 Colour: 2119; turbidity: 48 (ii) Additive (5) plus Additive (1) Colour: 2232; turbidity: 41.
(iii) Taloflote A-100 plus Talofloc Colour: 2259; turbidity: 62.
~ ~7~
(C) Soft Sugar feed.
(i) Taloflote 120 above.
Colour: 15,525; ~urbidity: 592.
(ii) Additive (5) above Colour: 16,376; -turbidity: 606.
Example 4 In a similar experiment to Example 3 a comparison was made between the commercially-used Taloflote/Talofloc combination and Additives ~1) and (5) combined, which represent a cationic ancl an anionic polymer, respectively. Again, W.S.L., Remel~, and Soft Sugar liquors were tested. In the following Table, colour and turbidities are given as a/b.
W.S.L. RemeltSoft SugarL.
Feed 822/723 1128/31012172/912 Talofloc + Taloflote A-100 679/8 523/09309/308 Additives (1) and (5) 604/8 614/910200/374 In each of these Experiments Additives (1) - (3) and ~5) were used as a water-in-oil emulsion containing typically about 35-40% polymex, 20-25~ mineral oil, and 35-40~ water, together with about 2-3% of suitable surfactants, and stabilizers. For all of these additives the mineral oil is substantially transparent at 280 to 350 m~, indicating no aromatic compounds are present.
Before addition to the sugar liquors, these water-in-oil emulsions were inverted to oil-in-water emulsion containing about 0.1 active polymers.
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for improving the removal of floc precipitates consisting mainly of calcium phosphate obtained in sugar liquors during the refining thereof which comprises adding to the sugar liquor a small but effective amount of a cationic water soluble polyelectrolyte homopolymer or copolymer.
2. A method for improving the removal of floc precipitates consisting mainly of calcium phosphate obtained in sugar liquors during the refining thereof which comprises adding to the sugar liquor in sequence a small but effective amount of a cationic water soluble polyelectrolyte homopolymer or copolymer, and of a small but effective amount of an oil-in-water emulsion of at lest one anionic acrylamide copolymer polyelectrolyte.
3. A method according to claim 2 wherein the oil in the oil-in-water emulsion is substantially free of aromatic substan-ces.
4. A method according to claim 2 wherein the cationic poly-electrolyte is added in an amount of from 100 to 500 ppm.
5. A method according to claim 2 wherein the cationic poly-electrolyte is added in an amount of about 200 to 500 ppm.
6. A method according to claim 2 wherein the anionic poly-mer oil-in-water emulsion is added in an amount of from 20 to 100 ppm.
7. A method according to claim 2 wherein the oil-in-water emulsion is added in an amount of about 40 ppm.
8. A method according to claim 2, wherein the acrylamide copolymer is chosen from copolymers containing acrylamide, acrylic acid, and sodium acrylate.
9. A method according to claims 1 or 2 wherein the cationic polymer is chosen from poly(dimethyl diallyl ammonium chloride);
acrylamide copolymers containing acrylamide, acrylic acid, sodium acrylate and N-(dimethylaminomethyl)acrylamide monomer units;
polyethyleneamine polymers, and polyamine condensation products of epichlorhydrin with dimethylamine.
acrylamide copolymers containing acrylamide, acrylic acid, sodium acrylate and N-(dimethylaminomethyl)acrylamide monomer units;
polyethyleneamine polymers, and polyamine condensation products of epichlorhydrin with dimethylamine.
10. A method according to claim 1 wherein the polymer has a molecular weight of from about 25,000 to 100 million.
11. A method according to claim 2 wherein the anionic poly-mer has a molecular weight of at least about 10 million, and the cationic polymer has a molecular weight of at least about 25,000.
12. A method according to claim 2 wherein the oil-in-water emulsion contains up to about 1% by weight of active polymer.
13. A method according to claim 12 wherein the oil-in-water emulsion contains from about 003% to about 0.7% by weight of active polymer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000512485A CA1272191A (en) | 1986-06-26 | 1986-06-26 | Method of clarifying sugar liquors using a cationic polyelectrolyte treatment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000512485A CA1272191A (en) | 1986-06-26 | 1986-06-26 | Method of clarifying sugar liquors using a cationic polyelectrolyte treatment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1272191A true CA1272191A (en) | 1990-07-31 |
Family
ID=4133440
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000512485A Expired CA1272191A (en) | 1986-06-26 | 1986-06-26 | Method of clarifying sugar liquors using a cationic polyelectrolyte treatment |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1272191A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6238486B1 (en) | 1999-03-10 | 2001-05-29 | Nalco Chemical Company | Detectable cationic flocculant and method of using same in industrial food processes |
-
1986
- 1986-06-26 CA CA000512485A patent/CA1272191A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6238486B1 (en) | 1999-03-10 | 2001-05-29 | Nalco Chemical Company | Detectable cationic flocculant and method of using same in industrial food processes |
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