Claims:WE CLAIM:
1. A scale inhibiting composition comprising;
a) a polymer having a structure of formula I;

Formula I
wherein,

x, y and n are integers;
where, x is in the range of 1 to 40;
y is in the range of 1 to 80 and
n is in the range of 1 to 120;
b) at least one phosphonate compound; and
c) optionally, an additive selected from a corrosion inhibitor and a biocide.
2. The composition as claimed in claim 1, wherein said composition for reverse osmosis water treatment comprises;
a) 40 to 75% of said polymer with respect to the total weight of the composition; and
b) 25 to 60% of said at least one phosphonate compound with respect to the total weight of the composition.
3. The composition as claimed in claim 1, wherein said composition for cooling system water treatment comprises;
a) 10 to 40% of said polymer with respect to the total weight of the composition;
b) 25 to 50% of said at least one phosphonate compound with respect to the total weight of the composition;
c) 10 to 35% of said corrosion inhibitor with respect to the total weight of the composition; and
d) 15 to 45% of said biocide with respect to the total weight of the composition.
4. The composition as claimed in any one of preceding claims, wherein said polymer is a copolymer or a terpolymer of polycarboxylate ether prepared by using at least one monomer selected from the group consisting of acrylic acid (AA), mathacrylic acid (MAA), maleic anhydride (MA), itaconic acid (IA), vinyl sulfonic acid (VSA), acrylamide (AAM), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), styrene sulfonic acid (SSA), methyl allyl sulfonate (MAS), sodium methacrylic sulfonate (SMAS), vinyl phosphonic acid (VPA), isobutenylpolyethylene glycol (IPEG), methylallylpoly oxygenethene ether (HPEG), isopentenyl polyethylene glycol (TPEG), 4-hydroxybutylvinyl polyoxyethylene ether (VPEG), allyl polyoxyethylene ether (APEG), methoxypolyethylene glycol methacrylate.
5. The composition as claimed in any one of the preceding claims, wherein a weight average molecular weight of said polymer is in the range of 2000 to 60,000 g/mole.
6. The composition as claimed in claims 1 to 3, wherein said phosphonate compound is at least one selected from the group consisting of aminomethylphosphonic acid (AMPA), dimethyl methylphosphonate (DMMP), ), 1-hydroxyethylidene(1,1-diphosphonic acid) (HEDP), aminotris(methylphosphonic acid) (ATMP), ethylenediaminetetra(methylene phosphonic acid) (EDTMP), tetramethylenediaminetetra(methylenephosphonic acid) (TDTMP), hexamethylenediaminetetra(methylenephosphonic acid) (HDTMP), diethylenetriaminepenta-(methylene phosphonic acid) (DTPMP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), N-(phosphonomethyl)iminodiacetic acid (PMIDA), 2-carboxyethyl phosphonic acid (CEPA), aminotris(methylenephosphonic acid) (AMP), phosphonocarboxylic Acid (POCA), hydroxyethylamino-Di(Methylene phosphonic Acid) (HEMPA), and polyamino polyether methylene phosphonic acid (PAPEMPA).
7. The composition as claimed in claim 3, wherein said corrosion inhibitor is selected from the group consisting of 2-hydroxyphosphonocarboxylic acid (HPAA), sodium hexametaphosphate (SHMP), trisodium phosphate (TSP), di-sodium phosphate (DSP), zinc chloride, zinc tungstate, sodium tungstate, sodium molybdate, sodium nitrite, sodium silicate, potassium silicate, imidazolines, triethanol amine TEA), polyaspartic acid (PASP), benzotriazole (BTA), tolytriazole (TTA), buttyl benzotriazole (BBT) pentoxy benzotriazole (POBT), and chloro-tolyltriazole.
8. The composition as claimed in claim 3, wherein said biocide is selected from the group consisting of sodium hypochlorite, chlorine dioxide, bromine, iodine, hydrogen peroxide, peracetic acid , isothiazoline (MIT/BIT), 2,2-dibromo3-nitrilo propionamide (DBNPA), sodium dimethyldithiocarbamate, potassium dimethyldithiocarbamate, 2-(tertbutylamino)-4- chloro -6-(ethylamino)-striazine, glutaraldehyde, and alkyldimethylbenzylammonium chloride.
9. The composition as claimed in claims 1 to 3, wherein said composition inhibits the scale formation in an aqueous system having a concentration of silica in the range of 50 ppm to 1000 ppm and a concentration of calcium in the range of 100 ppm to 1500 ppm.
10. The composition as claimed in claims 1 to 3, wherein said composition inhibits the scale formation when used at a concentration in the range of 1 ppm to 100 ppm.
11. The composition as claimed in claims 1 to 3, wherein said composition inhibits the scale formation at a temperature in the range of 10 °C to 80 °C.
12. A process for the preparation of a scale inhibiting composition as claimed in claims 1 to 3, said process comprises;
(i) mixing predetermined amounts of at least one polymer, at least one phosphonate compound and optionally an additive at a first predetermined speed at a temperature in the range of 25 °C to 35 °C for a first predetermined time period to obtain a mixture; and
(ii) blending said mixture at a second predetermined speed at a temperature in the range of 25 °C to 35 °C for a second predetermined time period to obtain said scale inhibiting composition.
13. The process as claimed in claim 12, wherein said first predetermined speed is in the range of 50 rpm to 150 rpm and wherein said second predetermined speed is in the range of 200 rpm to 400 rpm.
14. The process as claimed in claim 12, wherein said first predetermined time period in the range of 5 minutes to 20 minutes and wherein said second predetermined time period in the range of 50 minutes to 80 minutes
15. A method of inhibiting the scale deposition of silica and calcium compounds in an aqueous system comprising adding an effective amount of the composition as claimed in claim 1 to said aqueous system.
Dated this 07th day of July, 2021

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI
, Description:FIELD
The present disclosure relates to a scale inhibiting composition and a process for its preparation.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Scales are observed due to availability of Silica (SiO2) and hardness (e.g. calcium and magnesium) in fresh water. They are difficult to control once set in and are not soluble in most of the chemicals except hydrofluoric acid.
In cooling water systems, silica and silicate compounds, form deposits, on the internal metal surfaces which are in contact with water that is flowing through the system. Therefore, the heat transfer efficiency of the internal metal surfaces becomes severely impeded, which in turn has a deleterious effect on the overall operating efficiency of the cooling water system. Silica and silicate deposition also causes problems on other conduit and piping surfaces, as well as on equipment such as valves, nozzles and pumps.
Although, the current industrial cooling systems make use of sophisticated external treatments of the feed water, e.g., coagulation, filtration, softening of water prior to it being fed into the water system, these operations are only moderately effective. Conventionally, the silicate scales with calcium or magnesium are prevented by removal of silica or hardness or both from water via ion exchange or by using polyelectrolytes. However, only colloidal silica is removed in this way. If the scale deposition formed is less, they can be solubilized by use of alkali or by use of ammonium bifluoride like chemicals which generate hydrofluoric acid in situ and hydrofluoric acid is one of the most dangerous inorganic acids. Further, use of copolymers and terpolymers along with phoshponates to prevent scale formation or to effect scale dispersion are the common techniques. However, these solutions can help to prevent silicate scale deposit upto certain limit of silica and calcium/magnesium ions in water beyond which the formation of scale cannot be controlled.
In all cases, external treatment does not provide adequate treatment since muds, sludge, silts, and dissolved solids such as silicate can escape the treatment and eventually are introduced into the system. It is not possible to remove reactive silica completely thus, the complete prevention of scales by using the conventional methods are ruled out.
Therefore, there is felt a need to provide a scale inhibiting composition and a process for its preparation, which mitigates the drawbacks mentioned herein above.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
Another object of the present disclosure is to provide a scale inhibiting composition.
Yet another object of the present disclosure is to provide a scale inhibiting composition that can control calcium, magnesium, silicate scales during water treatment.
Still another object of the present disclosure is to provide a simple, economic and environment friendly process for the preparation of a scale inhibiting composition.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a scale inhibiting composition. The composition comprises;
a) a polymer having a structure of formula I;

Formula I
wherein,

x, y and n are integers;
where, x is in the range of 1 to 40;
y is in the range of 1 to 80 and
n is in the range of 1 to 120;
b) at least one phosphonate compound; and
c) optionally, an additive selected from a corrosion inhibitor and a biocide.
In an embodiment, the scale inhibiting composition for reverse osmosis water treatment comprises 40 to 75% of the polymer with respect to the total weight of the composition and 25 to 60% of at least one phosphonate compound with respect to the total weight of the composition.
In another embodiment, the scale inhibiting composition for cooling system water treatment comprises 10 to 40% of the polymer with respect to the total weight of the composition, 25 to 50% of at least one phosphonate compound with respect to the total weight of the composition, 10 to 35% of the corrosion inhibitor with respect to the total weight of the composition and 15 to 45% of the biocide with respect to the total weight of the composition.
The present disclosure further relates to a process for the preparation of the scale inhibiting composition. The process comprises the step of mixing predetermined amounts of at least one polymer, at least one phosphonate compound and optionally an additive at a first predetermined speed at a temperature in the range of 25 °C to 35 °C for a first predetermined time period to obtain a mixture. The mixture is blended at a second predetermined speed at a temperature in the range of 25 °C to 35 °C for a second predetermined time period to obtain said scale inhibiting composition.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
Figure I illustrates the general structure of polycarboxylate ether;
Figure II illustrates a first type of mechanism of polycarboxylate ether polymer as an antiscalant to inhibit the formation of scales i.e. chelation by encapsulation;

Figure III illustrates a second type of mechanism of polycarboxylate ether polymer as an antiscalant to inhibit the formation of scales i.e. dispersion by electrosteric effect; and
Figure IV illustrates a third type of mechanism of polycarboxylate ether polymer as an antiscalant to inhibit the formation of scales i.e. by crystal modification.
Reference Numerals:
1 Carboxylic/carboxylate group containing monomer segment
2 Ether containing monomer segment
3 Random copolymer molecules
3a Multivalent Cation
4 Encapsulation
5 Highly dissolved solid particles
6 Ionic product
7 Ion pairing
8 Aggregation
9 Nucleation
10 Macrocrystal formation
11 Agglomeration and deposition
12 Antiscalant
13 Antiscalant adsorbed on macrocrystals
14 Crystal modification
15 Dispersion
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
The silicate scales are observed due to availability of silica (SiO2) and hardness (e.g. calcium and magnesium) in a fresh water. They are difficult to control once set in and are not soluble in most of the chemicals except hydrofluoric acid.
Conventionally, the silicate scales with calcium or magnesium are prevented by removal of silica or removal of hardness or both from water via ion exchange or using polyelectrolytes. However, only colloidal silica is removed in this way. If the scale deposition formed is less, they can be solubilized by use of an alkali or by use of ammonium bifluoride like chemicals which generate hydrofluoric acid in situ and hydrofluoric acid is one of the most dangerous inorganic acids. Further, use of copolymers and terpolymers along with phoshponates to prevent scale formation or to effect scale dispersion are the common techniques. However, these solutions can help to prevent silicate scale deposit upto certain limit of silica and calcium/magnesium ions in water, beyond which the formation of scale cannot be controlled.
The present disclosure provides a scale inhibiting composition and a process for its preparation.
In an aspect, the present disclosure provides a scale inhibiting composition. The composition comprises:
a) a polymer having a structure of formula I;

Formula I
wherein,

x, y and n are integers;
where, x is in the range of 1 to 40;
y is in the range of 1 to 80 and
n is in the range of 1 to 120;
b) at least one phosphonate compound; and
c) optionally, an additive selected from a corrosion inhibitor and a biocide.
In an embodiment, the scale inhibiting composition for reverse osmosis water treatment comprises 40 to 75% of the polymer with respect to the total weight of the composition and 25 to 60% of at least one phosphonate compound with respect to the total weight of the composition.
In another embodiment, the scale inhibiting composition for cooling system water treatment comprises 10 to 40% of the polymer with respect to the total weight of the composition, 25 to 50% of at least one phosphonate compound with respect to the total weight of the composition, 10 to 35% of the corrosion inhibitor with respect to the total weight of the composition and 15 to 45% of the biocide with respect to the total weight of the composition.
In accordance with the present disclosure, the polymer is a copolymer or a terpolymer of polycarboxylate ether prepared by using at least one monomer selected from the group consisting of acrylic acid (AA), mathacrylic acid (MAA), maleic anhydride (MA), itaconic acid (IA), vinyl sulfonic acid (VSA), acrylamide (AAM), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), styrene sulfonic acid (SSA), methyl allyl sulfonate (MAS), sodium methacrylic sulfonate (SMAS), vinyl phosphonic acid (VPA), isobutenylpolyethylene glycol (IPEG), methylallylpoly oxygenethene ether (HPEG), isopentenyl polyethylene glycol (TPEG), 4-hydroxybutylvinyl polyoxyethylene ether (VPEG), allyl polyoxyethylene ether (APEG), methoxypolyethylene glycol methacrylate.
In accordance with the present disclosure, the copolymer of polycarboxylate ether is obtained by polymerizing an ether containing monomer and a carboxylic/carboxylate group containing monomer, wherein the ether containing monomer is selected from isobutenylpolyethylene glycol (IPEG), methylallylpoly oxygenethene ether (HPEG), isopentenyl polyethylene glycol (TPEG), 4-hydroxybutylvinyl polyoxyethylene ether (VPEG), allyl polyoxyethylene ether (APEG), methoxypolyethylene glycol methacrylate and the carboxylic/carboxylate group containing monomer is selected from acrylic acid (AA), methacrylic acid (MAA), maleic acid/maleic anhydride (MA), itaconic acid (IT), fumaric acid (FA).
In accordance with the present disclosure, the terpolymer of polycarboxylate ether is obtained by polymerizing the ether containing monomer, the carboxylic/carboxylate group containing monomer and a sulfonate/phosphonate/amide group containing monomer, wherein the ether containing monomer is selected from isobutenylpolyethylene glycol (IPEG), methylallylpoly oxygenethene ether (HPEG), isopentenyl polyethylene glycol (TPEG), 4-hydroxybutylvinyl polyoxyethylene ether (VPEG), allyl polyoxyethylene ether (APEG), methoxypolyethylene glycol methacrylate and the carboxylic/carboxylate group containing monomer is selected from acrylic acid (AA), methacrylic acid (MAA), maleic acid/maleic anhydride (MA), itaconic acid (IT), fumaric acid (FA) and wherein the sulfonate/phosphonate/amide group containing monomer is selected from vinyl suifonic acid (VSA), acrylamide (AM), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), styrene sulfonic acid (SSA), methyl allyl sulfonate (MAS), sodium methacrylic sulfonate (SMAS), vinyl phosphonic acid (VPA).
In an embodiment of the present disclosure, the copolymer or the terpolymer of polycarboxylate ether has a weight average molecular weight in the range of 2000 to 60,000 g/mole.
In accordance with the present disclosure, the phosphonate compound is at least one selected from the group consisting of aminomethylphosphonic acid (AMPA), dimethyl methylphosphonate (DMMP), ), 1-hydroxyethylidene(1,1-diphosphonic acid) (HEDP), aminotris(methylphosphonic acid) (ATMP), ethylenediaminetetra(methylene phosphonic acid) (EDTMP), tetramethylenediaminetetra(methylenephosphonic acid) (TDTMP), hexamethylenediaminetetra(methylenephosphonic acid) (HDTMP), diethylenetriaminepenta-(methylene phosphonic acid) (DTPMP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), N-(phosphonomethyl)iminodiacetic acid (PMIDA), 2-carboxyethyl phosphonic acid (CEPA), aminotris(methylenephosphonic acid) (AMP), phosphonocarboxylic cid (POCaA), hydroxyethylamino-di(Methylene phosphonic acid) (HEMPA), polyamino polyether methylene phosphonic acid (PAPEMPA).
In accordance with the present disclosure, the corrosion inhibitor is selected from the group consisting of 2-hydroxyphosphonocarboxylic acid (HPAA), sodium hexametaphosphate (SHMP), trisodium phosphate (TSP), di-sodium phosphate (DSP), zinc chloride, zinc tungstate, sodium tungstate, sodium molybdate, sodium nitrite, sodium silicate, potassium silicate, imidazolines, triethanol amine TEA), polyaspartic acid (PASP), benzotriazole (BTA), tolytriazole (TTA), buttyl benzotriazole (BBT) and pentoxy benzotriazole (POBT), chloro-tolyltriazole.
In accordance with the present disclosure, the biocide is selected from the group consisting of sodium hypochlorite, chlorine dioxide, bromine, iodine, hydrogen peroxide, peracetic acid, isothiazoline (MIT/BIT), 2,2-dibromo3-nitrilo propionamide (DBNPA), sodium dimethyldithiocarbamate, potassium dimethyldithiocarbamate, 2-(tertbutylamino)-4- chloro -6-(ethylamino)-striazine, glutaraldehyde, and alkyldimethylbenzylammonium chloride.
In an exemplary embodiment, the scale inhibiting composition for reverse osmosis water treatment comprises 60% of the polycarboxylate ether (PCE) polymer (isopentenyl polyethylene glycol (TPEG) acrylic acid (AA) copolymer) with respect to the total weight of the composition and 40% of phosphonate compounds (25% of polyamino polyether methylene phosphonic acid (PAPEMPA), 10% of 2-phosphonobutane 1,2,4-tricarboxylic acid (PBTC) and 5% of amino trimethylene phosphonic acid (ATMP)) with respect to the total weight of the composition.
In another exemplary embodiment, the scale inhibiting composition for cooling system water treatment comprises 30% of the polycarboxylate ether (PCE) polymer (isopentenyl polyethylene glycol (TPEG) acrylic acid (AA) copolymer) with respect to the total weight of the composition, 33% of phosphonate compounds (16% of 2-phosphonobutane 1,2,4-tricarboxylic acid (PBTC) and 17% of hydroxyethylidene diphosphonic acid (HEDP)) with respect to the total weight of the composition, 17% of 2-hydroxy phosphonoaacetic acid (HPAA) as a corrosion inhibitor with respect to the total weight of the composition and 20% of alkyldimethylbenzylammonium chloride as a biocide with respect to the total weight of the composition.
The scale inhibition composition of the present disclosure inhibits the scale formation in an aqueous system having a concentration of silica in the range of 50 ppm to 1000 ppm and a concentration of calcium in the range of 100 ppm to 1500 ppm.
The scale inhibition composition of the present disclosure inhibits the scale formation in an aqueous system when the composition is used at a concentration in the range of 1 ppm to 100 ppm.
In an exemplary embodiment of the present disclosure, 50 ppm of the scale inhibition composition inhibits the scale formation in the aqueous system having 350 ppm of silica and 800 ppm of calcium.
In accordance with the present disclosure, the scale inhibition composition inhibits the scale formation at a temperature in the range of 10 °C to 80 °C.
In another aspect, the present disclosure provides a process for the preparation of a scale inhibiting composition. The process comprises the following steps:
In a first step, predetermined amounts of at least one polymer, at least one phosphonate compound and optionally at least one additive are mixed at a first predetermined speed at a temperature in the range of 25 °C to 35 °C for a first predetermined time period to obtain a mixture.
The first predetermined speed is in the range of 50 rpm to 150 rpm. In an exemplary embodiment of the present disclosure, the first predetermined speed is 100 rpm.
The first predetermined time period is in the range of 5 minutes to 20 minutes. In an exemplary embodiment of the present disclosure, the first predetermined time period is 10 min.
In the next step, the mixture is blended at a second predetermined speed at a temperature in the range of 25 °C to 35 °C for a second predetermined time period to obtain the scale inhibiting composition.
The second predetermined speed is in the range of 200 rpm to 400 rpm. In an exemplary embodiment of the present disclosure, the second predetermined speed is 300 rpm.
The second predetermined time period is in the range of 50 minutes to 80 minutes. In an exemplary embodiment of the present disclosure, the first predetermined time period is 60 min.
In yet another aspect, the present disclosure provides a method for inhibiting the scale deposition of silica and calcium compounds in an aqueous system comprising adding an effective amount of the scale inhibiting composition to the aqueous system.
The present disclosure is further illustrated with the help of the figures.
Figure-I illustrates the general structure of polycarboxylate ether comprising a carboxylic/carboxylate group containing monomer segment (1) and a ether containing monomer segment (2).
In accordance with the present disclosure, the scale inhibiting composition comprising polycarboxylate ethers can inhibit the scale formation via three types of mechanism viz. chelation by encapsulation, dispersion by electrosteric effect and by crystal modification.
Figure-II illustrates a first type of mechanism of polycarboxylate ether polymer as an antiscalant in the composition of the present disclosure, wherein the polycarboxylate ether polymer inhibits the formation of scales via chelation by encapsulation, wherein the random copolymer molecules (3) bind with the multivalent cations (3a) and thus encapsulating (4) the scale forming multivalent cations which leads to the dissolution of the solid scale forming particles (5).
Both, the carboxylic/carboxylate group containing monomer segment (1) and the ether containing monomer segment (2) are hydrophilic in nature and exist as random copolymer molecules (3). When multivalent cation (3a) comes in contact with the antiscalant of the composition (random copolymer molecules), the carboxylic groups of antiscalant (random copolymer molecules), encapsulate the multivalent cation in solution and form polymer-cation complexes (4). Simultaneously, water compatible side chains of antiscalant surrounding the polymer-cation complex, form core shell structure which results in highly dissolved particles (5).
Figure III illustrates a second type of mechanism of polycarboxylate ether polymer as an antiscalant in the composition of the present disclosure, wherein the polycarboxylate ether polymer inhibits the formation of scales via dispersion by electrosteric effect, wherein the polycarboxylate ether polymer gets adsorbed on the scale forming crystals and the carboxylic/carboxylate group containing monomer segment results in electrostatic repulsion and the long side chains (ether containing monomer segment) in polymer matrix result in steric hindrance. Due to elecrosteric (electrostatic + steric hindrance) mechanism, the scale forming crystals are effectively dispersed and thus, crystal agglomeration and crystal growth are prevented.
Figure IV illustrates a third type of mechanism of polycarboxylate ether polymer as an antiscalant in the composition of the present disclosure, wherein the polycarboxylate ether polymer inhibits the formation of scales (6-9) by crystal modification, wherein the scale forming macrocrystals (10) when comes in contact with the polycarboxylate ether polymer (antiscalant) (12), crystal modification takes place (14) which prevents the build up of regular crystalline lattice.
The polycarbyxylate ether polymer (antiscalant) gets adsorbed on the active site of the macrocrystals (13) and modifies the macrocrystals (14). Crystal modification prevents the buildup of a regular crystalline lattice. Thus, the scale deposition is impeded due to the crystal modification.
The scale inhibiting composition of the present disclosure uses polycarboxylate ethers along with the phosphonate compounds that are found to prevent calcium/magnesium silicate scales in high silica and calcium ion containing water at ambient temperatures and even at higher temperatures. In addition, the polycarboxylate ethers containing composition of the present disclosure, exhibited excellent dispersion of formed silicate scales over a longer period of time.
The present disclosure provides the scale inhibiting composition that is appropriate for various important applications in the field of water treatments such as reverse osmosis system, cooling water system, boiler water system and desalination and the like.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENTAL DETAILS
Experiment 1: Process for the preparation of a scale inhibition composition in accordance with the present disclosure
Example 1: Preparation of a scale inhibition composition for reverse osmosis water treatment (RO application)
In 1 litter glass reactor/round bottom flask, 60 g of isopentenyl polyethylene glycol (TPEG) acrylic acid (AA) copolymer (PCE polymer) was added followed by adding a mixture of phosphonate compounds {25 g polyamino polyether methylene phosphonic acid (PAPEMPA), 10 g 2-phosphonobutane 1,2,4-tricarboxylic acid (PBTC) and 5 g amino trimethylene phosphonic acid (ATMP)}, under stirring at 100 rpm for 10 minutes at 30 °C to obtain a mixture. The mixture was blended at 300 rpm for 1 hour at 30 °C to obtain the scale inhibiting composition. The physical properties (pH and % of non-volatile solid matter) of the composition were checked. The pH was 0.8 and the non-volatile solid matter was 50.5%.
Example 2: Preparation of a scale inhibition composition, for cooling system water treatment
In 1 litter glass reactor/round bottom flask, 30 g of isopentenyl polyethylene glycol (TPEG) acrylic acid (AA) copolymer (PCE polymer) was added followed by adding a mixture of phosphonate compounds {16 g 2-phosphonobutane 1,2,4-tricarboxylic acid (PBTC) and 17 g hydroxyethylidene diphosphonic acid (HEDP)}, 17 g 2-hydroxy phosphonoaacetic acid (HPAA) as a corrosion inhibitor and 20 g myristyldimethylbenzylammonium chloride as a biocide under stirring at 100 rpm for 15 minutes at 30 °C to obtain a mixture. The mixture was blended at 300 rpm for 60 minutes at 30 °C to obtain the scale inhibiting composition. The physical properties (pH and % of non-volatile solid matter) of the composition were checked. The pH was 1.2 and the non-volatile solid matter was 52.8%.
Experiment 2: Method of inhibiting the scale deposition of silica and calcium compounds in aqueous systems by using the scale inhibition composition prepared in Examples 1 and 2
Example I: Inhibition of the scale deposition of silica and calcium compounds in an aqueous system by using the scale inhibition composition prepared in Example 1
Ia. Test for Scale inhibition composition (PCE polymer + Phosphonate compounds):
In a glass bottle, synthetically prepared water (containing 800 ppm calcium as calcium chloride, 350 ppm silica as sodium silicate) was added followed by adding 50 ppm of the scale inhibition composition prepared in Example 1 and was mixed properly to obtain a solution. The glass bottle containing the solution was kept in a water bath at 45 °C for 2 hours. After 2 hours, the solution was filtered using Whatman filter paper 42 to obtain a filtrate. The filtrate was used to determine the % inhibition of silica and calcium scales in the synthetically prepared water by color development with ammonium molybdate method.
Ib. Test for only PCE polymer:
The same procedure was followed as in Example Ia except that only PCE polymer (isopentenyl polyethylene glycol (TPEG) acrylic acid (AA) copolymer) was used instead of scale inhibition composition.
Ic. Test for only Phosphonate compounds:
The same procedure was followed as in Example Ia except that only phosphonate compounds (polyamino polyether methylene phosphonic acid (PAPEMPA), 2-phosphonobutane 1,2,4-tricarboxylic acid (PBTC) and amino trimethylene phosphonic acid (ATMP)) were used instead of scale inhibition composition.
% silica available at 0th time for all three experiments1a-1c) was 100%. As time passes, silica level falls due to complexation of silica scale with the scale inhibition composition.
The % inhibition of silica and calcium scales in the synthetically prepared water are as given in Table 1.
Table 1: Test Results of % inhibition
Examples I-(Ia-Ic) Product Product dose % Inhibition
Ia. Scale inhibition composition (PCE + Phosphonate compounds) 50 ppm 90.1%
Ib. Only PCE polymer 50 ppm 81.5%
Ic. Only Phosphonate compounds 50 ppm 39.2%
From the above Table 1, it is clear that the scale inhibition composition (PCE + Phosphonate composite) of the present disclosure is more effective in inhibiting the silica and calcium scales as compared to the PCE polymer and phosphonate compounds when used individually.
Using PCE polymer in combination with the phosphonate compounds show synergistic effect because they work in combination. PCE polymer inhibits scales by electrosteric mechanism and thus effectively disperses the scales. The phophonate compounds work by electrostatic repulsion mechanism. Further, the PCE polymer and the phophonate compounds also effectively chelate/encapsulate the positive ions (like calcium) and prevent formation of scales.
Example II: Inhibition of the scale deposition of silica and calcium compounds in an aqueous system by using the scale inhibition composition prepared in Example 2
IIa. Test for Scale inhibition composition (PCE polymer + Phosphonate compounds + corrosion inhibitor + biocide):
The same procedure was followed as in Example Ia except that the scale inhibition composition prepared in Example 2 was used.
IIb. Test for PCE polymer + corrosion inhibitor:
The same procedure was followed as in Example Ia except that the PCE polymer (isopentenyl polyethylene glycol (TPEG) acrylic acid (AA) copolymer) + corrosion inhibitor (2-hydroxy phosphonoaacetic acid (HPAA)) were used instead of scale inhibition composition.
IIc. Test for PCE polymer + biocide:
The same procedure was followed as in Example Ia except that the PCE polymer (isopentenyl polyethylene glycol (TPEG) acrylic acid (AA) copolymer) + biocide (myristyldimethyl benzyl ammonium chloride) were used instead of scale inhibition composition.
IId. Test for only PCE polymer:
The same procedure was followed as in Example Ia except that only PCE polymer (isopentenyl polyethylene glycol (TPEG) acrylic acid (AA) copolymer) was used instead of scale inhibition composition.
IIe. Test for only Phosphonate compounds:
The same procedure was followed as in Example Ia except that only phosphonate compounds (2-phosphonobutane 1,2,4-tricarboxylic acid (PBTC) and hydroxyethylidene diphosphonic acid (HEDP)) were used instead of scale inhibition composition.
IIf. Test for only corrosion inhibitor:
The same procedure was followed as in Example Ia except that only corrosion inhibitor (2-hydroxy phosphonoaacetic acid (HPAA)) was used instead of scale inhibition composition.
IIg. Test for only biocide:
The same procedure was followed as in Example Ia except that only biocide (myristyldimethyl benzyl ammonium chloride) was used instead of scale inhibition composition.
% silica available at 0th time for all experiments 2a-2f was 100%. As time passes, silica level falls due to complexation of silica scale with the scale inhibition composition.
The % inhibition of silica and calcium scales in the synthetically prepared water are as given in Table 2.
Table 2: Test Results of % inhibition
Examples II-(IIa-IIf) Product Product dose % Inhibition
IIa. Scale inhibition composition (PCE + Phosphonate compounds corrosion inhibitor + biocide) 50 ppm 86.3%
IIb. PCE + corrosion inhibitor 50 ppm 67.5%
IIc. PCE + Biocide 50 ppm 58.2%
IId. Only PCE polymer 50 ppm 81.5%
IIe. Only Phosphonate compounds 50 ppm 39.2%
IIf. Only Corrosion inhibitor 50 ppm 29.2%
IIg. Only Biocide 50 ppm 12.2%
From the above Table 2, it is clear that the scale inhibition composition (PCE + Phosphonate composite + corrosion inhibitor + biocide) of the present disclosure is more effective in inhibiting the silica and calcium scales as compared to the PCE polymer, phosphonate compounds, corrosion inhibitor and biocide when used individually.
Using PCE polymer in combination with the phosphonate compounds + corrosion inhibitor + biocide show synergistic effect because they work in combination. PCE work through electrosteric mechanism while phophonate compounds by electrostatic mechanism and chelation, corrosion inhibitors prevent corrosion while biocides kill the microorganism such as bacteria and also counter algae, fungi and the like. If the biocide is not used, it results in bioslime membrane formation, thus fouling with other impurities like scale.
Experiment 3: Effectiveness of the scale inhibition composition of the present disclosure in comparison to the conventional scale inhibition composition
The same procedure was followed as in Example Ia and the effectiveness of the scale inhibition composition of the present disclosure was studied in comparison to the conventional scale inhibition composition. The results are as shown in Table 3.
Table 3: Effectiveness of the scale inhibition composition of the present disclosure
Product Product dose Observation
No treatment 00 Scale formed within 5 minutes in the form of big flocs
Conventional composition
Acrylic sulphonic polymer composites 200 ppm
Scale formed after 40 minutes as diffused and particulatesettled as heavy flocs after 90 minutes
Conventional composition
Acrylic sulphonic nonionic Terpolymer composites 200 ppm
Scale formed after 60 minutes and settled as heavy flocs after 90 minutes
Scale inhibiting composition of the present disclosure containing Polycarboxylate ether 200 ppm
Scale formed as diffused after 60 minutes and remained in suspension for more than 4 hours
PCE composition has better ability to control calcium silicate scale when compared to other acrylic sulphonic copolymer and terpolymers based conventional compositions
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of,
? a scale inhibition composition that is more effective in preventing the scale formation and is less expensive as compared to the conventional compositions, and
? a simple, economic and scalable process for preparing the scale inhibition composition.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising, will be understood to imply the inclusion of a stated element, integer or step,” or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.