KR101817548B1 - Scale inhibiting agent for reverse-osmosis - Google Patents

Abstract

The present invention relates to a multi-purpose scale inhibiting agent for a reverse-osmosis membrane for preventing inorganic scale in a reverse osmosis membrane treatment facility in which demand for industrial water production and water recycling is increasing. The scale inhibiting agent is composed of phosphonic acid and a polymer (Quatropolymer), and especially, the Quatropolymer, when the phosphonic acid is used alone, reacts with calcium in water to precipitate as calcium phosphonate. Accordingly, rather, a carboxyl group, a sulfonate group, a hydroxyl group and a nonionic amide group which will solve the disadvantage of causing scale failure are contained.

Description

[0001] Scale inhibiting agent for reverse-osmosis comprising a phosphonic acid and a polymer [

The present invention relates to a multi-purpose scale inhibitor for preventing inorganic scale in a reverse osmosis membrane treatment facility where demand for industrial water production and water recycling is increasing. The scale inhibitor is composed of a phosphonic acid and a polymer (Quatropolymer). Particularly, when a phosphonic acid is used alone, the phosphonate reacts with calcium in water to precipitate calcium phosphonate and cause scale disorder A sulfonate group, a hydroxyl group and a nonionic amide group which will solve the disadvantages.

Demand for living water and industrial water has increased rapidly due to the recent rapid growth of the industry along with population growth. Particularly, as the shortage of industrial water required in various industries becomes serious, seawater containing a large amount of salts, brackish water mixed with seawater and fresh water, and groundwater are desalinated to be used as a water source or waste water is treated and recycled. In general, evaporation, electrodialysis, and desalination by reverse osmosis membrane process are widely used.

The reverse osmosis membrane facility is not only inexpensive in terms of initial construction investment and operation but also has a wide range of application to water quality to be treated and good water quality can be maintained. However, it is sensitive to water-related obstacles, Water with a high pollution index has a disadvantage that it needs to be filtered, but recently it has been widely spotlighted as a major desalination method.

Since water is a powerful solvent that can dissolve most of the materials it is in contact with, many substances are dissolved in water and exist in the ionic state. Representative examples thereof include cations such as calcium, magnesium, sodium, potassium, iron, manganese, aluminum, strontium and barium, and anions such as carbonic acid, bicarbonic acid, chlorine, sulfuric acid, phosphoric acid, fluorine and silica. These ion components are concentrated in the reverse osmosis membrane, which is operated at a recovery rate of raw water of 50 to 85%, so that it exceeds the solubility and precipitates on the surface of the membrane, causing scale failure.

Typical examples of inorganic scale in the reverse osmosis membrane include calcium carbonate, calcium sulfate, barium sulfate and strontium sulfate, calcium fluoride, calcium phosphate, metal oxides such as iron, manganese, copper and aluminum, condensed silica scale and various inorganic colloidal precipitates have. When such a scale is deposited on the surface of the membrane, it is important that the reverse osmosis membrane is not only deteriorated in efficiency but also requires a strong acid washing repeatedly in order to clean the inorganic scale, thereby causing irreversible damage to the membrane.

As countermeasures for preventing the scale of the reverse osmosis membrane, sulfuric acid is injected as an acid injecting method to lower the alkalinity to control the precipitation tendency of the calcium carbonate. However, this also increases the scale tendency of the sulfate such as calcium, strontium and barium. Another method is to soften the hardness component of the water through a chemical or cation exchange resin and increase the sodium concentration instead. The most commonly applied method is to prevent scale formation by using an anti-scale agent.

The functional group of the anti-scale agent has a chelating function with respect to the cation which is a scale component, so that the concentration required for preventing the scale reacts in a non-stoichiometric manner in an extremely small amount. This is because it adsorbs specifically to the active sites of the crystal nucleus and the scale of the scale and interferes with the growth of the crystals, so that the effect is exhibited even at a small amount of addition concentration rather than stoichiometric. This non-stoichiometric reaction is called the threshold effect. In addition, the anti-scale agent is adsorbed on the active site of the crystal to inhibit normal crystal growth, thereby modifying the crystal structure. This is called a "distortion effect". In addition, not all of the functional groups of the anti-scale agent are adsorbed on the crystal, and some of them do not participate in adsorption but ionic properties are imparted to the crystals to increase the electric repulsive force to maintain the dispersed state.

Phosphonic acid and its salts are the most commonly used anti-scale agents with these three functions. Phosphonic acid is a phosphorus and carbon-linked organic phosphoric acid. Unlike the phosphorus-phosphorus-linked phosphoric acid, phosphorus is not sensitive to hydrolysis and its Langelier saturation index and Ryznar stability index are saturated conditions. It is used as an excellent anti-scale agent in the demineralization facility. Representative phosphonic acids include aminotrimethylenephosphonic acid (ATMP), 1-hydroxyethylidene diphosphonic acid (HEDP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), diethylene (DTPMPA), hexamethylene diamine tetramethylene phosphonic acid (HMDTP), polyaminopolyether methylene phosphonic acid (PAPEMP), etc., in the form of acid or neutralized salt. These phosphonic acids have a scale inhibiting effect on calcium carbonate, calcium carbonate, barium and strontium sulfate, and silica though they are somewhat different from each other, and they are widely used as anti-scale components of reverse osmosis membranes.

However, at any calcium concentration, pH, and temperature, the phosphonic acid stoichiometrically reacts with calcium in the water to precipitate into insoluble calcium phosphonate. This insoluble calcium phosphonate precipitates in the reverse osmosis membrane to reduce the concentration of phosphonic acid in the solution, causing not only serious problems such as calcium carbonate and other inorganic scales, but also itself as a main factor of the reverse osmosis membrane scale failure Providing a potential nucleation site where other kinds of scales are formed. In addition, phosphonic acid itself is an excellent material for preventing scale-up of reverse osmosis membrane, but it has a disadvantage that it is necessary to pay close attention to its use in order to precipitate calcium phosphonate and cause scale in supersaturated condition.

Such measures to prevent precipitation of calcium phosphonate are an important issue in the application of phosphonic acid, and as a recent technology, there is a technique for inhibiting the precipitation of calcium phosphonate by applying the synthesized anionic polymer together. This is because the anionic polymer has a scale prevention function similar to that of phosphonic acid and is effective for application to a reverse osmosis membrane facility. Representative examples of the polymer include polyacrylic acid homopolymer and polymaleic acid homopolymer and copolymers thereof. However, the anionic polymer has a carboxyl group as a main functional group and has a scale inhibiting function. However, the anionic polymer precipitates into an insoluble white substance due to a cross-linking reaction between calcium and a carboxyl group, resulting in scale failure and difficulty in removing.

Korean Patent Laid-Open Publication No. 2011-56287 suggests a scale prevention method including a copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid. However, although the above-mentioned copolymer has an effect on the calcium carbonate scale, the effect of preventing precipitation of calcium phosphonate is insufficient, and the effect to prevent other scales is insufficient. On the other hand, gelation phenomenon occurs.

Therefore, there is still a demand for the development of a scale inhibitor which has excellent removal efficiency for various kinds of scales, in particular, an effect of preventing the precipitation of calcium phosphonate due to phosphonic acid and a problem of gelation.

Korean Patent No. 10-1682729

Korea Patent Publication No. 2011-0056287

Korean Patent Publication No. 2013-0113329

The present invention has been developed based on the need to develop a multi-purpose scale inhibitor for reverse osmosis membranes containing a polymer capable of significantly improving the formation of phosphonic acid or its salt by binding calcium to calcium phosphonate to cause scale disorder.

Particularly, since acrylic acid, maleic acid homopolymer or copolymer, which is conventionally used as a scale inhibitor, can react with calcium in water of high hardness to precipitate insoluble calcium polymer reactants, stability against gelation which reacts with calcium And that it is necessary to study these excellent copolymers. It was also recognized that such a polymer should exert a scale inhibiting effect based on phosphonic acid on the scale generated in the reverse osmosis membrane.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a reverse osmosis membrane scale inhibitor which is used in combination with phosphonic acid to prevent precipitation of calcium phosphonate while reacting with calcium in water to form a gel- The purpose is to provide.

In order to solve the above-mentioned problems, the present invention provides a multi-purpose scale inhibitor for a reverse osmosis membrane, which comprises a polymer which is capable of solving the problem of precipitating calcium phosphonate by reacting calcium phosphonate with at least one phosphonic acid in water, Also, the present invention provides a water treatment method using a reverse osmosis membrane, wherein the reverse osmosis membrane scale inhibitor is used.

The present invention

(- COOH), a sulfonate group (-SO ₃ H), a hydroxyl group (-OH) and an amide group (-CONH ₂ ) as a functional group in a polymer and at least one phosphonic acid or its salt And the phosphonic acid or its salt and the polymer are contained in a weight ratio of 1: 4 to 4: 1 on an active ingredient basis.

In the present invention, the phosphonic acid is at least one selected from the group consisting of aminotrimethylene phosphonic acid (ATMP), 1-hydroxyhexylidenediphosphonic acid (HEDP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) (DTPMPA), hexamethylene diamine tetramethylene phosphonic acid (HMDTP), and polyaminopolyether methylene phosphonic acid (PAPEMP). Reverse osmosis membrane scale inhibitor.

The present invention is characterized in that the polymer contains a monomer having a carboxyl group, a monomer having a sulfonate group, a monomer having a hydroxy group, and a monomer having a nonionic amide group in an amount of 5 to 8: 1 to 3: 1 to 3: 2 and having a weight average molecular weight (Mw) of 1,000 to 30,000. The present invention also provides a reverse osmosis membrane scale inhibitor.

The present invention provides a reverse osmosis membrane scale inhibitor characterized in that the monomer containing a carboxyl group is one type selected from the group consisting of acrylic acid, methacrylic acid, maleic acid and maleic anhydride.

The present invention is characterized in that the monomer containing the sulfonate group is selected from the group consisting of 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS), allylsulfonic acid, styrenesulfonic acid, isoprenesulfonic acid and 2- And 2-acrylamido-2-methylpropane sulfonic acid (AMPS). The present invention also provides a reverse osmosis membrane scale inhibitor, which is characterized in that it is at least one selected from the group consisting of 2-acrylamido-2-methylpropane sulfonic acid

The present invention provides a reverse osmosis membrane scale inhibitor characterized in that the monomer containing a hydroxy group is 2-hydroxyethyl methacrylate 2-HEMA or hydroxypropyl acrylate HPA. do.

The present invention also relates to a process for the preparation of the amide group-containing monomer, wherein the monomer containing the amide group is at least one selected from the group consisting of acrylamide, N, N-methylene-bis-acrylamide and N-tert-butylacrylamide And a reverse osmosis membrane scale inhibitor.

In addition,

In the water treatment method using a reverse osmosis membrane, one or more phosphonic acids or its salt and a functional group include a carboxyl group (-COOH), a sulfonate group (-SO ₃ H), a hydroxyl group (-OH) and an amide group (-CONH ₂ ) In a weight ratio of 1: 4 to 4: 1, based on the active ingredient, is used as the reverse osmosis membrane inhibiting agent.

The present invention provides a water treatment method using a reverse osmosis membrane, wherein 0.5 to 10 ppm of the anti-scale agent is injected.

The water treatment method using the reverse osmosis membrane of the present invention is characterized in that the pH of the treated water is adjusted to 6.0 to 8.0 and the water temperature is adjusted to 10 to 30 ° C.

The present invention provides a water treatment method using a reverse osmosis membrane capable of effectively inhibiting scale formation within the range of recovery of the reverse osmosis membrane from 45 to 99% and effectively inhibiting scale formation regardless of application or non-oxidizing microbial sterilizing agent application conditions.

The reverse osmosis membrane scale inhibitor of the present invention is a reverse osmosis membrane scale inhibitor which is obtained by combining a phosphonic acid and a phosphonic acid which exhibit excellent effects for preventing various inorganic scales and a water-soluble low molecular weight polymer having sufficient precipitation inhibiting ability to precipitate as insoluble calcium phosphonate, It has the effect of solving the major drawbacks of application.

In order to exhibit the effect of suppressing the precipitation of calcium phosphonate, the polymer should be stable to gelation with calcium and exhibit an excellent effect on precipitation of calcium phosphonate. In addition, for the formation of inorganic scale of reverse osmosis membrane such as phosphonic acid Must exhibit stable scale inhibition. In short, the proper mixing of the phosphonic acid and the low-molecular-weight synthetic polymer of the present invention prevents precipitation of calcium phosphonate by the use of phosphonic acid alone, thereby preventing formation of scale attributed to the drug as well as preventing drug consumption and reducing scale formation Thereby extending the service life of the membrane and increasing the cleaning cycle to prevent damage to the membrane due to the use of a strong detergent.

Fig. Exhibits an effect of inhibiting calcium phosphonate precipitation of the polymer to phosphonic acid.
Fig. Exhibit the calcium phosphonate inhibitory effect of various polymers on phosphonic acid HEDP.
3 schematically shows a reverse osmosis membrane testing apparatus.
4 shows the effect of the scale inhibitor in the reverse osmosis membrane test apparatus.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and the inventor can properly define the concept of the term to describe its invention in the best possible way And should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention.

The present invention relates to a polymer comprising a carboxyl group (-COOH), a sulfonate group (-SO ₃ H), a hydroxyl group (-OH) and an amide group (-CONH ₂ ) as functional groups with at least one phosphonic acid or a salt thereof A reverse osmosis membrane scale inhibitor containing a weight ratio of 1: 4 to 4: 1 on the basis of an active ingredient, and a water treatment method using a reverse osmosis membrane utilizing the same. The at least one phosphonic acid or salt thereof preferably comprises 1 to 40% by weight, more preferably 10 to 30% by weight, as an active ingredient, based on the total weight of the reverse osmosis membrane anticaking agent.

The anti-scale agent of the reverse osmosis membrane of the present invention can be used by diluting the reverse osmosis membrane scale inhibitor and can be used at an appropriate concentration of 0.5 ppm to 10 ppm. The anti-scale agent is effective for the main components which are concentrated on the inorganic scale calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, etc. and are precipitated when the solubility is exceeded, thereby causing contamination of the membrane. In particular, the effect of inhibiting precipitation of calcium phosphonate .

Hereinafter, the phosphonic acid and salts thereof included in the reverse osmosis membrane scale inhibitor of the present invention will be described.

Phosphonic acid also exhibits scale inhibitory effects on calcium, strontium and barium sulfate and silica. Preferred examples of the phosphonic acid include aminotrimethylenephosphonic acid (ATMP), 1-hydroxyhexylidenediphosphonic acid (HEDP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) At least one selected from the group consisting of diethylenetriaminepenta-methylenephosphonic acid (DTPMPA), hexamethylene diamine tetramethylene phosphonic acid (HMDTP), and polyaminopolyether methylene phosphonic acid (PAPEMP) My invention is not limited thereto.

However, the use of phosphonic acid alone as a reverse osmosis membrane scale inhibitor has disadvantages. In the desalting treatment using seawater or brine reverse osmosis membrane, phosphonic acid and calcium react with each other under supersaturation conditions to precipitate. This precipitation of calcium phosphonate directly leads to scale failure of the reverse osmosis membrane and indirectly decreases the concentration of phosphonic acid to cause severe calcium carbonate scale disorder.

Ashcraft studied the precipitation tendencies of ATMP, HEDP, and PBTC in the presence of iron ions and found PBTC to be more stable under high calcium conditions than ATMP or HEDP because of the high solubility of calcium and PBTC (Corrosion / 85 , Paper No. 132, NACE). Korean Patent No. 10-1682729 examined the application of a sulfonate copolymer for prevention of scale of reverse osmosis membrane, and Korean Patent Laid-Open No. 10-2013-0113329 examined the use of a maleic acid series in a sulfonate copolymer, but calcium phosphonate But the possibility of the use of phosphonic acid was not fully investigated.

Accordingly, the present inventors have made efforts to develop a polymer that is capable of acting as a reverse osmosis membrane scale inhibitor, in particular, a gel-forming polymer due to the reaction with calcium itself, while having an effect of inhibiting precipitation of calcium phosphonate, A polymer containing a carboxyl group (-COOH), a sulfonate group (-SO ₃ H), a hydroxyl group (-OH) and an amide group (-CONH ₂ ) was developed and the present invention was completed.

The polymer may be prepared by copolymerization of a monomer containing a carboxyl group, a monomer containing a sulfonate group, a monomer containing a hydroxy group, and a monomer containing a nonionic amide group.

The polymer of the present invention may preferably have a weight average molecular weight (Mw) of 1,000 to 30,000, more preferably 2,000 to 30,000.

When the weight average molecular weight (Mw) of the polymer is 1,000 or less, the chelating function is lowered. On the other hand, the larger the molecular weight is, the more the chelating function to calcium is increased. However, if the molecular weight is too large, the gelation with calcium is increased, so the weight average molecular weight is preferably 1000 to 30,000 or less, more preferably 2,000 to 30,000.

The carboxyl group of the monomer containing a carboxyl group plays a role of preventing scale against calcium carbonate and the like. The monomer containing a carboxyl group may preferably be at least one member selected from the group consisting of acrylic acid, methacrylic acid, maleic acid and maleic anhydride.

When the polymer is a homopolymer of acrylic acid or maleic acid, it has a good inhibitory effect on calcium carbonate. However, since the functional group is composed only of a carboxyl group (-COOH), a carboxyl group bonded to calcium is crosslinked with a carboxyl group existing in another chain Insoluble white crystals can be made. The present inventors have discovered that (meth) acrylic acid or maleic acid homopolymer is a gelation of a polymer, and as the molecular weight increases, it is sensitive to gelation and adversely affects the scale inhibition effect of the polymer. A monomer copolymerized with a monomer containing a hydroxyl group, a monomer containing a hydroxyl group, and a monomer containing an amide group has been developed as a reverse osmosis membrane scale inhibitor.

As a result of the development, it was found that the polymer of the present invention has a similar scale inhibiting power to the calcium carbonate, while the precipitation inhibiting effect against calcium phosphonate is increased and the precipitation inhibiting effect against calcium phosphate, iron hydroxide and zinc hydroxide also increases , The gelation caused by the crosslinking reaction is remarkably reduced.

In short, the antifouling agent containing the polymer of the present invention can be used for evaluating the degree of gelation of a polymer, evaluation of a chelating ability against calcium, precipitation inhibiting effect on calcium phosphonate, and various inorganic scales occurring in a reverse osmosis membrane And it is estimated that it can be used in actual field.

The present invention is based on the finding that the monomer containing the sulfonate group is preferably selected from the group consisting of 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS), allylsulfonic acid, styrenesulfonic acid, isoprene sulfonic acid or 2- 2-acrylamido-2-methylpropane sulfonic acid (AMPS).

The present invention includes a hydroxy group in the copolymer to bulk the polymer to reduce gelation. The monomer containing a hydroxy group may be preferably 2-hydroxyethyl methacrylate 2-HEMA or hydroxypropyl acrylate HPA.

The present invention can make the polymer bulk by including an amide group, which is a non-ionic functional group, in the copolymer, thereby reducing the gelation phenomena due to the polymer. The monomer containing the amide group is preferably selected from the group consisting of (meth) acrylamide, N, N-methylene-bis-acrylamide and N-tert-butylacrylamide. More than species can be.

In the present invention, the monomers are preferably copolymerized at a weight ratio of 5 to 8: 1 to 3: 1 to 3: 0.5 to 2, more preferably 5 to 7.5: 1 to 2.5: 1 to 2.5: do. When the monomers are copolymerized in the above ratio, the content of the necessary functional groups in the polymer can be adjusted, and the polymer can be sufficiently bulked to prevent gelation of the polymer.

It is most preferred that the phosphonic acid or its salt and the polymer are mixed in a weight ratio of 1: 4 to 4: 1, preferably 1: 2 to 2: 1, by weight of the reverse osmosis membrane scale inhibitor of the present invention.

In addition,

In the water treatment method using a reverse osmosis membrane, one or more phosphonic acids or its salt and a functional group include a carboxyl group (-COOH), a sulfonate group (-SO ₃ H), a hydroxyl group (-OH) and an amide group (-CONH ₂ ) In a weight ratio of 1: 4 to 4: 1, based on the active ingredient, is used as the reverse osmosis membrane inhibiting agent.

The present invention provides a water treatment method using a reverse osmosis membrane, wherein 0.5 to 10 ppm of the anti-scale agent is injected.

The water treatment method using the reverse osmosis membrane of the present invention is characterized in that the pH of the treated water is adjusted to 6.0 to 8.0 and the water temperature is adjusted to 10 to 30 ° C.

The present invention provides a water treatment method using a reverse osmosis membrane capable of effectively inhibiting scale formation within the range of recovery of the reverse osmosis membrane from 45 to 99% and effectively inhibiting scale formation regardless of application or non-oxidizing microbial sterilizing agent application conditions.

Hereinafter, the present invention will be described in more detail with reference to Synthesis Examples. These synthesis examples are merely illustrative of the invention, and the scope of the present invention is not construed as being limited by these synthesis examples.

The raw materials used for the polymerization were summarized as follows. Reagent-grade potassium persulfate was used as polymerization initiator and reagent-grade mercaptoethanol was used as a chain transfer agent to control the molecular weight of the polymer. The polymerization initiator was used in an amount of 0.5% by weight of the main monomer, which is a general synthetic condition, and a chain chain transfer system was used to that extent. (Purity: 99.5%), maleic anhydride (purity: 99.5%), 2-hydroxyethyl methacrylate (purity: 97.5%) manufactured by Nihon Shokubai Co., Acrylamide-2-methylpropanesulfonic acid (purity: 99%) of Liameng Chemical, sodium 3-allyloxy-2-hydroxy-1-propanesulfonate (Purity of 40%) and acrylic acid (50% purity) of Dongseo Petrochemical were used. The reactor for the synthesis of polymers was a one liter glass reactor in the form of a double jacket, which was composed of impeller for agitation, droplet for continuous feeding of raw materials in polymerization, cooler, thermometer, The synthesized polymer was finally diluted with pure water and evaluated by adjusting the solid content (active ingredient) to be 30% by weight. The molecular weight of the synthesized polymer was measured using a water soluble GPC. Waters 2410 RI Detector was used for the measurement. The standard molecular weights were determined by using 0.1 MK ₂ HPO ₄ and KH ₂ PO ₄ solution as the mobile phase using a standard solution of Pullulan polysaccharides at a flow rate of 1.0 ml / min without any special temperature condition.

Polymer synthesis

Production Example 1  : Acrylic acid homopolymer

After 546.8 gr of pure water was added to the reactor, 11.2 gr of caustic soda was added to dissolve and the temperature was raised. The reason for putting caustic soda first is to increase the efficiency of the chain transfer agent. Then, 0.15 gr of mercaptoethanol was added, and acrylic acid was dropped 240 gr at a rate of 1.3 ml / min while the temperature was elevated to 85 캜. 1.2 gr of the reaction initiator, potassium persulfate, was dissolved in 46.8 g of water and added dropwise at a rate of 0.27 ml / do. The reaction temperature is maintained at 85 ° C and the stirring speed is maintained at 100 rpm. After 3 hours of reaction, the solution is aged for 1 hour. Thereafter, a final homopolymer of acrylic acid (about 846 gr) was synthesized to finally prepare acrylic acid homopolymer A having a solid content of 30% by weight.

Production Example 2  : Maleic acid  Homopolymer

After 266 g of pure water was added to the reactor, 4.0 g of mercaptoethanol was added to raise the temperature. When the temperature rises to 85 ° C, 336 gr of maleic anhydride is dissolved in 200 g of pure water and 4.0 g of potassium persulfate dissolved in 30 g of pure water is added dropwise at a rate of 3.0 ml / min and 0.2 ml / min for 3 hours, respectively. After aging for 1 hour, the mixture was cooled to synthesize a brown polymer, and the mixture was diluted with pure water to prepare maleic homopolymer B having a solid content of 30% by weight.

Production Example 3  : Maleic acid  And acrylic acid copolymer

The weight ratio of maleic anhydride to acrylic acid was 9: 1. First, 32 g of caustic soda is added to 270.8 g of pure water and dissolved, and then 1.6 g of mercaptoethanol is added to the reactor to raise the temperature. Thereafter, a main monomer solution obtained by dissolving 238 g of maleic anhydride and 26 g of acrylic acid in 200 g of pure water and 1.6 g of potassium persulfate were dissolved in 30 g of pure water. When the temperature rises to 85 ° C, the main monomer solution and initiator diluent are added dropwise at a rate of 2.6 ml / min and 0.2 ml / min, respectively. After 3 hours of injection, the mixture was further aged for 1 hour, cooled, and then diluted with pure water as described above to prepare a copolymer C of maleic acid and acrylic acid having a solid content of 30% by weight.

Production Example 4  To 5: Acrylic acid  Copolymer

Acrylic acid and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) at a weight ratio of 8: 2. First, 10.4 gr of caustic soda was added to 450 g of pure water and dissolved. 1.2 gr of mercaptoethanol was added to the reactor and the temperature was raised. Thereafter, 181.8 gr of acrylic acid and 45.3 gr of AMPS were dissolved in 80 g of pure water and 1.12 gr of potassium persulfate and 30 g of pure water were prepared. When the temperature rises to 85 ° C, the main monomer solution and initiator diluent are added dropwise at a rate of 1.7 ml / min and 0.2 ml / min, respectively. Thereafter, the mixture was injected for 3 hours, aged for another hour, cooled, and then an acrylic acid copolymer D having a solid content of 30% by weight was prepared.

Also, a copolymer polymer having acrylic acid and 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS) in a weight ratio of 8: 2 was used as another sulfonate copolymer polymer. In the same manner, 181.8 g of acrylic acid and 113.2 g of AHPS were finally added to prepare an acrylic acid copolymer E having a solid content of 30% by weight.

Production Example 6  To 7: acrylic acid Terpolymer -One

Acrylic acid, 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and 2-hydroxyethyl methacrylate (2-HEMA) at a weight ratio of 7: 2: 1. First, 10.4 gr of caustic soda was added to 450 g of pure water and dissolved. 1.2 gr of mercaptoethanol was added to the reactor and the temperature was raised. Thereafter, a solution prepared by dissolving 1.12 gr of the main monomer solution and 15.2 g of acrylic acid, 45.6 gr of AMPS and 22.4 gr of 2-HEMA in pure water in 30 gr of pure water is prepared. When the temperature rises to 85 ° C, the main monomer solution and initiator diluent are added dropwise at a rate of 1.7 ml / min and 0.2 ml / min, respectively. After 3 hours of injection, the mixture was again aged for 1 hour, cooled and diluted to prepare acrylic acid terpolymer F having a solid content of 30% by weight.

In a similar polymerization process, acrylic acid, 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS) and 2-hydroxyethyl methacrylate (2-HEMA) were mixed in a weight ratio of 7: The prepared terpolymer G was prepared.

Production Examples 8 to 9: Acrylic acid terpolymer-2

Acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and hydroxypropylarylate (HPA) at a weight ratio of 6: 2: 2. First, 10.4 gr of caustic soda was added to 450 g of pure water and dissolved. 1.2 gr of mercaptoethanol was added to the reactor and the temperature was raised. Next, prepare a solution obtained by dissolving 1.12 gr of main monomer solution and 45.2 g of acrylic acid in 45.4 gr of pure water and 45.4 gr of pure acrylic acid in 30 g of pure water. When the temperature rises to 85 ° C, the main monomer solution and initiator diluent are added dropwise at a rate of 1.7 ml / min and 0.2 ml / min, respectively. After 3 hours of injection, the mixture was again aged for 1 hour, cooled and diluted to prepare an acrylic acid terpolymer H having a solid content of 30% by weight.

In the same polymerization procedure, acrylic acid, 2-hydroxyethyl methacrylate (2-HEMA) and 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS) were mixed in a weight ratio of 6: 2: 2 To prepare a terpolymer I.

Production Example 10  To 11: Acrylic acid Temple copolymer -1 < / RTI > (6: 2: 1: 1)

Acrylic acid, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), 2-hydroxyethyl methacrylate (2-HEMA) and acrylamide in a weight ratio of 6: 2: 1: 1 To synthesize the copolymer. First, 10.4 gr of caustic soda is added to 430 g of pure water and dissolved. 1.2 gr of mercaptoethanol is added to the reactor and the temperature is raised. Next, prepare a solution containing 1.12 gr of main monomer liquid and potassium persulfate dissolved in 80 g of pure water in an amount of 44.2 gr of acrylic acid, 45.6 gr of AMPS, 22.4 gr of 2-HEMA, and acrylamide (purity of 50%) in 30 g of pure water. When the temperature rises to 85 ° C, the main monomer solution and the initiator diluent are dripped at a rate of 1.8 ml / min and 0.2 ml / min, respectively. Thereafter, the mixture was injected for 3 hours, aged for another hour, cooled, and diluted to finally prepare acrylic acid temple polymer J having a solid content of 30% by weight.

(AHPS), 2-hydroxyethyl methacrylate (2-HEMA) and acrylamide in a weight ratio of 6: 2: A 1: 1 mixture was prepared.

Production Examples 12 to 13: Acrylic acid terpolymer-2 (5: 2: 2; 1)

The copolymer was prepared by mixing acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), hydroxypropylarylate (HPA) and acrylamide in a weight ratio of 5: 2: 2: 1. First, 10.4 gr of caustic soda is added to 430 g of pure water and dissolved. 1.2 gr of mercaptoethanol is added to the reactor and the temperature is raised. Then, prepare a solution containing 1.12 gr of main monomer solution and 45.2 g of acrylic acid, 45.4 gr of acrylic acid, 45.4 gr of HPA and 44.8 gr of acrylamide (purity: 50%) in pure water in 30 g of pure water. When the temperature rises to 85 ° C, the main monomer solution and the initiator diluent are dripped at a rate of 1.8 ml / min and 0.2 ml / min, respectively. After 3 hours of injection, the mixture was again aged for 1 hour and cooled. After the synthesis, the mixture was diluted to prepare acrylic acid temple polymer L having a solid content of 30% by weight.

In the same polymerization process, acrylic acid, 2-hydroxyethyl methacrylate (2-HEMA), 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS) and acrylamide were mixed in a weight ratio of 5: 2: 1 were prepared.

Polymer gelation point measurement

The formation of a white insoluble material by crosslinking reaction with calcium is called gelation and is an important factor for evaluating the performance of polymers for preventing scale. Gelation point refers to the calcium concentration at which the polymer reacts with harsh conditions of calcium to form insoluble precipitates of white. The method for measuring the gelation point is described in the Journal of Japan Chemical Society 9 1153-1160, 1986 and the patent WO 2012/114953 AL1. That is, the calcium hardness of the calcium chloride (5.0% by weight) in 500ml pure water increased from 100ppm (CaCO ₃₎ by 50ppm to tune to 600ppm (CaCO ₃₎ polymer is added according to the concentration of 100ppm with the active ingredient. Next, 7.4196 gr of boric acid for the next reagent and 7.6274 gr of borax (Na ₂ B ₄ O ₇ 10H ₂ O) were dissolved in pure water and 10 ml of the buffer prepared to be 1 liter was added. The pH was adjusted to 8.5 using dilute sulfuric acid and caustic soda And the mixture was allowed to stand at 60 DEG C for 20 hours in a constant temperature water bath to observe the trauma and analyze the calcium so that the precipitated calcium precipitate resulted in a gelling point. The gelation point of the synthesized polymer was measured, and the results are shown in Table 1.

polymer Furtherance Mn Mw PDI (Mw / Mn) Gelation point (ppm as CaCO ₃ ) A The PAA (100) 2,848 5,391 1.89 100 B The PMA (100) 2,771 5,260 1.90 50 C MA (9): AA (1) 2,703 4,555 1.69 50 D AA (8): AMPS (2) 4,864 13,465 2.77 150 E AA (8): AHPS (2) 5,199 13,973 2.69 200 F AA (7): AMPS (2): HEMA (1) 2,414 4,114 1.70 250 G AA (7): AHPS (2): HEMA (1) 2,422 4,442 1.83 250 H AA (6): AMPS (2): HPA (2) 4,930 13,595 2.82 300 I AA (6): AHPS (2): HEMA (2) 5,162 13,880 2.69 300 J AA (6): AMPS (2): HEMA (1): AM (1) 3,625 6.524 1.80 400 K AA (6): AHPS (2): HEMA (1): AM (1) 3,711 6,825 1.84 400 L AA (5): AMPS (2): HPA (2): AM (1) 5,625 14,681 2.61 450 M AA (5): AHPS (2): HEMA (2): AM (1) 5,733 14,791 2.58 500

The homopolymer of acrylic acid or maleic acid contains only carboxyl (COOH) group and reacts with calcium, which is a bivalent metal ion, so that it is very easy to chelate against calcium. However, in case of high calcium or high pH or temperature, It is likely to undergo a crosslinking reaction with the carboxyl group of one chain and precipitate into a calcium polymer. Therefore, the maleic homopolymer having more carboxyl groups is the most sensitive to gelation, and the sulfonate-containing copolymer has a gelation point of 1.5 to 2 times higher than that of the acrylic acid homopolymer. The terpolymer containing the sulfonate group and the hydroxyl group has a 2.5 to 3 It has risen to double. On the contrary, the addition of the nonionic amide group of the present invention improved the tetrapolymer to 4 to 5 times.

This is because homopolymers of simple acrylic acid or maleic acid are excellent in chelating ability to calcium but have a disadvantage in that they are easily gelated by reacting with calcium in the case of water having a high calcium or high pH, whereas the templating polymer of the present invention has a high gelation stability It can be seen that it is excellent.

This is because the homopolymer is sensitive to gelation because the carboxyl group binds strongly to calcium, whereas the templated polymer of the present invention has a sulfonate group and hydroxy, which makes it difficult for the polymer to bind calcium, and in particular, contains a nonionic amide group, And the gelation phenomenon is remarkably improved due to the nonionic property.

Calcium tolerance measurement

Calcium tolerance is a measure of how much the drug is dissolved in the presence of high temperature, pH and calcium ions. Generally, when the temperature rises or the pH rises, the calcium tolerance decreases, which is not an exception because the phosphonate used in the reverse osmosis membrane is precipitated by calcium phosphonate. Therefore, the extent to which the homopolymers, copolymers, terpolymers, and silane polymers synthesized above increase the calcium tolerance of various phosphonic acids was evaluated.

In this method, the calcium is adjusted to 1,000 ppm (CaCO ₃ ) and 5.0 wt% of calcium chloride in 400 ml of pure water while keeping the constant temperature bath maintained at 25 ° C. Thereafter, each of the two precision syringe pumps is filled with 0.1 N caustic soda solution and phosphonic acid 2,000 ppm (active ingredient) solution is injected. The pH of the test solution was adjusted to 9.50 ± 0.05 using a magnetic bar at 300 rpm because the pH was lowered when the acidic phosphonic acid was injected. Phosphonic acid was continuously injected at 0.25 ml per minute and stirred continuously for uniform mixing. The turbidity meter measures the transmittance using a Brinkman PC 700. The method measures the amount of light transmitted through the tungsten lamp through the tungsten lamp when the electrode is immersed in the solution and calculates the amount of reflected light to detect the transmittance. Was measured and recorded 20 minutes after injection of phosphonic acid. When the phosphonic acid is injected above a certain critical concentration, the experimental solution becomes turbid and the turbidity permeability begins to decrease sharply. Phosphonic acid was used as an active ingredient in Dequest 2000 (ATMP 50%), Dequest 2010 (HEDP 60%), Dequest 2060S (DTPMPA 50%) and Dequset 7000 The polymer input concentration was 20 ppm as the active ingredient. The evaluation results are shown in Table 2 and Figs.

polymer HEDP (ppm) ATMP (ppm) DTPMPA (ppm) PBTC (ppm) Blank 12 26 34 98 A: PAA (100) 12 26 30 100 B: PMA (100) 10 24 35 100 C: MA (9): AA (1) 10 23 32 99 D: AA (8): AMPS (2) 16 30 42 115 E: AA (8): AHPS (2) 16 32 44 122 F: AA (7): AMPS (2)): HEMA (1) 17 33 47 124 G: AA (7): AHPS (2): HEMA (1) 17 34 48 125 H: AA (6): AMPS (2): HPA (2) 18 34 50 124 I: AA (6): AHPS (2): HEMA (2) 19 35 50 126 J: AA (6): AMPS (2): HEMA (1): AM (1) 23 38 58 129 K: AA (6): AHPS (2): HEMA (1); AM (1) 24 38 56 127 L: AA (5): AMPS (2); HPA (2): AM (1) 25 44 58 130 M: AA (5): AHPS (2); HEMA (2): AM (1) 26 46 62 133

The calcium tolerance of phosphonic acid was in the order of PBTC (98ppm> DTPMPA (34ppm)> ATMP (26ppm)> HEDP (12ppm) in the presence of calcium at 1,000 ppm CaCO ₃ , pH 9.5, It is considered that HEDP, ATMP, and DTPMPA, which are vulnerable to calcium resistance, have phosphono groups (-PO (OH) ₂ ) in the molecule and three phosphodiesters in the molecule.

The homopolymer showed almost no inhibitory effect on precipitation of calcium phosphonate. That is, polyacrylic acid, polymaleic acid and polymalein / acrylic polymers tended to have insufficient synergistic effect on calcium resistance, because the homopolymer had a strong calcium-polymer bond and promoted gelation, It is considered that it does not exert any significant effect on inhibition of precipitation of calcium phosphonate. Compared with a homopolymer having only a simple carboxyl group, a copolymer containing a sulfonate group and / or a hydroxy group has improved calcium resistance of the phosphonic acid to some extent (about 1.3 to 1.5 times as much as a polymer having only a carboxyl group) , Whereas the non-ionic amide group-containing silane polymerization of the present invention showed the best calcium phosphonate inhibition from 1.9 to 2.2.

 That is, the addition of a sulfonate and a hydroxy functional group to a simple carboxyl functional group increases the calcium tolerance. On the other hand, in the case of the present invention, the addition of an amide group leads to a rapid decrease in the gelation phenomenon between the calcium and the polymer, And it was found that it greatly contributes to prevention of precipitation of phosphonic acid.

Estimation of reverse osmosis membrane scale inhibition

The scaling inhibitory effect on the scale of calcium carbonate, calcium sulfate, barium sulfate, calcium phosphate, iron hydroxide and calcium fluoride, which are scales generated in the reverse osmosis membrane against the combination of phosphonic acid, polymer and phosphonic acid and polymer, Respectively. The evaluation method is as follows. Phosphonic acid or synthetic polymer is added in concentration without considering the active ingredient. In addition, the reverse osmosis membrane scale inhibitor comprising a polymer for inhibiting precipitation of phosphonic acid and calcium phosphonate of the present invention was prepared and evaluated by the following method.

Example 1

Hydroxy-1-propanesulfonic acid (AHPS) and 2-hydroxyethyl methacrylate (2-HEMA) in a ratio of 6: 1 were mixed with commercial HEDP Dequest 2010 (active ingredient 60%), acrylic acid, 3-allyloxy- The reverse osmosis membrane scale inhibitor of Example 1 was prepared by combining 2: 2 terpolymer I (30% active ingredient) in a weight ratio of 5: 5. This reverse osmosis membrane scale inhibitor corresponds to a 2: 1 weight ratio of phosphonic acid and terpolymer as active ingredients.

Example 2

The commercial HEDP, Dequest 2010 (active ingredient 60%), acrylic acid, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), and hydroxypropyl acrylate (HPA) The reverse osmosis membrane scale inhibitor of Example 2 was prepared by blending a templating polymer L (active ingredient 30%) prepared by mixing 2: 1 by weight in a weight ratio of 5: 5. This reverse osmosis membrane scale inhibitor is a 2: 1 ratio of phosphonic acid to a temple polymer as an active ingredient.

Example 3

Hydroxy-1-propanesulfonic acid (AHPS), and 2-hydroxy-2-hydroxy-2-hydroxypropionic acid were added to the commercial HEDP Dequest 2010 (active ingredient 60%) and ATMP Dequest 2000 (active ingredient 50% (30% active ingredient) prepared by mixing 5: 2: 2: 1 by weight of chilled methacrylate (2-HEMA) and acrylamide (AM) in a weight ratio of 2.5: 2.5: 5 The reverse osmosis membrane scale inhibitor of Example 3 was prepared. This reverse osmosis membrane scale inhibitor is a 1.8: 1 ratio of phosphonic acid to a propylene polymer as an active ingredient.

Example 4

Copolymer D (30% active ingredient) prepared by mixing commercial ATMP Dequest 2000 (active ingredient 50%), acrylic acid and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) in a weight ratio of 8: Weight ratio of 5: 5 to prepare a reverse osmosis membrane scale inhibitor of Example 4. This reverse osmosis membrane scale inhibitor corresponds to a 1.7: 1 ratio of phosphonic acid to polymer as an active ingredient.

Calcium carbonate dispersing capacity (CDC)

The calcium carbonate dispersing ability is used as an index of the calcium carbonate precipitation inhibiting effect of the scale inhibitor, and it is made by titration to calcium acetate in the presence of excessive carbonate ion, referring to BASF's method.

Each phosphonic acid or polymer was put into the commercial product without regard to the active ingredient, and the polymer was also accurately placed in the flask at a weight of 1.0 gr at 30 wt%. 100 ml of pure water and 10 ml of 10% Na ₂ CO _{3 were} added, and the pH was adjusted to 11 with 1 N NaOH solution and titrated with 4.4% Ca (AC) ₂ · H ₂ O solution. The end point was turbidity Respectively. The calcium carbonate dispersion capacity was obtained by the following formula.

CDC (as CaCO ₃ mg / g) = 4.4% Ca (AC) ₂ .H ₂ O consumption mlx25 / sample (gr)

Calcium sulfate inhibition assessment

The calcium sulphate inhibitory effect was evaluated in supersaturation conditions of sulfate ion, calcium hardness and reference to the NACE Standard TM 0374-2007 test method. That is, 3 ppm of an anti-scale agent is added to a 125 ml bottle, 50 ml of SO ₄ solution (Na ₂ SO ₄ ) and 50 ml of Ca solution (CaCl ₂ ) are added and thoroughly mixed. Sealed and kept in a thermostatic chamber at 71 占 1 占 폚 for 24 hours and then cooled to 25 占 폚 within 2 hours, and then 1 ml of the solution was sampled and diluted to analyze calcium to determine the inhibition rate.

Calcium phosphate precipitation inhibition evaluation

Take 2,000 ml of pure water (500x samples), add 20 ml of NaH ₂ PO ₄ solution (0.1% as PO ₄ ^-3 ) to make 10 ppm (as PO ₄ ^-3 ) solution, take 480 ml of Erlenmeyer flask and add CaCl ₂ (0.5% as CaCO ₃ ) and 10 ml of NaHCO ₃ solution (0.5% as CaCO ₃ ) were added to the mixture to make 100 ppm (as CaCO ₃ ) of calcium. Add the M-alkali to 100 ppm (as CaCO ₃ ) by mixing well and adjust to pH 8.5 with sulfuric acid solution or sodium hydroxide solution. Thereafter, the mixture was sealed and allowed to stand in a constant temperature water bath at 60 DEG C for 40 hours. The test solution was filtered with NO.5C filter paper to determine the inhibition rate by measuring the phosphoric acid concentration.

Iron oxide precipitation inhibition evaluation

Take 2,000 ml of pure water (500x sample), add 40 ml of FeCl ₃ 6H ₂ O solution (0.05% as Fe ³⁺ ) and mix well to make 10 ppm (as Fe ³⁺ ) solution. Take 500 ml of Erlenmeyer flask Add 30ppm of anti-scale agent, mix well and adjust to pH 8.8 with sulfuric acid solution or sodium hydroxide solution. After completion of the incubation, the plate was allowed to stand in a constant temperature water bath at 30 DEG C for 24 hours, and then the test solution was filtered with NO.5C filter paper to determine the iron content of iron hydroxide.

Evaluation of barium sulfate precipitation inhibition

Take 2,000 ml of pure water (500 × sample counts), mix 8.93 ml of 1% BaCl ₂ solution and 6.1 ml of 1% Na ₂ SO ₄ solution to make 50 ppm of BaSO ₄ , then take 500 ml of Erlenmeyer flask. Apply 10 ppm of scale inhibitor and mix thoroughly. The solution was adjusted to pH 7.0 using a sulfuric acid solution or a sodium hydroxide solution. The solution was completely sealed and allowed to stand in a constant temperature water bath at 50 DEG C for 24 hours. Then, the test solution was filtered with NO.5C filter paper to measure the barium concentration.

Calcium fluoride precipitation inhibiting effect

Take 2,000 ml of pure water (500 × number of samples), add 10 ml of NaF solution (1% as F ^- ) to make 50 ppm (as F ^- ) solution, then take 500 ml of Erlenmeyer flask. Apply 10ppm scale inhibitor and mix thoroughly. After the addition of 250 ppm (as CaCO ₃ ) of calcium solution, the pH is adjusted to 8.0 using a sodium hydroxide solution, and the mixture is completely closed and left to stand in a constant temperature water bath at 40 ° C for 24 hours. After completion of the experiment, the test solution was filtered through a 0.45 μm filter paper, and then fluorine ions and calcium were measured.

The suppression rate for the above scale is obtained by the following equation.

(%) = (C _E - C _O ) / (C _T - C _O ) x 100

C _T : Ion concentration of sample before test (concentration of addition) ppm

C _O : Ion concentration of sample without scale inhibitor after test ppm

C _E : Ion concentration of sample added with scale inhibitor after test ppm

Table 3 shows the precipitation inhibiting effect of the scale inhibitor.

CDC (CaCO ₃ mg / gr) CaSO ₄ (%) Ca ₃ (PO ₄ ) ₂ (%) Fe (OH) ₃ (%) BaSO ₄ (%) CaF ₂ (%) Concentration (ppm) 10,000 3 10 30 10 10 HEDP 558 28 63 89 92 80 ATMP 319 100 65 74 48 85 Polymer A 33 91 72 23 80 72 Polymer D 25 88 82 80 82 72 Polymer H 21 90 85 82 83 75 Polymer I 21 91 84 84 84 75 Polymer L 20 100 96 92 91 90 Polymer M 20 100 97 94 94 90 Example 1 290 85 73 86 85 78 Example 2 290 95 80 91 92 85 Example 3 250 100 86 91 88 89 Example 4: 205 92 68 76 71 78

The acrylic homopolymer has a good dispersing ability to calcium carbonate but has a poor ability to inhibit precipitation of calcium phosphate or iron hydroxide. On the other hand, the acrylic acid copolymer, the terpolymer and the acrylic copolymer have poor dispersibility of calcium carbonate, , And exhibit the best properties of the copolymer.

Such a templated polymer contains monomers having other functional groups besides the carboxyl group, making it molecular structurally bulky and lowering the chelating function to calcium, while exhibiting an excellent precipitation inhibiting effect as opposed to other scale components. Therefore, when the tempo- rary copolymers of Examples 1 to 3 are used, the precipitation-inhibiting effect on other inorganic scale formed in the reverse osmosis membrane is maintained while maintaining the precipitation-preventing effect of phosphonic acid on calcium carbonate, There is an advantage that the polymer is advantageous in combination with more phosphonic acid. Therefore, it has been confirmed that the combination of one or more phosphonic acid and the copolymer of the present invention not only solves the disadvantage of calcium phosphonate precipitation of phosphonic acid but also exhibits an excellent scale prevention effect against other inorganic scales not possessed by phosphonic acid have.

Evaluation of reverse osmosis membrane flat membrane test

The effect of the anti-scale agent of the present invention was evaluated using a reverse osmosis membrane testing apparatus shown in FIG. The production conditions of the sample water were as shown in Table 4 based on the water concentration of 5 times as much as the recovery rate of 80% based on the water quality of Asan Lake used as industrial water. At this time, when water quality is simulated, LSI is 1.35, and water quality is worried about scale failure due to supersaturation of 1628% of calcium carbonate and 1361% of barium sulfate. Each scale inhibitor was evaluated under the condition that 2 ppm was added to the influent water under 5-fold concentration condition and 10 ppm at 80% recovery rate. The membranes used for the evaluation were evaluated on the basis of TORAY CHEMICAL RE8040-FEN43. For the experiment, the membranes were cut into 15 × 10 cm and fixed with a clamp. After 25 ° C , the sample volume was 15 bar and the flow rate per minute was 1.515 liters were held in the concentrated water flow rate conditions, 1.5 liters per minute, can be produced that 0.015 liters per minute generated from, where production initial condition of 15ml / min in consideration of 0.015m ² membrane area conditions and 60ℓ / m ² hr in LMH unit The effect of anti - scale agent was evaluated by changing the production quantity with time.

LMH = 15 ml / min (production quantity) x 60 min / hr ÷ 1000 (liter / ml) ÷ 0.015 m ² = 60 LMH

 After confirming the concentrated water (flow rate confirmed by the flow meter) and the quantity of production (the quantity of water produced by weighing on the scale) which were recovered to the raw water tank in order to confirm the proper flow rate at the start of operation, after stabilizing for 30 minutes, the concentrated water was fixed at 1.5 liters And the change of flux with time was measured. In addition, during the evaluation period, 10 ppm of bound chlorine-type disinfectant was added for microbial inhibition.

Cations (ppm as CaCO ₃₎ 2,399 Anions (ppm as CaCO ₃₎ 2,399 Na (ppm) 460 Cl 1,000 K (ppm)) 225 SO ₄ 800 Ca (ppm as CaCO ₃₎ 1,000 _{M-Al (ppm as CaCO 3} ) 300 Mg (ppm as CaCO ₃₎ 250 PO ₄ 0.25 Ba (ppm) 0.25 SiO ₂ (ppm) 10.0 Sr (ppm) 1.25 Recovery rate (%) 80 Fe ³⁺ (ppm) 0.05 Temperature 25 ℃ Conductivity (us / cm) 2,470 pH 7.5

The decrease in flux in the present reverse osmosis membrane evaluation means that the reverse osmosis membrane is contaminated and the yield of treated water is decreased. Example 1, which is a combination of HEDP and ATMP alone, a phosphonic acid used in the past, and a terpolymer, A comparative evaluation was conducted with respect to Example 2, Example 3, and Example 4 in which a copolymer was blended.

As shown in FIG. 4, the flux reduction rate was evaluated during the evaluation period of 80 hours. As a result, it was confirmed that if the anti-scale agent was not added, the flux reduction rate dropped to 90% and the scale tendency of the sample water was high I could. In addition, flux reduction, which was evaluated by phosphonic acid alone, reached 43% for HEDP and 42% for ATMP, and there was no practical difference in ATMP or HEDP. On the other hand, Example 4 in which a copolymer was incorporated in phosphonic acid showed a reduction rate of flux of 28% as compared to phosphonic acid and an improvement of about 20% to 25% as compared with the use of phosphonic acid alone. Example 1 in which the terpolymer was blended exhibited a flux reduction rate of 25% and a 30 to 35% improvement over the use of phosphonic acid alone. In Example 2 and Example 3 in which the polymer of the present invention was incorporated, the reduction rate was 12% and 8%, respectively, showing the lowest reduction rate, and the improvement effect was 56 to 62% higher than that of the phosphonic acid alone treatment.

Therefore, the present invention's templating polymer containing a sulfonate group, a hydroxyl group and an amide group of a non-ionic hydrophilic group other than the basic carboxyl group is stable in the gelation phenomenon in which the molecular structure of the polymer is reacted with calcium by the bulk, When used together with phosphonic acid, which is widely applied as an inhibitor, it can solve the problem of calcium phosphonate precipitation by reacting with calcium, which is the biggest disadvantage of phosphonic acid.

Therefore, the present invention can prevent the scale failure by applying a chemical range of 0.5 ppm to 10 ppm or less for the purpose of preventing scale formation against influent water quality conditions in which calcium and inorganic scale disturbance is expected when the chemical application is not performed in the reverse osmosis membrane, , And when the influent water is introduced in the range of pH 6.0 to 8.0 and influent water temperature 10 to 30 ° C based on seawater or fresh water quality, strong scale prevention function is performed. Therefore, reverse osmosis membrane recovery rate is 45 % ≪ / RTI > to < RTI ID = 0.0 > 99%. ≪ / RTI >

 In this case, the scale inhibition function can be maintained in parallel with other drugs, and the scale prevention function can be maintained regardless of the effect of the fungicide even in the application of the reverse osmosis membrane disinfectant and the unused condition. In other words, calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, etc., which are inorganic scale, are concentrated in the reverse osmosis membrane and precipitated when solubility is exceeded, which is effective for the main component to contaminate the membrane. In particular, there is an advantageous effect on precipitation suppression effect of calcium phosphonate.

Claims (9)

A polymer containing at least one phosphonic acid or its salt and a functional group such as a carboxyl group (-COOH), a sulfonate group (-SO ₃ H), a hydroxyl group (-OH) and an amide group (-CONH ₂ ) Based on a weight ratio of 1: 4 to 4: 1,
The polymer is copolymerized in a weight ratio of 5 to 8: 1 to 3: 1 to 3: 0.5 to 2 by weight of a monomer containing (meth) acrylic acid, a sulfonate group-containing monomer, a hydroxyl group- And having a weight average molecular weight (Mw) of 1,000 to 30,000. The reverse osmosis membrane scale inhibitor [3] The method of claim 1, wherein the phosphonic acid is at least one selected from the group consisting of aminotrimethylene phosphonic acid (ATMP), 1-hydroxyethylidenediphosphonic acid (HEDP), 2-phosphonobutane-1,2,4-tricarboxylic acid ), Diethylenetriaminepenta-methylenephosphonic acid (DTPMPA), hexamethylenediamine tetramethylenephosphonic acid (HMDTP), and polyaminopolyether methylenephosphonic acid (PAPEMP). Reverse osmosis membrane scale inhibitor delete 3. The composition of claim 1, wherein the monomer comprising the sulfonate group is selected from the group consisting of 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS), allylsulfonic acid, styrenesulfonic acid, isoprene sulfonic acid, And 2-acrylamido-2-methylpropane sulfonic acid (AMPS). 2. A reverse osmosis membrane scale inhibitor according to claim 1, The antifouling paint composition according to claim 1, wherein the monomer having a hydroxy group is 2-hydroxyethyl methacrylate 2-HEMA or hydroxypropyl acrylate HPA. The method of claim 1, wherein the monomer containing the amide group is selected from the group consisting of acrylamide, N, N-methylene-bis-acrylamide and N-tert-butylacrylamide. By weight of a reverse osmosis membrane scale inhibitor In a water treatment method using a reverse osmosis membrane,
A polymer containing a carboxyl group (-COOH), a sulfonate group (-SO ₃ H), a hydroxyl group (-OH) and an amide group (-CONH ₂ ) as a functional group with at least one phosphonic acid or its salt as an active ingredient (Meth) acrylic acid, a monomer containing a sulfonate group, a monomer containing a hydroxy group, and a monomer containing a nonionic amide group at a weight ratio of 1: 4 to 4: 1, To 3: 1 to 3: 0.5 to 2 by weight, and a weight average molecular weight (Mw) of 1,000 to 30,000 is used as a reverse osmosis membrane. The method according to claim 7, wherein 0.5 to 10 ppm of the anti-scale agent is injected. [7] The method according to claim 7, wherein the water treatment method using the reverse osmosis membrane comprises adjusting the pH of the treated water to 6.0 to 8.0 and adjusting the water temperature to 10 to 30 ° C.

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