KR101137459B1 - Method of water treatment for preventing corrosion and scale formation of metal - Google Patents

Abstract

The present invention relates to a process for the production of a polymer electrolyte membrane, which comprises adding a phosphonate, an acrylate-based copolymer, a zinc salt and an azole-based compound in a water quality, The concentration of the copolymer is 0.1 to 50 ppm, the concentration of the zinc ion by the zinc salt is 0.01 to 5 ppm, and the concentration of the azole compound is maintained at 0.01 to 10 ppm, thereby suppressing corrosion and scale formation of the metal , It is possible to reduce the environmental pollution and toxicity to the human body by keeping the concentration of phosphorus low, while minimizing the conditions that corrosion can occur on metal surfaces such as iron and copper compounds in a wide range of water quality, Which is capable of suppressing the scale formation of a metal salt that can be generated due to the generated ions.

Phosphonates, zinc salts, acrylate-based copolymers, azole-based compounds, corrosion, scale, open circulation cooling systems

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a water treatment method for preventing corrosion and scale formation of metal,

The present invention relates to a water treatment method for preventing corrosion of a metal material composed of iron, copper compounds and the like which can occur in an open circulation cooling system and scale formation that can be caused by ions contained in water, and more particularly, (P) by the phosphonate in the water quality is less than 0.1 to 2 ppm, the concentration of the acrylate-based copolymer is lower than the concentration of the acrylate-based copolymer 0.1 to 50 ppm by weight of the zinc salt, 0.01 to 5 ppm of the zinc ion by the zinc salt, and 0.01 to 10 ppm of the azole compound, thereby inhibiting corrosion and scaling of the metal.

Open circulation cooling systems use water as a refrigerant, and major industrial facilities such as petrochemical, refinery, textile, steel, electronics, and power plants use an open circulation cooling system to cool the heat generated during the process. In Korea, more than 70% of the total amount of industrial water is used as cooling water for open circulation cooling system.

The materials constituting the open circulation cooling system are mostly metals such as iron or copper compounds. The metal is made of the material that you want to use by applying energy to the oxide state. Energy is an artificial force but energy is a natural force.

Corrosion is an extremely natural metal oxidation process in which a metal emits energy and is going to return to its oxide state, which is the nature of the metal. Therefore, when the metal, which is an electric conductor, is brought into contact with the cooling water containing minerals, the cooling water acts as an electrolyte, and a corrosion phenomenon occurs, which is a natural phenomenon in which an anode and a cathode are formed on the metal surface due to a potential difference and return to an oxide state.

On the other hand, when various metal ions present in the sediment or water quality due to corrosion on the metal surface are combined with the anionic chemical substances, the scale is formed by the decrease of the solubility. When the scale is attached, porous sediments are formed on the heat transfer surface of the heat exchanger or the like to interfere with the smooth flow of water or block the water pipe, and in some cases, local corrosion due to the difference in concentration of dissolved oxygen in the water quality may be caused .

Corrosion or scale problems can easily be found in various industrial installations using water piping as well as cooling exchanger heat exchangers installed in actual industrial sites. In this case, not only does it greatly obstruct the open circulation cooling system, Causing huge economic losses.

In order to solve the above problems, a cooling water treatment agent is indispensably used and is widely used in all industrial fields.

In the case of a water treatment agent containing a high concentration of aphosphate, which is widely used as a conventional cooling water treatment agent, when the cooling water having a relatively high content of phosphorus (P) is discharged to the outside of the open circulation cooling system, phosphorus and algae And a scale composed of calcium phosphate is generated when the concentration of divalent metal ions such as calcium and magnesium is applied to a water quality which is high in the inside of the open circulation cooling system.

As a conventional water treatment composition, a technique using chromium salts in the 1960s has been widely used, but the use of chromium salts is regulated because it causes environmental pollution by heavy metals and toxicity to the human body is very high.

Recently, examples using inorganic phosphates, azole compounds, acrylic polymers, and maleic polymers have been disclosed and are widely used in industry.

For example, U.S. Patent No. 4,303,568 discloses a water treatment composition using inorganic phosphate and organic phosphate, and U.S. Patent No. 4,149,969 discloses a composition comprising a zinc salt, a molybdate, a manganese salt, a nickel salt, an azole compound, a phosphonate U.S. Patent No. 5,589,106 discloses compositions of hydrocarboxylic acids, silicates and water-soluble polymers, and U.S. Patent No. 4,411,865 discloses compositions comprising zinc salts, chromium salts, phosphates, acrylate copolymers And U.S. Patent No. 5,227,133 reports a cooling water treatment technique by composition of zinc salt, molybdate salt, and phosphate.

However, the conventional water treatment techniques can not achieve satisfactory results although they are somewhat different from each other in the effect of preventing corrosion or suppressing scale. In addition, when the concentration of the phosphate is increased, If it is relatively low and has anti-scale ability, the corrosion prevention effect may be weakened.

In addition, corrosion and scale problems can be solved by using chromium salts, but its use is regulated due to various problems such as pollution, human toxicity and stability.

Therefore, it is necessary to develop a water treatment method which has better inhibitory effect on corrosion and scale generation in a wide range of water quality, and can solve environmental problems, human toxicity and stability problems.

Accordingly, the present invention relates to a method for producing a polymer electrolyte membrane, which comprises adding a phosphonate, an acrylate-based copolymer, a zinc salt, and an azole-based compound to a water quality to adjust the concentration of phosphorus (P), the concentration of an acrylate- The concentration of the zinc ion and the concentration of the azole compound are kept constant but the concentration of the phosphorus is reduced as much as possible so as to solve the problems of environmental problems and human toxicity, It is an object of the present invention to provide a safe water treatment method which is less likely to cause problems in an open circulation cooling system composed of a material of copper as well as iron.

The present invention relates to a process for the production of a polymer electrolyte membrane, which comprises adding a phosphonate, an acrylate-based copolymer, a zinc salt and an azole-based compound in a water quality, The concentration of the copolymer is 0.1 to 50 ppm, the concentration of the zinc ion by the zinc salt is 0.01 to 5 ppm, and the concentration of the azole compound is maintained at 0.01 to 10 ppm, thereby suppressing corrosion and scale formation of the metal .

The present invention also provides a water treatment method for suppressing corrosion and scale formation of a metal by using the water treatment method in a cooling tower, a heat exchanger, and / or a water pipe of an open circulation cooling system.

Hereinafter, the present invention will be described in detail.

In order to prevent corrosion of a metal material composed of iron, copper compounds and the like in all water quality including cooling water and to inhibit scale formation that can be caused by ions contained in water, Wherein the concentration of phosphorus (P) in the water quality is less than 0.1 to 2 ppm, the concentration of the acrylate-based copolymer is 0.1 to 50 ppm, the amount of the zinc salt The concentration of the zinc ion by 0.01 to 5 ppm and the concentration of the azole compound by 0.01 to 10 ppm, respectively, so as to inhibit metal corrosion and scale formation.

In the water treatment method according to the present invention, the phosphonate used for maintaining the concentration of phosphorus (P) at less than 0.1 to 2 ppm is preferably selected from the group consisting of hydroxyethylidene diphosphonic acid, hydroxyphosphonocarboxylic acid, It is preferable to use at least one selected from methylene phosphonic acid, phosphonobutane tricarboxylic acid, and ethylenediamine tetramethylidine phosphonic acid.

The phosphonate is added to the water quality to inhibit the corrosion reaction and scale formation. When the concentration of phosphorus (P) is maintained at 2 ppm or more, the corrosion inhibition effect is further increased, but the effluent containing phosphorus (P) Can cause greenhouse and red tide problems in rivers and marine ecosystems.

The acrylate copolymer used for maintaining the concentration of the acrylate copolymer of the present invention is preferably at least one selected from the compounds having the structure represented by the following formula (1).

In Formula 1, R is selected from the group consisting of a hydrogen atom, an alkyl group, and a hydroxy group, and X and Y are each independently an integer of 1 to 20.

The acrylate copolymer has a function of inhibiting scale formation in water, and is maintained at a concentration of 0.1 to 50 ppm, preferably 0.5 to 45 ppm. If the concentration is less than 0.1 ppm, the effect of suppressing scale formation is insignificant. If the concentration exceeds 50 ppm, it is not economical. If the cooling water is discharged to the river, the COD concentration of the effluent is high.

In the present invention, it is preferable that at least one selected from zinc chloride, zinc sulfate, zinc nitrate and zinc oxide is used as the zinc salt used for maintaining the zinc ion concentration.

The zinc ions function to inhibit the corrosion reaction of the metal and are suitably maintained at a concentration of 0.01 to 5.0 ppm, preferably 0.1 to 4.5 ppm. If the concentration is less than 0.01 ppm, the effect of inhibiting the corrosion reaction is insignificant. If the concentration is more than 5 ppm, there is a danger to the fish and shellfish when the cooling water is discharged.

As the azole compound for maintaining the concentration of the azole-based compound, at least one selected from benzotriazole, tolyltriazole, and mercaptobenzothiazole is preferably used.

The azole compound has a function of suppressing the corrosion reaction, and is suitably maintained at a concentration of 0.01 to 10 ppm, preferably 0.02 to 8 ppm. If the concentration is less than 0.01 ppm, the effect of inhibiting the corrosion reaction is insignificant. If the concentration is more than 10 ppm, it is not economical.

The water treatment method of the present invention as described above can be used more effectively as a water treatment method for preventing corrosion of metals and suppressing scale formation by using various industrial water pipes including cooling towers and heat exchangers constituting an open circulation cooling system have. Therefore, the present invention can exhibit excellent efficacy in an open circulation cooling system in which ions and salts are concentrated due to the high concentration operation, and the corrosion tendency and scale tendency are higher.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited by the following examples.

(Examples 1 to 5 and Comparative Examples 1 to 5)

The test piece (surface area: 0.218 dm ² ) of the carbon steel and the copper compound metal, which is made of ferrous metal, was rotated at a rotation speed of 170 rpm for 5 days at a temperature of 30 ° C to measure the corrosion rate. The corrosion rate [mdd, mg / (dm ² ? Day)] according to the weight loss of the carbon steel and brass after holding the respective concentrations of the water treatment components of Examples 1 to 5 shown in Table 2 below, The results are shown in Table 4 below. In the case of Comparative Examples 1 to 5 shown in the following Table 3, the same methods as those of the examples were also tested, and the results are shown in Table 4 below.

Water quality One 2 3 4 5 pH 8.3 8.1 7.8 7.5 7.3 Calcium Hardness (ppm) 200 400 600 800 1000 Methyl orange-alkalinity (ppm) 100 80 60 50 40 Magnesium Hardness (ppm) 40 80 120 160 200 Chloride ion (ppm) 150 300 450 600 750

In Table 1, pH was adjusted to 0.1 N aqueous sodium hydroxide solution and 0.05 N aqueous sulfuric acid solution, and calcium hardness (Ca-H) was adjusted to calcium chloride. The M-Alkalinity was controlled with sodium bicarbonate, and the magnesium hardness (Mg-H) was controlled with magnesium sulfate. Chloride was used for chloride ion concentration and calcium chloride was used for controlling calcium hardness. The deficiency was controlled by using sodium chloride.

ingredient
Content (ppm) Example 1 Example 2 Example 3 Example 4 Example 5 Phosphorus (P) -1 0.42 0.52 0.62 0.72 0.81 Phosphorus (P) -2 0.65 0.75 0.85 0.95 1.04 Acrylate copolymer 8 10 12 14 16 Zinc ion 1.7 2.0 2.3 2.6 2.9 Azole-based compound One 2 3 4 5

In Table 2, the content of phosphorus (P) -1 is represented by the concentration of phosphorus (P) using hydroxyethylidene diphosphonic acid (HEDP, manufactured by LONZA) (P) using phonobutane tricarboxylic acid (PBTC, manufactured by BAYER). The content of the acrylate copolymer is represented by the concentration of the acrylate copolymer using BELCLEAN 400 (manufactured by BIOLAB). The content of the zinc ion is 47% by weight of zinc chloride, The content of the sol-based compound is the concentration of benzotriazole.

Each of them was diluted to 10,000 ppm by the ingredient content and then diluted to an appropriate concentration.

ingredient
Content (ppm) Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Phosphorus (P) -1 0 0 0.65 0 0 Phosphorus (P) -2 0 0.65 0 0 0 Acrylate copolymer 0 0 0 0 5 Zinc ion 0 0 0 2 0 Azole-based compound 0 0 0 0 3

As shown in Table 2, the content of phosphorus (P) -1 is represented by the concentration of phosphorus (P) using hydroxyethylidene diphosphonic acid (HEDP, manufactured by LONZA) 2 is represented by the concentration of phosphorus (P) using phosphonobutane tricarboxylic acid (PBTC, manufactured by BAYER). The content of the acrylate copolymer is represented by the concentration of the acrylate copolymer using BELCLEAN 400 (manufactured by BIOLAB), and the content of the zinc ion is represented by the concentration of the zinc ion using 47% of zinc chloride, The content of the azole compound is the concentration of benzotriazole.

Each of them was diluted to 10,000 ppm by the ingredient content and then diluted to an appropriate concentration.

Metal type Corrosion rate of carbon steel (mdd) Brass corrosion rate (mdd) Water quality One 2 3 4 5 One 2 3 4 5 Example 1 2.0 2.2 2.5 2.6 2.8 0.1 0.2 0.2 0.3 0.3 Example 2 1.9 2.0 2.1 2.3 2.6 0.1 0.1 0.1 0.2 0.2 Example 3 1.7 1.8 2.0 2.0 2.4 0.1 0.1 0.1 0.1 0.2 Example 4 1.4 1.5 1.8 2.0 2.3 0.1 0.1 0.1 0.1 0.1 Example 5 1.2 1.4 1.7 2.0 2.1 0.1 0.1 0.1 0.1 0.1 Comparative Example 1 165.4 172.5 194.7 200.6 214.1 1.5 1.3 1.3 1.4 1.2 Comparative Example 2 44.2 46.4 47.6 50.1 53.1 1.6 1.4 1.3 1.2 1.2 Comparative Example 3 40.6 42.0 49.4 54.3 63.2 1.4 1.3 1.2 1.1 1.1 Comparative Example 4 35.3 44.3 45.5 48.3 51.1 0.6 0.5 0.5 0.4 0.4 Comparative Example 5 147.4 161.1 163.9 176.4 191.1 0.1 0.2 0.2 0.2 0.2

As shown in Table 4, when the corrosion test was conducted on the carbon steel and the brass material using the components constituting the water treatment agent of Examples 1 to 5 of the present invention, the corrosion rate was remarkably lowered as compared with Comparative Examples 1 to 5 .

Scale performance test method

The test solution was sealed and allowed to stand at 70 DEG C for 24 hours, and then the test solution was filtered with a 0.45 microfilter, and the total diameter was measured to measure the scale inhibition rate using the following equation (1). The scale performance test water quality A containing 500 ppm of calcium hardness and 250 ppm of methyl orange alkalinity and the scale performance test water quality B containing 1,000 ppm of calcium hardness and 500 ppm of methyl orange alkalinity are shown in Table 1, 5 and the concentrations of the components of Comparative Examples 1 to 5 shown in Table 3 were maintained, and the scale inhibition rate was tested. The results are shown in Table 5 below.

In the above equation (1), Ce is the total diameter of the test liquid before the test, and Ct is the total diameter of the test liquid after the test.

Scale inhibition rate (%) Water quality A (calcium hardness 500 ppm,
Methyl orange alkalinity of 250 ppm) Water quality B (calcium hardness 1,000 ppm,
Methyl orange alkalinity of 500 ppm) Example 1 98 94 Example 2 98 96 Example 3 100 96 Example 4 100 98 Example 5 100 98 Comparative Example 1 52 50 Comparative Example 2 62 59 Comparative Example 3 58 55 Comparative Example 4 52 50 Comparative Example 5 84 76

As shown in Table 5, when the scale performance was tested using the components of the water treatment agents of Examples 1 to 5 of the present invention, the scale inhibition rate was remarkably improved as compared with Comparative Examples 1 to 5.

As described above, the water treatment method of the present invention reduces the environmental pollution and the toxicity to the human body by keeping the concentration of phosphorus low, while minimizing the conditions that can cause corrosion on metal surfaces such as iron and copper compounds in a wide range of water quality It has excellent ability to control corrosion and scale at the same time, because it has excellent ability to prevent corrosion of metals and to inhibit scale formation of metal salts that can occur due to ions contained in water.

Claims (6)

Wherein the concentration of phosphorus (P) by the phosphonate in the water quality is less than 0.1 ppm and the concentration of phosphorus (P) in the water quality is less than 0.1 ppm, Wherein the concentration of the zinc salt is 0.1 to 50 ppm, the concentration of the zinc ion is 0.01 to 5 ppm by the zinc salt, and the concentration of the azole compound is 0.01 to 10 ppm. Way. The method of claim 1, wherein the phosphonate is selected from the group consisting of hydroxyethylidene diphosphonic acid, hydroxyphosphonocarboxylic acid, aminotrimethylenephosphonic acid, phosphonobutanetricarboxylic acid, ethylenediaminetetramethylidinephosphonic acid Wherein the metal is at least one selected from the group consisting of a metal and a metal. The water treatment method according to claim 1, wherein the acrylate polymer is at least one selected from the group consisting of compounds represented by the following general formula (1). [Chemical Formula 1]

In Formula 1, R is selected from the group consisting of a hydrogen atom, an alkyl group, and a hydroxy group, and X and Y are each independently an integer of 1 to 15. The water treatment method according to claim 1, wherein the zinc salt is at least one selected from zinc chloride, zinc sulfate, zinc nitrate, and zinc oxide. The method according to claim 1, wherein the azole compound is at least one selected from the group consisting of benzotriazole, tolyltriazole, and mercaptobenzothiazole. A water treatment method for suppressing corrosion and scaling of a metal by using the water treatment method of claim 1 in a cooling tower, a heat exchanger and / or a water pipe of an open circulation cooling system.