Low-cost phosphorus-free scale and corrosion inhibitor and preparation method thereof

Abstract

The invention provides a low-cost phosphorus-free scale and corrosion inhibitor and a preparation method thereof, and belongs to the technical field of scale and corrosion inhibition. According to the invention, cane molasses, N-hydroxyethyl ethylenediamine triacetic acid, citric acid, aminoethyl ethanolamine, a sodium hydroxide aqueous solution, deionized water and the like are mainly used as raw materials to carry out polymerization reaction, the finally obtained polymer contains more hydroxyl and sodium carboxylate, and is grafted with a proper amount of amino groups, so that not only can easy-to-scale ions such as calcium ions be effectively complexed, but also the anti-scaling effect is good. And an effective corrosion inhibition film can be formed on the metal surface to achieve a corrosion inhibition effect, and after the polymer and deionized water are prepared into a product, the product is used in circulating water and has excellent scale and corrosion inhibition performance. The product comprehensively utilizes the by-product cane molasses in the sugar industry, is low in raw material cost, and has important environmental protection and economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of scale inhibition and corrosion inhibition, and particularly relates to a low-cost phosphorus-free scale inhibition and corrosion inhibitor and a preparation method thereof. Background Art

[0002] In industry, it is widely used in various industrial production in the form of cooling water or hot water. Whether it is cooling water or hot water for heaters, scaling and corrosion of equipment and pipelines will occur during the circulation process due to the high hardness of water. For example, in the process of heating water in the boiler, the concentration of some salt substances increases with the evaporation of water. When the concentration reaches a supersaturated state, these substances will crystallize and adsorb on the surface of the equipment to form scale, such as calcium carbonate (CaCO 3 ), calcium sulfate (CaSO 4 ) etc. If these scales are adsorbed on the surface of the equipment during the circulation of hot water or cooling water, the inner diameter of the equipment will become smaller, the flow rate of the fluid will be restricted, the working efficiency will be reduced, and the long-term adsorption of scale will cause corrosion of the equipment. The corrosion process is mainly the chemical and electrochemical reaction of the medium environment to the metal material. If it is in a corrosive environment for a long time, the surface of the equipment is prone to perforation, making the equipment unsafe. In severe cases, it may cause explosions and leakages in boilers and circulating equipment due to uneven local heating and excessive pressure, causing great harm to society and the economy. At the same time, since scaling is inside the equipment, it not only wastes energy and causes large losses to the equipment, but is also difficult to remove. At present, the most economical and commonly used method is to add scale inhibitors and corrosion inhibitors to prevent or reduce the occurrence of scaling and corrosion.

[0003] At present, most scale and corrosion inhibitor products are phosphorus-containing complexes, such as aminotrimethylene phosphate substances. Due to the high phosphorus content, sewage treatment is difficult and its drainage pollutes the environment. Phosphorus-free scale and corrosion inhibitor products are mainly polymerized scale and corrosion inhibitor components such as polyaspartic acid and polyepoxysuccinic acid. Not only are the raw material costs high, but the polymerization temperature and reaction conditions are also relatively harsh. If the polymerization is not properly controlled, the product application effect is not ideal, resulting in a high final cost. Since scale and corrosion inhibitors are widely used and are almost required in industrial production, how to develop lower-cost phosphorus-free scale and corrosion inhibitors is a research and development direction that the industry continues to work hard on. Summary of the invention

[0004] In view of the above problems, the present invention provides a low-cost phosphorus-free scale and corrosion inhibitor and a preparation method thereof, which is mainly obtained by polymerization reaction using sugarcane molasses, N-hydroxyethylethylenediaminetriacetic acid, citric acid, aminoethylethanolamine, sodium hydroxide aqueous solution, deionized water and the like as raw materials. The final polymer has more hydroxyl groups and sodium carboxylates and is grafted with a proper amount of amino groups, which can not only effectively complex calcium ions and other scale-forming ions, but also form an effective corrosion inhibition film on the metal surface to achieve the corrosion inhibition effect.

[0005] One of the purposes of the present invention is to provide a low-cost phosphorus-free scale and corrosion inhibitor.

[0006] The second object of the present invention is to provide a method for preparing the low-cost phosphorus-free scale and corrosion inhibitor.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] In a first aspect, the present invention provides a low-cost phosphorus-free scale and corrosion inhibitor, wherein the low-cost phosphorus-free scale and corrosion inhibitor is prepared from raw materials including the following mass fractions:

[0009]

[0010] Sugarcane molasses is a by-product produced in the process of making sugar from sugarcane. It appears as a brown viscous liquid and its indicators meet the requirements of the industry standard QB / T2684-2024 "Sugarcane Molasses".

[0011] Preferably, the solid content of sugarcane molasses is 80-85%, and can be purchased from Guangxi Zhongfuxin Sugar Industry Co., Ltd.

[0012] Typical but non-limiting mass parts of sugar cane molasses are, for example, 32, 33, 34, 35, 36, 37 parts;

[0013] Typical but non-limiting weight fractions of N-hydroxyethylethylenediaminetriacetic acid (HEDTA) are, for example, 12, 13, 14, 15, 16 parts;

[0014] Typical but non-limiting weight parts of citric acid are, for example, 10, 11, 12, 13 parts;

[0015] Typical but non-limiting weight fractions of aminoethylethanolamine are, for example, 4, 5, or 6 parts.

[0016] In some embodiments, the raw material further includes a catalyst, the catalyst includes catalyst A and catalyst B, catalyst A is concentrated sulfuric acid, and the amount used is 0.05-0.08% of the mass of citric acid; catalyst B is p-toluenesulfonic acid, and the amount used is 0.2-0.5% of the mass of sugarcane molasses.

[0017] The amount of catalyst A used is, for example, 0.05%, 0.06%, 0.07%, or 0.08% of the mass of citric acid, and the amount of catalyst B used is, for example, 0.2%, 0.3%, 0.4%, or 0.5% of the mass of sugarcane molasses.

[0018] In some embodiments, the raw materials further include appropriate amounts of sodium hydroxide and deionized water;

[0019] Preferably, the sodium hydroxide is a 30-35 wt % sodium hydroxide aqueous solution.

[0020] In a second aspect, the present invention provides a method for preparing the above-mentioned low-cost phosphorus-free scale and corrosion inhibitor, comprising the following steps:

[0021] A. Add the formulated amount of aminoethylethanolamine, citric acid and catalyst A into a reaction kettle, start stirring and heating, and simultaneously start the vacuum system to carry out an amidation reaction;

[0022] B. When the conversion rate of aminoethylethanolamine is greater than 98%, release the vacuum system, cool down to obtain the citric acid amidated intermediate, and set aside;

[0023] C. Add the formulated amount of sugar cane molasses to another reactor, raise the temperature, and start the vacuum system to fully remove the residual water in the sugar cane molasses during the heating process;

[0024] D. When the water content in the system is lower than 2%, release the vacuum system, add the formulated amount of catalyst B and N-hydroxyethylethylenediaminetriacetic acid, stir well, continue to heat up, start the vacuum system, and carry out the first chain extension polymerization reaction. Remove the small molecule water generated in the polymerization chain extension process under high vacuum to promote the reaction;

[0025] E. When the acid value of the reactant reaches 150-170 mgKOH / g, add the citric acid amidated intermediate obtained in step B to carry out a secondary graft chain extension polymerization reaction, increase the reaction temperature, and maintain the vacuum degree;

[0026] F. When the acid value of the polymer is reduced to 210-235 mgKOH / g, release the vacuum system, cool down, and then add sodium hydroxide aqueous solution to neutralize the reaction. When the pH value of the polymer solution reaches 7.1-7.6, stop the reaction to obtain the scale inhibitor and corrosion inhibitor component, and then add deionized water to stir and dissolve to obtain a scale inhibitor with a solid content of 70-75%.

[0027] In some embodiments, in step A, the temperature is raised to 140-145° C. and the vacuum degree is -0.08 MPa to -0.085 MPa.

[0028] In some embodiments, in step C, the temperature is raised to 105-110° C. and the vacuum degree is -0.097 MPa to -0.099 MPa.

[0029] In some embodiments, in step D, the temperature is continued to rise to 120-125° C.; the vacuum degree is -0.096 MPa to -0.098 MPa.

[0030] In some embodiments, in step E, the reaction temperature is increased to 130-135° C.; and the vacuum degree is maintained at -0.096 MPa to -0.098 MPa.

[0031] In some embodiments, in step F, the mass fraction of the sodium hydroxide aqueous solution is 30-35%, and the temperature is reduced to 90-95°C.

[0032] In a specific embodiment, the preparation method of the low-cost phosphorus-free scale and corrosion inhibitor comprises the following steps:

[0033] A. Add the formulated amount of aminoethylethanolamine, citric acid and catalyst A into the reaction kettle, start stirring and heat to 140-145°C for amidation reaction, and start the vacuum system at the same time, and control the vacuum degree at -0.08Mpa to -0.085Mpa;

[0034] B. Sampling and detecting free aminoethylethanolamine by gas chromatography. When the conversion rate of aminoethylethanolamine is greater than 98%, indicating that the amidation reaction is basically completed, the vacuum system is released, and the temperature is lowered to obtain the citric acid amidated intermediate for standby use;

[0035] C. Add the formulated amount of sugar cane molasses to another reactor, gradually raise the temperature to 105-110° C., and start the vacuum system at the same time, control the vacuum degree at -0.097 MPa to -0.099 MPa, and fully remove the residual moisture in the sugar cane molasses during the heating process;

[0036] D. Sampling and testing. When the water content in the system is lower than 2%, it means that the water is basically removed. At this time, the vacuum system is released, and the catalyst B and N-hydroxyethylethylenediaminetriacetic acid in the formula are added and stirred thoroughly. Then the temperature is continued to rise to 120-125°C, and the vacuum system is started to carry out the first chain extension polymerization reaction. The vacuum degree is maintained at -0.096Mpa to -0.098Mpa. The small molecular water generated in the polymerization chain extension process is removed under high vacuum to promote the reaction.

[0037] E. Sampling and testing the acid value of the polymer. When the acid value of the reactant reaches 150-170 mgKOH / g, it indicates that the first chain extension polymerization reaction has reached the requirement. At this time, the citric acid amidated intermediate obtained in step B is added to carry out a secondary graft chain extension polymerization reaction. The reaction temperature is raised to 130-135° C., and the vacuum degree is still maintained at -0.096 MPa to -0.098 MPa.

[0038] F. Take samples to detect the acid value of the polymer. When the acid value of the polymer is reduced to 210-235 mgKOH / g, it indicates that the secondary grafting and chain extension polymerization reaction has been completed. At this time, release the vacuum system, cool to 90-95°C, and then add an appropriate amount of 30-35wt% sodium hydroxide aqueous solution to carry out neutralization reaction. At the same time, test the pH of the polymer solution. When the pH value of the polymer solution reaches 7.1-7.6, stop the reaction to obtain the scale inhibitor and corrosion inhibitor component, and then add an appropriate amount of deionized water to stir and dissolve to obtain a scale inhibitor with a solid content of 70-75%.

[0039] The low-cost phosphorus-free scale and corrosion inhibitor obtained by the invention is a light yellow transparent solution with a solid content of 70-75% and a pH of 7.1-7.6.

[0040] Beneficial effects:

[0041] (1) The present invention mainly uses sugarcane molasses, N-hydroxyethylethylenediaminetriacetic acid, citric acid, aminoethylethanolamine, sodium hydroxide aqueous solution, deionized water and the like as raw materials to carry out polymerization reaction to obtain the polymer. The polymer finally obtained has more hydroxyl groups and sodium carboxylates and is grafted with an appropriate amount of amino groups. It can not only effectively complex calcium ions and other scale-forming ions, but also form an effective corrosion inhibition film on the metal surface to achieve the corrosion inhibition effect. The polymer is mixed with deionized water to form a product and used in circulating water, and has excellent scale inhibition and corrosion inhibition performance.

[0042] (2) The product of the present invention comprehensively utilizes sugarcane molasses, a by-product of the sugarcane sugar industry, which not only has low raw material costs but also can increase the added value of sugarcane molasses, thus having important environmental and economic benefits.

[0043] The present invention has been described in detail above, but the above embodiments are only illustrative in nature and are not intended to limit the present invention. In addition, this article is not limited by any theory described in the above prior art or invention content or the following examples. DETAILED DESCRIPTION

[0044] The present invention is further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

[0045] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, methods in the art.

[0046] Sugarcane molasses comes from Guangxi Zhongfuxin Sugar Industry Co., Ltd. and has a solid content of 80-85%.

[0047] Determination of acid value: in accordance with GB / T 12008.5-2010 "Plastic polyether polyols Part 5: Determination of acid value".

[0048] Example 1

[0049] A low-cost phosphorus-free scale and corrosion inhibitor, comprising the following raw materials in parts by weight:

[0050]

[0051] Catalyst A (concentrated sulfuric acid), the dosage is 0.07% of the mass of citric acid;

[0052] Catalyst B (p-toluenesulfonic acid) was used in an amount of 0.5% of the mass of sugarcane molasses.

[0053] The method for preparing the above-mentioned low-cost phosphorus-free scale and corrosion inhibitor comprises the following steps:

[0054] A. Add the formulated amount of aminoethylethanolamine, citric acid and catalyst A into the reactor, start stirring and heat to 143°C for amidation reaction, and start the vacuum system at the same time, and control the vacuum degree at -0.083Mpa;

[0055] B. Sampling and detecting free aminoethylethanolamine by gas chromatography. When the conversion rate of aminoethylethanolamine is greater than 98%, indicating that the amidation reaction is basically completed, the vacuum system is released, and the temperature is lowered to obtain the citric acid amidated intermediate for standby use;

[0056] C. Add the formulated amount of sugar cane molasses to another reactor, gradually raise the temperature to 108° C., and start the vacuum system at the same time, control the vacuum degree at -0.098 MPa, and fully remove the residual moisture in the sugar cane molasses during the heating process;

[0057] D. Sampling and testing. When the water content in the system is lower than 2%, it means that the water is basically removed. At this time, the vacuum system is released, and the catalyst B and N-hydroxyethylethylenediaminetriacetic acid in the formula are added and stirred thoroughly. Then the temperature is continued to rise to 122°C, and the vacuum system is started to carry out the first chain extension polymerization reaction. The vacuum degree is maintained at -0.098Mpa. The small molecular water generated in the polymerization chain extension process is removed under high vacuum to promote the reaction.

[0058] E. Take a sample to detect the acid value of the polymer. When the acid value of the reactant reaches 150-170 mgKOH / g, it means that the first chain extension polymerization reaction has reached the requirement. At this time, the citric acid amidated intermediate obtained in step B is added to carry out a secondary graft chain extension polymerization reaction. The temperature is raised to 132° C. and the vacuum degree is still maintained at -0.098 MPa.

[0059] F. Take samples to detect the acid value of the polymer. When the acid value of the polymer is reduced to 210-235 mgKOH / g, it indicates that the secondary grafting and chain extension polymerization reaction has been completed. At this time, release the vacuum system, cool to 92°C, and then add an appropriate amount of 30wt% sodium hydroxide aqueous solution for neutralization reaction. At the same time, detect the pH of the polymer solution. When the pH value of the polymer solution reaches 7.2, stop the reaction to obtain the scale inhibitor and corrosion inhibitor component, and then add an appropriate amount of deionized water for stirring and dissolving to obtain a scale inhibitor with a solid content of 70%.

[0060] The prepared low-cost phosphorus-free scale and corrosion inhibitor is a light yellow transparent solution with a solid content of 70% and a pH value of 7.2.

[0061] Example 2

[0062] A low-cost phosphorus-free scale and corrosion inhibitor comprises the following raw materials in parts by weight:

[0063]

[0064] Catalyst A (concentrated sulfuric acid), the dosage is 0.06% of the mass of citric acid;

[0065] Catalyst B (p-toluenesulfonic acid) was used in an amount of 0.4% of the mass of sugarcane molasses.

[0066] The preparation method is the same as Example 1.

[0067] The prepared low-cost phosphorus-free scale and corrosion inhibitor is a light yellow transparent solution with a solid content of 72% and a pH value of 7.3.

[0068] Example 3

[0069] A low-cost phosphorus-free scale and corrosion inhibitor comprises the following raw materials in parts by weight:

[0070]

[0071] Catalyst A (concentrated sulfuric acid), the dosage is 0.05% of the mass of citric acid;

[0072] Catalyst B (p-toluenesulfonic acid) was used in an amount of 0.3% of the mass of sugarcane molasses.

[0073] The preparation method is the same as Example 1.

[0074] The prepared low-cost phosphorus-free scale and corrosion inhibitor is a light yellow transparent solution with a solid content of 75% and a pH value of 7.1.

[0075] Example 4

[0076] A low-cost phosphorus-free scale and corrosion inhibitor comprises the following raw materials in parts by weight:

[0077]

[0078] Catalyst A (concentrated sulfuric acid), the dosage is 0.08% of the mass of citric acid;

[0079] Catalyst B (p-toluenesulfonic acid) was used in an amount of 0.2% of the mass of sugarcane molasses.

[0080] The preparation method is the same as Example 1.

[0081] The prepared low-cost phosphorus-free scale and corrosion inhibitor is a light yellow transparent solution with a solid content of 73% and a pH value of 7.5.

[0082] Comparative Example 1

[0083] Commercially available common scale and corrosion inhibitor product, model LD-ZG001, Shandong Ludong Environmental Protection Technology Co., Ltd.

[0084] Performance Testing

[0085] The scale inhibitor was added to the test liquid at a concentration of 20 mg / L. After stirring evenly, the scale inhibition performance of calcium carbonate and calcium phosphate was tested according to GB / T16632-2019 "Determination of scale inhibition performance of water treatment agents - Calcium carbonate deposition method" and GB / T22626-2008 "Determination of scale inhibition performance of water treatment agents - Calcium phosphate deposition method".

[0086] The corrosion inhibition performance is based on GB / T 18175-2014 "Determination of corrosion inhibition performance of water treatment agents - Rotating coupon method", the test temperature is 45±1℃, the test piece linear speed is 0.3m / s, and the test cycle is 72h.

[0087] The application performance test results are shown in Table 1 below.

[0088] Table 1 Application performance test results

[0089]

[0090] From the comparison of Examples 1-4 and Comparative Example 1 in the above table, it can be seen that the scale and corrosion inhibitor product prepared by the present invention not only has excellent storage stability, and no stratification and sedimentation occurs during long-term storage, but also has excellent scale inhibition performance for calcium carbonate and calcium phosphate, with the scale inhibition rate of calcium carbonate reaching more than 93%, and the scale inhibition rate of calcium phosphate reaching more than 85%. At the same time, the corrosion inhibition performance is also good, with the corrosion inhibition rate reaching more than 95%.

[0091] Comparative Example 1 uses a common commercially available scale and corrosion inhibitor product, which will experience slight sedimentation after long-term storage (12 months), and its scale and corrosion inhibition performance for calcium carbonate and calcium phosphate is also slightly lower than that of the product of the present invention.

[0092] The product of the invention not only has excellent scale and corrosion inhibition performance, but also uses a large amount of sugarcane molasses, a by-product of the sugar industry, which not only reduces the cost of scale and corrosion inhibitors, but also provides a method for high value-added comprehensive utilization of sugarcane molasses.

[0093] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and essence of the claims of the present invention; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A low-cost phosphorus-free scale and corrosion inhibitor, characterized in that: The low-cost phosphorus-free scale and corrosion inhibitor is prepared from the following raw materials in parts by weight: 32-37 parts of sugarcane molasses; 12-16 parts of N-hydroxyethylethylenediaminetriacetic acid; 10-13 parts of citric acid; 4-6 parts of aminoethylethanolamine.

2. The low-cost phosphorus-free scale and corrosion inhibitor according to claim 1, characterized in that: Sugarcane molasses has a solids content of 80-85%.

3. The low-cost phosphorus-free scale and corrosion inhibitor according to claim 1, characterized in that: The raw materials also include catalysts, which include catalyst A and catalyst B. Catalyst A is concentrated sulfuric acid, and its usage is 0.05-0.08% of the mass of citric acid; catalyst B is p-toluenesulfonic acid, and its usage is 0.2-0.5% of the mass of sugarcane molasses.

4. A method for preparing a low-cost phosphorus-free scale and corrosion inhibitor according to any one of claims 1 to 3, characterized in that: The following steps are involved: A. Add the formulated amount of aminoethylethanolamine, citric acid and catalyst A into a reaction kettle, start stirring and heating, and simultaneously start the vacuum system to carry out an amidation reaction; B. When the conversion rate of aminoethylethanolamine is greater than 98%, release the vacuum system, cool down to obtain the citric acid amidated intermediate, and set aside; C. Add the formulated amount of sugar cane molasses to another reactor, raise the temperature, and start the vacuum system to fully remove the residual water in the sugar cane molasses during the heating process; D. When the water content in the system is lower than 2%, release the vacuum system, add the formulated amount of catalyst B and N-hydroxyethylethylenediaminetriacetic acid, stir well, continue to heat up, start the vacuum system, and carry out the first chain extension polymerization reaction. Remove the small molecule water generated in the polymerization chain extension process under high vacuum to promote the reaction; E. When the acid value of the reactant reaches 150-170 mgKOH / g, add the citric acid amidated intermediate obtained in step B to carry out a secondary graft chain extension polymerization reaction, increase the reaction temperature, and maintain the vacuum degree; F. When the acid value of the polymer is reduced to 210-235 mgKOH / g, release the vacuum system, cool down, and then drop a sodium hydroxide aqueous solution for neutralization reaction. When the pH value of the polymer solution reaches 7.1-7.6, stop the reaction to obtain the scale inhibitor and corrosion inhibitor component, and then add deionized water for stirring and dissolving to obtain the scale inhibitor and corrosion inhibitor.

5. The preparation method according to claim 4, characterized in that: In step A, the temperature is raised to 140-145° C.; the vacuum degree is -0.08 MPa to -0.085 MPa.

6. The preparation method according to claim 4, characterized in that: In step C, the temperature is raised to 105-110° C.; the vacuum degree is -0.097 MPa to -0.099 MPa.

7. The preparation method according to claim 4, characterized in that: In step D, the temperature is continued to rise to 120-125° C.; the vacuum degree is -0.096 MPa to -0.098 MPa.

8. The preparation method according to claim 4, characterized in that: In step E, the reaction temperature is increased to 130-135° C.; the vacuum degree is maintained at -0.096 MPa to -0.098 MPa.

9. The preparation method according to claim 4, characterized in that: In step F, the temperature is lowered to 90-95°C.

10. The preparation method according to claim 4, characterized in that: In step F, the solid content of the scale and corrosion inhibitor is 70-75%.

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