Novel composite organic phosphonic acid corrosion and scale inhibitor and preparation method thereof

Abstract

The invention discloses a novel composite organic phosphonic acid corrosion and scale inhibitor and a preparation method thereof, the novel composite organic phosphonic acid corrosion and scale inhibitor is prepared from the following raw materials in parts by mass: 7-10 parts of 2-hydroxy-5-methoxy-1, 3-phenylene bis (methylphosphonic acid), 3-5 parts of zinc sulfate, 7-10 parts of polyacrylic acid, 1-2 parts of benzotriazole and 30-50 parts of water, the 2-hydroxy-5-methoxy-1, 3-phenylene bis (methylphosphonic acid) is synthesized by the following method: adding 2, 6-bis (hydroxymethyl)-4-methoxyphenol into trimethyl phosphite, reacting under the conditions of room temperature and nitrogen reflux, and then hydrolyzing the reaction product in a methanol-water mixed solution to obtain the 2-hydroxy-5-methoxy-1, 3-phenylene bis (methylphosphonic acid). The corrosion and scale inhibitor has excellent scale inhibition and corrosion inhibition performance, and can effectively remove scale in an industrial circulating cooling water system, protect water pipes and equipment, improve heat exchange efficiency and reduce energy consumption and equipment loss.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment chemicals, in particular to a novel composite organic phosphonic acid corrosion and scale inhibitor and a preparation method thereof. Background Art

[0002] In industrial circulating cooling water systems, scale formation can lead to reduced heat exchange efficiency, increased energy consumption, and increased equipment wear and tear. With increasing water resource scarcity and rising environmental protection requirements, the application of traditional scale inhibitors, such as inorganic polyphosphoric acid, is limited by their high phosphorus content and the tendency to hydrolyze into orthophosphate, which can lead to eutrophication and severe environmental pollution. Therefore, the development of new, highly efficient, low-phosphorus or phosphorus-free, and environmentally friendly scale inhibitors has become a key research direction for water treatment agents both domestically and internationally.

[0003] Organophosphonic acid compounds contain atoms with lone electron pairs (P, O, N, and S) or π systems, conjugated bonds, and aromatic rings, and are considered effective corrosion inhibitors. The donor-acceptor synergistic effect between the metal and the inhibitor forms a thin protective layer on the metal surface through the formation of coordinated covalent bonds (chemisorption) or electronic interactions (physisorption). The resulting film isolates the metal's outer surface from the corrosive environment, thereby reducing the severity of corrosion. Organophosphonic acid compounds contain C-P bonds in their molecular structure, which are much stronger than the P-O-P bonds found in polyphosphates. Therefore, they have excellent chemical stability, a wide pH range, and are not easily hydrolyzed. During use, they do not hydrolyze to form orthophosphoric acid, which can lead to excessive growth of bacteria and algae. They are particularly suitable for cooling water systems operating under high hardness, high pH, ​​and high temperatures. Therefore, the development of new, efficient, low-phosphorus or phosphorus-free, environmentally friendly scale inhibitors has become a research hotspot. Summary of the Invention

[0004] The purpose of the present invention is to provide a novel composite organic phosphonic acid corrosion and scale inhibitor and a preparation method thereof. The synergistic effect of organic phosphonic acid and metal salt is used to improve the corrosion and scale inhibition efficiency. At the same time, polyacrylic acid and benzotriazole are used to enhance the dispersibility and copper corrosion inhibition, thereby solving the scaling and corrosion problems of industrial water systems.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solution: a novel composite organic phosphonic acid corrosion inhibitor and scale inhibitor, characterized in that it is composed of the following raw materials in parts by mass: 7 to 10 parts of 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid); 3 to 5 parts of zinc sulfate; 7 to 10 parts of polyacrylic acid; 1 to 2 parts of benzotriazole; and 30 to 50 parts of deionized water.

[0006] Preferably, the present invention provides a novel composite organic phosphonic acid corrosion and scale inhibitor, wherein the preparation method of the 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid) comprises the following steps:

[0007] Step 1: Add 2,6-bis(hydroxymethyl)-4-methoxyphenol to trimethyl phosphite to initiate a vigorous reaction, while producing methanol (CH3OH);

[0008] Step 2: hydrolyze the product in step 1 in a methanol-water mixed solution (volume ratio 2:1-1:2) at a temperature of 80-100° C. for 18-20 hours to generate 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid).

[0009] Preferably, the present invention provides a method for preparing a novel composite organic phosphonic acid corrosion inhibitor and scale inhibitor, which includes the following steps: mixing 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid), zinc sulfate, polyacrylic acid, benzotriazole and water according to a ratio under stirring conditions, controlling the mixing temperature to 30-50°C, the stirring rate to 300-500rpm, and the mixing time to 0.5-1 hour to obtain a homogeneous corrosion inhibitor and scale inhibitor.

[0010] Preferably, the present invention provides a novel composite organic phosphonic acid corrosion and scale inhibitor, wherein the 2-hydroxy-5-methoxy-1,3-phenylene bis(methylphosphonic acid) ester synthesis reaction is carried out at room temperature under nitrogen protection, and the reaction time is 2-4 hours.

[0011] Preferably, the present invention provides a novel composite organic phosphonic acid corrosion and scale inhibitor, wherein the hydrolysis step uses a methanol-water mixed solution as a reaction medium (preferably a volume ratio of 1:1), and the hydrolysis temperature is preferably 95°C.

[0012] Preferably, the present invention provides a novel composite organic phosphonic acid corrosion inhibitor and scale inhibitor, wherein the mass proportions of each component are preferably: 8 parts of 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid); 4 parts of zinc sulfate; 8 parts of polyacrylic acid; 1.5 parts of benzotriazole; and 40 parts of water.

[0013] Preferably, the present invention provides a novel composite organic phosphonic acid corrosion and scale inhibitor, wherein the working concentration of the corrosion and scale inhibitor is 0.005-0.05 mmol / L.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) 2-Hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid) contains a phosphonic acid group, a methoxy group, a phenolic hydroxyl group, and a benzene ring. The phosphorus atom (P), oxygen atom (O), and phenolic hydroxyl group (-OH) provide lone pairs of electrons, forming coordination bonds with empty d orbitals on the metal surface (such as Fe), generating a stable metal-inhibitor complex (such as an Fe-OP bond). The benzene ring in the molecule physically adsorbs to the metal surface through π electrons, increasing the coverage density of the molecule on the metal surface. Ultimately, a dense protective film is formed on the metal surface, isolating the corrosive medium from direct contact with the metal.

[0016] (2) Zinc sulfate forms a film through the synergistic effect of zinc ions and phosphonic acid, enhancing the corrosion inhibition effect.

[0017] (3) Polyacrylic acid disperses suspended particles, and benzotriazole inhibits corrosion of copper equipment.

[0018] (4) The formula is environmentally friendly and easy to prepare. It does not require solvents or catalysts and is suitable for high hardness and high alkalinity water. The scale inhibition rate is ≥95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structural formula of hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid) in an embodiment of the present invention; DETAILED DESCRIPTION

[0020] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0021] The present invention provides a technical solution: a novel composite organic phosphonic acid corrosion and scale inhibitor, the proportions by mass are as follows:

[0022] 2-Hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid): 7-10 parts; zinc sulfate: 3-5 parts; polyacrylic acid: 7-10 parts; benzotriazole: 1-2 parts; deionized water: 30-50 parts.

[0023] Preparation method of a new composite organic phosphonic acid corrosion and scale inhibitor:

[0024] Step 1: Synthesize 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid), the molecular structure of which is as follows: Figure 1 shown

[0025] 2,6-bis(hydroxymethyl)-4-methoxyphenol and trimethyl phosphite were mixed in a molar ratio of 1:2.2 and reacted for 2 hours to produce an intermediate product; a methanol-water mixed solution (volume ratio 1:1) was then added and hydrolyzed at 80°C for 20 hours, and finally dried to obtain the target product;

[0026] Step 2: Prepare composite antiscalant

[0027] Heat deionized water to 40°C, add polyacrylic acid and 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid) in sequence, stir to dissolve, then add zinc sulfate and benzotriazole, stir at constant temperature for 1 hour, adjust the pH to 6.5-7.5, and filter to obtain the finished product.

[0028] Example 1:

[0029] Synthesis of 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid)

[0030] In a dry three-necked flask, add 2,6-bis(hydroxymethyl)-4-methoxyphenol (0.1 mol) and trimethyl phosphite (0.22 mol) and stir magnetically for 2 hours;

[0031] The reaction solution was transferred to a beaker containing 50 mL of methanol / water (1:1), hydrolyzed at 80°C for 18 hours, filtered, and dried under vacuum at 60°C to obtain 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid) with a yield of 80%;

[0032] Preparation of composite scale inhibitor

[0033] 40 parts of deionized water were placed in a reaction kettle and heated to 40°C. Polyacrylic acid (8 parts) and 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid) (7 parts) were added in sequence and stirred until completely dissolved.

[0034] Add zinc sulfate (4 parts) and benzotriazole (1.5 parts), maintain stirring at 40°C for 1 hour, adjust the pH to 7.0 with sodium hydroxide solution, filter through a 0.45 μm filter membrane, and fill to obtain the finished product.

[0035] Example 2:

[0036] Synthesis of 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid)

[0037] In a dry three-necked flask, add 2,6-bis(hydroxymethyl)-4-methoxyphenol (0.1 mol) and trimethyl phosphite (0.24 mol) and stir magnetically for 2 hours;

[0038] The reaction solution was transferred to a beaker containing 60 mL of methanol / water (1:1.1), hydrolyzed at 100° C. for 19 hours, filtered, and dried in vacuo at 60° C. to obtain 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid) with a yield of 82%.

[0039] Preparation of composite scale inhibitor

[0040] 50 parts of deionized water were placed in a reaction kettle and heated to 40°C. Polyacrylic acid (10 parts) and 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid) (10 parts) were added in sequence and stirred until completely dissolved.

[0041] Add zinc sulfate (5 parts) and benzotriazole (1 part), maintain stirring at 40°C for 1 hour, adjust the pH to 7.0 with sodium hydroxide solution, filter through a 0.45 μm filter membrane, and fill to obtain the finished product.

[0042] Application effect test

[0043] Corrosion and scale inhibition performance of corrosion and scale inhibitors was tested in accordance with the "Determination of Corrosion Inhibition Performance of Water Treatment Agents - Rotating Coupon Method" (GB / T 18175-2014), "Determination of Scale Inhibition Performance of Water Treatment Agents - Calcium Carbonate Precipitation Method" (GB / T 16632-2019), and "Determination of Scale Inhibition Performance of Water Treatment Agents - Calcium Phosphate Precipitation Method" (GB / T 22626-2008). The main indicators of commercially available hydroxyethylidene diphosphonic acid corrosion and scale inhibitors are shown in the table below. It can be seen that the present invention exhibits excellent corrosion and scale inhibition performance.

[0044]

[0045] Anything not described in detail in the present invention is well known to those skilled in the art.

[0046] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified and replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A novel composite organic phosphonic acid corrosion and scale inhibitor, characterized by: The invention is composed of the following raw materials in parts by mass: 7-10 parts of 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid); 3-5 parts of zinc sulfate; 7-10 parts of polyacrylic acid; 1-2 parts of benzotriazole; and 30-50 parts of deionized water.

2. The novel composite organic phosphonic acid corrosion and scale inhibitor according to claim 1, characterized in that: The preparation method of the 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid) comprises the following steps: Step 1: Add 2,6-bis(hydroxymethyl)-4-methoxyphenol to trimethyl phosphite to initiate a vigorous reaction, while producing methanol; Step 2: hydrolyze the product in step 1 in a methanol-water mixed solution (volume ratio 2:1-1:2) at a temperature of 80-100° C. for 18-20 hours to generate 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid).

3. A method for preparing a novel composite organic phosphonic acid corrosion and scale inhibitor, characterized by: The following steps are involved: 2-Hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid), zinc sulfate, polyacrylic acid, benzotriazole and water are mixed under stirring conditions according to the proportion, and the mixing temperature is controlled at 30-50° C., the stirring speed is 300-500 rpm, and the mixing time is 0.5-1 hour to obtain a homogeneous corrosion and scale inhibitor.

4. The novel composite organic phosphonic acid corrosion and scale inhibitor according to claim 2, characterized in that: The synthesis reaction of 2-hydroxy-5-methoxy-1,3-phenylene bis(methylphosphonate) is carried out at room temperature under nitrogen protection, and the reaction time is 2-4 hours.

5. The novel composite organic phosphonic acid corrosion and scale inhibitor according to claim 2, characterized in that: The hydrolysis step uses a methanol-water mixed solution as a reaction medium (preferably a volume ratio of 1:1), and the hydrolysis temperature is preferably 95°C.

6. The novel composite organic phosphonic acid corrosion and scale inhibitor according to claim 1, characterized in that: The weight proportions of the components are preferably: 8 parts of 2-hydroxy-5-methoxy-1,3-phenylenebis(methylphosphonic acid); 4 parts of zinc sulfate; 8 parts of polyacrylic acid; 1.5 parts of benzotriazole; and 40 parts of water.

7. The novel composite organic phosphonic acid corrosion and scale inhibitor according to claim 3, characterized in that: The working concentration of the corrosion and scale inhibitor is 0.005-0.05 mmol / L.

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