A phosphorus-free corrosion-inhibiting water treatment agent and preparation method thereof

Abstract

The present invention relates to the field of water treatment agents, and provides a phosphorus-free corrosion-inhibiting water treatment agent and a preparation method thereof. The water treatment agent comprises the following raw materials by weight: 20-30 parts of modified polyaspartic acid, 10-15 parts of polyacrylamide, 1-5 parts of inorganic metal salt, 5-15 parts of polyacrylic acid, 0.5-3 parts of dispersant, and 40-60 parts of deionized water. The water treatment agent provided by the present invention has the characteristics of high-efficiency scale inhibition, corrosion inhibition and bactericidal performance.

Description

Technical Field

[0001] The invention relates to the field of water treatment agents, and in particular to a phosphorus-free corrosion-inhibiting water treatment agent and a preparation method thereof. Background Art

[0002] With the rapid development of economy and industry, the global water resources are consumed in large quantities and the global water environment is also deteriorating. Therefore, the control of water pollution and the recycling of water resources have become increasingly important. At present, most water treatment agents are organic phosphorus formulas, and some companies are still using inorganic phosphorus formulas. Although phosphorus is non-toxic, the long-term use of phosphorus-containing water treatment agents will cause eutrophication of water bodies and damage the ecological environment.

[0003] In order to meet the needs of sustainable development, in recent years, phosphorus-free, green and biodegradable water treatment agents have been

[0004] Gradually developed and put into use, such as polyaspartic acid, which contains a large number of amide bonds in its structure and has the advantages of biodegradability, chelation and dispersion, and can bind to Ca 2+ Mg 2+ Chelating effect occurs, especially for CaSO 4 、CaCO 3 Common calcium salts such as polyaspartic acid have good inhibitory effects and show good scale inhibition performance in low temperature environments. However, although polyaspartic acid has the above-mentioned excellent characteristics, its scale inhibition performance in high temperature environments is not ideal, which limits its application range. In addition, the long-term adsorption of dirt will cause corrosion of equipment. However, the corrosion inhibition effect of polyaspartic acid itself is general, and it is impossible to achieve the ideal effect of water treatment agents. In addition, bacteria are easily bred in water bodies, and suitable fungicides are often required to be added to water treatment agents.

[0005] Patent CN 107055819 B discloses a green water treatment agent with corrosion and scale inhibition performance and its application. The water treatment agent is composed of components such as polyaspartic acid, sodium molybdate, triethanolamine, sulfonated lignin, sodium tripolyphosphate and thiobenzothiazole. Although the water treatment agent prepared in this application has good corrosion and scale inhibition performance, and the preparation method is simple and the cost is low, the applicant has not solved the problem that the scale inhibition performance of polyaspartic acid in a high temperature environment is not ideal, which will limit the application scope of the water treatment agent to a certain extent.

[0006] Therefore, there is an urgent need in the market for a phosphorus-free corrosion-inhibiting water treatment agent with high-efficiency scale inhibition, corrosion inhibition and bactericidal properties. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention uses modified polyaspartic acid as the main component of the water treatment agent, adds polyacrylamide, inorganic metal salt, polyacrylic acid, bactericide, dispersant and deionized water to synthesize a phosphorus-free corrosion-inhibiting water treatment agent, which has the characteristics of high-efficiency scale inhibition, corrosion inhibition and bactericidal performance.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] On one hand, the present invention provides a phosphorus-free corrosion-inhibiting water treatment agent, which comprises the following raw materials in parts by weight: 20-30 parts of modified polyaspartic acid, 10-15 parts of polyacrylamide, 1-5 parts of inorganic metal salt, 5-15 parts of polyacrylic acid, 0.5-3 parts of dispersant, and 40-60 parts of deionized water.

[0010] In some embodiments of the present invention, the method for preparing the modified polyaspartic acid comprises the following steps:

[0011] (1) Add polysuccinimide and 1,4-bis(3-aminopropyl)piperazine into a reaction vessel, stir at 85-95° C. for 1.5-2.5 h, and dry to obtain an intermediate product for later use;

[0012] (2) mixing chitosan and a hydrochloric acid / acetic acid mixture, stirring to obtain a liquid for use; adding deionized water to the intermediate product of step (1), stirring, and then adding it to the liquid, stirring, adding a glutaraldehyde aqueous solution and a hydrochloric acid aqueous solution to adjust the pH to 6-7, stirring, washing, filtering, and drying to obtain modified polyaspartic acid.

[0013] In some embodiments of the present invention, in step (1), the mass ratio of polysuccinimide to 1,4-bis(3-aminopropyl)piperazine is 1:(2-3).

[0014] Preferably, in step (1), the mass ratio of polysuccinimide to 1,4-bis(3-aminopropyl)piperazine is 1:2.5.

[0015] In some embodiments of the present invention, in step (2), the mass ratio of the intermediate product to chitosan is 1:(0.3-0.6).

[0016] Preferably, in step (2), the mass ratio of the intermediate product to chitosan is 1:0.5.

[0017] Polyaspartic acid (PASP) is a green and degradable water treatment agent with certain scale inhibition and corrosion inhibition capabilities. However, compared with traditional non-degradable water treatment agents, there is a certain gap in its scale inhibition and corrosion inhibition performance. In addition, polyaspartic acid can often show good scale inhibition performance in low temperature environments, but its scale inhibition performance is not ideal in high temperature environments, which limits its application range.

[0018] On the one hand, the applicant uses 1,4-bis(3-aminopropyl)piperazine to perform ring-opening modification on polysuccinimide. 1,4-bis(3-aminopropyl)piperazine contains an N heterocyclic structure and has a high content of N atoms. Introducing 1,4-bis(3-aminopropyl)piperazine into the polyaspartic acid chain can effectively enhance the bonding between polyaspartic acid and Ca 2+ The chelating ability of 1,4-bis(3-aminopropyl)piperazine is conducive to interfering with the growth of calcium scale crystals, thereby improving the scale inhibition performance, and the piperazine heterocycle can also improve the heat resistance of polyaspartic acid to a certain extent, so that it can also show excellent scale inhibition performance at high temperature; further, the N atom introduced by 1,4-bis(3-aminopropyl)piperazine forms a coordination bond with the Fe empty orbital and adsorbs on the surface of carbon steel, while the non-polar groups are arranged outward in an orderly manner, thereby blocking the contact between carbon steel and the environmental medium, thereby effectively improving the corrosion inhibition performance of polyaspartic acid; on the other hand, the applicant introduced chitosan to react with the intermediate product with a side chain amino group to obtain modified polyaspartic acid. Chitosan is a polycationic compound with a certain scale inhibition ability, and the modified polyaspartic acid modified by chitosan contains both carboxyl and hydroxyl groups, which can react with Ca 2+ The modified polyaspartic acid and the carbonyl group in the modified polyaspartic acid can interact with each other to prevent the formation of crystal nuclei and reduce the generation of calcium scale precipitation, thereby effectively preventing the formation of calcium scale; further, the amino and carbonyl groups in the modified polyaspartic acid can adsorb metals, and with the adsorption of hydroxyl groups, a corrosion inhibition film can be formed, so that the modified polyaspartic acid can inhibit the diffusion of water and dissolved oxygen to the metal surface through steric hindrance, thereby improving the corrosion inhibition performance.

[0019] In some embodiments of the present invention, the inorganic metal salt is molybdate or tungstate.

[0020] Preferably, the molybdate is any one of anhydrous sodium molybdate, dihydrated sodium molybdate and pentahydrated sodium molybdate; and the tungstate is sodium tungstate or potassium tungstate.

[0021] In some embodiments of the present invention, 2-6 parts of fungicide are also included by weight.

[0022] In some embodiments of the present invention, the method for preparing the fungicide comprises the following steps:

[0023] 1) Mix methyl 5-chlorovalerate and acetonitrile, add 2-octyl-4-isothiazoline-3-one while stirring, stir, condense and reflux, react at 90-100° C. for 8-10 hours, distill under reduced pressure, wash, and dry to obtain the product for use;

[0024] 2) Add triethylenetetramine and anhydrous methanol to the product of step 1), stir, condense and reflux, react at 80-90° C. for 9-11 hours, distill under reduced pressure, extract and dry to obtain a fungicide.

[0025] In some embodiments of the present invention, the molar ratio of 5-chlorovaleric acid methyl ester, 2-octyl-4-isothiazoline-3-one and triethylenetetramine is 1:(1-2):(1.5-2.5).

[0026] Preferably, the molar ratio of the 5-chlorovaleric acid methyl ester, 2-octyl-4-isothiazoline-3-one and triethylenetetramine is 1:1.5:2.

[0027] Bacteria are easily bred in water bodies, so water treatment agents must have bactericidal properties on the basis of scale inhibition and corrosion inhibition. The heterocyclic compound isothiazolinone can rely on the active ingredients on the heterocyclic ring to form hydrogen bonds with the bases in the bacteria, adsorb on the bacterial cells and destroy the bacterial structure, and has strong bactericidal properties. However, a disadvantage of isothiazolinone substances is that they are less water-soluble, resulting in limited water solubility in water, which in turn leads to limited bactericidal properties.

[0028] The applicant uses 5-chlorovaleric acid methyl ester, 2-octyl-4-isothiazoline-3-one and triethylenetetramine as raw materials, firstly causes 5-chlorovaleric acid methyl ester and 2-octyl-4-isothiazoline-3-one to undergo quaternization reaction, then introduces triethylenetetramine to undergo amidation reaction, and then synthesizes a fungicide having an amide and a quaternary ammonium salt structure. The 5-chlorovaleric acid methyl ester has high reactivity and selectivity, and the 2-octyl-4-isothiazoline-3-one reacts with the 5-chlorovaleric acid methyl ester to generate a quaternary ammonium salt structure and introduce a long alkyl chain segment, thereby making the fungicide have good water solubility and stability. In addition, the amide, amino group and heterocyclic structure contained in the prepared fungicide molecule can also improve the corrosion inhibition performance of the water treatment agent to a certain extent.

[0029] In some embodiments of the present invention, the dispersant is polyvinyl alcohol.

[0030] Another aspect of the present invention further provides a method for preparing the phosphorus-free corrosion-inhibiting water treatment agent described in the above technical solution, comprising the following steps:

[0031] The modified polyaspartic acid, polyacrylamide, inorganic metal salt, polyacrylic acid, dispersant, bactericide and deionized water are mixed, stirred for 15-25 minutes, heated to 45-60° C., and stirred for 2-4 hours to obtain a phosphorus-free corrosion-inhibiting water treatment agent.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention uses modified polyaspartic acid as the main component of the water treatment agent, and adds polyacrylamide, inorganic metal salt, polyacrylic acid, bactericide, dispersant and deionized water to synthesize a phosphorus-free corrosion-inhibiting water treatment agent. Through the synergistic effect of the various components, the agent has the characteristics of high-efficiency scale inhibition, corrosion inhibition and bactericidal performance.

[0034] (2) The present invention uses 1,4-bis(3-aminopropyl)piperazine to perform ring-opening modification on polysuccinimide, which effectively improves the temperature resistance and scale inhibition performance, and then introduces chitosan to obtain modified polyaspartic acid, which plays a role in improving the scale inhibition and corrosion inhibition performance.

[0035] (3) The present invention uses 5-chlorovaleric acid methyl ester, 2-octyl-4-isothiazoline-3-one and triethylenetetramine as raw materials, firstly causes 5-chlorovaleric acid methyl ester and 2-octyl-4-isothiazoline-3-one to undergo quaternization reaction, then introduces triethylenetetramine to undergo amidation reaction, and then synthesizes a fungicide having an amide and a quaternary ammonium salt structure, so that the fungicide has both good water solubility and stability, thereby improving the fungicide effect, and also improving the corrosion inhibition performance of the water treatment agent to a certain extent.

[0036] (4) The water treatment agent prepared by the present invention has high-efficiency scale inhibition, corrosion inhibition and bactericidal properties, can be widely used in the field of phosphorus-free water treatment agents, and has good commercial application value. DETAILED DESCRIPTION

[0037] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0038] In the following examples and comparative examples, except for modified polyaspartic acid and bactericide, the other compound monomers and related reagents used can be purchased from the market, among which polysuccinimide was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; chitosan with a deacetylation degree of 80% was purchased from Wuhan Jiyesheng Chemical Co., Ltd.; polyacrylamide was anionic polyacrylamide, purchased from Gongyi Hongyuan Environmental Protection Technology Co., Ltd.; polyacrylic acid was purchased from Shandong Wanhua Tianhe New Materials Co., Ltd.; and polyvinyl alcohol was PVA 1788.

[0039] Preparation Example 1

[0040] The synthetic method of modified polyaspartic acid A comprises the following steps:

[0041] (1) Add 9.8 g of polysuccinimide and 24.5 g of 1,4-bis(3-aminopropyl)piperazine into a reaction vessel, stir at 90° C. for 2 h, and dry at 60° C. for 8 h to obtain an intermediate product for later use;

[0042] (2) 10 g of chitosan was mixed with 40 ml of a 2 wt% hydrochloric acid aqueous solution / 10 ml of a 2 wt% acetic acid aqueous solution, and stirred for 30 min to obtain a liquid for use; 100 ml of deionized water was added to 20 g of the intermediate product of step (1), and the mixture was stirred for 30 min. The mixture was added to the liquid, and stirred for 30 min. 20 g of a 50 wt% glutaraldehyde aqueous solution and a 10 wt% hydrochloric acid aqueous solution were added to adjust the pH to 6.5. The mixture was stirred for 2 h, and washed with a 2 wt% acetic acid aqueous solution for 3 times. The mixture was filtered and dried at 60° C. for 8 h to obtain modified polyaspartic acid A.

[0043] Preparation Example 2

[0044] The specific implementation method of modified polyaspartic acid B is the same as that of modified polyaspartic acid A, except that in step (1), the mass of 1,4-bis(3-aminopropyl)piperazine is replaced with 18 g.

[0045] Preparation Example 3

[0046] The specific implementation method of modified polyaspartic acid C is the same as that of modified polyaspartic acid A, except that in step (2), the mass of chitosan is replaced by 5 g.

[0047] Preparation Example 4

[0048] The synthesis method of fungicide A comprises the following steps:

[0049] 1) Mix 0.1 mol of methyl 5-chlorovalerate and 80 ml of acetonitrile, add 0.15 mol of 2-octyl-4-isothiazoline-3-one while stirring, stir for 20 min, condense and reflux, react at 95 ° C for 9 h, distill under reduced pressure, wash with acetone, and vacuum dry at 60 ° C for 4 h to obtain the product for use;

[0050] 2) Add 0.2 mol of triethylenetetramine and 200 ml of anhydrous methanol to the product of step 1), stir for 20 min, condense and reflux, react at 85° C. for 10 h, distill under reduced pressure, extract with ether for 3 times, and vacuum dry at 60° C. for 4 h to obtain fungicide A.

[0051] Preparation Example 5

[0052] The specific implementation method of fungicide B is the same as that of fungicide A, except that in step 1), the molar number of 2-octyl-4-isothiazoline-3-one is replaced with 0.09 mol.

[0053] Preparation Example 6

[0054] Bactericide C, the specific implementation method is the same as that of bactericide A, except that: in step 2), the molar number of triethylenetetramine is replaced with 0.14 mol.

[0055] Example 1

[0056] A phosphorus-free corrosion-inhibiting water treatment agent comprises the following raw materials by weight: 25 parts of modified polyaspartic acid A, 13 parts of polyacrylamide, 3 parts of sodium tungstate, 10 parts of polyacrylic acid, 4 parts of bactericide A, 1.5 parts of polyvinyl alcohol and 50 parts of deionized water.

[0057] The preparation method of the phosphorus-free corrosion-inhibiting water treatment agent in this embodiment comprises the following steps:

[0058] Modified polyaspartic acid A, polyacrylamide, sodium tungstate, polyacrylic acid, polyvinyl alcohol, fungicide A and deionized water were mixed, stirred for 20 minutes, heated to 50° C., and stirred for 3 hours to obtain a phosphorus-free corrosion-inhibiting water treatment agent.

[0059] Example 2

[0060] A phosphorus-free corrosion-inhibiting water treatment agent comprises the following raw materials by weight: 20 parts of modified polyaspartic acid A, 10 parts of polyacrylamide, 1 part of sodium molybdate pentahydrate, 5 parts of polyacrylic acid, 2 parts of bactericide A, 0.5 parts of polyvinyl alcohol and 40 parts of deionized water.

[0061] The preparation method of the phosphorus-free corrosion-inhibiting water treatment agent in this embodiment comprises the following steps:

[0062] Modified polyaspartic acid A, polyacrylamide, sodium molybdate pentahydrate, polyacrylic acid, polyvinyl alcohol, fungicide A and deionized water were mixed, stirred for 15 minutes, heated to 45° C., and stirred for 4 hours to obtain a phosphorus-free corrosion-inhibiting water treatment agent.

[0063] Example 3

[0064] A phosphorus-free corrosion-inhibiting water treatment agent comprises the following raw materials by weight: 30 parts of modified polyaspartic acid A, 15 parts of polyacrylamide, 5 parts of potassium tungstate, 15 parts of polyacrylic acid, 6 parts of bactericide A, 3 parts of polyvinyl alcohol and 60 parts of deionized water.

[0065] The preparation method of the phosphorus-free corrosion-inhibiting water treatment agent in this embodiment comprises the following steps:

[0066] Modified polyaspartic acid A, polyacrylamide, potassium tungstate, polyacrylic acid, polyvinyl alcohol, fungicide A and deionized water were mixed, stirred for 25 minutes, heated to 60° C., and stirred for 2 hours to obtain a phosphorus-free corrosion-inhibiting water treatment agent.

[0067] Example 4

[0068] A phosphorus-free corrosion-inhibiting water treatment agent comprises the following raw materials by weight: 25 parts of modified polyaspartic acid A, 13 parts of polyacrylamide, 3 parts of sodium tungstate, 10 parts of polyacrylic acid, 1.5 parts of polyvinyl alcohol and 50 parts of deionized water.

[0069] The preparation method of the phosphorus-free corrosion-inhibiting water treatment agent in this embodiment comprises the following steps:

[0070] Modified polyaspartic acid A, polyacrylamide, sodium tungstate, polyacrylic acid, polyvinyl alcohol and deionized water were mixed, stirred for 20 minutes, heated to 50° C., and stirred for 3 hours to obtain a phosphorus-free corrosion-inhibiting water treatment agent.

[0071] Example 5

[0072] This embodiment provides a phosphorus-free corrosion-inhibiting water treatment agent and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that modified polyaspartic acid A is replaced by modified polyaspartic acid B in equal amounts.

[0073] Example 6

[0074] This embodiment provides a phosphorus-free corrosion-inhibiting water treatment agent and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that modified polyaspartic acid C is used to replace modified polyaspartic acid A in equal amounts.

[0075] Example 7

[0076] This embodiment provides a phosphorus-free corrosion-inhibiting water treatment agent and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that bactericide A is replaced by bactericide B in an equal amount.

[0077] Example 8

[0078] This embodiment provides a phosphorus-free corrosion-inhibiting water treatment agent and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that bactericide C replaces bactericide A in equal amounts.

[0079] Example 9

[0080] This embodiment provides a phosphorus-free corrosion-inhibiting water treatment agent and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that the fungicide A is replaced by an equal amount of 2-octyl-4-isothiazoline-3-one.

[0081] Comparative Example 1

[0082] This comparative example provides a phosphorus-free corrosion-inhibiting water treatment agent and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that polyaspartic acid is used to replace modified polyaspartic acid A in an equal amount.

[0083] Polyaspartic acid was purchased from Chiping County Jinshun Chemical Co., Ltd.

[0084] Performance Testing

[0085] The scale inhibition, corrosion inhibition and bactericidal performance of the phosphorus-free corrosion-inhibiting water treatment agents of the above-mentioned Examples 1-9 and Comparative Example 1 were tested, and the test results are shown in Table 1.

[0086] (1) Scale and corrosion inhibition performance

[0087] The main indicators of the test water quality are total hardness 756 mg / L (calculated as calcium carbonate), calcium hardness 522 mg / L (calculated as calcium carbonate), pH=8.45, alkalinity 375 mg / L (calculated as calcium carbonate), and the concentration of phosphorus-free corrosion inhibitor added to the water sample is 100 mg / L.

[0088] The scale inhibition performance test method is carried out in accordance with GB / T 16632-2008 "Determination of scale inhibition performance of water treatment agents - Calcium carbonate deposition method";

[0089] The corrosion inhibition performance test method is carried out in accordance with GB / T 18175-2014 "Determination of Corrosion Inhibition Performance of Water Treatment Agents - Rotating Coupon Method", and 20# carbon steel is used as the corrosion inhibition performance test piece.

[0090] (2) Bactericidal properties

[0091] The phosphorus-free corrosion-inhibiting water treatment agent prepared in the embodiment and the comparative example was added to the water sample (the concentration of the phosphorus-free corrosion-inhibiting water treatment agent was 60 mg / L). After contacting at 35±2°C for 72 hours, the number of sulfate-reducing bacteria was determined by the dilution culture number method (MPN method) according to the method in GB / T14643.5-2009, taking sulfate-reducing bacteria as an example. At the same time, a blank sample was made to calculate the sterilization rate, which was sterilization rate = (the number of bacteria in the blank sample at the same time - the number of bacteria in the sample at the same time) × 100% / the number of bacteria in the blank sample at the same time.

[0092] Table 1

[0093]

[0094] It can be seen from the data in Table 1 that the phosphorus-free corrosion-inhibiting water treatment agents in Examples 1-3 of the present invention have good scale inhibition, corrosion inhibition and bactericidal properties as a whole. Among them, Examples 5-6 changed the modification ratio of 1,4-bis(3-aminopropyl)piperazine and chitosan in the synthesis process of modified polyaspartic acid, resulting in a significant decrease in the scale inhibition and corrosion inhibition performance of the water treatment agent, but had little effect on the bactericidal property of the water treatment agent. Comparative Example 1 used polyaspartic acid to replace modified polyaspartic acid A in equal amounts, and the test found that the scale inhibition and corrosion inhibition performance of the water treatment agent showed poor results; Examples 7-8 changed the addition ratio of key components in the synthesis process of the bactericide, resulting in the water solubility and bactericidal property of 2-octyl-4-isothiazoline-3-one not being well improved, Example 9 selected the conventional bactericide 2-octyl-4-isothiazoline-3-one to replace bactericide A, and Example 4 did not add bactericide A relative to Example 1, all of which resulted in the bactericidal performance of the water treatment agent showing poor results, and had a smaller impact on the corrosion and scale inhibition performance.

[0095] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A phosphorus-free corrosion-inhibiting water treatment agent, characterized in that: The water treatment agent comprises the following raw materials by weight: 20-30 parts of modified polyaspartic acid, 10-15 parts of anionic polyacrylamide, 1-5 parts of inorganic metal salt, 5-15 parts of polyacrylic acid, 0.5-3 parts of dispersant, 2-6 parts of bactericide, and 40-60 parts of deionized water; The preparation method of the modified polyaspartic acid comprises the following steps: (1) Add polysuccinimide and 1,4-bis(3-aminopropyl)piperazine into a reaction vessel, stir at 85-95° C. for 1.5-2.5 h, and dry to obtain an intermediate product for later use; (2) mixing chitosan and a hydrochloric acid / acetic acid mixture, stirring to obtain a liquid for use; adding deionized water to the intermediate product of step (1), stirring, and then adding to the liquid, stirring, adding a glutaraldehyde aqueous solution and a hydrochloric acid aqueous solution to adjust the pH to 6-7, stirring, washing, filtering, and drying to obtain modified polyaspartic acid; In the step (1), the mass ratio of polysuccinimide to 1,4-bis(3-aminopropyl)piperazine is 1:(2-3); In the step (2), the mass ratio of the intermediate product to chitosan is 1:(0.3-0.6); The preparation method of the bactericide comprises the following steps: 1) Mix methyl 5-chlorovalerate and acetonitrile, add 2-octyl-4-isothiazoline-3-one while stirring, stir, condense and reflux, react at 90-100° C. for 8-10 hours, distill under reduced pressure, wash, and dry to obtain the product for use; 2) Add triethylenetetramine and anhydrous methanol to the product of step 1), stir, condense and reflux, react at 80-90° C. for 9-11 hours, distill under reduced pressure, extract, and dry to obtain a fungicide; The molar ratio of 5-chlorovaleric acid methyl ester, 2-octyl-4-isothiazoline-3-one and triethylenetetramine is 1:(1-2):(1.5-2.5).

2. The phosphorus-free corrosion-inhibiting water treatment agent according to claim 1, characterized in that: The inorganic metal salt is molybdate or tungstate.

3. The phosphorus-free corrosion-inhibiting water treatment agent according to claim 1, characterized in that: The dispersant is polyvinyl alcohol.

4. A method for preparing the phosphorus-free corrosion-inhibiting water treatment agent according to any one of claims 1 to 3, characterized in that: The following steps are involved: The modified polyaspartic acid, polyacrylamide, inorganic metal salt, polyacrylic acid, dispersant, bactericide and deionized water are mixed, stirred for 15-25 minutes, heated to 45-60° C., and stirred for 2-4 hours to obtain a phosphorus-free corrosion-inhibiting water treatment agent.

Images