Easily biodegradable phosphorus-free scale and corrosion inhibitor and preparation method thereof

Abstract

The invention discloses an easily biodegradable phosphorus-free scale and corrosion inhibitor and a preparation method thereof, and belongs to the technical field of water treatment. The phosphorus-free scale and corrosion inhibitor is prepared from the following components in parts by weight: 360 to 400 parts of water, 30 to 40 parts of modified polyepoxysuccinic acid, 20 to 30 parts of composite adsorption corrosion inhibitor, 20 to 25 parts of hydrolytic polymaleic anhydride, 8 to 15 parts of sodium gluconate, 4 to 6 parts of alanine, 2 to 5 parts of sodium alginate and 1 to 3 parts of sodium carboxymethyl cellulose, the compound adsorption corrosion inhibitor is obtained by forming an inclusion compound from plant polyphenol and hydroxypropyl-beta-cyclodextrin and then reacting the inclusion compound with sodium tartrate, sodium citrate and polyaspartic acid. The modified polyepoxysuccinic acid is obtained by modifying epoxysuccinic acid with urea, N-hydroxymaleimide and citraconomide. The phosphorus-free scale and corrosion inhibitor prepared by the invention is easy to biodegrade and has good scale and corrosion inhibition performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to a phosphorus-free scale and corrosion inhibitor that is easily biodegradable and a preparation method thereof. Background Art

[0002] With the average annual growth of global industrial water consumption by 3.5%, the ecological environment problems caused by traditional phosphorus-containing scale and corrosion inhibitors have become increasingly prominent. The tolerance of microorganisms to acrylamide polymers can increase by 1000 times within 3 years, resulting in an average annual increase of 23% in the dosage of the agent and a substantial increase in operating costs, forming a vicious cycle of "pollution-treatment-re-pollution".

[0003] In addition, traditional scale and corrosion inhibitors often can only exhibit good scale and corrosion inhibition effects within a specific pH range. When the pH value of the water quality exceeds this range, its performance will drop significantly, resulting in the inability to stably ensure the normal operation of equipment in a complex water quality environment and unable to meet the adaptability requirements of different industrial production and water treatment scenarios for pH changes in water quality. In some industrial circulating water systems or hot water treatment equipment with high-temperature operations, existing scale and corrosion inhibitors are prone to problems such as decomposition, volatilization, or performance decline under high-temperature conditions. This not only greatly reduces their scale and corrosion inhibition efficacy but also generates new impurities due to compositional changes, affecting the normal operation of the water system and even causing additional damage to the equipment.

[0004] Therefore, the present invention develops a phosphorus-free scale and corrosion inhibitor that is easily biodegradable and a preparation method thereof to solve the technical problems of existing scale and corrosion inhibitors, such as containing phosphorus, being difficult to biodegrade, and poor stability of the compounding system. Summary of the Invention

[0005] The purpose of the present invention is to provide a phosphorus-free scale and corrosion inhibitor that is easily biodegradable and a preparation method thereof to solve the technical problems of existing scale and corrosion inhibitors, such as containing phosphorus, being difficult to biodegrade, and poor stability of the compounding system.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] The phosphorus-free scale and corrosion inhibitor that is easily biodegradable comprises the following components in parts by weight: 360 - 400 parts of water, 30 - 40 parts of modified polyepoxysuccinic acid, 20 - 30 parts of composite adsorption corrosion inhibitor, 20 - 25 parts of hydrolyzed polymaleic anhydride, 8 - 15 parts of sodium gluconate, 4 - 6 parts of alanine, 2 - 5 parts of sodium alginate, and 1 - 3 parts of sodium carboxymethylcellulose; the composite adsorption corrosion inhibitor is obtained by reacting an inclusion complex formed by plant polyphenols and hydroxypropyl-β-cyclodextrin with sodium tartrate, sodium citrate, and polyaspartic acid; the modified polyepoxysuccinic acid is synthesized by reacting sodium hydroxide solution, maleic anhydride solution, and hydrogen peroxide to form epoxysuccinic acid, and then modified with urea, N-hydroxymaleimide, and citraconimide.

[0008] Preferably, the preparation method of the composite adsorption inhibitor comprises the following steps:

[0009] Q1. Add the plant polyphenol solution to the saturated aqueous solution of hydroxypropyl-β-cyclodextrin, stir, perform ultrasonic treatment, cool, stand, filter, wash, and dry to obtain the inclusion compound;

[0010] Q2. Add the inclusion compound, sodium tartrate, and sodium citrate to water, adjust the pH value to 8 - 9, heat and stir for reaction to obtain the reaction solution. Cool to room temperature, add the polyaspartic acid solution and N,N'-dicyclohexylcarbodiimide to the reaction solution, stir for reaction, add dilute hydrochloric acid to adjust the pH value to 6 - 7, filter, collect the filtrate, add the filtrate to absolute ethanol to obtain a precipitate, wash, and dry to obtain the composite adsorption inhibitor.

[0011] Preferably, in Q1, the volume ratio of the plant polyphenol solution to the saturated aqueous solution of cyclodextrin is 1:6 - 8, the plant polyphenol is a mixture of tea polyphenols and tannic acid, the mass ratio of tea polyphenols to tannic acid is 1:1 - 2, the plant polyphenol solution is prepared by mixing plant polyphenols and ethanol according to a mass ratio of 1:5 - 8; the ultrasonic power is 100 - 300 W, the ultrasonic temperature is 30 - 50 °C, the ultrasonic time is 30 - 60 min, cool to room temperature, the standing temperature is 2 - 8 °C, and the standing time is 12 - 24 h.

[0012] Preferably, in Q2, the mass ratio of the inclusion compound, sodium tartrate, sodium citrate, and water is 1:2 - 3:1 - 2:10 - 20, adjust the pH value to 8 - 9 with 1 mol / L NaOH, the heating temperature is 50 - 70 °C, the stirring speed is 300 - 500 r / min, the stirring reaction time is 2 - 4 h, the mass concentration of the polyaspartic acid solution is 10 - 30 wt%, the dosage ratio of the reaction solution, the polyaspartic acid solution, and N,N'-dicyclohexylcarbodiimide is 10 g:50 - 100 mL:0.05 - 0.3 g, the room temperature stirring reaction time is 4 - 6 h, the concentration of the dilute hydrochloric acid is 0.1 - 1 mol / L, and the volume ratio of the filtrate to absolute ethanol is 1:10 - 20.

[0013] Preferably, the preparation method of the modified polyepoxysuccinic acid comprises the following steps:

[0014] S1. Drop the sodium hydroxide solution into the maleic anhydride solution, stir, add a catalyst, and drop hydrogen peroxide for reaction to obtain the epoxysuccinic acid solution; add an initiator to the epoxysuccinic acid solution and heat to obtain polyepoxysuccinic acid;

[0015] S2. Dissolve polyepoxysuccinic acid in N,N-dimethylformamide, add urea, N-hydroxymaleimide, citraconimide, p-toluenesulfonic acid, dicyclohexylcarbodiimide and 4-dimethylaminopyridine respectively, heat for reaction, after completion, cool the reaction, filter, collect the filtrate, pour the filtrate into deionized water to obtain a precipitate, filter, wash and dry to obtain modified polyepoxysuccinic acid.

[0016] Preferably, in S1, the concentration of the maleic anhydride solution is 0.5 - 2 mol / L, the concentration of the sodium hydroxide solution is 1 - 3 mol / L, the catalyst is silicotungstic acid, the mass concentration of hydrogen peroxide is 30 wt%, and the dosage ratio of the maleic anhydride solution, sodium hydroxide solution, silicotungstic acid and hydrogen peroxide is 100 mL : 50 - 100 mL : 0.05 - 0.2 g : 30 - 40 mL, the reaction temperature is 65 - 70 °C, and the reaction time is 2 - 3 h; the initiator is an equimass mixture of sodium hydroxide and potassium hydroxide, and the dosage ratio of the initiator to the epoxysuccinic acid solution is 0.1 - 0.5 g : 100 mL; the heating temperature is 85 - 90 °C, and the reaction time is 3 - 4 h.

[0017] Preferably, in S2, the dosage ratio of polyepoxysuccinic acid, N,N-dimethylformamide, urea, N-hydroxymaleimide, citraconimide, p-toluenesulfonic acid, dicyclohexylcarbodiimide and 4-dimethylaminopyridine is 10 g : 100 - 200 mL : 1 - 2.5 g : 1 - 2.5 g : 1 - 2 g : 0.1 - 0.3 g : 10 - 12 g : 0.1 - 0.5 g, the heating temperature is 80 - 100 °C, the heating reaction time is 4 - 6 h, the cooling temperature is 20 - 25 °C, and the reaction time is 12 - 24 h.

[0018] Furthermore, a preparation method of an easily biodegradable phosphorus-free scale and corrosion inhibitor includes the following steps:

[0019] (1) Mix the modified polyepoxysuccinic acid and hydrolyzed polymaleic anhydride to obtain a mixture one, grind the composite adsorption corrosion inhibitor, add it to the mixture one, and stir to obtain a mixture two;

[0020] (2) Add sodium carboxymethylcellulose to water, stir to dissolve to obtain a sodium carboxymethylcellulose solution; add sodium alginate and sodium gluconate to the sodium carboxymethylcellulose solution respectively, stir to dissolve to obtain a mixed solution; add the mixed solution to the mixture two, stir evenly, and finally add alanine and stir to obtain an easily biodegradable phosphorus-free scale and corrosion inhibitor.

[0021] Preferably, in step (1), the grinding particle size of the composite adsorption corrosion inhibitor is 10 - 100 microns, the stirring speed is 200 - 400 r / min, and the stirring time is 30 - 60 min.

[0022] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0023] 1. Through the synergistic effect of components such as modified polyepoxysuccinic acid, composite adsorption corrosion inhibitor, sodium polyacrylate, hydrolyzed polymaleic anhydride, sodium carboxymethyl cellulose, and sodium gluconate, the modified polyepoxysuccinic acid, hydrolyzed polymaleic anhydride, and sodium gluconate, as metal-organic chelating agents, can effectively prevent the formation of scale layers by calcium, magnesium and other ions in water, soften the water quality and slow down the scale formation rate. At the same time, a protective film is formed on the metal surface to inhibit the corrosion of the metal and extend the service life of the equipment. The components in this scale and corrosion inhibitor have good biodegradability, and the components act synergistically to form a stable compound system, which is not prone to phenomena such as stratification and precipitation during storage and use.

[0024] 2. After the formation of an inclusion complex between plant polyphenols and hydroxypropyl-β-cyclodextrin, the present invention not only improves the stability and solubility of plant polyphenols, but also makes them more easily adsorbed on the metal surface. The introduction of sodium tartrate and sodium citrate further enhances the stability and compactness of the protective film by forming complexes with metal ions. In addition, the addition of polyaspartic acid forms an adsorption network with a rich pore structure and active sites, which has good adsorption performance and chelating ability, and can cooperate with components such as plant polyphenols to improve the adhesion of the corrosion inhibitor on the metal surface and the barrier ability to corrosive media, thereby significantly enhancing the corrosion inhibition effect of the phosphorus-free scale and corrosion inhibitor.

[0025] 3. Epoxysuccinic acid is synthesized by the reaction of sodium hydroxide solution, maleic anhydride solution and hydrogen peroxide, and then modified by urea, N-hydroxymaleimide and citraconimide. A variety of active groups are introduced into the molecular structure of polyepoxysuccinic acid, enhancing the chelating ability for metal ions such as calcium, magnesium and iron, and being able to more effectively prevent the formation of scale precipitates by metal ions. At the same time, the modified molecular structure has a stronger interference effect on the growth of scale crystals, inhibiting the aggregation and growth of scale crystals, thereby significantly improving the scale inhibition performance of the phosphorus-free scale and corrosion inhibitor. Specific Embodiments

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] Example 1:

[0028] This example provides a preparation method of a composite adsorption corrosion inhibitor, including the following steps:

[0029] Q1. The plant polyphenol solution is obtained by mixing plant polyphenols and ethanol at a mass ratio of 1:5, with the mass ratio of tea polyphenols to tannic acid being 1:1. Add 100 mL of the plant polyphenol solution to 600 mL of a saturated aqueous solution of hydroxypropyl-β-cyclodextrin, stir, and perform ultrasonic treatment. The ultrasonic power is 100 W, the ultrasonic temperature is 30 °C, and the ultrasonic time is 30 min. Cool to room temperature, and let it stand at a temperature of 2 °C for 12 h. Then filter, wash, and dry to obtain the inclusion compound.

[0030] Q2. Add 10 g of the inclusion compound, 20 g of sodium tartrate, and 10 g of sodium citrate to 100 g of water, and adjust the pH value to 8 with 1 mol / L NaOH. Heat and stir for reaction. The heating temperature is 50 °C, the stirring speed is 300 r / min, and the stirring reaction time is 2 h to obtain the reaction solution. Cool to room temperature. Add 50 mL of a 10 wt% polyaspartic acid solution and 0.05 g of N,N'-dicyclohexylcarbodiimide to 10 g of the reaction solution, and stir at room temperature for 4 h. Then add 0.1 - 1 mol / L dilute hydrochloric acid to adjust the pH value to 6, filter, and collect the filtrate. Add 50 mL of the filtrate to 500 mL of absolute ethanol to obtain a precipitate, wash, and dry to obtain the composite adsorption inhibitor.

[0031] This example provides a preparation method of modified polyepoxysuccinic acid, which includes the following steps:

[0032] S1. Drop 50 mL of a 1 mol / L sodium hydroxide solution into 100 mL of a 0.5 mol / L maleic anhydride solution, stir, add 0.05 g of silicotungstic acid, and drop 30 mL of 30 wt% hydrogen peroxide for reaction. The reaction temperature is 65 °C, and the reaction time is 2 h to obtain an epoxysuccinic acid solution. Add 0.05 g of sodium hydroxide and 0.05 g of potassium hydroxide to 100 mL of the epoxysuccinic acid solution, heat, with the heating temperature being 85 °C and the reaction time being 3 h to obtain polyepoxysuccinic acid.

[0033] S2. Dissolve 10 g of polyepoxysuccinic acid in 100 mL of N,N-dimethylformamide, and add 1 g of urea, 1 g of N-hydroxymaleimide, 1 g of citraconimide, 0.1 g of p-toluenesulfonic acid, 10 g of dicyclohexylcarbodiimide, and 0.1 g of 4-dimethylaminopyridine respectively. Heat for reaction. The heating temperature is 80 °C, and the heating reaction time is 4 h. After completion, cool the reaction. The cooling temperature is 20 °C, and the reaction time is 12 h. Filter and collect the filtrate, pour the filtrate into deionized water to obtain a precipitate, filter, wash, and dry to obtain the modified polyepoxysuccinic acid.

[0034] This embodiment provides a phosphorus-free scale and corrosion inhibitor that is easily biodegradable, comprising the following components by weight: 360 g of water, 30 g of modified polyepoxysuccinic acid, 20 g of composite adsorption corrosion inhibitor, 20 g of hydrolyzed polymaleic anhydride, 8 g of sodium gluconate, 4 g of alanine, 2 g of sodium alginate, and 1 g of sodium carboxymethylcellulose.

[0035] Among them, the preparation method of the phosphorus-free scale and corrosion inhibitor that is easily biodegradable comprises the following steps:

[0036] (1) Mix the modified polyepoxysuccinic acid and hydrolyzed polymaleic anhydride to obtain a mixture one. Grind the composite adsorption corrosion inhibitor, and the grinding particle size of the composite adsorption corrosion inhibitor is 100 microns. Add it to the mixture one and stir at a stirring speed of 200 r / min for 30 min to obtain a mixture two;

[0037] (2) Add sodium carboxymethylcellulose to water and stir to dissolve to obtain a sodium carboxymethylcellulose solution; add sodium alginate and sodium gluconate to the sodium carboxymethylcellulose solution respectively and stir to dissolve to obtain a mixed solution; add the mixed solution to the mixture two, stir evenly, and finally add alanine and stir to obtain the phosphorus-free scale and corrosion inhibitor that is easily biodegradable.

[0038] Example 2:

[0039] This embodiment provides a preparation method of a composite adsorption corrosion inhibitor, comprising the following steps:

[0040] Q1. The plant polyphenol solution is obtained by mixing plant polyphenols and ethanol in a mass ratio of 1:6, and the mass ratio of tea polyphenols to tannic acid is 1:1.2. Add 100 mL of the plant polyphenol solution to 650 mL of a saturated aqueous solution of hydroxypropyl-β-cyclodextrin, stir, perform ultrasonic treatment, the ultrasonic power is 180 W, the ultrasonic temperature is 35 °C, the ultrasonic time is 35 min, cool to room temperature, the standing temperature is 4 °C, the standing time is 16 h, filter, wash, and dry to obtain an inclusion compound;

[0041] Q2. Add 10 g of the inclusion compound, 22 g of sodium tartrate, and 14 g of sodium citrate to 120 g of water, adjust the pH value to 8.3 with 1 mol / L NaOH, heat and stir the reaction, the heating temperature is 55 °C, the stirring speed is 350 r / min, the stirring reaction time is 2.5 h to obtain a reaction solution. Cool to room temperature, add 60 mL of 15 wt% polyaspartic acid solution and 0.1 g of N,N-dicyclohexylcarbodiimide to 10 g of the reaction solution, stir at room temperature for 5 h, add 0.4 mol / L dilute hydrochloric acid to adjust the pH value to 6.2, filter, collect the filtrate, add 50 mL of the filtrate to 600 mL of absolute ethanol to obtain a precipitate, wash, and dry to obtain the composite adsorption corrosion inhibitor.

[0042] This embodiment provides a method for preparing modified polyepoxysuccinic acid, which comprises the following steps:

[0043] S1. Add 60 mL of 1.6 mol / L sodium hydroxide solution dropwise to 100 mL of 0.8 mol / L maleic anhydride solution, stir, add 0.1 g of silicotungstic acid, and dropwise add 33 mL of 30 wt% hydrogen peroxide for reaction. The reaction temperature is 66 °C and the reaction time is 2.5 h to obtain an epoxysuccinic acid solution; add 0.1 g of sodium hydroxide and 0.1 g of potassium hydroxide to 100 mL of the epoxysuccinic acid solution, heat, and the heating temperature is 86 °C and the reaction time is 3.2 h to obtain polyepoxysuccinic acid;

[0044] S2. Dissolve 10 g of polyepoxysuccinic acid in 120 mL of N,N-dimethylformamide, add 1.5 g of urea, 1.5 g of N-hydroxymaleimide, 1.2 g of citraconimide, 0.15 g of p-toluenesulfonic acid, 10.5 g of dicyclohexylcarbodiimide and 0.2 g of 4-dimethylaminopyridine respectively, heat for reaction, the heating temperature is 85 °C and the heating reaction time is 4.5 h. After completion, cool the reaction, the cooling temperature is 21 °C and the reaction time is 16 h, filter, collect the filtrate, pour the filtrate into deionized water to obtain a precipitate, filter, wash and dry to obtain modified polyepoxysuccinic acid.

[0045] This embodiment provides an easily biodegradable phosphorus-free scale and corrosion inhibitor, which comprises the following components by weight: 370 g of water, 32 g of modified polyepoxysuccinic acid, 22 g of composite adsorption corrosion inhibitor, 21 g of hydrolyzed polymaleic anhydride, 10 g of sodium gluconate, 4 g of alanine, 3 g of sodium alginate and 1 g of sodium carboxymethylcellulose.

[0046] Among them, the preparation method of the easily biodegradable phosphorus-free scale and corrosion inhibitor comprises the following steps:

[0047] (1) Mix the modified polyepoxysuccinic acid and hydrolyzed polymaleic anhydride to obtain a mixture one, grind the composite adsorption corrosion inhibitor, and the grinding particle size of the composite adsorption corrosion inhibitor is 40 microns, add it to the mixture one, stir, and the stirring speed is 250 r / min and the stirring time is 40 min to obtain a mixture two;

[0048] (2) Add sodium carboxymethylcellulose to water, stir and dissolve to obtain a sodium carboxymethylcellulose solution; add sodium alginate and sodium gluconate to the sodium carboxymethylcellulose solution respectively, stir and dissolve to obtain a mixed solution; add the mixed solution to the mixture two, stir evenly, and finally add alanine and stir to obtain the easily biodegradable phosphorus-free scale and corrosion inhibitor.

[0049] Example 3:

[0050] This embodiment provides a method for preparing a composite adsorption corrosion inhibitor, which comprises the following steps:

[0051] Q1. The plant polyphenol solution is obtained by mixing plant polyphenols and ethanol at a mass ratio of 1:7, and the mass ratio of tea polyphenols to tannic acid is 1:1.8. Add 100 mL of the plant polyphenol solution to 750 mL of a saturated aqueous solution of hydroxypropyl-β-cyclodextrin, stir, and perform ultrasonic treatment. The ultrasonic power is 250 W, the ultrasonic temperature is 45 °C, and the ultrasonic time is 50 min. Cool to room temperature, and let it stand at a temperature of 6 °C for 16 h. Filter, wash, and dry to obtain the inclusion compound;

[0052] Q2. Add 10 g of the inclusion compound, 28 g of sodium tartrate, and 18 g of sodium citrate to 180 g of water, and adjust the pH value to 8.5 with 1 mol / L NaOH. Heat and stir for reaction. The heating temperature is 60 °C, the stirring speed is 400 r / min, and the stirring reaction time is 3 h to obtain the reaction solution. Cool to room temperature. Add 90 mL of 20 wt% polyaspartic acid solution and 0.2 g of N,N-dicyclohexylcarbodiimide to 10 g of the reaction solution, and stir at room temperature for 5 h. Add 0.8 mol / L dilute hydrochloric acid to adjust the pH value to 6.8, filter, collect the filtrate, add 50 mL of the filtrate to 800 mL of absolute ethanol to obtain a precipitate, wash, and dry to obtain the composite adsorption corrosion inhibitor.

[0053] This example provides a preparation method of modified polyepoxysuccinic acid, including the following steps:

[0054] S1. Drop 90 mL of 2 mol / L sodium hydroxide solution into 100 mL of 1.5 mol / L maleic anhydride solution, stir, add 0.15 g of silicotungstic acid, and drop 38 mL of 30 wt% hydrogen peroxide for reaction. The reaction temperature is 68 °C, and the reaction time is 3 h to obtain the epoxysuccinic acid solution; add 0.2 g of sodium hydroxide and 0.2 g of potassium hydroxide to 100 mL of the epoxysuccinic acid solution, heat, and the heating temperature is 89 °C, and the reaction time is 4 h to obtain polyepoxysuccinic acid;

[0055] S2. Dissolve 10 g of polyepoxysuccinic acid in 180 mL of N,N-dimethylformamide, add 2 g of urea, 2 g of N-hydroxymaleimide, 1.8 g of citraconimide, 0.2 g of p-toluenesulfonic acid, 11 g of dicyclohexylcarbodiimide, and 0.4 g of 4-dimethylaminopyridine respectively, and heat for reaction. The heating temperature is 95 °C, and the heating reaction time is 5 h. After completion, cool the reaction, the cooling temperature is 24 °C, and the reaction time is 16 h. Filter, collect the filtrate, pour the filtrate into deionized water to obtain a precipitate, filter, wash, and dry to obtain the modified polyepoxysuccinic acid.

[0056] This embodiment provides a phosphorus-free scale and corrosion inhibitor that is easily biodegradable, comprising the following components by weight: 390 g of water, 38 g of modified polyepoxysuccinic acid, 26 g of composite adsorption corrosion inhibitor, 24 g of hydrolyzed polymaleic anhydride, 13 g of sodium gluconate, 5 g of alanine, 4 g of sodium alginate, and 2 g of sodium carboxymethylcellulose.

[0057] Among them, the preparation method of the phosphorus-free scale and corrosion inhibitor that is easily biodegradable comprises the following steps:

[0058] (1) Mix the modified polyepoxysuccinic acid and the hydrolyzed polymaleic anhydride to obtain a mixture one. Grind the composite adsorption corrosion inhibitor, and the grinding particle size of the composite adsorption corrosion inhibitor is 30 microns. Add it to the mixture one and stir at a stirring speed of 300 r / min for 50 min to obtain a mixture two;

[0059] (2) Add the sodium carboxymethylcellulose to water and stir to dissolve to obtain a sodium carboxymethylcellulose solution; add the sodium alginate and the sodium gluconate to the sodium carboxymethylcellulose solution respectively and stir to dissolve to obtain a mixed solution; add the mixed solution to the mixture two, stir evenly, and finally add alanine and stir to obtain the phosphorus-free scale and corrosion inhibitor that is easily biodegradable.

[0060] Example 4:

[0061] This embodiment provides a preparation method of a composite adsorption corrosion inhibitor, comprising the following steps:

[0062] Q1. The plant polyphenol solution is obtained by mixing plant polyphenols and ethanol at a mass ratio of 1:8, and the mass ratio of tea polyphenols to tannic acid is 1:2. Add 100 mL of the plant polyphenol solution to 800 mL of a saturated aqueous solution of hydroxypropyl-β-cyclodextrin, stir, perform ultrasonic treatment, the ultrasonic power is 300 W, the ultrasonic temperature is 50 °C, the ultrasonic time is 60 min, cool to room temperature, the standing temperature is 8 °C, the standing time is 24 h, filter, wash, and dry to obtain an inclusion compound;

[0063] Q2. Add 10 g of the inclusion compound, 30 g of sodium tartrate, and 20 g of sodium citrate to 200 g of water, adjust the pH value to 9 with 1 mol / L NaOH, heat and stir to react, the heating temperature is 70 °C, the stirring speed is 500 r / min, the stirring reaction time is 4 h to obtain a reaction solution, cool to room temperature, add 100 mL of 30 wt% polyaspartic acid solution and 0.3 g of N,N-dicyclohexylcarbodiimide to 10 g of the reaction solution, stir at room temperature for 6 h, add 1 mol / L dilute hydrochloric acid to adjust the pH value to 7, filter, collect the filtrate, add 50 mL of the filtrate to 1000 mL of absolute ethanol to obtain a precipitate, wash, and dry to obtain the composite adsorption corrosion inhibitor.

[0064] This embodiment provides a method for preparing modified polyepoxysuccinic acid, which comprises the following steps:

[0065] S1. Add 100 mL of 3 mol / L sodium hydroxide solution dropwise to 100 mL of 2 mol / L maleic anhydride solution, stir, add 0.2 g of silicotungstic acid, and dropwise add 40 mL of 30 wt% hydrogen peroxide for reaction. The reaction temperature is 70 °C and the reaction time is 3 h to obtain an epoxysuccinic acid solution; add 0.25 g of sodium hydroxide and 0.25 g of potassium hydroxide to 100 mL of the epoxysuccinic acid solution, heat, and the heating temperature is 90 °C and the reaction time is 4 h to obtain polyepoxysuccinic acid;

[0066] S2. Dissolve 10 g of polyepoxysuccinic acid in 200 mL of N,N-dimethylformamide, add 2.5 g of urea, 2.5 g of N-hydroxymaleimide, 2 g of citraconimide, 0.3 g of p-toluenesulfonic acid, 12 g of dicyclohexylcarbodiimide, and 0.5 g of 4-dimethylaminopyridine respectively, and heat for reaction. The heating temperature is 100 °C and the heating reaction time is 6 h. After completion, cool the reaction, and the cooling temperature is 25 °C and the reaction time is 24 h. Filter and collect the filtrate. Pour the filtrate into deionized water to obtain a precipitate, filter, wash, and dry to obtain modified polyepoxysuccinic acid.

[0067] This embodiment provides an easily biodegradable phosphorus-free scale and corrosion inhibitor, which comprises the following components by weight: 400 g of water, 40 g of modified polyepoxysuccinic acid, 30 g of composite adsorption corrosion inhibitor, 25 g of hydrolyzed polymaleic anhydride, 15 g of sodium gluconate, 6 g of alanine, 5 g of sodium alginate, and 3 g of sodium carboxymethylcellulose.

[0068] Among them, the preparation method of the easily biodegradable phosphorus-free scale and corrosion inhibitor comprises the following steps:

[0069] (1) Mix modified polyepoxysuccinic acid and hydrolyzed polymaleic anhydride to obtain mixture one. Grind the composite adsorption corrosion inhibitor, and the grinding particle size of the composite adsorption corrosion inhibitor is 10 microns. Add it to mixture one and stir at a stirring speed of 200 r / min for 30 min to obtain mixture two;

[0070] (2) Add sodium carboxymethylcellulose to water and stir to dissolve to obtain a sodium carboxymethylcellulose solution; add sodium alginate and sodium gluconate to the sodium carboxymethylcellulose solution respectively and stir to dissolve to obtain a mixed solution; add the mixed solution to mixture two, stir evenly, and finally add alanine and stir to obtain the easily biodegradable phosphorus-free scale and corrosion inhibitor.

[0071] Comparative example 1:

[0072] Comparative Example 1 is compared with Example 3. In the preparation process of the easily biodegradable phosphorus-free scale and corrosion inhibitor, the composite adsorption corrosion inhibitor is not added, and other conditions remain unchanged.

[0073] Comparative Example 2:

[0074] Comparative Example 2 is compared with Example 3. In the preparation process of the easily biodegradable phosphorus-free scale and corrosion inhibitor, the modified polyepoxysuccinic acid is not added, and other conditions remain unchanged.

[0075] Experimental Example:

[0076] Perform performance tests on the easily biodegradable phosphorus-free scale and corrosion inhibitors prepared in Examples 1-4 and Comparative Examples 1-3. The water quality indexes of the water samples used for the tests at 25 °C are as follows: Ca 2+ 183 mg / L, Mg 2+ 140 mg / L, Cl- 230 mg / L, HCO3 - 125 mg / L, SO4 2- 99 mg / L, pH is 9.4, dissolved oxygen is 12.8 mg / L; during the test, the dosing concentration is 20 mg / L, the water temperature is 80 °C, and the test duration is 16 h; according to GB / T 16632-2019 "Determination of Scale Inhibition Performance of Water Treatment Agents - Calcium Carbonate Deposition Method" to test the scale inhibition rate, and GB / T 18175-2014 "Determination of Corrosion Inhibition Performance of Water Treatment Agents - Rotating Hanging Specimen Method" to test the corrosion inhibition rate (the standard corrosion hanging specimen is 20# carbon steel, constant temperature 40 °C, rotating at 75 r / min for 72 h). The test results are shown in Table 1:

[0077] Table 1

[0078]

[0079]

[0080] It can be seen from the test results in Table 1 that the scale and corrosion inhibition performance of the easily biodegradable phosphorus-free scale and corrosion inhibitors prepared in Examples 1-4 of the present invention has significant advantages compared with Comparative Examples 1-2. Through comparison, it is found that adding the composite adsorption corrosion inhibitor and the modified polyepoxysuccinic acid can significantly improve the scale and corrosion inhibition performance of the phosphorus-free scale and corrosion inhibitor.

[0081] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

[0082] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only the specific implementation manners. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An easily biodegradable phosphorus-free scale and corrosion inhibitor, characterized in that, It comprises the following components in parts by weight: 360 - 400 parts of water, 30 - 40 parts of modified polyepoxysuccinic acid, 20 - 30 parts of composite adsorption inhibitor, 20 - 25 parts of hydrolyzed polymaleic anhydride, 8 - 15 parts of sodium gluconate, 4 - 6 parts of alanine, 2 - 5 parts of sodium alginate and 1 - 3 parts of sodium carboxymethylcellulose; the composite adsorption inhibitor is obtained by reacting an inclusion complex formed by plant polyphenols and hydroxypropyl-β-cyclodextrin with sodium tartrate, sodium citrate and polyaspartic acid; the modified polyepoxysuccinic acid is synthesized by reacting sodium hydroxide solution, maleic anhydride solution and hydrogen peroxide to form epoxysuccinic acid, and then modified with urea, N-hydroxymaleimide and citraconimide.

2. The biodegradable phosphorus-free scale and corrosion inhibitor according to claim 1, characterized in that, The preparation method of the composite adsorption inhibitor comprises the following steps: Q1. Add the plant polyphenol solution to the saturated aqueous solution of hydroxypropyl-β-cyclodextrin, stir, perform ultrasonic treatment, cool, stand, filter, wash and dry to obtain the inclusion complex; Q2. Add the inclusion complex, sodium tartrate and sodium citrate to water, adjust the pH value to 8 - 9, heat and stir for reaction to obtain a reaction solution, cool to room temperature, add the polyaspartic acid solution and N,N'-dicyclohexylcarbodiimide to the reaction solution, stir for reaction, add dilute hydrochloric acid to adjust the pH value to 6 - 7, filter, collect the filtrate, add the filtrate to anhydrous ethanol to obtain a precipitate, wash and dry to obtain the composite adsorption inhibitor.

3. The easily biodegradable phosphorus-free scale and corrosion inhibitor according to claim 2, characterized in that, In Q1, the volume ratio of the plant polyphenol solution to the saturated aqueous solution of cyclodextrin is 1:6 - 8, the plant polyphenols are a mixture of tea polyphenols and tannic acid, the mass ratio of tea polyphenols to tannic acid is 1:1 - 2, and the plant polyphenol solution is prepared by mixing plant polyphenols and ethanol in a mass ratio of 1:5 - 8.

4. The easily biodegradable phosphorus-free scale and corrosion inhibitor according to claim 2, wherein In Q2, the mass ratio of the inclusion complex, sodium tartrate, sodium citrate and water is 1:2 - 3:1 - 2:10 - 20, the pH value is adjusted to 8 - 9 with 1mol / L NaOH, the mass concentration of the polyaspartic acid solution is 10 - 30wt%, and the dosage ratio of the reaction solution, the polyaspartic acid solution and N,N'-dicyclohexylcarbodiimide is 10g:50 - 100mL:0.05 - 0.3g.

5. The biodegradable phosphorus-free scale and corrosion inhibitor according to claim 1, characterized in that, The preparation method of the modified polyepoxysuccinic acid comprises the following steps: S1. Drop the sodium hydroxide solution into the maleic anhydride solution, stir, add a catalyst, dropwise add hydrogen peroxide for reaction to obtain an epoxysuccinic acid solution; add an initiator to the epoxysuccinic acid solution and heat to obtain polyepoxysuccinic acid; S2. Dissolve the polyepoxysuccinic acid in N,N-dimethylformamide, add urea, N-hydroxymaleimide, citraconimide, p-toluenesulfonic acid, dicyclohexylcarbodiimide and 4-dimethylaminopyridine respectively, heat for reaction, after completion, cool the reaction, filter, collect the filtrate, pour the filtrate into deionized water to obtain a precipitate, filter, wash and dry to obtain the modified polyepoxysuccinic acid.

6. The biodegradable phosphorus-free scale and corrosion inhibitor according to claim 5, characterized in that, In S1, the concentration of the maleic anhydride solution is 0.5 - 2 mol / L, the concentration of the sodium hydroxide solution is 1 - 3 mol / L, the catalyst is silicotungstic acid, the mass concentration of hydrogen peroxide is 30 wt%, and the dosage ratio of the maleic anhydride solution, sodium hydroxide solution, silicotungstic acid, and hydrogen peroxide is 100 mL : 50 - 100 mL : 0.05 - 0.2 g : 30 - 40 mL.

7. The easily biodegradable phosphorus-free scale and corrosion inhibitor according to claim 5, characterized in that The initiator is an equimass mixture of sodium hydroxide and potassium hydroxide, and the dosage ratio of the initiator to the epoxy succinic acid solution is 0.1 - 0.5 g : 100 mL.

8. The easily biodegradable phosphorus-free scale and corrosion inhibitor according to claim 5, characterized in that, In S2, the dosage ratio of polyepoxysuccinic acid, N,N - dimethylformamide, urea, N - hydroxymaleimide, citraconimide, p - toluenesulfonic acid, dicyclohexylcarbodiimide, and 4 - dimethylaminopyridine is 10 g : 100 - 200 mL : 1 - 2.5 g : 1 - 2.5 g : 1 - 2 g : 0.1 - 0.3 g : 10 - 12 g : 0.1 - 0.5 g.

9. A preparation method of a biodegradable phosphorus-free scale and corrosion inhibitor, characterized in that, It includes the following steps: (1) Mix the modified polyepoxysuccinic acid and hydrolyzed polymaleic anhydride to obtain mixture one, grind the composite adsorption inhibitor, add it to mixture one, and stir to obtain mixture two; (2) Add sodium carboxymethylcellulose to water, stir to dissolve it to obtain a sodium carboxymethylcellulose solution; Add sodium alginate and sodium gluconate to the sodium carboxymethylcellulose solution respectively, stir to dissolve them to obtain a mixed solution; Add the mixed solution to mixture two, stir evenly, and finally add alanine, stir to obtain a biodegradable phosphorus - free scale and corrosion inhibitor.

10. The preparation method of the easily biodegradable phosphorus-free scale and corrosion inhibitor according to claim 9, characterized in that, In step (1), the grinding particle size of the composite adsorption inhibitor is 10 - 100 microns.

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