Self-tracing type scale and corrosion inhibitor based on novel fluorescent copolymer and preparation method of self-tracing type scale and corrosion inhibitor

Abstract

The invention relates to the field of water treatment, and discloses a self-tracing type scale and corrosion inhibitor based on a novel fluorescent copolymer and a preparation method, and the scale and corrosion inhibitor comprises the following components: the novel fluorescent copolymer, an auxiliary polymer, a conventional AMPS copolymer, organic phosphonate, zinc salt and the balance of water. The novel fluorescent copolymer is obtained by carrying out copolymerization reaction on a fluorescent monomer B, acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid; and the fluorescent monomer B is prepared by reacting 4-chloro-1, 8-naphthalic anhydride with 3-dimethylaminopropylamine, reacting the product with sodium methoxide, and further reacting the obtained intermediate with chloropropene. And the auxiliary polymer is a lauryl methacrylate-N, N-dimethylaminoethyl methacrylate copolymer. According to the self-tracing type scale and corrosion inhibitor, the fluorophore is covalently bonded to a polymer main chain, accurate online monitoring of the concentration of the agent is achieved, and the self-tracing type scale and corrosion inhibitor has excellent scale and corrosion inhibition performance.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a self-tracing scale and corrosion inhibitor based on a novel fluorescent copolymer and its preparation method. Background Technology

[0002] During operation, industrial circulating cooling water systems are prone to scale formation due to factors such as water evaporation, increased concentration, and temperature changes. Scale adheres to the surfaces of heat exchange equipment, significantly reducing heat exchange efficiency, increasing energy consumption, and even causing equipment damage. Simultaneously, the presence of corrosive media such as dissolved oxygen and chloride ions can also lead to corrosion of metal equipment, shortening its lifespan and potentially causing environmental pollution due to corrosion product leakage. Therefore, adding scale and corrosion inhibitors to circulating cooling water is a common and effective method to suppress scaling and corrosion and ensure the safe and stable operation of the system.

[0003] Currently, widely used scale and corrosion inhibitors are typically compound formulations of various chemical agents, such as organophosphonates, polycarboxylic acid polymers, zinc salts, and other corrosion inhibitors. To achieve optimal water treatment results and save on chemical costs, precise control of the scale and corrosion inhibitor concentration in circulating water is crucial. Too low a concentration will not effectively inhibit scaling and corrosion; too high a concentration will not only waste the agent but may also lead to additional environmental emissions, and in some cases, excessive amounts of certain agents can even have negative effects.

[0004] To achieve real-time monitoring of water treatment agent concentrations, fluorescent tracer technology has gained attention due to its high sensitivity, rapid response, and ease of online detection. The traditional approach involves adding a chemically stable fluorescent substance as a tracer to the scale and corrosion inhibitor formulation. However, this added tracer and the active functional components in the scale and corrosion inhibitor (such as polymer scale inhibitors and organophosphonates) are independent chemical entities. In complex circulating water environments, these active functional components are gradually consumed or reduced due to participation in scale and corrosion inhibition reactions, chemical degradation, or system flushing. Ideally, changes in tracer concentration should accurately and synchronously reflect changes in the concentration of active functional components. However, in reality, the consumption rate, degradation pathway, and residence behavior of the added tracer in the system are often inconsistent with those of the main functional components of the agent. For example, some active polymers may partially fail due to oxidation or hydrolysis, but the added inert fluorescent tracer may still maintain its original concentration. In this case, the agent concentration reading obtained by detecting fluorescence intensity will be too high, misleading operators and leading to insufficient agent replenishment, thus affecting the water treatment effect. Conversely, if the tracer is more easily degraded or adsorbed than the active component, it may lead to overdosing of the reagent. This asynchrony between the tracer signal and the actual efficacy of the reagent is a common problem in the precise control of water treatment reagent concentration by existing external fluorescent tracer technology, which limits its application in the pursuit of refined water quality management.

[0005] Therefore, developing a water treatment agent that can more accurately reflect the effective concentration of the scale and corrosion inhibitor itself, and which also has excellent scale and corrosion inhibition properties, is of great practical significance for improving water treatment efficiency, reducing operating costs, and protecting the environment. Summary of the Invention

[0006] The technical problem to be solved by this invention is that in the existing circulating cooling water treatment, it is difficult to accurately monitor the concentration of water treatment agent, especially the tracer deviation caused by the inconsistency between the consumption rate of the added fluorescent tracer and the agent itself, and how to further improve the effect of the agent on the metal surface and its corrosion inhibition performance.

[0007] The first aspect of this invention provides a self-tracing scale and corrosion inhibitor, which achieves synchronous response of agent concentration and fluorescence signal by copolymerizing fluorescent groups onto polymer molecular chains, and introduces specific auxiliary polymers to enhance its interfacial properties.

[0008] The self-tracing scale and corrosion inhibitor comprises, by weight percentage:

[0009] Novel fluorescent copolymers: 5.0% to 10.0%;

[0010] Auxiliary polymer: 0.25% to 5.0%;

[0011] Conventional AMPS copolymers: 10.0% to 30.0%;

[0012] Carboxylic acid polymers: 10.0% to 30.0%;

[0013] Optional organophosphates: 0% to 10.0%;

[0014] Zinc salts: 3.0% to 10.0%;

[0015] The rest is water.

[0016] In some embodiments of the present invention, the novel fluorescent copolymer is prepared by copolymerizing a specially designed fluorescent monomer B with acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS).

[0017] Specifically, the mass ratio of acrylic acid to 2-acrylamido-2-methylpropanesulfonic acid can be controlled within the range of (65%-74%):(26%-35%), and the amount of fluorescent monomer B added is 0.20% to 0.30% of the total mass of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid.

[0018] This specific monomer ratio and low loading of fluorescent monomers not only ensure the excellent scale inhibition and dispersion performance of the copolymer (mainly provided by AA and AMPS), but also endow the copolymer with stable fluorescence properties that show a good linear relationship with concentration. Its excitation and emission wavelengths effectively avoid interference from the ultraviolet region commonly found in water. As part of the copolymer structure, the fluorescent group is consumed synchronously with the polymer bulk, thereby achieving precise "self-tracing" of the reagent concentration.

[0019] The fluorescent monomer B (WL-2003) has a unique chemical structure and is prepared by a three-step synthetic method:

[0020] First, 4-chloro-1,8-naphthalenedicarboxylic anhydride and 3-dimethylaminopropylamine are reacted under specific mass ratios (the former to the latter is 2.05:1 to 2.15:1) and specific conditions to generate intermediate WL-2001. The optimization of the raw material ratio and process conditions in this step aims to improve the yield of the target product and reduce the generation of by-products.

[0021] Next, intermediate WL-2001 reacts with sodium methoxide in methanol to convert chlorine atoms into methoxy groups, yielding intermediate WL-2002. The conversion efficiency of this step has a significant impact on the fluorescence properties of the final monomer.

[0022] Finally, intermediate WL-2002 reacts with allyl chloride to introduce a polymerizable allyl functional group, yielding fluorescent monomer B (WL-2003). This series of specific chemical transformations endows fluorescent monomer B with good fluorescence quantum yield, suitable solubility, and reactivity in subsequent copolymerization.

[0023] In a further embodiment of the invention, the auxiliary polymer may be, for example, a lauryl methacrylate-N,N-dimethylaminoethyl methacrylate copolymer P (LMA-co-DMAEMA).

[0024] The number-average molecular weight of the auxiliary polymer should preferably be controlled in the range of 500 to 5000 g / mol. For example, it can be copolymerized from 50 to 80 molar parts of lauryl methacrylate (LMA) and 20 to 50 molar parts of N,N-dimethylaminoethyl methacrylate (DMAEMA).

[0025] The introduction of this auxiliary polymer is an important innovation of this invention: the hydrophobic long chains (such as lauryl) and Lewis basic groups (such as tertiary amine groups) contained in its structure can undergo non-covalent intermolecular interactions (such as hydrophobic effect, electrostatic attraction, coordination) with specific structural units (such as naphthalene ring, quaternary ammonium salt group) in the novel fluorescent copolymer or metal surface.

[0026] This synergistic effect enables the novel fluorescent copolymer to be more effectively adsorbed and anchored on the metal heat exchange surface, forming a more uniform and denser composite protective film. This not only improves the overall corrosion inhibition efficiency of the formulation, especially its ability to suppress localized corrosion such as pitting, but also allows the fluorescence signal to more accurately reflect the actual concentration of the effective agent at the interface, rather than just the bulk concentration.

[0027] Other components in the composition, such as carboxylic acid polymers (one or more of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), hydroxyethylidene diphosphonic acid (HEDP), and ethylenediaminetetramethylenephosphonic acid (EDTPMPS)) and zinc salts (one or more of zinc chloride, zinc sulfate heptahydrate, and zinc sulfate monohydrate), are conventional scale and corrosion inhibitors. They work synergistically with novel fluorescent copolymers and auxiliary polymers to provide comprehensive water treatment effects.

[0028] A second aspect of the present invention provides a method for preparing the aforementioned self-tracing scale and corrosion inhibitor. The method comprises the following steps:

[0029] First, the novel fluorescent copolymer is prepared. This step is further subdivided into:

[0030] (a) Synthesis of the core fluorescent monomer B (WL-2003). This includes:

[0031] (i) 60-65 parts by weight of 4-chloro-1,8-naphthalenedicarboxylic anhydride and 28.5-32.5 parts by weight of 3-dimethylaminopropylamine were reacted in 350-360 parts by weight of glacial acetic acid at 108-112°C for 4.5-5.5 hours, and then the pH was adjusted to 10.8-11.2 with a sodium hydroxide solution of a specific concentration (47-49%) to obtain intermediate WL-2001.

[0032] The precise control of the raw material ratio and the optimization of reaction conditions in this step aim to maximize the formation of the target imide and suppress side reactions.

[0033] (ii) Take 18-22 parts by weight of the above WL-2001, add 4.6-4.9 times its mass of methanol and an appropriate amount of sodium methoxide (the mass ratio of methanol to sodium methoxide is controlled at 3.4:1 to 3.8:1), and react at 60-62°C for 5.5-6.5 hours under inert gas protection (nitrogen).

[0034] After the reaction was completed, the pH was adjusted to 7.0-7.4 using concentrated hydrochloric acid of a specific concentration (29-31%), and the intermediate WL-2002 was obtained by vacuum distillation.

[0035] This methoxylation step is crucial to the fluorescence properties of the final monomer.

[0036] (iii) 18-22 parts by weight of WL-2002 and 58-62 parts by weight of allyl chloride are reacted in 230-245 parts by weight of acetone at 40-44°C for 5.5-6.5 hours to obtain the target fluorescent monomer B (WL-2003). This step introduces polymerizable active groups.

[0037] (b) The fluorescent monomer B (0.20-0.30 parts by weight) obtained by step (a) above is copolymerized with acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) (the total amount of both is 145 parts by weight, and the mass ratio of AA to AMPS is (65%-74%):(26%-35%)) in deionized water in the presence of an initiator (a mixture of tert-butyl hydroperoxide and hydrogen peroxide, the total amount of which can be 2.5-3.5% of the total mass of the monomers) at 83-87°C.

[0038] The addition of the initiator and the subsequent heat treatment time (1.8-2.2 hours each) have a significant impact on the molecular weight and properties of the copolymer.

[0039] This copolymerization step chemically bonds the fluorescent unit to the polymer backbone, which is key to achieving the "self-tracing" function.

[0040] Secondly, auxiliary polymers are prepared. For example, P(LMA-co-DMAEMA) can be prepared by reacting 50-80 moles of lauryl methacrylate (LMA) with 20-50 moles of N,N-dimethylaminoethyl methacrylate (DMAEMA) in a suitable organic solvent (toluene or ethyl acetate) in the presence of free radical initiators such as azobisisobutyronitrile and chain transfer agents such as dodecyl mercaptan, for 4-8 hours at 65-80°C.

[0041] By controlling the amount of chain transfer agent, the number-average molecular weight of the copolymer can be controlled within the target range of 500-5000 g / mol.

[0042] Finally, the novel fluorescent copolymer prepared according to the above method (e.g., 5.0-10.0 parts by weight), auxiliary polymer (0.25-5.0 parts by weight), and other components such as conventional AMPS copolymer (10.0-30.0 parts by weight), carboxylic acid polymer (10.0-30.0 parts by weight), optional organophosphate (0-10.0 parts by weight), zinc salt (3.0-10.0 parts by weight), and the balance water are thoroughly mixed under suitable conditions (30-35°C, stirring for 1.0-1.5 hours) to obtain the self-tracing scale and corrosion inhibitor. The parts by weight of each component are based on the percentage of the total weight of the final scale and corrosion inhibitor.

[0043] The preparation method of this invention, through precise control of each synthesis step, especially the synthesis of fluorescent monomer B and subsequent copolymerization reaction conditions, can stably obtain polymer products with excellent self-tracing properties and scale and corrosion inhibition efficiency. Simultaneously, the preparation of auxiliary polymers and their compounding with novel fluorescent copolymers further enhance the overall performance of the final product.

[0044] In summary, this invention, through innovative molecular design and compounding strategies, provides a water treatment agent and its preparation method that can accurately monitor concentration, possesses efficient scale and corrosion inhibition and excellent interfacial adsorption properties, and provides strong technical support for the refined and intelligent management of circulating cooling water systems.

[0045] In summary, the present invention has at least one of the following beneficial technical effects:

[0046] 1. This invention forms a novel fluorescent copolymer by copolymerizing a specially designed fluorescent monomer B onto the molecular chains of a polymer primarily composed of acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS). Since the fluorescent group is part of the polymer structure, its consumption in the water system is synchronized with the polymer matrix. Therefore, its fluorescence intensity can directly and accurately reflect the actual concentration of the reagent, avoiding monitoring deviations caused by the asynchronous consumption rate of traditional external fluorescent tracers. This enables online, real-time monitoring, providing a reliable basis for precise dosing and optimized control in water treatment.

[0047] 2. This invention introduces a specific auxiliary polymer into the scale and corrosion inhibitor. This auxiliary polymer can synergistically interact with the novel fluorescent copolymer, enhancing its adsorption selectivity and film-forming ability on the metal surface. This results in a denser, more uniform, and stronger composite protective film formed on the metal surface, thereby significantly improving corrosion inhibition performance, especially the inhibition effect on localized corrosion such as pitting and crevice corrosion.

[0048] 3. The novel fluorescent copolymer of this invention not only possesses self-tracing functionality, but its main backbone is composed of acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), both of which are themselves high-performance scale inhibitors and dispersants. Through copolymerization in a specific ratio, their synergistic effect in dispersing common scale such as calcium carbonate and calcium phosphate is fully utilized. Therefore, this fluorescent copolymer itself contributes to scale inhibition efficiency, which can reduce the amount of other scale inhibitors used to a certain extent, simplify the formulation, and improve the utilization efficiency of the active component.

[0049] 4. In the three-step synthesis method of fluorescent monomer B of the present invention, the process parameters such as the raw material ratio, reaction temperature and pH control of the key steps have been optimized. These specific process conditions help to improve the yield and purity of the target product, reduce side reactions, and ensure that fluorescent monomer B has good fluorescence properties and polymerization activity, thereby ensuring the performance stability and reliability of the final novel fluorescent copolymer.

[0050] 5. In addition to the core novel fluorescent copolymer and auxiliary polymer, the self-tracing scale and corrosion inhibitor of this invention also contains conventional AMPS copolymers, carboxylic acid polymers, zinc salts, etc. Each component performs its specific function: the conventional AMPS copolymer and carboxylic acid polymer provide basic scale inhibition and partial corrosion inhibition capabilities, while the zinc salt, as a corrosion inhibitor, further enhances the protection of the metal. The components achieve synergistic effects through a scientific ratio, thus providing a comprehensive solution for circulating cooling water systems that combines accurate monitoring, efficient scale inhibition, and excellent corrosion inhibition. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that these embodiments are merely illustrative and not intended to limit the scope of protection of this invention.

[0052] For experimental methods that do not specify specific conditions, they are generally performed under standard conditions or as recommended by the manufacturer. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. Percentages mentioned in this invention, unless specifically stated otherwise, generally refer to weight percentages.

[0053] Example 1: Preparation of fluorescent monomer B (WL-2003)

[0054] This embodiment provides a three-step synthesis process for fluorescent monomer B (WL-2003).

[0055] 1.1 Preparation of intermediate WL-2001

[0056] In a 500 mL four-necked flask equipped with a mechanical stirrer, thermometer, reflux condenser, and dropping funnel, add 355 g of glacial acetic acid. Start stirring and add 63.0 g of 4-chloro-1,8-naphthalenedicarboxylic anhydride to the flask. After it has partially dissolved, slowly add 30.0 g of 3-dimethylaminopropylamine dropwise. During this process, the mass ratio of 4-chloro-1,8-naphthalenedicarboxylic anhydride to 3-dimethylaminopropylamine is 2.1:1.

[0057] After the addition is complete, the reaction mixture is heated to 110°C and refluxed for 5 hours in the temperature range of 108-112°C.

[0058] After the reaction is complete, stop heating and allow the reaction system to cool naturally to approximately 40°C. Slowly pour the resulting reaction solution into a beaker containing 2.0 L of stirred pure water, causing solids to precipitate. Continue stirring and slowly add approximately 460 g of a 48% sodium hydroxide solution to adjust the pH of the system to 11.0.

[0059] After cooling to room temperature, stop stirring and let stand. Collect the precipitated solid by vacuum filtration and wash the filter cake with pure water. Place the obtained brownish-yellow solid in an oven at 85°C and dry for 5 hours, then grind it into powder to obtain intermediate WL-2001, weighing 78.5g.

[0060] 1.2 Preparation of intermediate WL-2002

[0061] In a clean, dry 250 mL four-necked flask, add 74.6 g of anhydrous methanol and 20.4 g of sodium methoxide. Then, add 20.0 g of the dry powdered intermediate WL-2001 prepared in Section 1.1.

[0062] Start stirring and purge the reaction system with nitrogen for 20 minutes. Then, under nitrogen protection, heat the reaction mixture to 61°C and maintain stirring at 60-62°C for 6 hours.

[0063] After the reaction is complete, stop the nitrogen flow. Cool the reaction system to approximately 45°C. Slowly add approximately 15g of 30% concentrated hydrochloric acid to adjust the pH of the system to 7.2. Stop stirring and perform vacuum filtration.

[0064] The filtrate was collected and transferred to a rotary evaporator. Vacuum distillation was performed at a water bath temperature controlled at 48°C to remove the methanol solvent, yielding a brown solid intermediate, WL-2002. This intermediate was further dried in a vacuum drying oven at 50°C for 2 hours and weighed to 18.2 g.

[0065] 1.3 Preparation of fluorescent monomer B (WL-2003)

[0066] In a clean, dry 250 mL four-necked flask, add 240 g of acetone. Then add 60.0 g of allyl chloride. Finally, add all of the dried intermediate WL-2002 (18.2 g) prepared in section 1.2.

[0067] Start stirring, heat the mixture to 42°C, and maintain the stirring reaction at 40-44°C for 6 hours.

[0068] After the reaction was complete, the reaction mixture was cooled to room temperature. Most of the acetone and unreacted allyl chloride were removed by vacuum distillation to obtain the crude product. The crude product was washed twice with 100 g of acetone. The washed brown solid was dried in an oven at 85 °C for 5 hours to obtain the final product, fluorescent monomer B (WL-2003), weighing 20.5 g. The obtained product was a brown powder.

[0069] Example 2: Preparation of a novel fluorescent copolymer

[0070] This embodiment provides a process for preparing a novel fluorescent copolymer by copolymerizing the fluorescent monomer B (WL-2003) prepared in Example 1 with acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS).

[0071] In a 500 mL four-necked flask equipped with a mechanical stirrer, thermometer, dropping funnel, and reflux condenser, add 0.36 g of the fluorescent monomer B (WL-2003) prepared in Example 1 and 50 mL of deionized water. Start stirring and heat the mixture to 85°C to dissolve the fluorescent monomer B.

[0072] Weigh 101.5g of acrylic acid (AA) monomer and 43.5g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) monomer (at this point, the mass ratio of AA to AMPS is approximately 70%:30%, and the total mass of both is 145g; the amount of fluorescent monomer B is approximately 0.25% of the total mass of AA and AMPS monomers). Mix the two monomers thoroughly in a beaker.

[0073] Take another beaker and weigh 4.8g of tert-butyl hydroperoxide (70% aqueous solution) and 2.4g of hydrogen peroxide (30% aqueous solution) as a composite initiator (the total active mass of the initiator is about 2.8% of the total mass of AA and AMPS monomers), and dilute with a small amount of deionized water.

[0074] The mixed AA and AMPS monomer solutions and the diluted initiator solution were placed into separate dropping funnels. At a reaction temperature of 83-87℃, the mixed monomer solution and initiator solution were added dropwise to the reaction system in a four-necked flask uniformly and synchronously over 2 hours.

[0075] After the addition is complete, continue stirring at 83-87℃ for 2 hours to ensure complete monomer conversion.

[0076] After the reaction was complete, heating was stopped, and the reaction system was allowed to cool naturally to room temperature. A light yellow, transparent, viscous liquid was obtained, which is the novel fluorescent copolymer solution. Its solid content was determined to be approximately 65.2%.

[0077] Example 3: Preparation of auxiliary polymer P (LMA-co-DMAEMA)

[0078] This embodiment provides a process for synthesizing the auxiliary polymer lauryl methacrylate-N,N-dimethylaminoethyl methacrylate copolymer (P(LMA-co-DMAEMA)).

[0079] Add 80 mL of toluene as a solvent to a 250 mL four-necked flask equipped with a mechanical stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel.

[0080] Weigh 17.8 g (0.07 mol) lauryl methacrylate (LMA) and 4.7 g (0.03 mol) N,N-dimethylaminoethyl methacrylate (DMAEMA). Add the two monomers (the molar ratio of LMA to DMAEMA is 70:30) and 0.45 g (approximately 2.0% of the total monomer mass) dodecyl mercaptan (DDM) into a flask and stir to dissolve them in toluene.

[0081] Nitrogen gas was introduced into the reaction system for 20 minutes to remove dissolved oxygen.

[0082] Dissolve 0.225 g (approximately 1.0% of the total monomer mass) of azobisisobutyronitrile (AIBN) initiator in 5 mL of toluene and place the solution into a dropping funnel.

[0083] Under nitrogen protection, the reaction mixture in the flask was heated to 75°C. After the temperature stabilized, a toluene solution of AIBN was slowly added dropwise over approximately 30 minutes.

[0084] After the addition is complete, continue stirring the reaction at 73-77℃ for 6 hours.

[0085] After the reaction was complete, heating was stopped, and the reaction system was cooled to room temperature. A pale yellow to colorless viscous polymer solution was obtained. This polymer solution was slowly added dropwise to 500 mL of vigorously stirred n-hexane, and a white or pale yellow solid precipitate was observed to form.

[0086] The precipitate was collected by vacuum filtration, and the filter cake was washed 2-3 times with a small amount of n-hexane.

[0087] The obtained polymer was dried to constant weight in a vacuum oven at 45°C to obtain a white to light yellow powdery solid P(LMA-co-DMAEMA), weighing 19.5 g. Its number-average molecular weight (Mn) was determined to be approximately 3200 g / mol and its molecular weight distribution index (PDI) to be approximately 1.8 by gel permeation chromatography (GPC).

[0088] Example 4: Formulation of self-tracing scale and corrosion inhibitor

[0089] This embodiment provides a formulation process for a self-tracing scale and corrosion inhibitor comprising the novel fluorescent copolymer prepared in Example 2 and the auxiliary polymer prepared in Example 3.

[0090] Weigh each component according to the following weight percentages:

[0091] Novel fluorescent copolymer solution (from Example 2, solid content 65.2%): 12.27% (equivalent to 8.0% solids);

[0092] Auxiliary polymer P (LMA-co-DMAEMA) (from Example 3, solid): 1.0%;

[0093] Conventional AMPS copolymer (commercially available, polyacrylate-hydroxypropyl acrylate-AMPS terpolymer, solid content 40%): 37.5% (equivalent to 15.0% solids);

[0094] 2-Phosphoylbutane-1,2,4-tricarboxylic acid (PBTC) (commercially available, 50% solids): 30.0% (equivalent to 15.0% solids);

[0095] Zinc sulfate heptahydrate (ZnSO4·7H2O) (commercially available, analytical grade): 7.0% (equivalent to Zn 2+ (Approximately 1.59%);

[0096] Deionized water: 12.23%;

[0097] The preparation steps are as follows:

[0098] First, add 12.23g of deionized water to a 100mL beaker equipped with a stirrer.

[0099] While stirring, slowly add 7.0g of zinc sulfate heptahydrate until it is completely dissolved.

[0100] Then add 30.0g of PBTC solution and stir well.

[0101] Next, add 37.5g of conventional AMPS copolymer solution and stir until homogeneous.

[0102] Then add 1.0 g of the dry P(LMA-co-DMAEMA) powder prepared in Example 3, and continue stirring until it is completely dissolved or uniformly dispersed.

[0103] Finally, 12.27 g of the novel fluorescent copolymer solution prepared in Example 2 was added.

[0104] After all components have been added, the mixture is stirred continuously at 30-35°C for 1 hour to ensure complete dissolution and uniform mixing, resulting in a uniform and stable light yellow transparent liquid, which is the self-tracer scale and corrosion inhibitor of this invention. The solid content (weight percentage) of each active component in the final product is as follows: novel fluorescent copolymer 8.0%, auxiliary polymer P (LMA-co-DMAEMA) 1.0%, conventional AMPS copolymer 15.0%, PBTC 15.0%, and zinc sulfate heptahydrate (calculated as ZnSO4·7H2O) 7.0%.

[0105] Test example:

[0106] This test example evaluated the performance of the self-tracing scale and corrosion inhibitor prepared according to Example 4, including its fluorescence tracing performance, scale inhibition performance, and corrosion inhibition performance.

[0107] I. Evaluation of Fluorescent Tracer Performance

[0108] Water from the clarifier of a power plant was used as background water sample. Aqueous solutions with concentrations of 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, 80 mg / L, and 100 mg / L were prepared using the self-tracing scale and corrosion inhibitor prepared in Example 4. The fluorescence intensity of each concentration was measured using a fluorescence spectrophotometer with an excitation wavelength set to 365 nm and an emission wavelength set to 450 nm. The test results are shown in Table 1.

[0109] Table 1: Relationship between drug concentration and fluorescence intensity in Example 4

[0110]

[0111] Linear regression analysis was performed on the data in Table 1, and the regression equation between the reagent concentration (C, mg / L) and the fluorescence intensity (C2) measured in the water sample was obtained as follows:

[0112] C = 9.1148 × C²;

[0113] The correlation coefficient of the linear regression was r = 0.9987.

[0114] The results show that there is a good linear relationship between the concentration of the self-tracing scale and corrosion inhibitor of Example 4 of the present invention and its fluorescence intensity in the water sample, with a correlation coefficient close to 1, proving that the actual concentration of the scale and corrosion inhibitor in the water sample can be accurately reflected by measuring the fluorescence intensity of the water sample.

[0115] II. Scale inhibition and corrosion inhibition performance tests

[0116] Test method: The scale inhibition performance test adopts GB / T16632-2008 "Determination of Scale Inhibition Performance of Water Treatment Agents - Calcium Carbonate Deposition Method", using a solution containing a certain concentration of Ca. 2+ Prepare a test solution by mixing alkalinity-neutralizing water and test reagents as described in Example 1, and immerse it in a constant temperature water bath (80±1℃) for 10 hours.

[0117] The corrosion inhibition performance test was conducted according to GB / T 18175-2014 "Determination of Corrosion Inhibition Performance of Water Treatment Agents - Rotary Plating Method". Newly treated, dried, and weighed platings were fixed on the plating rack of the corrosion testing instrument and placed in a 2L glass beaker filled with scale and corrosion inhibitor and test water. The temperature was maintained at 45±1℃, and the rotation speed was kept at 75 r / min. During the test, the test solution was allowed to evaporate naturally, and test water was added every 1-2 hours to maintain the liquid level. The test duration was 72 hours. The test water quality is shown in Tables 2 and 3.

[0118] Table 2: Water quality for scale inhibition test

[0119]

[0120] Note: Calcium ions and total alkalinity are both expressed as CaCO3.

[0121] Table 3: Water quality in corrosion inhibition test

[0122]

[0123] Note: Total hardness, calcium ion content, and total alkalinity are all expressed as CaCO3.

[0124] The test results are shown in Table 4.

[0125] Table 4: Test Results of Scale and Corrosion Inhibition Performance

[0126]

[0127] The results show that the self-tracing scale and corrosion inhibitor of Example 4 of the present invention has excellent scale inhibition performance; at the same time, it shows excellent corrosion inhibition effect on 20# carbon steel, 304 stainless steel and copper, and the corrosion rate is much lower than the usual control index of industrial circulating cooling water system.

[0128] Based on the above performance evaluation results, the self-tracing scale and corrosion inhibitor prepared in Example 4 can not only accurately monitor its concentration in water through fluorescence intensity, but also has high-efficiency scale inhibition and corrosion inhibition performance, meeting the requirements of circulating water system treatment.

[0129] Comparative Example 1:

[0130] The main difference between the formulation of Comparative Example 1 and Example 4 is that:

[0131] It does not contain the novel fluorescent copolymer prepared in Example 2.

[0132] It does not contain the auxiliary polymer P (LMA-co-DMAEMA) prepared in Example 3.

[0133] 0.05% (by weight) of sodium fluorescein was added as an external fluorescent tracer.

[0134] The amount of conventional AMPS copolymer was adjusted to a solids content of 20.0% so that the total solids content of the main scale and corrosion inhibitory active components (conventional AMPS copolymer, PBTC, and zinc sulfate heptahydrate) in Comparative Example 1 was substantially equivalent to the total solids content (approximately 35%) of the corresponding components (novel fluorescent copolymer, conventional AMPS copolymer, PBTC, and zinc sulfate heptahydrate) in Example 4. The remaining components were PBTC (15.0% solids content), zinc sulfate heptahydrate (7.0%), and water.

[0135] The preparation method is the same as in Example 4, and all components are mixed evenly.

[0136] Evaluation of fluorescence tracer performance and comparison of simulated degradation:

[0137] (1) Initial fluorescence tracer performance

[0138] Using the same method as the test example, the concentration of the main active component of the reagent in Comparative Example 1 and its fluorescence intensity (excitation wavelength 490 nm, emission wavelength 515 nm) showed a linear relationship in the initial state, with a correlation coefficient r of 0.9952.

[0139] (2) Comparison of fluorescence tracer performance after partial degradation of simulated drugs

[0140] Take 100 mL each of the aqueous solutions of Comparative Example 1 (60 mg / L) and Example 4 (60 mg / L). Add sodium hypochlorite solution (to bring the initial effective chlorine concentration to 2 mg / L), and stir at room temperature in the dark for 2 hours. After the reaction, measure the percentage decrease in COD and the change in fluorescence intensity; the results are shown in Table 5.

[0141] Table 5: Comparison of fluorescence tracer performance of the reagent in Example 4 and the reagent in Comparative Example 1 after simulated degradation.

[0142]

[0143] Note: F0 represents the baseline fluorescence intensity value measured at an initial concentration of 60 mg / L for Comparative Example 1. The fluorescence tracer concentration of the reagent in Example 4 was calculated based on its actual calibration curve C = 9.1148 × C². The fluorescence tracer concentration of the reagent in Comparative Example 1 was calculated accordingly based on its initial calibration curve.

[0144] As can be seen from the data in Table 5:

[0145] 1. After undergoing similar oxidative degradation treatment (COD reduction of approximately 20%), the fluorescence intensity of the reagent in Example 4 decreased accordingly. The decrease in reagent concentration obtained by fluorescence tracing (approximately 16.5%) was highly consistent with the actual consumption of the main organic matter of the reagent as characterized by COD (approximately 20%), with a small deviation (approximately 3.5%).

[0146] 2. Comparative Example 1 reagent (using added sodium fluorescein) showed a significantly smaller decrease in fluorescence intensity after undergoing the same degradation treatment compared to the actual consumption of the main organic matter in the reagent. The decrease in reagent concentration obtained by fluorescence tracing (approximately 8.0%) differed significantly (approximately 12.0%) from the actual consumption of the main organic matter in the reagent as characterized by COD (approximately 20%).

[0147] This indicates that the self-tracing scale and corrosion inhibitor of the present invention can more accurately reflect changes in the actual effective concentration of the agent due to consumption or degradation through fluorescence signals. In contrast, conventional methods using external tracers are prone to distorted tracking results and overestimation of the effective concentration of the remaining agent in the system due to inconsistencies in the stability and consumption rate of the tracer and the main agent.

[0148] Comparative Example 2:

[0149] The main difference between the formulation of Comparative Example 2 and Example 4 is that:

[0150] It does not contain the auxiliary polymer P (LMA-co-DMAEMA) prepared in Example 3. Its weight percentage is replaced by deionized water.

[0151] The remaining components, including the novel fluorescent copolymer (from Example 2, solid content 8.0%), conventional AMPS copolymer (solid content 15.0%), PBTC (solid content 15.0%), zinc sulfate heptahydrate (7.0%), and their contents in the final product are consistent with those in Example 4.

[0152] The preparation method is the same as in Example 4, and all components are mixed evenly.

[0153] Corrosion inhibition performance evaluation:

[0154] The corrosion inhibition performance of the reagents in Example 4 and Comparative Example 2 was evaluated using the same test methods and water quality conditions as the test examples. The dosage concentration for both was 60 mg / L. The test results are shown in Table 6.

[0155] Table 6: Comparison of corrosion inhibition performance between the reagent in Example 4 and the reagent in Comparative Example 2 (dosage concentration 60 mg / L)

[0156]

[0157] As shown in Table 6, without the auxiliary polymer P (LMA-co-DMAEMA), its corrosion inhibition rates for 20# carbon steel, 304 stainless steel, and copper were all higher than those of the agent in Example 4. For example, the corrosion rate for 20# carbon steel increased from 0.028 mm / a to 0.045 mm / a.

[0158] This indicates that the addition of the auxiliary polymer P (LMA-co-DMAEMA) can significantly enhance the corrosion inhibition performance of the scale and corrosion inhibitor of the present invention, and help to form a more effective protective film on the metal surface.

[0159] Comparative Example 3:

[0160] Comparative Example 3 uses a commercially available, commonly used, phosphorus-free composite scale and corrosion inhibitor based on polymers and organophosphonates, which does not possess fluorescent tracer functionality. Its main active components include polyacrylic acid copolymers, HEDP or ATMP analogs, and organic amine corrosion inhibitors.

[0161] Evaluation of scale inhibition and corrosion inhibition performance:

[0162] The scale inhibition and corrosion inhibition performance tests, as well as the water quality conditions, were used to evaluate the performance of the reagents in Example 4 and Comparative Example 3, respectively. The dosage concentration for both was 60 mg / L. The test results are shown in Table 7.

[0163] Table 7: Comparison of scale inhibition and corrosion inhibition performance between the reagent in Example 4 and the reagent in Comparative Example 3 (dosage concentration 60 mg / L)

[0164]

[0165] As can be seen from the data in Table 7:

[0166] In terms of scale inhibition performance, the calcium carbonate scale inhibition rate of the agent in Example 4 was 89.6%, which was better than that of the agent in Comparative Example 3 (85.2%).

[0167] Regarding corrosion inhibition performance, the agent in Example 4 showed significantly better corrosion inhibition effects on 20# carbon steel, 304 stainless steel, and copper than the agent in Comparative Example 3. For example, the corrosion rate of 20# carbon steel was 0.028 mm / a in Example 4, while it was 0.055 mm / a in Comparative Example 3.

[0168] In summary, the self-tracing scale and corrosion inhibitor of the present invention not only has accurate online concentration monitoring capabilities, but its overall scale inhibition and corrosion inhibition performance is also superior to that of commercially available conventional phosphorus-free scale and corrosion inhibitors.

[0169] The performance evaluation results of the test cases and comparative examples 1 to 3 show that:

[0170] 1. Excellent fluorescence tracer performance and accuracy:

[0171] As shown in the test examples, the self-tracing scale and corrosion inhibitor prepared in Example 4 of this invention exhibits a good linear relationship between its concentration in water and fluorescence intensity (correlation coefficient r = 0.9987), enabling accurate monitoring of the agent concentration. More importantly, as shown in the comparison between Comparative Example 1 and Example 4, because the fluorescent group is covalently bonded to the polymer molecule, the fluorescence signal of the agent of this invention can more realistically reflect the actual effective concentration change caused by the consumption or degradation of the agent bulk. Its tracking accuracy (the absolute value of the deviation between the decrease in fluorescence tracer concentration and the decrease in COD is about 3.5%) is significantly better than the conventional method using an external fluorescent tracer (the absolute value of the deviation is about 12.0%).

[0172] 2. Highly efficient scale inhibition performance:

[0173] As shown in the test examples, at a dosage concentration of 60 mg / L, the agent in Example 4 achieved a scale inhibition rate of 89.6% for calcium carbonate. Compared with the commercially available conventional phosphorus-free scale and corrosion inhibitor in Comparative Example 3 (scale inhibition rate of 85.2%), the agent of the present invention exhibits superior scale inhibition performance.

[0174] 3. Excellent corrosion inhibition performance:

[0175] As shown in the test examples, the agent in Example 4, at a dosage concentration of 60 mg / L, exhibited corrosion rates of 0.028 mm / a for 20# carbon steel, 0.0005 mm / a for 304 stainless steel, and 0.0012 mm / a for copper, all demonstrating excellent corrosion inhibition effects. A comparison with Comparative Example 2 shows that the introduction of the auxiliary polymer P (LMA-co-DMAEMA) positively impacted the corrosion inhibition performance (e.g., the corrosion rate of 20# carbon steel decreased from 0.045 mm / a without the auxiliary polymer to 0.028 mm / a). Furthermore, compared to the commercially available conventional phosphorus-free scale and corrosion inhibitor in Comparative Example 3 (corrosion rate of 0.055 mm / a for 20# carbon steel), the agent of this invention also demonstrates a significant advantage in corrosion inhibition performance.

[0176] In summary, this invention successfully developed a novel self-tracing scale and corrosion inhibitor by copolymerizing fluorescent monomers with specific structures onto the main chain of a scale-inhibiting polymer and compounding them with specific auxiliary polymers and other water treatment components. This agent not only possesses convenient and accurate online fluorescent tracing capabilities, overcoming the drawback of inconsistent consumption rates between traditional external tracers and the main agent, but also exhibits highly efficient scale inhibition performance and excellent multi-metal corrosion inhibition performance. Its overall effect surpasses that of some existing products, meeting the demands of modern industrial circulating cooling water systems for efficient and precise control of water treatment agents.

[0177] Those skilled in the art should understand that the above embodiments are merely illustrative of the present invention and not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-tracing type scale and corrosion inhibitor based on a novel fluorescent copolymer, characterized in that, The scale and corrosion inhibitor comprises the following components by weight percentage: Novel fluorescent copolymers, 5.0%–10.0%; Auxiliary polymer 0.25%–5.0%; Conventional AMPS copolymers: 10.0%–30.0%; Carboxylic acid polymers: 10.0%–30.0%; Organophosphates 0%–10.0%; Zinc salts 3.0%–10.0%; The remainder is water.

2. The self-tracked scale and corrosion inhibitor based on novel fluorescent copolymer according to claim 1, characterized in that, The novel fluorescent copolymer is copolymerized from fluorescent monomer B, acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, wherein the mass ratio of acrylic acid to 2-acrylamido-2-methylpropanesulfonic acid is (65-74%):(26-35%), and the amount of fluorescent monomer B is 0.20%-0.30% of the total mass of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid.

3. The self-tracked scale and corrosion inhibitor based on novel fluorescent copolymer according to claim 2, characterized in that, The fluorescent monomer B is prepared by the following steps: (i) Synthesis of the first intermediate: 4-chloro-1,8-naphthalenedicarboxylic anhydride and 3-dimethylaminopropylamine were reacted in glacial acetic acid, wherein the mass ratio of 4-chloro-1,8-naphthalenedicarboxylic anhydride to 3-dimethylaminopropylamine was 2.05:1 to 2.15:1; (ii) Synthesis of the second intermediate: The first intermediate obtained in step (i) is reacted with sodium methoxide as a raw material in methanol; (iii) Synthesis of fluorescent monomer B: The second intermediate obtained in step (ii) is reacted with allyl chloride as a raw material in acetone.

4. The self-tracked scale and corrosion inhibitor based on novel fluorescent copolymer according to claim 1, characterized in that, The auxiliary polymer is a lauryl methacrylate-N,N-dimethylaminoethyl methacrylate copolymer with a number average molecular weight of 500-5000 g / mol, which is copolymerized from 50-80 molar parts of lauryl methacrylate and 20-50 molar parts of N,N-dimethylaminoethyl methacrylate.

5. The self-tracked scale inhibitor and corrosion inhibitor based on novel fluorescent copolymer according to claim 1, characterized in that, The carboxylic acid polymer is selected from one or a mixture of several of 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxyethylidene diphosphonic acid, and ethylenediaminetetramethylenephosphonic acid; and / or the zinc salt is selected from one or a mixture of several of zinc chloride, zinc sulfate heptahydrate, and zinc sulfate monohydrate.

6. A process for the preparation of a self-tracing scale and corrosion inhibitor based on novel fluorescent copolymer as claimed in any one of claims 1 to 5, characterized by, Includes the following steps: (I) Preparation of novel fluorescent copolymers, including: (a) Synthesis of fluorescent monomer B, including: (i) In 350–360 parts by weight of glacial acetic acid, 60–65 parts by weight of 4-chloro-1,8-naphthalenedicarboxylic anhydride and 28.5–32.5 parts by weight of 3-dimethylaminopropylamine are reacted at 108–112 °C for 4.5–5.5 hours, and then the pH is adjusted to 10.8–11.2 with a sodium hydroxide solution of 47–49% by mass to obtain the first intermediate; (ii) Using 18 to 22 parts by weight of the first intermediate obtained in step (i) as raw material, add 4.6 to 4.9 times its mass of methanol and sodium methoxide, wherein the mass ratio of methanol to sodium methoxide is 3.4:1 to 3.8:1; react at 60 to 62°C for 5.5 to 6.5 hours under nitrogen protection, then adjust the pH to 7.0 to 7.4 with concentrated hydrochloric acid with a mass concentration of 29 to 31%, and distill under reduced pressure to obtain the second intermediate; (iii) reacting 18-22 parts by weight of the second intermediate obtained in step (ii) with 58-62 parts by weight of chloropropene in 230-245 parts by weight of acetone at 40-44 °C for 5.5-6.5 hours to obtain the fluorescent monomer B; (b) copolymerizing the fluorescent monomer B prepared in step (a) with acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid in deionized water at 83-87 °C under the action of an initiator to obtain the novel fluorescent copolymer; wherein the amount of the fluorescent monomer B is 0.20-0.30 parts by weight, the total amount of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid is 145 parts by weight, and the mass ratio of acrylic acid to 2-acrylamido-2-methylpropanesulfonic acid is (65-74%):(26-35%); (II) uniformly mixing 5.0-10.0 parts by weight of the novel fluorescent copolymer prepared in step (I), 0.25-5.0 parts by weight of an auxiliary polymer, 10.0-30.0 parts by weight of a conventional AMPS copolymer, 10.0-30.0 parts by weight of a carboxylic acid polymer, 0-10.0 parts by weight of an organic phosphate, 3.0-10.0 parts by weight of a zinc salt, and the balance of water, wherein the parts by weight are percentages based on the total weight of the final scale and corrosion inhibitor.

7. The production method according to claim 6, wherein In step (i), the mass ratio of the 4-chloro-1,8-naphthalene anhydride to 3-dimethylaminopropylamine is controlled at 2.05:1 to 2.15:

1.

8. The preparation method according to claim 6, characterized in that, In step (b), the initiator is a mixture of tert-butyl hydroperoxide and hydrogen peroxide, the total amount of which is 2.5-3.5% of the total mass of the acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid monomers, and the initiator is added dropwise and the subsequent holding reaction time is 1.8-2.2 hours.

9. The preparation method according to claim 6, characterized in that, The auxiliary polymer is lauryl methacrylate-N,N-dimethylaminoethyl methacrylate copolymer, which is prepared by reacting 50-80 moles of lauryl methacrylate and 20-50 moles of N,N-dimethylaminoethyl methacrylate in the presence of azobisisobutyronitrile initiator and dodecyl mercaptan chain transfer agent in toluene or ethyl acetate solvent at 65-80 °C for 4-8 hours, and the number average molecular weight is controlled at 500-5000 g / mol.

10. The method of claim 6, wherein, The mixing in step (II) is carried out at a temperature of 30-35 °C with continuous stirring for 1.0-1.5 hours.

Images