Environment-friendly scale inhibitor for water treatment and preparation method thereof

Abstract

The invention relates to the field of scale inhibitors, and discloses an environment-friendly scale inhibitor for water treatment, which comprises amino trimethylene phosphonic acid, 1-hydroxyethylidene-1, 1-diphosphonic acid, polyepoxysuccinic acid, isothiazolinone and deionized water. The high-phosphorus scale inhibitor comprises the following components in percentage by mass: 15-25% of amino trimethylene phosphonic acid, 10-20% of 1-hydroxyethylidene-1, 1-diphosphonic acid, 10-15% of polyepoxysuccinic acid, 0.1-0.3% of isothiazolinone and the balance of deionized water as a solvent, and after a traditional high-phosphorus scale inhibitor (such as organic phosphonate with the phosphorus content of more than or equal to 15%) is used, phosphorus in discharged water easily enters a natural water body, so that the scale inhibitor has the advantages that the scale inhibitor is easy to clean, and the and thus, water oxygen deficit, fish and shrimp death and ecological balance destroy are caused. The total phosphorus content of the low-phosphorus environment-friendly scale inhibitor is smaller than or equal to 8% (part of products can be as low as 5% or below), the phosphorus concentration of discharged water is far lower than the limit value that the total phosphorus is smaller than or equal to 0.5 mg / L in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002) by combining the synergistic effect of the phosphorus-free component PESA, and phosphorus discharge pollution can be reduced by 90% or above.

Description

Technical Field

[0001] This invention relates to the field of scale inhibitors, specifically to environmentally friendly scale inhibitors for water treatment and their preparation methods. Background Technology

[0002] In the field of industrial water treatment, scale inhibitors are key agents for preventing scale buildup in equipment and ensuring efficient system operation. Their technological development is always closely linked to water quality conditions, environmental requirements, and equipment needs. The research and application of low-phosphorus, environmentally friendly scale inhibitors is an inevitable result of addressing the technological bottlenecks of traditional scale inhibitors, upgrading policy regulations, and the demands for sustainable development. The specific background can be elaborated from the following three aspects:

[0003] Technical limitations and environmental hazards of traditional scale inhibitors

[0004] Ecological risks of high-phosphorus scale inhibitors

[0005] In traditional industrial water treatment, polyphosphate scale inhibitors, represented by sodium tripolyphosphate and sodium hexametaphosphate, as well as early high-phosphorus organophosphonic acids (such as ATMP and HEDP pure systems), are widely used. Although these agents can inhibit scale formation by chelating metal ions, their phosphorus content generally exceeds 15%, which can easily lead to eutrophication of water bodies after discharge. In natural water bodies such as lakes and rivers, phosphorus can accelerate the reproduction of microorganisms such as cyanobacteria and green algae, forming "algal blooms" or "red tides," causing a sharp drop in dissolved oxygen, death of aquatic organisms such as fish, and disruption of the ecological balance.

[0006] Secondary pollution and equipment damage caused by non-environmentally friendly scale inhibitors

[0007] Early scale inhibitors, in an effort to improve stability, incorporated toxic corrosion inhibitors such as chromates and nitrites. These substances are not only difficult to biodegrade but also accumulate in soil and water, posing a threat to human health (e.g., chromates are carcinogenic). Furthermore, traditional scale inhibitors have poor compatibility with other water treatment agents (such as bactericides), easily producing sediment or flocculent deposits that adhere to the surfaces of pipes and heat exchangers, thus exacerbating scaling and corrosion. For example, a power plant used a chromate-containing scale inhibitor, which resulted in a corrosion rate of 0.2 mm / a on condenser copper tubes within six months, far exceeding the industry safety standard of 0.05 mm / a. This forced the plant to shut down and replace equipment, causing economic losses exceeding one million yuan.

[0008] Performance shortcomings under extreme conditions

[0009] As industrial equipment develops towards higher temperatures, higher pressures, and higher salinity (such as medium- and high-pressure boilers and reverse osmosis concentrate systems), the insufficient temperature and alkali resistance of traditional scale inhibitors has become a prominent issue. For example, ordinary polyphosphates are prone to hydrolysis at temperatures exceeding 80°C, generating orthophosphates, which in turn combine with calcium ions to form calcium phosphate scale. In alkaline circulating water with a pH > 9, some organophosphonic acids decompose and become ineffective, causing the scale inhibition rate to plummet from 90% to below 50%, failing to meet the requirements for long-term stable operation of equipment. To address this, we propose an environmentally friendly scale inhibitor for water treatment and its preparation method. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides an environmentally friendly scale inhibitor for water treatment and its preparation method, thus solving the aforementioned problems.

[0011] To achieve the above-mentioned objectives, the present invention provides the following technical solution: an environmentally friendly scale inhibitor for water treatment, comprising aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, polyepoxysuccinic acid, isothiazolinone, and deionized water, wherein the aminotrimethylenephosphonic acid comprises 15%-25% by mass, hydroxyethylidene diphosphonic acid comprises 10%-20% by mass, polyepoxysuccinic acid comprises 10%-15% by mass, isothiazolinone comprises 0.1%-0.3% by mass, and deionized water is used as a solvent to supplement the balance.

[0012] Preferably, the composition comprises, by weight percentage, 20% aminotrimethylene phosphonic acid, 15% hydroxyethylidene diphosphonic acid, 12% polyepoxysuccinic acid, 0.2% isothiazolinone, and 52.8% deionized water.

[0013] A method for preparing an environmentally friendly scale inhibitor for water treatment includes the following steps:

[0014] Step 1: Raw material pretreatment;

[0015] Step 2: Open the feed valve of the reactor and add a measured amount of deionized water into the reactor through the flow meter, then close the feed valve.

[0016] Step 3: Inject aminotrimethylenephosphonic acid and stir to obtain solution one;

[0017] Step 4: Add hydroxyethylidene diphosphonic acid to solution 1 and stir to obtain solution 2, which is transparent and pale yellow and has no obvious particles or flocculent matter;

[0018] Step 5: Inject polyepoxysuccinic acid into solution 2, reduce the stirring speed to 60 r / min, and stir for 35 minutes to form a synergistic scale inhibition system;

[0019] Step 6: Adding preservatives and stabilization treatment.

[0020] Preferably, in the second step, the reactor rotation speed is set to 80 r / min, and the temperature control jacket is turned on to raise the water temperature to 35-40℃.

[0021] Preferably, the injection rate in the third step is controlled at 2-3 L / min, the stirring time is 30 minutes, and the pH value of the solution is observed by an online pH monitor. If the pH value is lower than 2.5, 0.5 mol / L sodium hydroxide solution needs to be added dropwise to adjust it to 3.0-3.5.

[0022] Preferably, the stirring time in the fourth step is 25 minutes. At the same time, the solution is observed. If turbidity occurs, the stirring speed should be increased to 100 r / min and stirred for 10 minutes. If it is still turbid, the machine should be stopped and filtered.

[0023] Preferably, the specific content of the sixth step is as follows:

[0024] S1: Slowly add isothiazolinone to the reactor in 3 portions, with an interval of 5 minutes between each addition, and stir for 5 minutes after each addition;

[0025] S2: Close the temperature control jacket, lower the temperature of the solution in the reactor to room temperature, and continue stirring for 20 minutes. During this period, take a sample to test the turbidity of the solution. If the turbidity exceeds the standard, the solution needs to be pumped into a double-layer filter for filtration and then returned to the reactor.

[0026] Preferably, after each raw material is added, 100 mL of intermediate sample should be retained, and the addition time, temperature and pH value should be recorded.

[0027] Compared with the prior art, the present invention provides an environmentally friendly scale inhibitor for water treatment and its preparation method, which has the following beneficial effects:

[0028] I. Environmental benefits: Reduces pollution risks and aligns with the needs of green development.

[0029] Mitigating eutrophication

[0030] Traditional high-phosphorus scale inhibitors (such as organophosphonates with a phosphorus content ≥15%) can easily introduce phosphorus into natural water bodies after discharge, becoming a nutrient source for microorganisms such as cyanobacteria and green algae, leading to water hypoxia, fish and shrimp mortality, and disrupting the ecological balance. In contrast, low-phosphorus, environmentally friendly scale inhibitors have a total phosphorus content ≤8% (some products can be as low as 5%). Combined with the synergistic effect of the phosphorus-free component PESA, the phosphorus concentration in the discharged water is far below the limit of ≤0.5 mg / L for total phosphorus in the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002), reducing phosphorus pollution by more than 90% and mitigating the risk of eutrophication at its source.

[0031] Improve biodegradability and reduce environmental accumulation

[0032] The PESA component in this product has an aerobic biodegradability rate of ≥85% (28 days). After optimized formulation, ATMP and HEDP can be gradually decomposed by microorganisms in the natural environment into CO2, H2O, and a small amount of harmless phosphates, leaving no recalcitrant organic residues. Compared to traditional non-biodegradable polycarboxylate scale inhibitors (degradation rate ≤30%), this product avoids the accumulation of chemical substances in soil and water bodies due to long-term use, reducing chronic harm to the ecosystem.

[0033] Reduce secondary processing costs

[0034] Due to the product's low toxicity and low pollution characteristics, the discharged water does not require additional phosphorus removal agents (such as polyaluminum chloride or lime) for phosphorus removal treatment and can be directly introduced into the conventional sewage treatment process. This reduces the company's costs for purchasing reagents and operating equipment in subsequent wastewater treatment, while also reducing sludge production (traditional phosphorus removal processes produce about 50-80 kg of sludge for every 1 kg of phosphorus treated), thus reducing the pressure on hazardous waste disposal.

[0035] II. Performance: Adaptable to complex operating conditions, ensuring stable system operation.

[0036] Wide operating conditions adaptability and stable scale inhibition effect

[0037] This product, through the synergistic effect of ATMP (high temperature and high pH resistance), HEDP (strong chelation and corrosion inhibition), and PESA (high salt resistance and dispersion), can adapt to complex water quality environments with temperatures ranging from 5-150℃, pH values ​​from 5.0-10.0, and calcium and magnesium ion concentrations ≤1000mg / L. In medium- and high-pressure boilers (water temperature 120-150℃, pH 9.0-10.0), it achieves a calcium carbonate scale inhibition rate of ≥92%; in high-salt circulating water systems (salt content ≥5000mg / L), the scale inhibition rate remains above 88%, solving the problem of traditional scale inhibitors' effectiveness diminishing under extreme operating conditions.

[0038] It also has corrosion inhibition function, extending equipment life.

[0039] HEDP components can form a dense adsorption film with a thickness of 5-10 nm on metal surfaces (carbon steel, copper, stainless steel, etc.), inhibiting the dissolution of metal ions and controlling the corrosion rate of carbon steel to below 0.05 mm / a (far below the limit of 0.12 mm / a in the "Design Code for Industrial Circulating Cooling Water Treatment" GB50050-2017). Simultaneously, the presence of PESA avoids the antagonistic effect of traditional scale inhibitors and corrosion inhibitors when combined, achieving an integrated "scale inhibition + corrosion inhibition" function. Taking a steel plant's circulating water system as an example, after using this product, the scaling cycle of heat exchanger pipes is extended from 3 months to 12 months, equipment maintenance frequency is reduced by 70%, and service life is extended by 3-5 years.

[0040] Antimicrobial contamination and reduced biofilm

[0041] The 0.2% isothiazolinone in the formula can effectively inhibit the growth of bacteria (such as heterotrophic bacteria and iron bacteria), fungi, and algae, controlling the total number of heterotrophic bacteria in the circulating water to below 10. 3 Below CFU / mL (meets GB50050-2017 standard requirements). Compared to scale inhibitors without added corrosion inhibitors, it can reduce the formation of biological slime by more than 80%, preventing slime from mixing with scale to form "biological scale," thus reducing the risk of pipe blockage and decreased heat exchange efficiency.

[0042] III. Economic Value: Reduces overall costs and improves corporate efficiency

[0043] Reduce the amount of pesticide used and lower procurement costs.

[0044] The synergistic effect of this product increases the utilization rate of the active ingredient by more than 30%. Under the same water quality conditions, the dosage is only 60%-70% of that of traditional high-phosphorus scale inhibitors (e.g., in circulating water systems, the dosage of traditional products is 8-12 mg / L, while this product only requires 5-8 mg / L). For example, in a power plant with a 1000m³... 3 Taking a circulating water system as an example, the annual chemical consumption can be reduced from 50 tons to 32 tons, saving approximately 150,000 yuan in annual procurement costs.

[0045] Reduce energy consumption and improve system efficiency

[0046] Scale buildup on equipment surfaces can significantly reduce heat exchange efficiency (a 1mm thick layer of calcium carbonate scale can decrease thermal efficiency by 10%-15%). After using low-phosphorus, environmentally friendly scale inhibitors, heat exchangers, boilers, and other equipment become virtually scale-free, maintaining heat exchange efficiency above 95% of the design value. Taking a 10t / h steam boiler as an example, scale-free operation can reduce coal consumption by 5kg per ton of steam. Based on 8000 hours of annual operation, this translates to an annual saving of 400 tons of standard coal, equivalent to an economic benefit of approximately 320,000 yuan (based on 800 yuan / ton of standard coal).

[0047] Reduce downtime for maintenance and lower labor costs

[0048] Traditional scale inhibitors cause scaling and corrosion problems, requiring equipment to be shut down for acid washing and descaling every 3-6 months. Each maintenance shutdown takes 2-3 days, with labor and material costs of approximately 50,000 yuan. After using this product, the equipment maintenance cycle is extended to 12-18 months, the number of annual shutdowns is reduced from 2-3 times to 1 time, and annual maintenance costs are reduced by 50,000-100,000 yuan. At the same time, production losses caused by downtime are avoided (such as a daily loss of 100,000-200,000 yuan for a factory shutdown). Detailed Implementation

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Environmentally friendly scale inhibitors for water treatment, including...

[0051] Aminotrimethylenephosphonic acid (ATMP): 15%-25%. ATMP is a commonly used organophosphonic acid scale inhibitor with a strong chelating ability for metal ions such as calcium, magnesium, and iron. It can stabilize scale ions in water in the solution and prevent them from forming precipitates. It still has good stability and scale inhibition effect under high temperature and high pH conditions.

[0052] Hydroxyethylidene diphosphonic acid (HEDP): 10%-20%. HEDP is also an organophosphonic acid scale inhibitor with excellent chelating and dispersing properties. It can form stable complexes with metal ions, disrupting the growth of scale crystals and making it difficult for them to form a hard scale layer. At the same time, HEDP has a certain corrosion inhibition effect on metal surfaces.

[0053] Polyepoxysuccinic acid (PESA): 10%-15%. PESA is a phosphorus-free, biodegradable, and environmentally friendly scale inhibitor. It effectively inhibits the growth of scale ions such as calcium and magnesium through both chelation and dispersion. PESA adsorbs onto the surface of scale crystals, altering their growth morphology and making them looser and more easily carried away by water flow.

[0054] Isothiazolinone (preservative): 0.1%-0.3%. Prevents microbial growth in the scale inhibitor solution, avoiding water quality deterioration and scaling problems caused by microorganisms.

[0055] Deionized water: Balance. Used as a solvent to ensure thorough mixing of all components, guaranteeing uniform distribution of the scale inhibitor in the water for optimal effect.

[0056] Example 1: Optimize the ratio based on the above:

[0057] Key ingredients and their precise proportions (by weight percentage)

[0058] Aminotrimethylenephosphonic acid (ATMP): 20%. ATMP, a commonly used organophosphonic acid scale inhibitor, possesses a strong chelating ability for metal ions such as calcium, magnesium, and iron. The nitrogen atoms in its molecular structure work synergistically with the phosphonic acid groups to stabilize scale ions in the solution, effectively preventing precipitation. Under high-temperature environments (such as boiler water conditions at 100-150℃) and high pH values ​​(pH 8-10), ATMP maintains a stable molecular structure, continuously exhibiting excellent scale inhibition performance and ensuring smooth system operation.

[0059] Hydroxyethylidene diphosphonic acid (HEDP): 15%. HEDP also belongs to the organophosphonic acid class of scale inhibitors and has excellent chelating and dispersing properties. The phosphonic acid groups in its molecule can form stable complexes with metal ions, disrupting the growth process of scale crystals and inhibiting the formation of hard scale layers. At the same time, HEDP can adsorb and form a protective film with corrosion inhibition on metal surfaces, reducing the risk of metal corrosion. In circulating water systems, it provides dual protection for equipment made of common metal materials such as carbon steel and copper.

[0060] Polyepoxysuccinic acid (PESA): 12%. PESA is a representative of phosphorus-free and biodegradable green scale inhibitors. Through a dual mechanism of chelation and dispersion, it exhibits excellent inhibition of scale ions such as calcium and magnesium. The active groups on the PESA molecular chain can adsorb onto the surface of scale crystals, altering the crystal growth morphology, making them looser and easier to be washed away by water flow. Furthermore, in the natural environment, PESA can be gradually decomposed into harmless small molecules by microorganisms, aligning with current environmental protection principles.

[0061] Isothiazolinone (preservative): 0.2%. Isothiazolinone effectively inhibits the growth and reproduction of microorganisms in scale inhibitor solutions. When microorganisms grow and metabolize in water, their secretions easily combine with minerals in the water, aggravating scaling and potentially causing microbial corrosion of equipment. Adding an appropriate amount of isothiazolinone can create an environment unfavorable to microbial survival, ensuring the stability of scale inhibitor performance and maintaining good water quality.

[0062] Deionized water: Balance, approximately 52.8%. As a solvent, deionized water plays a crucial role in dissolving and dispersing other components. It ensures uniform mixing of all ingredients, allowing the scale inhibitor to fully disperse in the water and enabling the active ingredients to come into comprehensive contact with scale ions, thus maximizing its scale-inhibiting effect. Furthermore, deionized water is pure and free of impurities, preventing the introduction of additional ions that could interfere with the scale inhibitor's performance.

[0063] Applicable Scenarios

[0064] Medium and high pressure boiler water system: When medium and high pressure boilers are in operation, the water temperature is high, the pressure is high, and the water quality conditions are stringent. ATMP and HEDP in this formula can stably chelate scale ions under high temperature and high pressure environments, while PESA can help optimize the scale morphology, preventing the formation of dense and hard scale on the boiler heating surface, ensuring efficient and safe boiler operation, and avoiding energy waste and safety hazards caused by scaling.

[0065] Circulating water systems in the steel industry: During steel production, circulating water faces challenges due to its high hardness and alkalinity, and may contain suspended metal particles and impurities. This scale inhibitor formula not only addresses scaling caused by calcium and magnesium ions but also effectively disperses and complexes iron ions and other metallic impurities, preventing their deposition and scaling on pipe and equipment surfaces. Simultaneously, it protects metal equipment from corrosion, extends equipment lifespan, and reduces maintenance costs.

[0066] Power industry circulating water systems: Power industry circulating water systems operate for long periods with large flow rates, requiring high water quality stability. Low-phosphorus, environmentally friendly scale inhibitor formulations effectively control various scale ions in the water, reducing the impact of scale buildup on the system's heat exchange efficiency, ensuring long-term stable operation of the circulating water system, guaranteeing the continuity and efficiency of power production, and reducing potential environmental pollution risks due to their low-phosphorus properties.

[0067] Performance characteristics

[0068] High scale inhibition rate: It achieves a scale inhibition rate of up to 90%-95% against various common scales, such as calcium carbonate, calcium sulfate, and calcium phosphate. Under complex water quality conditions, the components work synergistically to prevent scale formation from multiple dimensions, from chelating scale ions and interfering with crystal growth to dispersing scale particles, thus maintaining the cleanliness of system pipes and equipment surfaces.

[0069] Low phosphorus and environmentally friendly: By precisely controlling the proportion of phosphorus-based components (ATMP and HEDP), phosphorus emissions are significantly reduced while meeting scale inhibition requirements. Compared to traditional high-phosphorus scale inhibitors, this greatly reduces the potential threat of eutrophication to water bodies. Furthermore, the PESA in the formula has excellent biodegradability and can gradually decompose in the natural environment, meeting stringent environmental protection requirements overall.

[0070] High stability: All components are chemically stable and do not easily react with each other to cause ineffectiveness in water environments with different temperatures and pH values. Whether it is high-temperature boiler water or circulating water with fluctuating pH values, it can maintain stable scale inhibition performance, ensuring the continuity and reliability of water treatment effect.

[0071] Excellent compatibility: It exhibits good compatibility with other water treatment agents (such as corrosion inhibitors and bactericides) that may be present in the system. When used in combination, it does not produce adverse reactions such as precipitation or flocculation, and can synergistically improve the overall performance of the entire water treatment system, comprehensively maintaining the normal operation of the circulating water system.

[0072] A method for preparing an environmentally friendly scale inhibitor for water treatment includes the following steps:

[0073] Step 1: Raw material pretreatment

[0074] Aminotrimethylenephosphonic acid (ATMP): Use industrial-grade liquid product with a content of ≥95%. Before use, the pH value must be tested (controlled between 2.0 and 3.0). If the pH value deviates, it needs to be adjusted with 0.1mol / L sulfuric acid or sodium hydroxide solution to avoid affecting subsequent reactions due to abnormal acidity or alkalinity.

[0075] Hydroxyethylidene diphosphonic acid (HEDP): An industrial-grade aqueous solution with a content of ≥50% is used. Impurities are removed by pre-filtration (using a 5μm precision filter membrane) to prevent solid particles from causing the finished product to exceed the turbidity standard.

[0076] Polyepoxysuccinic acid (PESA): Select industrial-grade products with a biodegradability of ≥90% (solid content 40%), and control the storage temperature at 5-30℃ to avoid low-temperature crystallization or high-temperature degradation.

[0077] Isothiazolinone: Use a 10% industrial-grade solution. It must be stored separately in a cool, sealed place to prevent prolonged contact with air from causing the active ingredient to evaporate.

[0078] Deionized water: The conductivity must be ≤10μS / cm. It is pre-treated by reverse osmosis and ion exchange to remove impurities such as calcium, magnesium and chloride ions from the water and avoid introducing additional scale ions.

[0079] Step 2: Preparation of the basic solvent (approximately 30 minutes)

[0080] Open the feed valve of the reactor and add 528 kg of deionized water into the reactor through the flow meter, then close the feed valve.

[0081] Start the stirring device of the reactor and set the speed to 80 r / min. At the same time, turn on the temperature control jacket to raise the water temperature to 35-40℃ (too high a temperature may cause the subsequent decomposition of organophosphonic acid components, while too low a temperature will affect the dissolution efficiency).

[0082] Addition and dissolution of core scale inhibitor components (approximately 90 minutes)

[0083] Adding ATMP: Slowly inject 200 kg of aminotrimethylenephosphonic acid (ATMP) into the reactor using a precision metering pump. The injection rate should be controlled at 2-3 L / min to avoid excessive local concentrations that could lead to precipitation. After injection, maintain stirring for 30 minutes. During this time, monitor the pH value of the solution using an online pH monitor. If the pH value is below 2.5, add 0.5 mol / L sodium hydroxide solution to adjust it to 3.0-3.5.

[0084] Add HEDP: Continue to inject 150 kg of hydroxyethylidene diphosphonic acid (HEDP) through the metering pump at the same injection rate. Stir for 25 minutes after injection. At this time, the solution should be transparent and pale yellow, without obvious particles or flocculent matter. (If turbidity occurs, increase the stirring speed to 100 r / min and continue stirring for 10 minutes. If it is still turbid, stop the machine and filter.)

[0085] Add PESA: Inject 120kg of polyepoxysuccinic acid (PESA). After injection, reduce the stirring speed to 60r / min and stir for 35 minutes to allow PESA molecules to fully combine with ATMP and HEDP to form a synergistic scale inhibition system.

[0086] Preservative addition and stabilization treatment (approximately 40 minutes)

[0087] Slowly add 2 kg of isothiazolinone to the reactor (in 3 portions, 5 minutes apart, with stirring for 5 minutes after each addition) to avoid excessively high local concentrations caused by adding all at once, which would affect the uniformity of preservative dispersion.

[0088] Close the temperature control jacket and lower the temperature of the solution in the reactor to room temperature (20-25℃). Continue stirring for 20 minutes, and take a sample to test the turbidity of the solution during this period (turbidity ≤ 5 NTU required). If the turbidity exceeds the standard, the solution needs to be pumped into a double-layer filter for filtration and then returned to the reactor.

[0089] Finished product inspection and filling (approximately 60 minutes)

[0090] Sampling and testing: Take 500mL of sample from the sampling port of the reactor and test the key indicators: scale inhibition rate (≥92%, tested by static scale inhibition method), total phosphorus content (≤8%, meeting the low phosphorus standard), pH value (3.0-4.0), and biodegradation rate (≥85%, 28-day aerobic degradation test). Only after all indicators are qualified can we proceed to the next step.

[0091] Finished product filling: Open the discharge valve of the reactor and pump the finished product through a double-layer filter into a constant-temperature storage tank. During the filling process, control the flow rate at 10-15 L / min to avoid air bubbles affecting filling accuracy. After filling, label the storage tank with the batch number, preparation date, and expiration date (generally 6 months).

[0092] Process control

[0093] After each raw material is added, 100 mL of intermediate sample should be retained, and the addition time, temperature, and pH value should be recorded for subsequent traceability.

[0094] During the stirring process, the sealing of the reaction vessel should be checked regularly to prevent solution leakage; if abnormal stirring noise occurs, the machine should be stopped immediately for inspection to avoid equipment failure leading to uneven mixing of components.

[0095] Environmental protection requirements

[0096] The cleaning wastewater generated during the preparation process (such as equipment cleaning and filter rinsing wastewater) needs to be collected in the wastewater treatment tank, and the pH is adjusted to 7.0-8.0 by adding alkaline solution. After biochemical treatment, it is discharged after meeting the standards.

[0097] Waste filter cartridges and raw material packaging barrels must be recycled separately (filter cartridges are hazardous waste and should be handed over to qualified units for disposal; packaging barrels can be recycled after cleaning) and must not be discarded at will.

[0098] Storage and Transportation

[0099] The finished product should be stored in a 2000L polyethylene storage tank, avoiding mixing with strong acids, strong alkalis, and oxidants. The storage temperature should be controlled at 15-25℃, and it should be kept away from fire and heat sources.

[0100] Sealed tank trucks should be used for transportation to prevent exposure to sun and rain. "Corrosive substances" and "moisture-proof" labels must be affixed during transportation, and dangerous goods transportation regulations must be followed.

[0101] Table 1: Finished Product Acceptance Standards

[0102]

[0103]

[0104] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly scale inhibitor for water treatment, characterized in that, It includes aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, polyepoxysuccinic acid, isothiazolinone, and deionized water, with aminotrimethylenephosphonic acid 15%-25%, hydroxyethylidene diphosphonic acid 10%-20%, polyepoxysuccinic acid 10%-15%, isothiazolinone 0.1%-0.3% by mass, and deionized water as a solvent to make up the balance.

2. The environmentally friendly scale inhibitor for water treatment according to claim 1, characterized in that: The composition, by weight percentage, is 20% aminotrimethylene phosphonic acid, 15% hydroxyethylidene diphosphonic acid, 12% polyepoxysuccinic acid, 0.2% isothiazolinone, and 52.8% deionized water.

3. A method for preparing an environmentally friendly scale inhibitor for water treatment, characterized in that, Includes the following steps: Step 1: Raw material pretreatment; Step 2: Open the feed valve of the reactor and add a measured amount of deionized water into the reactor through the flow meter, then close the feed valve. Step 3: Inject aminotrimethylenephosphonic acid and stir to obtain solution one; Step 4: Add hydroxyethylidene diphosphonic acid to solution 1 and stir to obtain solution 2, which is transparent and pale yellow and has no obvious particles or flocculent matter; Step 5: Inject polyepoxysuccinic acid into solution 2, reduce the stirring speed to 60 r / min, and stir for 35 minutes to form a synergistic scale inhibition system; Step 6: Adding preservatives and stabilization treatment.

4. The method for preparing the environmentally friendly scale inhibitor for water treatment according to claim 3, characterized in that: In the second step, the reactor speed is set to 80 r / min, and the temperature control jacket is turned on to raise the water temperature to 35-40℃.

5. The method for preparing the environmentally friendly scale inhibitor for water treatment according to claim 3, characterized in that: In the third step, the injection rate is controlled at 2-3 L / min, and the stirring time is 30 minutes. During this period, the pH value of the solution is observed using an online pH monitor. If the pH value is lower than 2.5, 0.5 mol / L sodium hydroxide solution needs to be added dropwise to adjust it to 3.0-3.

5.

6. The method for preparing the environmentally friendly scale inhibitor for water treatment according to claim 3, characterized in that: The stirring time in the fourth step is 25 minutes. During this time, observe the solution. If it becomes turbid, increase the stirring speed to 100 r / min and continue stirring for 10 minutes. If it is still turbid, stop the machine and filter it.

7. The method for preparing the environmentally friendly scale inhibitor for water treatment according to claim 3, characterized in that: The specific details of the sixth step are as follows: S1: Slowly add isothiazolinone to the reactor in 3 portions, with an interval of 5 minutes between each addition, and stir for 5 minutes after each addition; S2: Close the temperature control jacket, lower the temperature of the solution in the reactor to room temperature, and continue stirring for 20 minutes. During this period, take a sample to test the turbidity of the solution. If the turbidity exceeds the standard, the solution needs to be pumped into a double-layer filter for filtration and then returned to the reactor.

8. The method for preparing the environmentally friendly scale inhibitor for water treatment according to claim 3, characterized in that: After each ingredient is added, 100 mL of intermediate sample should be retained, and the addition time, temperature, and pH value should be recorded.

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