Antiscaling agent with mineralization function and controllable release and preparation method thereof

Abstract

The application provides a scale inhibitor with mineralization function and controllable release and a preparation method thereof, and belongs to the technical field of water treatment materials, and comprises the following steps: dissolving carboxymethylated polyaspartic acid sodium salt in water, adding an aqueous SrCl2 solution to react, then adding an aqueous ZnSO4 solution to continue the reaction, and then centrifugally separating to obtain FOF-Zn / Sr; dissolving chitosan in an acetic acid solution, adding zinc citrate and a crosslinking agent to react, and then obtaining a chitosan-zinc citrate gel solution; dissolving N-isopropyl acrylamide and N,N-methylene bisacrylamide in water, pre-polymerizing, then adding the chitosan-zinc citrate gel solution, and then stirring and reacting to obtain a porous composite gel; adding FOF-Zn / Sr and a dispersing agent into water, putting the porous composite gel into the water, stirring at low temperature, washing, and granulating to obtain the scale inhibitor. The scale inhibitor obtained by the application can realize the controllable release of scale inhibiting substances, and can also mineralize water bodies and slowly release beneficial mineral elements.

Description

Technical Field

[0001] This invention relates to the field of water treatment materials technology, specifically to a scale inhibitor with mineralization function and controllable release, and its preparation method. Background Technology

[0002] Scale inhibitors are water treatment agents that mainly inhibit the deposition of inorganic salts such as calcium carbonate and calcium sulfate in water through chemical means. Their main mechanisms include: (1) lattice distortion, which interferes with the crystal growth structure in water, preventing the formation of hard scale; (2) chelation and dispersion, which chelates with polyvalent metal ions such as calcium and magnesium in water, dispersing microcrystals to prevent scale aggregation; and (3) film protection, which forms a protective layer on the surface of equipment to reduce corrosion and scaling. However, the functions of scale inhibitors are relatively limited at present. They cannot release beneficial elements into the water while inhibiting scale, in order to meet the needs of different water bodies for beneficial elements. For example, mineral water or hot spring water needs to be mineralized to meet the needs of beneficial mineral elements such as Zn. 2+ and Sr 2+ The concentration requirements are as follows. Strontium, in particular, has antioxidant, anti-aging, and skin-beautifying effects, and is especially effective for skin diseases such as chronic eczema and psoriasis. It can also soothe skin allergies. In drinking mineral water, the strontium content must be greater than 0.2 mg / L. Zinc, on the other hand, has beautifying effects. Zinc plays an important role in the structure and function of the skin, as well as in the development and decline of inflammation, tumors, and ulcers. Zinc also promotes wound healing and has UV protection properties. In drinking mineral water and therapeutic hot spring water, the zinc content must be greater than 0.2 mg / L.

[0003] Furthermore, the materials currently used for scale inhibition are diverse and face environmental challenges, such as pollution problems from phosphorus-containing scale inhibitors and the fact that the materials used are difficult to degrade, failing to meet green and environmental protection requirements. They also cannot meet health and safety requirements for some high-demand water treatments.

[0004] In addition, although current scale inhibitors have a certain slow-release effect, the slow-release effect is uncontrollable. At higher temperatures, the release amount is too large, which can lead to waste and local over-expansion, causing reverse scaling. At low temperatures, the release amount is insufficient, and it cannot achieve a good scale inhibition effect.

[0005] Therefore, there is a need to provide a scale inhibitor with mineralization function and controllable release, as well as a method for preparing the same, to solve the problems existing in the prior art. Summary of the Invention

[0006] In view of this, the present invention provides a scale inhibitor with mineralization function and controllable release, and a method for preparing the same, which can achieve controllable release of scale inhibitory substances while also mineralizing water and slowly releasing beneficial mineral elements.

[0007] To achieve the above objectives, the specific solution of the present invention is as follows: a method for preparing a scale inhibitor with mineralization function and controllable release, comprising the following preparation steps:

[0008] S1. Dissolve sodium carboxymethyl polyaspartate in water, add SrCl2 aqueous solution and ZnSO4 aqueous solution, react, centrifuge, wash, freeze dry to obtain FOF-Zn / Sr;

[0009] S2. Dissolve chitosan in acetic acid solution, add zinc citrate, stir to react, add crosslinking agent, react to obtain chitosan-zinc citrate gel solution;

[0010] S3. Dissolve N-isopropylacrylamide and N,N-methylenebisacrylamide in water, add an initiator, prepolymerize, add to chitosan-zinc citrate gel solution, stir to react, wash, freeze dry to obtain porous composite gel;

[0011] S4. Add FOF-Zn / Sr and dispersant to water and ultrasonically disperse. Add porous composite gel, vacuum, stir at low temperature, wash, and granulate to obtain scale inhibitor.

[0012] This invention uses carboxymethylated polyaspartic acid sodium salt (CM-PASP-Na) as the FOF (focal surface arrestor) matrix. By introducing more carboxyl groups through carboxymethylation of polyaspartic acid (CM-PASP), the ion exchange capacity of the scale inhibitor is enhanced, and the binding of Ca is more efficient. 2+ / Mg 2+ To inhibit scale formation, for metal ions such as Ca 2+ Mg 2+ Fe 2+ The binding ability of these substances is stronger, interfering with the ordered arrangement of the crystal lattice and improving the scale inhibition rate. Simultaneously, carboxymethylated sodium polyaspartate and Zn... 2+ / Sr 2+ The chelate FOF-Zn / Sr is formed. During water treatment, the carboxyl groups of CM-PASP adsorb onto the crystal nuclei of CaCO3, interfering with the directional growth of crystals and thus playing a scale inhibition role. At the same time, the chelate FOF-Zn / Sr slowly releases the beneficial mineral element Zn. 2+ / Sr 2+ It achieves mineralization function, thereby achieving efficient scale inhibition while slowly releasing beneficial mineral elements to carry out water mineralization.

[0013] Compared to traditional polyaspartic acid (PASP) scale inhibitors, carboxymethylated sodium polyaspartate achieves superior scale inhibition at lower dosages, while also increasing chelation site density, which is beneficial for better chelation of the beneficial mineral element Zn during the early stages of production. 2+ / Sr 2+Furthermore, due to the increased number of water-based groups, it has better dispersibility in water, effectively preventing the deposition of existing microcrystal clusters, and exhibits higher chemical stability, as well as greater resistance to temperature and pH.

[0014] This invention utilizes the interaction between chitosan and zinc citrate by adding chitosan and zinc citrate. 2+ Chelation is performed to form a chitosan-zinc chelate, which is then cross-linked with a cross-linking agent to form a chitosan-zinc citrate gel, serving as an ion-responsive layer. Further, N-isopropylacrylamide and N,N-methylenebisacrylamide are added, and polymerization occurs under the action of an initiator, forming poly(N-isopropylacrylamide) (PNIPAM) on the surface of the chitosan-zinc citrate gel, serving as a temperature-sensitive layer, thus obtaining a porous composite gel. By loading the mineralizing scale inhibitor FOF-Zn / Sr onto the porous composite gel, direct contact between the scale inhibitor and the water is avoided; instead, the scale inhibitor and beneficial mineralizing elements are slowly released through the porous channels of the carrier.

[0015] By employing an inner chitosan-zinc citrate gel as an ion-responsive layer, it exhibits relative stability in typical water bodies. However, at high calcium concentrations, the zinc citrate in the gel readily dissociates, releasing Zn. 2+ Interfering with CaCO3 crystal growth and binding calcium ions to carboxyl groups in the gel weakens the carboxyl groups' ability to inhibit release, promoting the release of more scale-inhibiting components and thus reducing calcium ion concentration more quickly, further enhancing the scale inhibition effect. By using PNIPAM as a temperature-sensitive layer, at relatively low temperatures (<32℃), when the chelate FOF-Zn / Sr generally has low activity and slow release, the temperature-sensitive layer swells, the gel channels enlarge, and the release of scale-inhibiting components FOF and mineral element Zn is promoted. 2+ / Sr 2+ At relatively high temperatures (≥32℃), when the mineralized scale inhibitors are generally more active and released more quickly, the temperature-sensitive layer shrinks to protect the core, the gel channels become smaller, and the release of the scale inhibitor is restricted. Thus, through the ion-responsive layer and temperature-sensitive layer in the porous composite gel, the scale inhibitors can be released in a controlled manner, making the utilization of the scale inhibitors more efficient and the scale inhibition effect more durable.

[0016] Furthermore, the scale inhibitor of this invention uses green and safe materials, and the prepared scale inhibitor can be well degraded without causing environmental and water pollution after degradation, making it environmentally friendly and healthy.

[0017] Preferably, the carboxymethylated polyaspartic acid is prepared by the following steps: dispersing polysuccinimide in water, adding sodium chloroacetate, reacting under alkaline conditions, precipitating in anhydrous ethanol, filtering, washing, and vacuum drying to obtain sodium carboxymethylated polyaspartic acid.

[0018] By subjecting polysuccinimide (PSI) to a carboxymethylation reaction with sodium chloroacetate under alkaline conditions, additional carboxylic acid groups (-CH2COOH) are introduced to obtain carboxymethylated sodium aspartate, which significantly increases the density of chelating sites, enhances the ion exchange capacity of the scale inhibitor, and more efficiently binds Ca. 2+ / Mg 2+ To inhibit scale formation and improve the scale inhibition rate.

[0019] Preferably, in the preparation process of the carboxymethylated polyaspartic acid, polysuccinimide is dispersed in water, cooled in an ice bath, and 20wt% NaOH solution is slowly added dropwise to adjust the pH to 10. Sodium chloroacetate is added, the temperature is raised to 60°C, and the reaction is stirred for 3-4 hours. After cooling to room temperature, the pH is adjusted to 11-12 with 20wt% NaOH, hydrolyzed at 85°C for 1 hour, and after cooling, neutralized with hydrochloric acid to a pH of 6-7. The product is then poured into anhydrous ethanol for precipitation, filtered, washed three times with a 1:1 ethanol / water mixture, and dried under vacuum at 60°C to obtain sodium carboxymethylated polyaspartic acid.

[0020] By ring-opening polysuccinimide (PSI) under alkaline conditions and nucleophilic reaction with sodium chloroacetate, a carboxymethyl side chain is introduced. A reaction temperature of 60°C can better balance efficiency and control side reactions. Subsequently, the pH and temperature are further increased to 85°C to completely open the remaining imide ring, making the reaction more complete and thorough.

[0021] Preferably, in step S1, after dissolving sodium carboxymethyl polyaspartate in water, the pH is adjusted, an inert gas is introduced to remove oxygen, dopamine and ascorbic acid are added, the temperature is raised, and a stirring reaction is carried out in the dark. Then, an aqueous solution of SrCl2 is added, the reaction is carried out, centrifuged, an aqueous solution of ZnSO4 is added, the reaction is continued, centrifuged, washed, and freeze-dried to obtain FOF-Zn / Sr.

[0022] By adding dopamine, the catechol groups contained in dopamine are oxidized to quinones under weakly alkaline conditions. These quinones then undergo a Schiff base reaction with the -SH / -NH2 groups in carboxymethylated polyaspartic acid, grafting them onto CM-PASP. This introduces catechol groups into the side chains of CM-PASP, forming multidentate coordination sites (-COOH, -OH, -NH2). This facilitates the subsequent addition of SrCl2 and ZnSO4, allowing for the addition of more Zn groups. 2+ / Sr 2+ The formation of multidentate coordination chelates FOF-Zn / Sr is beneficial for scale inhibition while providing long-term sustained release of beneficial minerals such as Zn. 2+ / Sr 2+ During water treatment, CM-PASP adsorbs carboxyl groups onto the crystal nuclei of CaCO3, interfering with the directional growth of crystals and thus inhibiting scale growth. Simultaneously, the multidentate coordination chelate FOF-Zn / Sr slowly releases the beneficial mineral element Zn.2+ / Sr 2+ To achieve mineralization.

[0023] Furthermore, by employing a gradient chelation method, an aqueous SrCl2 solution is first added, allowing strong binding sites (such as -COOH) to preferentially chelate Sr. 2+ Then add ZnSO4, Zn 2+ By occupying some remaining carboxyl sites and replacing weak binding sites (such as -OH) through ion exchange, the scale inhibitor can preferentially release Zn into the water. 2+ Through Zn 2+ It inhibits CaCO3 crystallization, exerts a mineralizing effect, interferes with scale growth, and delays Sr crystal growth. 2+ Release, achieving differential release, while the zinc citrate in the porous composite gel also supplements the release of a small amount of Zn. 2+ This makes Zn 2+ The later release amount is not too low, thus achieving a more lasting release effect of both mineral elements.

[0024] Preferably, in step S1, 0.1M Tris-HCl buffer solution is added to adjust the pH to 8.5, inert gas N2 or Ar is introduced to remove oxygen, dopamine and ascorbic acid are added, the temperature is raised to 40-50℃, and the mixture is stirred and reacted in the dark for 2-3 hours. Then, SrCl2 aqueous solution is slowly added dropwise to adjust the pH to 7.5, the reaction is carried out for 1 hour, centrifuged, ZnSO4 aqueous solution is added to adjust the pH to 6.0, the reaction is continued at 50℃ for 1 hour, centrifuged, washed 2-3 times with anhydrous ethanol, and freeze-dried to obtain FOF-Zn / Sr.

[0025] By removing oxygen with N2 or Ar, reacting under an inert atmosphere, and adding ascorbic acid and light protection, dopamine self-polymerization is effectively inhibited, and the grafting of dopamine with CM-PASP is better promoted.

[0026] Preferably, the SrCl2 aqueous solution is prepared by mixing SrCl2·6H2O and water at a mass ratio of 1:20; the ZnSO4 aqueous solution is prepared by mixing ZnSO4·7H2O and water at a mass ratio of 1:25.

[0027] Preferably, in step S2, CNF suspension is added before adding the crosslinking agent and mixed thoroughly; the crosslinking agent is genipin.

[0028] By adding CNF (nanocellulose) and chitosan for cross-linking, the nanofibers are dispersed in the gel to form a cross-linked network, extending the diffusion path of FOF-Zn / Sr and enhancing the gel's toughness. This makes the gel more stable in water, thereby prolonging the release period of the scale-inhibiting components within the gel carrier and improving the long-lasting sustained-release effect. Furthermore, genipin is used as a cross-linking agent, forming a cross-linked network through the reaction of genipin with the primary amine groups of chitosan. Genipin itself can be extracted and prepared from plants, making it safe and non-toxic, thus avoiding the introduction of toxic or harmful cross-linking agents.

[0029] Preferably, in step S2, chitosan is dissolved in a 2wt% acetic acid solution, zinc citrate is added, and the mixture is stirred at 45°C for 2 hours. The pH is adjusted to 6 with NaOH, CNF suspension is added and mixed well, then the crosslinking agent genipin is added, and the mixture is reacted for 3 hours. The temperature is then lowered to 25°C to obtain a chitosan-zinc citrate gel solution. The CNF suspension is obtained by weighing 0.3 parts of nanocellulose and adding it to 50 mL of water, then sonicating at 300W for 30 minutes. The degree of deacetylation of the chitosan is ≥90%.

[0030] Preferably, in step S3, after adding initiator APS and prepolymerizing at 25°C for 10 minutes, the mixture is added to a chitosan-zinc citrate gel solution, stirred for 1 hour, washed with deionized water, injected into a mold, frozen at -20°C for 12 hours, and then freeze-dried for 24 hours to obtain a porous composite gel.

[0031] Preferably, in step S4, FOF-Zn / Sr and dispersant sodium polyacrylate are added to water and ultrasonically dispersed. A porous composite gel is then placed in the water, and the mixture is vacuumed at -0.1 MPa for 10 minutes. The mixture is then stirred at a low temperature of 15-20°C for 1 hour. N-hydroxyethyl acrylamide is also added, and the temperature is raised to 25°C. The mixture is stirred and reacted for 1 hour. The mixture is washed with deionized water and then placed at 45°C for 20 minutes. It is then rapidly cooled to 4°C and maintained for 3 minutes. The temperature is then raised to 45°C again. Finally, the mixture is granulated using an extrusion granulator to obtain the scale inhibitor.

[0032] The dispersion effect of FOF-Zn / Sr is improved by adding sodium polyacrylate dispersant, and efficient and full loading is achieved by using vacuum loading to drive FOF-Zn / Sr to quickly penetrate into the gel pores using negative pressure.

[0033] After loading FOF-Zn / Sr, N-hydroxyethylacrylamide was added and heated to promote copolymerization and crosslinking with PNIPAM. This caused the porous composite gel to shrink and encapsulate the FOF-Zn / Sr chelate, while simultaneously enhancing PNIPAM crosslinking and incorporating FOF-crosslinks, thus strengthening the gel crosslinking effect. Furthermore, by maintaining the temperature at 45°C to shrink the surface of the porous composite gel, followed by rapid freezing to lock in the shrunken state, and then heating again to strengthen the internal encapsulation, the crosslinking strength and stability of the porous composite gel were improved. This prevented localized cracking or degradation when exposed to rapid water flow, further enhancing the long-term stable sustained-release effect.

[0034] The present invention also provides a scale inhibitor with mineralization function and controllable release, comprising the following raw materials in parts by weight: 16-25 parts FOF-Zn / Sr, 0.1-0.3 parts dispersant and 25-40 parts porous composite gel;

[0035] The FOF-Zn / Sr comprises the following raw materials in parts by weight: 150-200 parts carboxymethylated sodium aspartate, 3-5 parts dopamine, 0.3-0.6 parts ascorbic acid, 12-15 parts SrCl2·6H2O, and 10-12 parts ZnSO4·7H2O; the porous composite gel comprises the following raw materials in parts by weight: 20-25 parts chitosan, 3-5 parts zinc citrate, 0.8-1.5 parts crosslinking agent, 5-8 parts N-isopropylacrylamide, 0.3-0.5 parts N,N-methylenebisacrylamide, and 0.1-0.2 parts initiator.

[0036] By using the above-mentioned raw material components and controlling the amount of components, the final scale inhibitor is of better quality. It can slowly release beneficial mineral elements, achieve mineralization function, and at the same time, achieve the controlled release of scale inhibitory components, thereby improving the scale inhibition effect.

[0037] The above-described technical solution of the present invention has at least the following beneficial effects:

[0038] 1. This invention, by employing carboxymethylated sodium polyaspartate, introduces more carboxyl groups, enhancing the ion exchange capacity of the scale inhibitor and thus improving its ability to inhibit the exchange of metal ions such as Ca. 2+ Mg 2+ Fe 2+ It has stronger binding ability, interferes with the ordered arrangement of the crystal lattice, and has higher scale inhibition efficiency, achieving better scale inhibition effect with lower dosage; at the same time, through carboxymethylated sodium polyaspartate and Zn 2+ / Sr 2+ The chelate FOF-Zn / Sr is formed. During water treatment, the carboxyl groups of CM-PASP adsorb onto the crystal nuclei of CaCO3, interfering with the directional growth of crystals and thus playing a scale inhibition role. At the same time, the chelate FOF-Zn / Sr slowly releases the beneficial mineral element Zn.2+ / Sr 2+ It achieves mineralization, thereby enabling efficient scale inhibition while slowly releasing beneficial mineral elements.

[0039] 2. This invention involves adding chitosan and zinc citrate to crosslink and form a chitosan-zinc citrate gel. Then, by adding N-isopropylacrylamide and N,N-methylenebisacrylamide, poly(N-isopropylacrylamide) is polymerized on the surface of the chitosan-zinc citrate gel to form poly(N-isopropylacrylamide), resulting in a porous composite gel. This gel is then loaded with the mineralizing scale inhibitor FOF-Zn / Sr, avoiding direct contact between the mineralizing scale inhibitor and the water. Instead, the scale inhibitor and beneficial mineral elements are slowly released through the porous channels in the carrier, achieving a slow-release effect.

[0040] 3. This invention utilizes an inner chitosan-zinc citrate gel as an ion-responsive layer, which is relatively stable in normal water bodies. However, at high calcium concentrations, the zinc citrate in the gel readily dissociates, releasing Zn. 2+ Interfering with the growth of CaCO3 crystal lattice and the combination of calcium ions with carboxyl groups in the gel promotes the release of more scale-inhibiting components from the porous composite gel, thereby achieving a high-concentration calcium ion response and improving the scale inhibition effect; by using PNIPAM as a temperature-sensitive layer, the temperature-sensitive layer swells at relatively low temperatures, promoting the release of chelates FOF-Zn / Sr, while at relatively high temperatures, the temperature-sensitive layer shrinks, restricting the release of scale-inhibiting components, thereby achieving controlled release of scale-inhibiting components and a more durable scale inhibition effect. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0042] Example 1

[0043] 100g of polysuccinimide (PSI) was dispersed in 1000mL of deionized water and cooled in an ice bath. 20wt% NaOH solution was slowly added dropwise to adjust the pH to 10. 100g of sodium chloroacetate was added, and the mixture was heated to 60℃ and stirred for 3 hours. After cooling to room temperature, the pH was adjusted to 11 with 20wt% NaOH. The mixture was hydrolyzed at 85℃ for 1 hour to completely open the remaining imide ring. After cooling, the pH was neutralized to 6 with hydrochloric acid (HCl), and the mixture was poured into 3000mL of anhydrous ethanol for precipitation. The solid was collected by filtration, washed three times with a 1:1 ethanol / water mixture, and dried under vacuum at 60℃ to obtain carboxymethylated sodium aspartate.

[0044] 150g of carboxymethylated polyaspartic acid sodium salt (CMPA-Na) was dissolved in 1000mL of deionized water. The pH was adjusted to 8.5 by adding 0.1M Tris-HCl buffer. Oxygen was removed by purging with an inert atmosphere of N2. 3g of dopamine and 0.3g of ascorbic acid were added. The mixture was heated to 40℃ and stirred. The reaction was carried out in the dark for 2 hours. Then, 300mL of SrCl2 aqueous solution (prepared by dissolving 12g of SrCl2·6H2O in 300mL of water) was slowly added dropwise to adjust the pH to 7.5. The reaction was continued for 1 hour to form Sr-PASP-DA chelate. The chelate was separated by centrifugation. 300mL of ZnSO4 aqueous solution (prepared by dissolving 10g of ZnSO4·7H2O in 300mL of water) was added to adjust the pH to 6.0. The reaction was continued at 50℃ for 1 hour. The chelate was separated by centrifugation, washed twice with anhydrous ethanol, and freeze-dried to obtain the chelate powder FOF-Zn / Sr.

[0045] 0.3 g of nanocellulose (CNF) was added to 50 mL of water and sonicated at 300 W for 30 min to obtain a homogeneous CNF suspension for later use. 20 g of chitosan (degree of deacetylation ≥90%) was dissolved in 200 mL of 2 wt% acetic acid solution, and 3 g of zinc citrate was added. The mixture was stirred at 45 °C for 2 h, and the pH was adjusted to 6 with NaOH. The CNF suspension was then added and mixed thoroughly, followed by the addition of 0.8 g of genipin. The reaction was continued for 3 h to obtain a chitosan-zinc citrate gel solution. Separately, 5 g of N-isopropylacrylamide (NIPAM) and 0.3 g of N,N-methylenebisacrylamide (MBA) were dissolved in 80 mL of water, and 0.1 g of ammonium persulfate initiator (APS) was added. After prepolymerization at 25 °C for 10 min, the mixture was transferred to the chitosan-zinc citrate gel solution cooled to 25 °C and stirred for 1 h. The mixture was washed with deionized water, poured into a mold, frozen at -20 °C for 12 h, and then freeze-dried for 24 h to obtain a porous composite gel.

[0046] 16g of FOF-Zn / Sr and 0.1g of sodium polyacrylate (PAAS) were ultrasonically dispersed in 100 mL of water. 25g of porous composite gel was added, and the mixture was vacuumed at -0.1MPa for 10 min and stirred at 15℃ for 1 h. 0.2g of N-hydroxyethylacrylamide was added, and the mixture was stirred at 25℃ for 1 h. The mixture was washed with deionized water, then placed at 45℃ for 20 min, rapidly cooled to 4℃ and held for 5 min, and then heated to 45℃ again. Finally, the mixture was granulated using an extruder to obtain the scale inhibitor.

[0047] Example 2

[0048] 100 g of polysuccinimide (PSI) was dispersed in 1000 mL of deionized water and cooled in an ice bath. 20 wt% NaOH solution was slowly added dropwise to adjust the pH to 10. 110 g of sodium chloroacetate was added, and the mixture was heated to 60 °C and stirred for 4 hours. After cooling to room temperature, the pH was adjusted to 12 with 20 wt% NaOH and hydrolyzed at 85 °C for 1 hour to completely open the remaining imide ring. After cooling, the pH was neutralized to 7 with hydrochloric acid (HCl), and the mixture was poured into 3000 mL of anhydrous ethanol for precipitation. The solid was collected by filtration, washed three times with a 1:1 ethanol / water mixture, and dried under vacuum at 60 °C to obtain carboxymethylated sodium aspartate.

[0049] 200g of carboxymethylated polyaspartic acid sodium salt (CMPA-Na) was dissolved in 1000mL of deionized water. The pH was adjusted to 8.5 by adding 0.1M Tris-HCl buffer. An inert Ar atmosphere was introduced to remove oxygen. 5g of dopamine and 0.6g of ascorbic acid were added. The mixture was heated to 50℃ and stirred. The reaction was carried out in the dark for 3 hours. Then, 300mL of SrCl2 aqueous solution (prepared by dissolving 15g of SrCl2·6H2O in 300mL of water) was slowly added dropwise to adjust the pH to 7.5. The reaction was carried out for 1 hour to form Sr-PASP-DA chelate. The chelate was separated by centrifugation. 300mL of ZnSO4 aqueous solution (prepared by dissolving 12g of ZnSO4·7H2O in 300mL of water) was added to adjust the pH to 6.0. The reaction was continued at 50℃ for 1 hour. The chelate was separated by centrifugation and washed three times with anhydrous ethanol. The chelate was then freeze-dried to obtain chelate powder FOF-Zn / Sr.

[0050] 0.6 g of nanocellulose (CNF) was added to 50 mL of water and sonicated at 300 W for 30 min to obtain a homogeneous CNF suspension for later use. 25 g of chitosan (degree of deacetylation ≥90%) was dissolved in 300 mL of 2 wt% acetic acid solution, and 5 g of zinc citrate was added. The mixture was stirred at 45 °C for 2 h, and the pH was adjusted to 6 with NaOH. The CNF suspension was then added and mixed thoroughly, followed by the addition of 1.5 g of genipin. The reaction was continued for 3 h to obtain a chitosan-zinc citrate gel solution. Separately, 8 g of N-isopropylacrylamide (NIPAM) and 0.5 g of N,N-methylenebisacrylamide (MBA) were dissolved in 80 mL of water, and 0.2 g of ammonium persulfate initiator (APS) was added. After prepolymerization at 25 °C for 10 min, the mixture was transferred to the chitosan-zinc citrate gel solution cooled to 25 °C and stirred for 1 h. The mixture was washed with deionized water, poured into a mold, frozen at -20 °C for 12 h, and then freeze-dried for 24 h to obtain a porous composite gel.

[0051] 25g of FOF-Zn / Sr and 0.3g of sodium polyacrylate (PAAS) were ultrasonically dispersed in 100 mL of water. 40g of porous composite gel was added, and the mixture was vacuumed at -0.1MPa for 10 min and stirred at 20℃ for 1 h. 0.5g of N-hydroxyethylacrylamide was added, and the mixture was stirred at 25℃ for 1 h. The mixture was washed with deionized water, then placed at 45℃ for 20 min, rapidly cooled to 4℃ and held for 5 min, and then heated to 45℃ again. Finally, the mixture was granulated using an extruder to obtain the scale inhibitor.

[0052] Example 3

[0053] 100 g of polysuccinimide (PSI) was dispersed in 1000 mL of deionized water and cooled in an ice bath. 20 wt% NaOH solution was slowly added dropwise to adjust the pH to 10. 110 g of sodium chloroacetate was added, and the mixture was heated to 60 °C and stirred for 4 hours. After cooling to room temperature, the pH was adjusted to 11 with 20 wt% NaOH and hydrolyzed at 85 °C for 1 hour to completely open the remaining imide ring. After cooling, the pH was neutralized to 7 with hydrochloric acid (HCl), and the mixture was poured into 3000 mL of anhydrous ethanol for precipitation. The solid was collected by filtration, washed three times with a 1:1 ethanol / water mixture, and dried under vacuum at 60 °C to obtain sodium carboxymethyl polyaspartate.

[0054] 180g of carboxymethylated polyaspartic acid sodium salt (CMPA-Na) was dissolved in 1000mL of deionized water. The pH was adjusted to 8.5 by adding 0.1M Tris-HCl buffer. Oxygen was removed by purging with an inert atmosphere of N2. 4g of dopamine and 0.5g of ascorbic acid were added. The mixture was heated to 45℃ and stirred. The reaction was carried out in the dark for 2 hours. Then, 300mL of SrCl2 aqueous solution (prepared by dissolving 13g of SrCl2·6H2O in 300mL of water) was slowly added dropwise to adjust the pH to 7.5. The reaction was continued for 1 hour to form Sr-PASP-DA chelate. The chelate was separated by centrifugation. 300mL of ZnSO4 aqueous solution (prepared by dissolving 11g of ZnSO4·7H2O in 300mL of water) was added to adjust the pH to 6.0. The reaction was continued at 50℃ for 1 hour. The chelate was separated by centrifugation, washed three times with anhydrous ethanol, and freeze-dried to obtain the chelate powder FOF-Zn / Sr.

[0055] 0.5 g of nanocellulose (CNF) was added to 50 mL of water and sonicated at 300 W for 30 min to obtain a homogeneous CNF suspension for later use. 23 g of chitosan (degree of deacetylation ≥90%) was dissolved in 250 mL of 2 wt% acetic acid solution, and 4 g of zinc citrate was added. The mixture was stirred at 45 °C for 2 h, and the pH was adjusted to 6 with NaOH. The CNF suspension was then added and mixed thoroughly, followed by the addition of 1.0 g of genipin. The reaction was continued for 3 h to obtain a chitosan-zinc citrate gel solution. Separately, 6 g of N-isopropylacrylamide (NIPAM) and 0.4 g of N,N-methylenebisacrylamide (MBA) were dissolved in 80 mL of water, and 0.1 g of ammonium persulfate initiator (APS) was added. After prepolymerization at 25 °C for 10 min, the mixture was transferred to the chitosan-zinc citrate gel solution cooled to 25 °C and stirred for 1 h. The mixture was washed with deionized water, poured into a mold, frozen at -20 °C for 12 h, and then freeze-dried for 24 h to obtain a porous composite gel.

[0056] 20g of FOF-Zn / Sr and 0.2g of sodium polyacrylate (PAAS) were ultrasonically dispersed in 100 mL of water. 35g of porous composite gel was added, and the mixture was stirred at -0.1MPa for 10 min at 18℃ for 1 h under vacuum. 0.3g of N-hydroxyethylacrylamide was added, and the mixture was stirred at 25℃ for 1 h. The mixture was washed with deionized water, then placed at 45℃ for 20 min, rapidly cooled to 4℃ and held for 5 min, and then heated to 45℃ again. Finally, the mixture was granulated using an extruder to obtain the scale inhibitor.

[0057] Example 4

[0058] 100 g of polysuccinimide (PSI) was dispersed in 1000 mL of deionized water and cooled in an ice bath. 20 wt% NaOH solution was slowly added dropwise to adjust the pH to 10. 110 g of sodium chloroacetate was added, and the mixture was heated to 60 °C and stirred for 4 hours. After cooling to room temperature, the pH was adjusted to 11 with 20 wt% NaOH and hydrolyzed at 85 °C for 1 hour to completely open the remaining imide ring. After cooling, the pH was neutralized to 7 with hydrochloric acid (HCl), and the mixture was poured into 3000 mL of anhydrous ethanol for precipitation. The solid was collected by filtration, washed three times with a 1:1 ethanol / water mixture, and dried under vacuum at 60 °C to obtain sodium carboxymethyl polyaspartate.

[0059] 180g of carboxymethylated polyaspartic acid sodium salt (CMPA-Na) was dissolved in 1000mL of deionized water. The pH was adjusted to 8.5 by adding 0.1M Tris-HCl buffer. Oxygen was removed by purging with an inert atmosphere of N2. 4g of dopamine and 0.5g of ascorbic acid were added. The mixture was heated to 45℃ and stirred. The reaction was carried out in the dark for 3 hours. Then, 300mL of SrCl2 aqueous solution (prepared by dissolving 14g of SrCl2·6H2O in 300mL of water) was slowly added dropwise to adjust the pH to 7.5. The reaction was continued for 1 hour to form Sr-PASP-DA chelate. The chelate was separated by centrifugation. 300mL of ZnSO4 aqueous solution (prepared by dissolving 11g of ZnSO4·7H2O in 300mL of water) was added to adjust the pH to 6.0. The reaction was continued at 50℃ for 1 hour. The chelate was separated by centrifugation, washed three times with anhydrous ethanol, and freeze-dried to obtain the chelate powder FOF-Zn / Sr.

[0060] 0.5 g of nanocellulose (CNF) was added to 50 mL of water and sonicated at 300 W for 30 min to obtain a homogeneous CNF suspension for later use. 22 g of chitosan (degree of deacetylation ≥90%) was dissolved in 300 mL of 2 wt% acetic acid solution, and 4 g of zinc citrate was added. The mixture was stirred at 45 °C for 2 h, and the pH was adjusted to 6 with NaOH. The CNF suspension was then added and mixed thoroughly, followed by the addition of 1 g of genipin. The reaction was continued for 3 h to obtain a chitosan-zinc citrate gel solution. Separately, 6 g of N-isopropylacrylamide (NIPAM) and 0.4 g of N,N-methylenebisacrylamide (MBA) were dissolved in 80 mL of water, and 0.1 g of ammonium persulfate initiator (APS) was added. After prepolymerization at 25 °C for 10 min, the mixture was transferred to the chitosan-zinc citrate gel solution cooled to 25 °C and stirred for 1 h. The mixture was washed with deionized water, poured into a mold, frozen at -20 °C for 12 h, and then freeze-dried for 24 h to obtain a porous composite gel.

[0061] 22g of FOF-Zn / Sr and 0.2g of sodium polyacrylate (PAAS) were ultrasonically dispersed in 100 mL of water. 36g of porous composite gel was added, and the mixture was stirred at -0.1MPa for 10 min at 16℃ for 1 h under vacuum. 0.4g of N-hydroxyethylacrylamide was added, and the mixture was stirred at 25℃ for 1 h. The mixture was washed with deionized water, then placed at 45℃ for 20 min, rapidly cooled to 4℃ and held for 5 min, and then heated to 45℃ again. Finally, the mixture was granulated using an extruder to obtain the scale inhibitor.

[0062] Example 5

[0063] 100 g of polysuccinimide (PSI) was dispersed in 1000 mL of deionized water and cooled in an ice bath. 20 wt% NaOH solution was slowly added dropwise to adjust the pH to 10. 110 g of sodium chloroacetate was added, and the mixture was heated to 60 °C and stirred for 4 hours. After cooling to room temperature, the pH was adjusted to 12 with 20 wt% NaOH and hydrolyzed at 85 °C for 1 hour to completely open the remaining imide ring. After cooling, the pH was neutralized to 7 with hydrochloric acid (HCl), and the mixture was poured into 3000 mL of anhydrous ethanol for precipitation. The solid was collected by filtration, washed three times with a 1:1 ethanol / water mixture, and dried under vacuum at 60 °C to obtain carboxymethylated sodium aspartate.

[0064] 180g of carboxymethylated polyaspartic acid sodium salt (CMPA-Na) was dissolved in 1000mL of deionized water. The pH was adjusted to 8.5 by adding 0.1M Tris-HCl buffer. Oxygen was removed by purging with an inert atmosphere of N2. 4g of dopamine and 0.5g of ascorbic acid were added. The mixture was heated to 45℃ and stirred. The reaction was carried out in the dark for 3 hours. Then, 300mL of SrCl2 aqueous solution (prepared by dissolving 13g of SrCl2·6H2O in 300mL of water) was slowly added dropwise to adjust the pH to 7.5. The reaction was continued for 1 hour to form Sr-PASP-DA chelate. The chelate was separated by centrifugation. 300mL of ZnSO4 aqueous solution (prepared by dissolving 11g of ZnSO4·7H2O in 300mL of water) was added to adjust the pH to 6.0. The reaction was continued at 50℃ for 1 hour. The chelate was separated by centrifugation, washed three times with anhydrous ethanol, and freeze-dried to obtain the chelate powder FOF-Zn / Sr.

[0065] 0.5 g of nanocellulose (CNF) was added to 50 mL of water and sonicated at 300 W for 30 min to obtain a homogeneous CNF suspension for later use. 22 g of chitosan (degree of deacetylation ≥90%) was dissolved in 300 mL of 2 wt% acetic acid solution, and 4 g of zinc citrate was added. The mixture was stirred at 45 °C for 2 h, and the pH was adjusted to 6 with NaOH. The CNF suspension was then added and mixed thoroughly, followed by the addition of 1 g of genipin. The reaction was continued for 3 h to obtain a chitosan-zinc citrate gel solution. Separately, 6 g of N-isopropylacrylamide (NIPAM) and 0.4 g of N,N-methylenebisacrylamide (MBA) were dissolved in 80 mL of water, and 0.1 g of ammonium persulfate initiator (APS) was added. After prepolymerization at 25 °C for 10 min, the mixture was transferred to the chitosan-zinc citrate gel solution cooled to 25 °C and stirred for 1 h. The mixture was washed with deionized water, poured into a mold, frozen at -20 °C for 12 h, and then freeze-dried for 24 h to obtain a porous composite gel.

[0066] 20g of FOF-Zn / Sr and 0.2g of sodium polyacrylate (PAAS) were ultrasonically dispersed in 100 mL of water. 36g of porous composite gel was added, and the mixture was stirred at -0.1MPa for 10 min at 18℃ for 1 h under vacuum. 0.4g of N-hydroxyethylacrylamide was added, and the mixture was stirred at 25℃ for 1 h. The mixture was washed with deionized water, then placed at 45℃ for 20 min, rapidly cooled to 4℃ and held for 5 min, and then heated to 45℃ again. Finally, the mixture was granulated using an extruder to obtain the scale inhibitor.

[0067] Example 6

[0068] Compared with Example 5, no CNF suspension or N-hydroxyethyl acrylamide was added, but all other preparation steps were the same, resulting in a scale inhibitor.

[0069] Example 7

[0070] Compared with Example 5, dopamine and ascorbic acid were not added, and SrCl2 aqueous solution and ZnSO4 aqueous solution were added simultaneously. All other preparation steps were the same, and a scale inhibitor was obtained.

[0071] The present invention also includes comparative examples and related comparative experiments.

[0072] Comparative Example 1

[0073] Compared with Example 5, sodium polyaspartate was used directly instead of carboxymethylated sodium polyaspartate to prepare the chelate FOF-Zn / Sr, and all other preparation steps were the same, resulting in a scale inhibitor.

[0074] Comparative Example 2

[0075] Compared with Example 5, the chitosan-zinc citrate gel solution was not prepared; instead, a poly(N-isopropylacrylamide) porous gel was prepared to replace the porous composite gel. All other preparation steps were the same, and a scale inhibitor was obtained.

[0076] Performance testing

[0077] (i) Referring to standard GB / T 22626-2008, the calcium phosphate deposition method (Ca...) was adopted. 2+ Concentration 250 mg / L, PO4 3- The scale inhibitors obtained in Examples 1-6 and Comparative Examples 1-3 were tested for scale inhibition performance at a concentration of 5 mg / L. The tests were conducted at room temperature (25°C) and temperature (60°C) with an addition rate of 20 mg / L for 24 hours. The scale inhibition efficiency of calcium phosphate was calculated, and the results are summarized in Table 1 below.

[0078] (ii) Referring to standard GB / T 16632-2019, the calcium carbonate deposition method (Ca...2+ Concentration 240 mg / L, HCO3 - The scale inhibitors obtained in Examples 1-6 and Comparative Examples 1-3 were tested for scale inhibition performance at a concentration of 732 mg / L. The tests were conducted at room temperature (25°C) and temperature (60°C) with an addition rate of 20 mg / L for 24 hours. The scale inhibition efficiency of calcium carbonate was calculated, and the results are summarized in Table 1 below.

[0079] (iii) In addition, prepare a high-calcium water sample (Ca 2+ Concentration 1000 mg / L, HCO3 - Using simulated hot spring water (concentration 500 mg / L), the scale inhibitors obtained in Examples 1-6 and Comparative Examples 1-3 were tested for scale inhibition performance and beneficial element release at 45°C for 24 hours. The dosage of the scale inhibitor was 100 mg / L. The scale inhibition efficiency and Zn were calculated. 2+ / Sr 2+ The concentrations in the water are summarized in Table 2 below.

[0080] Table 1

[0081]

[0082] Table 2

[0083]

[0084] The results in Tables 1 and 2 show that the scale inhibitors obtained in Examples 1-7 all have very high scale inhibition efficiencies. Even in high-calcium water, their scale inhibition efficiency for calcium carbonate can reach over 96.5%, demonstrating excellent scale inhibition performance. Furthermore, they can release a significant amount of Zn. 2+ / Sr 2+ It can mineralize water, better replenishing and maintaining the high levels of beneficial element Zn in hot spring water. 2+ / Sr 2+ Concentration. In Example 7, due to the absence of dopamine binding and the lack of gradient chelation, the number of chelation sites was reduced, although the Zn... 2+ By vying for chelation sites, the chelation amount will not be too low, while Sr 2+ The amount of chelation was significantly reduced, resulting in a significant decrease in the amount released.

[0085] Furthermore, the scale inhibitors obtained in Examples 1-7 can maintain a high level of scale inhibition efficiency for calcium phosphate and calcium carbonate at relatively high or low temperatures, with little fluctuation. This is mainly because PNIPAM, as a temperature-sensitive layer, expands at low temperatures and contracts at high temperatures to regulate the balance of scale inhibitor release, thereby achieving the effect of controllable scale inhibitor release.

[0086] Compared with Example 5, the scale inhibition efficiency of Comparative Example 1 was significantly reduced, while Zn was released. 2+ / Sr 2+ The concentration also decreased significantly, indicating that carboxymethylation of polyaspartic acid can effectively improve the scale inhibition effect and provide more chelation sites to ensure good chelation with calcium and zinc ions, facilitating the subsequent release of mineralized calcium and zinc ions. Although Comparative Example 2 showed very high scale inhibition efficiency in conventional water, its scale inhibition efficiency in high-calcium water decreased significantly, far below the 97.9% of the scale inhibitor in Example 5. This indicates that the chitosan-zinc citrate gel solution can respond to calcium ions and adjust according to the calcium ion concentration to maintain a stable scale inhibition effect. Furthermore, the zinc ion release concentration in Comparative Example 2 also decreased, mainly because the zinc ions contained in the chitosan-zinc citrate gel, in addition to playing a certain scale inhibition role, are partially released into the water to increase the zinc ion concentration.

[0087] (iv) Long-term mineralization and scale inhibition performance tests were conducted on the scale inhibitors obtained in Examples 5-6 and Comparative Examples 1-3. 8g of the scale inhibitor was wrapped in gauze and placed in a flowing water system at a flow rate of 500mL / h. 2+ Concentration 300 mg / L, HCO3 - The concentration was 200 mg / L, the temperature was 25℃, and the monitoring was carried out continuously for 30 days. Water samples were taken at 15 days and 30 days to test the scale inhibition rate and the concentration of zinc ions and strontium ions in the water. The results are summarized in Table 3.

[0088] Table 3

[0089]

[0090] As can be seen from the results in Table 3 above, the scale inhibitors obtained in Examples 5-7 of this invention can still maintain a scale inhibition rate of over 82% after 30 days, exhibiting good long-lasting and slow-release scale inhibition effects and greater durability; at the same time, they can also maintain a relatively long Zn release. 2+ / Sr 2+ The effect, especially the slow release of Zn by the scale inhibitor obtained in Example 5 within 15 days. 2+ The concentration can reach 0.21 mg / L, Sr 2+ The concentration can reach 0.23 mg / L, which meets the requirements for Zn in mineral water. 2+ / Sr 2+ The requirement is greater than or equal to 0.20 mg / L; and it can still maintain Zn after 30 days. 2+ Concentration 0.08 mg / L, Sr 2+ The concentration of 0.10 mg / L is sufficient to meet the dosage required for osteoporosis prevention and treatment, indicating that the scale inhibitor obtained in Example 5 has a long-lasting mineralization function.

[0091] Compared to Example 5, the scale inhibitor obtained in Example 6 showed significantly lower scale inhibition efficiency and beneficial element release concentrations within 30 days. This was mainly due to CNF effectively improving the toughness of the porous composite gel and prolonging the release channels, and the addition of N-hydroxyethylacrylamide effectively enhancing the crosslinking strength of the porous composite gel, thus achieving a longer-lasting sustained-release effect. While the scale inhibitor obtained in Example 7 maintained a high scale inhibition efficiency within 30 days, the release concentrations of beneficial elements decreased significantly, primarily due to the lack of dopamine grafting, which reduced the chelation sites for beneficial elements, particularly Zn. 2+ / Sr 2+ Reduced chelation makes it difficult to achieve prolonged release of mineral elements, and it cannot preferentially chelate easily released strontium ions at sites with strong binding forces through gradient chelation. This results in an excessively rapid initial release of strontium ions followed by a significant decrease in release amount in the later stages, shortening the Sr... 2+ Release timeliness affects Sr 2+ The stable release effect is achieved, and zinc ions are more easily chelated and occupy strong binding sites. In addition, zinc citrate in the porous composite gel can also supplement zinc ions to a certain extent, so that the concentration of zinc ions decreases slightly.

[0092] Compared with Example 1, due to the use of uncarboxylated sodium polyaspartate, the carboxyl content is low, resulting in a significant decrease in scale inhibition efficiency over a long period of time. Furthermore, the number of chelation sites is limited, leading to lower utilization. This is in contrast to Zn. 2+ / Sr 2+ The chelation effect is low, making it difficult to achieve long-term sustained release of Zn. 2+ / Sr 2+ The effect of the chitosan-zinc citrate gel was not observed in Comparative Example 2. Because chitosan-zinc citrate gel was not prepared, the porous release channels were shorter and the overall strength of the porous composite gel was insufficient, making it difficult to withstand prolonged water flow and thus hindering the maintenance of scale inhibition and the release of beneficial elements for an extended period.

[0093] The above are preferred embodiments of the present invention. For those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a scale inhibitor with mineralization function and controllable release, characterized in that: The preparation steps include the following: S1. Dissolve sodium carboxymethyl polyaspartate in water, add SrCl2 aqueous solution and ZnSO4 aqueous solution, react, centrifuge, wash, freeze dry to obtain FOF-Zn / Sr; S2. Dissolve chitosan in acetic acid solution, add zinc citrate to react, add crosslinking agent, react to obtain chitosan-zinc citrate gel solution; S3. Dissolve N-isopropylacrylamide and N,N-methylenebisacrylamide in water, add an initiator, prepolymerize, add to chitosan-zinc citrate gel solution, stir to react, wash, freeze dry to obtain porous composite gel; S4. Add FOF-Zn / Sr and dispersant to water and ultrasonically disperse. Add porous composite gel, vacuum, stir at low temperature, wash, and granulate to obtain scale inhibitor.

2. The method for preparing a scale inhibitor with mineralization function and controllable release according to claim 1, characterized in that: The carboxymethylated polyaspartic acid was prepared by the following steps: polysuccinimide was dispersed in water, sodium chloroacetate was added, the mixture was reacted under alkaline conditions, and the mixture was precipitated in anhydrous ethanol, filtered, washed, and vacuum dried to obtain sodium carboxymethylated polyaspartic acid.

3. The method for preparing a scale inhibitor with mineralization function and controllable release according to claim 2, characterized in that: In the preparation of the carboxymethylated polyaspartic acid, polysuccinimide is dispersed in water, cooled in an ice bath, and 20wt% NaOH solution is slowly added dropwise to adjust the pH to 10. Sodium chloroacetate is added, the temperature is raised to 60℃, and the reaction is stirred for 3-4 hours. After cooling to room temperature, the pH is adjusted to 11-12 with 20wt% NaOH, and hydrolyzed at 85℃ for 1 hour. After cooling, the pH is neutralized with hydrochloric acid to 6-7, and the product is poured into anhydrous ethanol for precipitation. After filtration, the product is washed three times with a 1:1 ethanol / water mixture and dried under vacuum at 60℃ to obtain sodium carboxymethylated polyaspartic acid.

4. The method for preparing a scale inhibitor with mineralization function and controllable release according to claim 1, characterized in that: In step S1, after dissolving sodium carboxymethyl polyaspartate in water, the pH is adjusted, an inert gas is introduced to remove oxygen, dopamine and ascorbic acid are added, the temperature is raised, and a stirring reaction is carried out in the dark. Then, an aqueous solution of SrCl2 is added, the reaction is carried out, centrifuged, an aqueous solution of ZnSO4 is added, the reaction is continued, centrifuged, washed, and freeze-dried to obtain FOF-Zn / Sr.

5. The method for preparing a scale inhibitor with mineralization function and controllable release according to claim 4, characterized in that: In step S1, 0.1M Tris-HCl buffer solution is added to adjust the pH to 8.5, inert gas N2 or Ar is introduced to remove oxygen, dopamine and ascorbic acid are added, the temperature is raised to 40-50℃, and the mixture is stirred and reacted in the dark for 2-3 hours. Then, SrCl2 aqueous solution is slowly added dropwise to adjust the pH to 7.5, and the reaction is carried out for 1 hour. After centrifugation, ZnSO4 aqueous solution is added to adjust the pH to 6.0, and the reaction is continued at 50℃ for 1 hour. After centrifugation, the mixture is washed 2-3 times with anhydrous ethanol and freeze-dried to obtain FOF-Zn / Sr. The SrCl2 aqueous solution was prepared by mixing SrCl2·6H2O and water at a mass ratio of 1:20; the ZnSO4 aqueous solution was prepared by mixing ZnSO4·7H2O and water at a mass ratio of 1:

25.

6. The method for preparing a scale inhibitor with mineralization function and controllable release according to claim 1, characterized in that: In step S2, CNF suspension is added before adding the crosslinking agent and mixed thoroughly; the crosslinking agent is genipin.

7. The method for preparing a scale inhibitor with mineralization function and controllable release according to claim 6, characterized in that: In step S2, chitosan is dissolved in a 2wt% acetic acid solution, zinc citrate is added, and the mixture is stirred at 45°C for 2 hours. The pH is adjusted to 6 with NaOH, CNF suspension is added and mixed well, then genipin, a crosslinking agent, is added, and the mixture is reacted for 3 hours. The temperature is then lowered to 25°C to obtain a chitosan-zinc citrate gel solution. The CNF suspension is obtained by weighing 0.3 parts of nanocellulose and adding it to 50 mL of water, then sonicating at 300W for 30 minutes. The degree of deacetylation of the chitosan is ≥90%.

8. The method for preparing a scale inhibitor with mineralization function and controllable release according to claim 1, characterized in that: In step S3, initiator APS is added, prepolymerized at 25°C for 10 minutes, then added to chitosan-zinc citrate gel solution, stirred for 1 hour, washed with deionized water, injected into a mold, frozen at -20°C for 12 hours, and then freeze-dried for 24 hours to obtain a porous composite gel.

9. The method for preparing a scale inhibitor with mineralization function and controllable release according to claim 1, characterized in that: In step S4, FOF-Zn / Sr and dispersant sodium polyacrylate are added to water and ultrasonically dispersed. A porous composite gel is then placed in the water, and the mixture is vacuumed at -0.1 MPa for 10 minutes. The mixture is then stirred at a low temperature of 15-20°C for 1 hour. N-hydroxyethyl acrylamide is added, and the mixture is heated to 25°C and stirred for 1 hour. The mixture is then washed with deionized water and placed at 45°C for 20 minutes. It is then rapidly cooled to 4°C and maintained for 3 minutes. The temperature is then raised to 45°C again. Finally, the mixture is granulated using an extrusion granulator to obtain the scale inhibitor.

10. A scale inhibitor with mineralization function and controllable release, characterized in that: The scale inhibitor with mineralization function and controllable release is prepared by any one of claims 1-9, comprising the following raw materials in parts by weight: 16-25 parts FOF-Zn / Sr, 0.1-0.3 parts dispersant and 25-40 parts porous composite gel; The FOF-Zn / Sr comprises the following raw materials in parts by weight: 150-200 parts carboxymethylated sodium aspartate, 3-5 parts dopamine, 0.3-0.6 parts ascorbic acid, 12-15 parts SrCl2·6H2O, and 10-12 parts ZnSO4·7H2O; the porous composite gel comprises the following raw materials in parts by weight: 20-25 parts chitosan, 3-5 parts zinc citrate, 0.8-1.5 parts crosslinking agent, 5-8 parts N-isopropylacrylamide, 0.3-0.5 parts N,N-methylenebisacrylamide, and 0.1-0.2 parts initiator.

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