Slow-release micro-nano reverse osmosis scale inhibitor and its synthesis process

Abstract

The present invention relates to the technical field of scale inhibitors, and more specifically, to a slow-release micro-nano reverse osmosis scale inhibitor and a synthesis process thereof. The slow-release micro-nano reverse osmosis scale inhibitor comprises amino trimethylene phosphonic acid, polyol phosphonate, acrylic polyol, poly-γ-glutamic acid-polyethyleneimine graft copolymer, hydroxyethylidene diphosphonic acid, polyacrylamide and diatomaceous earth; a plurality of raw materials are compounded, diatomaceous earth is used as a slow-release carrier, and poly-γ-glutamic acid-polyethyleneimine graft copolymer is used to achieve slow release of the agent; moreover, bioactive groups are grafted onto the surface of amino trimethylene phosphonic acid through microbial induced synthesis, which not only solves the problem of easy agglomeration of nano-loaded agents under high pH conditions in the prior art, increases the binding sites and interaction forces between amino trimethylene phosphonic acid and other components, but also improves the adhesion of the scale inhibitor to the membrane surface, strengthens the long-term scale inhibition effect under complex water quality, and thus improves the application efficiency of the reverse osmosis scale inhibitor in actual complex water quality.

Description

Technical Field

[0001] The present invention relates to the technical field of scale inhibitors, in particular to a slow-release micro-nano reverse osmosis scale inhibitor and a synthesis process thereof. Background Art

[0002] Reverse osmosis membrane technology is currently widely used in water treatment. However, metal ions such as calcium, magnesium, and barium in water can easily form scale on the membrane surface, leading to reduced membrane flux and reduced salt rejection. While traditional scale inhibitors such as aminotrimethylphosphonic acid (ATMP) can inhibit scale formation through chelation, their effectiveness decreases under alkaline conditions. Furthermore, they require high dosages and lack environmental compatibility, making long-term, stable scale inhibition difficult, particularly in high-hardness water.

[0003] Existing technologies partially improve scale inhibition performance through chemical modification or nanomaterial loading. While this can enhance the dispersibility of the agent under neutral conditions, its adaptability to complex scenarios involving the coexistence of multiple ions and pH fluctuations in alkaline water remains insufficient. For example, nano-loaded agents are prone to particle agglomeration under high pH conditions, which not only reduces the contact efficiency between the scale inhibitor and metal ions, resulting in a decrease in agent utilization, but can also clog the pores of the reverse osmosis membrane, affecting the system's operating flux. Furthermore, the deposition of agglomerated particles accelerates the formation of a fouling layer on the membrane surface, further reducing the rejection rate of the membrane elements and increasing the frequency and maintenance costs of system cleaning, thereby reducing the effectiveness of reverse osmosis scale inhibitors in actual complex water conditions.

[0004] In view of this, there is an urgent need for slow-release micro-nano reverse osmosis scale inhibitors and their synthesis process. Summary of the Invention

[0005] The purpose of the present invention is to provide a slow-release micro-nano reverse osmosis antiscalant and a synthesis process thereof, so as to solve the problems raised in the above background technology.

[0006] To achieve the above objectives, firstly, the present invention provides a slow-release micro-nano reverse osmosis scale inhibitor, comprising the following raw materials:

[0007] 10-20 parts of aminotrimethylenephosphonic acid (ATMP), 8-15 parts of polyol phosphonate, 5-10 parts of acrylic polyol, 3-8 parts of poly-γ-glutamic acid-polyethyleneimine graft copolymer, 5-10 parts of hydroxyethylidene diphosphonic acid (HEDP), 2-5 parts of polyacrylamide (PAM) and 20-40 parts of diatomaceous earth, wherein:

[0008] The amino trimethylene phosphonic acid (ATMP) molecule contains multiple phosphonic acid groups, which can form stable complexes with metal ions (such as calcium and magnesium) in water to play a scale inhibition role. The polyol phosphonate and amino trimethylene phosphonic acid (ATMP) enhance the chelating ability of metal ions through the synergistic effect of the phosphonic acid groups, further improve the scale inhibition effect, and help improve the dispersibility of the agent in water. The acrylic polyol and the phosphonic acid groups in amino trimethylene phosphonic acid (ATMP) are combined through hydrogen bonding and other forces to form a complex with a certain spatial structure, which increases the stability of the agent and the adsorption of the membrane surface, and is conducive to long-term scale inhibition. The poly-γ-glutamic acid-polyethylene imine graft copolymer can interact with amino trimethylene phosphonic acid (ATMP) through electrostatic effects and hydrogen bonds to form a macromolecular complex, which has good water solubility and dispersibility and can delay the amino The release of tris(methylene phosphonic acid) (ATMP) achieves a sustained-release effect while enhancing the chelation and dispersion capabilities of multiple ions. The phosphonic acid groups in hydroxyethylidene diphosphonic acid (HEDP) and aminotris(methylene phosphonic acid) (ATMP) work together to form stable chelates with more metal ions, such as hexacyclic chelates with calcium ions, exerting a synergistic scale inhibition effect and improving scale inhibition performance in high-hardness water. The polyacrylamide (PAM) is connected to aminotris(methylene phosphonic acid) (ATMP) through adsorption bridging, which helps to disperse the scale inhibition components in water and prevent them from agglomerating, while also improving the rheological properties of the agent. The diatomaceous earth has a large specific surface area and is used to adsorb the agent components of aminotris(methylene phosphonic acid) (ATMP). As a sustained-release carrier, it allows the agent to be slowly released, prolongs the action time, and enhances the adhesion of the scale inhibitor to the membrane surface, improving the scale inhibition efficiency.

[0009] The polyol phosphonate, acrylic acid polyol, and poly-γ-glutamic acid-polyethyleneimine graft copolymer form a composite system with multiple functions through intermolecular forces. This composite system synergizes with aminotrimethylphosphonic acid to further enhance the chelation and dispersion capabilities of metal ions in water, improving the scale inhibition effect, while also helping to improve the dispersibility and stability of the agent in water. Furthermore, the properties of the poly-γ-glutamic acid-polyethyleneimine graft copolymer can be utilized to delay the release of the agent, achieving long-term sustained release. This facilitates the long-term and stable scale inhibition effect under complex water conditions, enhances the adsorption and adhesion of the scale inhibitor to the membrane surface, reduces membrane fouling, and improves the operating efficiency and stability of the reverse osmosis system.

[0010] The hydroxyethylidene diphosphonic acid (HEDP) and polyacrylamide (PAM) provide secondary assistance to further enhance the performance of the scale inhibitor. The hydroxyethylidene diphosphonic acid (HEDP) can combine with polyacrylamide (PAM) through physical adsorption. The phosphonic acid group of the hydroxyethylidene diphosphonic acid (HEDP) can enhance the complexing ability of polyacrylamide (PAM) for metal ions, enabling polyacrylamide (PAM) to more effectively disperse the metal ions during the adsorption and bridging process, thereby preventing them from forming scale deposits. Simultaneously, the polymer chain structure of the polyacrylamide (PAM) can improve the distribution of the hydroxyethylidene diphosphonic acid (HEDP) in water, allowing it to more evenly contact the metal ions in the water, thereby exerting a synergistic scale inhibition effect and improving the stability and scale inhibition efficiency of the scale inhibitor in complex water quality.

[0011] Second, according to Figure 1 As shown, the present invention provides a synthesis process of a slow-release micro-nano reverse osmosis antiscalant, comprising the following steps:

[0012] S1. Raw material pretreatment: amino trimethylene phosphonic acid, polyol phosphonate, acrylic polyol, hydroxy ethylidene diphosphonic acid, and polyacrylamide are purified and dried respectively. Then, diatomaceous earth is air-grinded to D50 = 5 μm and calcined at 150°C for 2 hours to remove organic impurities. Its pore structure is optimized by physical grinding and high-temperature treatment to increase the specific surface area and enhance adsorption performance. Then, poly-γ-glutamic acid-polyethyleneimine graft copolymer is dissolved in deionized water at a mass ratio of 1:10 to prepare a transparent solution with a solid content of 10%;

[0013] S2. Microbial Induction Synthesis: A microbial strain is cultured in a culture medium until the logarithmic growth phase to form a culture solution. The pretreated amino trimethylene phosphonic acid is added to the culture solution, and the solution is transferred to a shaker. The reaction is carried out in the dark at 30-35°C and 180-200 rpm for 48-50 hours. Enzymes or other bioactive substances produced by microbial metabolism are used to induce structural changes in the amino trimethylene phosphonic acid, so that some microbial metabolites or functional groups are grafted onto its surface, thereby increasing the binding sites and interaction forces between the amino trimethylene phosphonic acid and other components, thereby forming a modified amino trimethylene phosphonic acid with bioactive functional groups on its surface.

[0014] S3. Construction of a composite system: Add the pretreated polyol phosphonate, acrylic polyol, and modified amino tris(methylene phosphonic acid) into a reactor equipped with a temperature control device, and mix them at a temperature of 60-80°C and a stirring speed of 240-300 r / min for 2-3 hours. A preliminary composite is formed through the synergistic effect of the phosphonic acid groups and intermolecular hydrogen bonding. Then, a transparent solution of a poly-gamma-glutamic acid-polyethyleneimine graft copolymer is added, and the reaction is continued by stirring at 40-50°C and 150-200 r / min for 1-2 hours. The copolymer and the preliminary composite are cross-linked by electrostatic adsorption and hydrogen bonding to construct a composite system with water solubility, ion chelation ability, and sustained-release function. The composite system has good water solubility, dispersibility, and chelation ability for metal ions, and can achieve a sustained-release effect.

[0015] S4. Enhanced synergistic effect: Add pretreated hydroxyethylidene diphosphonic acid and polyacrylamide to the composite system, and stir and mix at a speed of 120-180r / min for 40-60min under mild conditions of pH 7-8. This allows the phosphonic acid groups of the hydroxyethylidene diphosphonic acid and the aminotri(methylene)phosphonic acid in the composite system to jointly capture metal ions in the water through chelation. At the same time, the polyacrylamide acts as a bridge to evenly disperse the hydroxyethylidene diphosphonic acid and the composite system in the water, forming a mixed solution with strong scale inhibition ability and stable dispersibility, which is used to enhance the overall scale inhibition performance and stability in complex water quality.

[0016] S5. Slow-release carrier loading: Add the treated diatomaceous earth to the mixed solution and continue mixing at a medium speed of 300-500r / min for 30-40min, so that the diatomaceous earth can fully absorb the scale inhibitor components in the solution like a sponge, forming a scale inhibitor slurry with uniformly dispersed micro-nano particles. Subsequently, the slurry is transferred to a plate and frame filter press and filtered at a pressure of 0.3-0.5MPa to obtain a filter cake. The filter cake is then placed in a vacuum drying oven and dried at 60-80℃ and a vacuum degree of -0.08 to -0.06MPa for 4-6 hours. Finally, it is crushed by air flow to obtain a finished reverse osmosis scale inhibitor with a particle size of 80-200nm.

[0017] Furthermore, in S1, aminotrimethylenephosphonic acid is dried in a vacuum drying oven at 60°C for 4-4.5 hours, and free amine impurities are removed by ethanol recrystallization for purification; polyol phosphonate is subjected to reduced pressure distillation at -0.08 MPa vacuum and 120°C to remove low-boiling point byproducts, and then adsorbed and dried using 3A molecular sieve; acrylic polyol is filtered through a 0.22 μm membrane to remove mechanical impurities, and then rotary evaporated at 50°C under nitrogen protection to remove moisture; hydroxyethylidene diphosphonic acid is decolorized by activated carbon adsorption and concentrated under reduced pressure to a moisture content of <0.5%; polyacrylamide is purified by acetone precipitation, vacuum dried, and then ground through an 80-mesh sieve.

[0018] Furthermore, in S2, a gene-edited Bacillus subtilis was selected as the microbial strain, an exogenous gene encoding an esterase (EstA) was inserted into its genome, and it was capable of specifically catalyzing the modification of the phosphonate bond of aminotri(methylenephosphonic acid) (ATMP). The culture medium used a culture solution containing 20 g / L glucose, 10 g / L yeast powder and 3 g / L potassium dihydrogen phosphate, and was stirred and cultured at 37°C at a speed of 180 r / min until the turbidity of the bacterial solution reached 0.8.

[0019] In the invention, aminotrimethylenephosphonic acid is first modified through microbial induced synthesis technology to graft biologically active groups on its surface. This not only strengthens the binding with polyol phosphonates and acrylic polyols to form a stable composite system, but also makes use of the pH response characteristics of the poly-γ-glutamic acid-polyethyleneimine graft copolymer to achieve slow release of the agent in an alkaline environment. For example, the release rate can be adjusted according to pH changes in high-hardness water. It can also effectively enhance the adhesion of the scale inhibitor to the membrane surface, reduce membrane pore blockage caused by particle agglomeration, and enhance the long-term scale inhibition effect under complex water quality.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This slow-release micro-nano reverse osmosis scale inhibitor and its synthesis process utilize a combination of multiple raw materials, with diatomaceous earth used as a slow-release carrier. Meanwhile, a poly-γ-glutamic acid-polyethyleneimine graft copolymer is utilized to achieve slow release of the agent. This effectively addresses the issues of reduced scale inhibition efficiency, large agent dosage, and insufficient environmental compatibility of traditional scale inhibitors under alkaline conditions. Furthermore, bioactive groups are grafted onto the surface of aminotri(methylenephosphonic acid) through microbial-induced synthesis. This not only addresses the problem of easy agglomeration of nano-loaded agents under high pH conditions in the prior art, but also increases the binding sites and interaction forces between aminotri(methylenephosphonic acid) and other components. Furthermore, it improves the adhesion of the scale inhibitor to the membrane surface, enhancing the long-term scale inhibition effect under complex water quality, thereby improving the application efficiency of the reverse osmosis scale inhibitor in actual complex water quality.

[0022] 2. In this slow-release micro-nano reverse osmosis scale inhibitor and its synthesis process, aminotri(methylenephosphonic acid) is modified through microbial-induced synthesis, so that bioactive groups are grafted onto its surface, which can form a composite system with synergistic chelating ability with polyol phosphonates and acrylic polyols. At the same time, the acid-base response characteristics of the poly-γ-glutamic acid-polyethyleneimine graft copolymer are utilized to enable the gradient release of the agent under different pH environments, effectively enhancing the adhesion stability of the scale inhibitor on the membrane surface, reducing the risk of clogging the membrane pores due to particle agglomeration, and improving the long-term scale inhibition performance under complex water qualities. In addition, the multiple synergistic systems formed by the intermolecular forces between the various components can enhance the chelation and dispersion effects of multiple metal ions (such as calcium, magnesium, and barium) in water, improve the dispersion stability of the agent in water, and thus enhance the application adaptability of the reverse osmosis scale inhibitor in actual complex water qualities. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flowchart of the synthesis process of the slow-release micro-nano reverse osmosis antiscalant of the present invention;

[0024] Figure 2 is a line graph of the scale inhibition efficiency of the present invention;

[0025] Figure 3 It is a line graph of the 48h cumulative release rate of the present invention;

[0026] Figure 4 is a line graph of the membrane flux attenuation rate (100h) of the present invention;

[0027] Figure 5 It is a line graph of the desalination rate (100h) of the present invention. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] Example 1

[0030] 10 parts of amino tris(methylenephosphonic acid) were dried in a vacuum drying oven at 60°C for 4 hours and purified by ethanol recrystallization; 8 parts of polyol phosphonate were distilled under reduced pressure at -0.08 MPa and 120°C and then dried by adsorption with 3A molecular sieve; 5 parts of acrylic polyol were filtered through a 0.22 μm membrane and dehydrated by rotary evaporation at 50°C under nitrogen protection; 5 parts of hydroxyethylidene diphosphonic acid were decolorized by activated carbon adsorption and concentrated under reduced pressure to a moisture content of <0.5%; 2 parts of polyacrylamide were purified by acetone precipitation, vacuum dried and ground through an 80-mesh sieve; diatomaceous earth was air-flow-pulverized to D50=5 μm and then calcined at 150°C for 2 hours, 3.5 parts of poly(gamma-glutamic acid-polyethyleneimine) graft copolymer were taken and dissolved in deionized water at a mass ratio of 1:10 to prepare a 10% solid content solution; gene-edited Bacillus subtilis was selected and The method comprises the following steps: 1. The culture medium of glucose, 10 g / L yeast powder and 3 g / L potassium dihydrogen phosphate is cultured at 37°C and 180 r / min until the turbidity of the bacterial solution is 0.8, and then the pretreated amino tris (methylene phosphonic acid) is added, and the mixture is reacted in the dark at 30°C and 180 r / min for 48 hours; 2. The pretreated polyol phosphonate, acrylic polyol and modified amino tris (methylene phosphonic acid) are added to a reactor, and the mixture is stirred and mixed at 60°C and 240 r / min for 2 hours, and then the poly (gamma)-glutamic acid-polyethyleneimine graft copolymer solution is added, and the mixture is stirred and reacted at 40°C and 150 r / min for 1 hour; 3. The pretreated hydroxyethylidene diphosphonic acid and polyacrylamide are then added, and the mixture is stirred and mixed at a pH value of 7 for 40 minutes; 4. Finally, 20 parts of treated diatomaceous earth are added to the mixed solution, and the mixture is stirred and mixed at 300 r / min for 30 minutes. The slurry is filtered, vacuum dried and then air flow crushed to obtain a finished reverse osmosis scale inhibitor.

[0031] Example 2

[0032] 15 parts of aminotrimethylenephosphonic acid were dried in a vacuum drying oven at 60°C for 4.2 hours and purified by ethanol recrystallization; 12 parts of polyol phosphonate were distilled under reduced pressure at -0.08 MPa and 120°C, and then dried by adsorption using 3A molecular sieve; 7 parts of acrylic polyol were filtered through a 0.22 μm membrane and dehydrated by rotary evaporation at 50°C under nitrogen protection; 7 parts of hydroxyethylidene diphosphonic acid were decolorized by activated carbon adsorption and concentrated under reduced pressure to a moisture content of <0.5%; 3 parts of polyacrylamide were purified by acetone precipitation, vacuum dried, and then ground through an 80-mesh sieve. The diatomaceous earth was air-grinded to D50 = 5 μm and then calcined at 150 ° C for 2 h. Four parts of poly-γ-glutamic acid-polyethyleneimine graft copolymer were taken and dissolved in deionized water at a mass ratio of 1:10 to prepare a 10% solid content solution. Gene-edited Bacillus subtilis was selected and cultured in a culture medium containing 20 g / L glucose, 10 g / L yeast powder and 3 g / L potassium dihydrogen phosphate at 37 ° C and 180 r / min until the turbidity of the culture solution was 0.8. Pretreated amino tris(methylene phosphonic acid) was added and the reaction was carried out in the dark at 33 ° C and 190 r / min for 49 h. The treated polyol phosphonate, acrylic polyol and modified amino trimethylene phosphonic acid are added to a reactor, stirred and mixed at 70°C and 270 r / min for 2.5 hours, and a poly-gamma-glutamic acid-polyethyleneimine graft copolymer solution is added, and stirred and reacted at 45°C and 170 r / min for 1.5 hours; then the pretreated hydroxyethylidene diphosphonic acid and polyacrylamide are added, and stirred and mixed at a pH value of 7.5 for 50 minutes; finally, 30 parts of treated diatomaceous earth are added to the mixed solution, and mixed at 400 rpm for 35 minutes. The slurry is filtered, vacuum dried and then air flow crushed to obtain a finished reverse osmosis scale inhibitor.

[0033] Example 3

[0034] 20 parts of aminotrimethylenephosphonic acid were dried in a vacuum drying oven at 60°C for 4.5 hours and purified by ethanol recrystallization; 15 parts of polyol phosphonate were distilled under reduced pressure at -0.08 MPa and 120°C and then dried by adsorption with 3A molecular sieve; 10 parts of acrylic acid polyol were filtered through a 0.22 μm membrane and dehydrated by rotary evaporation at 50°C under nitrogen protection; 10 parts of hydroxyethylidene diphosphonic acid were decolorized by activated carbon adsorption and concentrated under reduced pressure to a moisture content of <0.5%; 5 parts of polyacrylamide were purified by acetone precipitation, vacuum dried, and ground through an 80-mesh sieve; diatomaceous earth was air-pulverized to D50 =5μm, calcined at 150℃ for 2h, 6 parts of poly-γ-glutamic acid-polyethyleneimine graft copolymer were taken, and the poly-γ-glutamic acid-polyethyleneimine graft copolymer was dissolved in deionized water at a mass ratio of 1:10 to prepare a 10% solid content solution; gene-edited Bacillus subtilis was selected and cultured in a culture medium containing 20g / L glucose, 10g / L yeast powder and 3g / L potassium dihydrogen phosphate at 37℃ and 180r / min until the turbidity of the culture medium was 0.8, pretreated aminotri(methylenephosphonic acid) was added, and the reaction was carried out in the dark at 35℃ and 200r / min for 50h. The pretreated polyol phosphonate, acrylic polyol and modified amino tris(methylene phosphonic acid) were added to a reactor, stirred and mixed at 80°C and 300 r / min for 3 hours, and a poly-gamma-glutamic acid-polyethyleneimine graft copolymer solution was added, and stirred and reacted at 50°C and 200 r / min for 2 hours; then the pretreated hydroxyethylidene diphosphonic acid and polyacrylamide were added, and stirred and mixed at a pH value of 8 for 60 minutes; finally, 40 parts of treated diatomaceous earth were added to the mixed solution, and mixed at 500 rpm for 40 minutes. The slurry was filtered, vacuum dried and then air flow crushed to obtain a finished reverse osmosis scale inhibitor.

[0035] Example 4

[0036] 12 parts of aminotrimethylphosphonic acid were dried in a vacuum drying oven at 60°C for 4.3 hours and purified by ethanol recrystallization; 10 parts of polyol phosphonate were distilled under reduced pressure at -0.08 MPa and 120°C and then dried by adsorption with 3A molecular sieve; 8 parts of acrylic polyol were filtered through a 0.22 μm membrane and dehydrated by rotary evaporation at 50°C under nitrogen protection; 6 parts of hydroxyethylidene diphosphonic acid were decolorized by activated carbon adsorption and concentrated under reduced pressure to a moisture content of <0.5%; 2.5 parts of polyacrylamide were purified by acetone precipitation, vacuum dried and ground through an 80-mesh sieve; diatomaceous earth was air-flow-pulverized to D50=5 μm and then calcined at 150°C for 2 hours, 5 parts of poly-γ-glutamic acid-polyethyleneimine graft copolymer were taken and dissolved in deionized water at a mass ratio of 1:10 to prepare a 10% solid content solution; gene-edited Bacillus subtilis was selected and in a solution containing 20 g / L grape The method comprises the following steps: 1. The culture medium of sugar, 10 g / L yeast powder and 3 g / L potassium dihydrogen phosphate is cultured at 37°C and 180 rpm until the turbidity of the culture medium is 0.8, and then pretreated amino trimethylene phosphonic acid is added, and the mixture is reacted in the dark at 32°C and 185 rpm for 48.5 h; 2. The pretreated polyol phosphonate, acrylic polyol and modified amino trimethylene phosphonic acid are added to a reactor, and the mixture is stirred at 65°C and 250 rpm for 2.2 h; 3. The poly-gamma-glutamic acid-polyethyleneimine graft copolymer solution is added, and the mixture is stirred at 42°C and 160 rpm for 1.2 h; 4. The pretreated hydroxyethylidene diphosphonic acid and polyacrylamide are then added, and the mixture is stirred at a pH of 7.2 for 45 min; 5. The treated diatomaceous earth is finally added to the mixed solution, and the mixture is stirred at 350 rpm for 32 min; 6. The slurry is filtered, vacuum dried and then air flow pulverized to obtain a finished reverse osmosis scale inhibitor.

[0037] 10-20 parts of aminotrimethylenephosphonic acid (ATMP), 8-15 parts of polyol phosphonate, 5-10 parts of acrylic polyol, 3-8 parts of poly-γ-glutamic acid-polyethyleneimine graft copolymer, 5-10 parts of hydroxyethylidene diphosphonic acid (HEDP), 2-5 parts of polyacrylamide (PAM) and 20-40 parts of diatomaceous earth

[0038] Table 1 Amounts of raw materials used in Examples 1-4

[0039] Example 1 Example 2 Example 3 Example 4 Aminotrimethylenephosphonic acid (parts) 10 15 20 12 Polyol phosphonate (parts) 8 12 15 10 Acrylic polyol (parts) 5 7 10 8 Poly-γ-glutamic acid-polyethyleneimine graft copolymer (parts) 3.5 4 6 5 Hydroxyethylidene diphosphonic acid (parts) 5 7 10 6 Polyacrylamide (parts) 2 3 5 2.5 Diatomaceous earth (parts) 20 30 40 25

[0040] In order to verify that the reverse osmosis antiscalant prepared in the embodiment of the present invention has good long-term antiscaling performance and membrane surface adaptability, the reverse osmosis antiscalant provided in the embodiment of the present invention is described through the following test examples.

[0041] Test example

[0042] The purpose of this test group is to explore the effects of different component ratios on the reverse osmosis antiscalant and to detect the antiscaling efficiency, slow-release performance and membrane surface adaptability of the reverse osmosis antiscalant of the present invention.

[0043] Test objectives: Test group A, test group B, test group C and test group D respectively use the component ratios of the slow-release micro-nano reverse osmosis antiscalant provided in Examples 1-4; the control examples use control group A, control group B, control group C, control group D, control group E and control group F, wherein:

[0044] Control group A

[0045] 30 parts of aminotri(methylenephosphonic acid), 20 parts of hydroxyethylidenediphosphonic acid, 25 parts of polyacrylic acid polymer and 25 parts of water were uniformly mixed to prepare a scale inhibitor.

[0046] Control group B

[0047] 10 parts of aminotrimethylenephosphonic acid, 8 parts of polyol phosphonate, 5 parts of acrylic polyol, 5 parts of hydroxyethylidene diphosphonic acid and 2 parts of polyacrylamide were uniformly mixed without using diatomaceous earth and poly-γ-glutamic acid-polyethyleneimine graft copolymer to prepare a scale inhibitor.

[0048] Control group C

[0049] 15 parts of amino trimethylene phosphonic acid, 12 parts of polyol phosphonate, 7 parts of acrylic polyol, 7 parts of hydroxy ethylidene diphosphonic acid, 3 parts of polyacrylamide and 30 parts of diatomaceous earth are mixed; the amino trimethylene phosphonic acid and other raw materials are first purified and dried, and the diatomaceous earth is treated, and then the raw materials except the diatomaceous earth are added to the reactor, and stirred and mixed at 70°C and 270 r / min for 2.5 hours, and then the diatomaceous earth is added, and mixed at 400 rpm for 35 minutes, and the slurry is filtered, vacuum dried and then air flow pulverized, and the microbial induction synthesis step is not performed to obtain a scale inhibitor.

[0050] Control group D

[0051] The invention discloses a scale inhibitor comprising 15 parts of amino trimethylene phosphonic acid, 12 parts of polyol phosphonate, 7 parts of acrylic polyol, 7 parts of hydroxy ethylidene diphosphonic acid, 3 parts of polyacrylamide and 30 parts of diatomaceous earth; the raw materials are first purified and dried, the diatomaceous earth is treated, the amino trimethylene phosphonic acid, hydroxy ethylidene diphosphonic acid and polyacrylamide are mixed, stirred for 50 minutes at a pH value of 7.5, the diatomaceous earth is added, and the mixture is stirred at 400 rpm for 35 minutes, the slurry is filtered, vacuum dried and then air flow pulverized to construct a composite system, thereby obtaining the scale inhibitor.

[0052] Control group E

[0053] The invention discloses a scale inhibitor comprising 15 parts of amino trimethylene phosphonic acid, 12 parts of polyol phosphonate, 7 parts of acrylic polyol, 7 parts of hydroxy ethylidene diphosphonic acid, 3 parts of polyacrylamide and poly-γ-glutamic acid-polyethyleneimine graft copolymer; the raw materials such as amino trimethylene phosphonic acid are purified and dried, and the poly-γ-glutamic acid-polyethyleneimine graft copolymer is prepared into a solution; gene-edited Bacillus subtilis is selected for culture, and pretreated amino trimethylene phosphonic acid is added for reaction; then polyol phosphonate, acrylic polyol and modified amino trimethylene phosphonic acid are added into a reactor to construct a composite system; then hydroxy ethylidene diphosphonic acid and polyacrylamide are added to enhance the synergistic effect; no diatomaceous earth is added; and finally, the scale inhibitor is dried and crushed.

[0054] Control group F

[0055] Ten parts of nano-titanium dioxide-loaded amino trimethylene phosphonic acid, eight parts of polyol phosphonate, five parts of acrylic polyol, five parts of hydroxy ethylidene diphosphonic acid, and two parts of polyacrylamide were uniformly mixed to prepare a scale inhibitor. The nano-loaded scale inhibitor did not use diatomaceous earth and poly-γ-glutamic acid-polyethyleneimine graft copolymer, and did not involve a microbial modification step.

[0056] Test method: According to the scale inhibition efficiency, slow-release performance and membrane surface adaptability of the reverse osmosis antiscalant of the present invention, tests were conducted respectively. The specific test methods are as follows:

[0057] Scale inhibition efficiency: Using static scale inhibition method: prepare simulated high hardness alkaline water ( , , , ), add 12ppm scale inhibitor, shake in a constant temperature water bath at 60℃ (150r / min) for 48h, centrifuge and take the supernatant, and measure it by ICP-OES Concentration; the calculation formula for scale inhibition efficiency is: scale inhibition efficiency (%) = ,in: The remaining amount in the solution after adding the drug concentration, The control group without drug addition concentration;

[0058] Slow-release performance: Dynamic release method: add 1g of scale inhibitor to 100mL of deionized water (pH=8.5), stir at 200r / min in a constant temperature water bath at 30℃, take 5mL of supernatant every 2h, and determine the ATMP concentration by UV-Vis spectroscopy (detection wavelength 210nm); the cumulative release rate is calculated as follows: Cumulative release rate (%) = ,in: For the The ATMP concentration of the second sampling, is the sampling volume, is the quality of the scale inhibitor, is the theoretical content of ATMP;

[0059] Membrane surface adaptability: RO membrane pollution simulation test is used; the effective area is 10 The polyamide composite membrane was injected with 200ppm of , 80ppm The simulated wastewater (pH = 8.5) was used, the scale inhibitor dosage was 10ppm, and the membrane flux attenuation rate and desalination rate were measured every 24 hours after continuous operation for 100 hours. The membrane flux attenuation rate was calculated as follows: Membrane flux attenuation rate (%) = ,in: is the initial membrane flux , is the membrane flux after running for t hours; the desalination rate is calculated by measuring the inlet and outlet water ion concentrations using a conductivity meter.

[0060] Specific detection indicators are shown in Table 2.

[0061] Table 2 Test indicators of each sample

[0062] Scale inhibition efficiency (%) 48h cumulative release rate (%) Membrane flux decay rate (100h) (%) Desalination rate (100h) (%) Experimental group A 96.3 68.5 5.2 98.2 Experimental group B 97.8 72.3 4.8 98.5 Experimental Group C 98.5 75.8 4.1 98.8 Experimental group D 97.2 70.6 5.5 97.9 Control group A 82.5 95.2 32.6 90.3 Control group B 88.3 91.4 28.3 92.7 Control group C 92.1 88.7 22.5 94.1 Control group D 89.7 89.2 25.7 93.5 Control group E 94.6 85.3 18.6 95.6 Control group F 85.4 93.6 29.4 91.2

[0063] according to Figure 2-5 As shown in Table 2, the summary of the above comparative data is as follows:

[0064] 1. The experimental group (AD) of the present invention achieved a 48-hour cumulative release rate of 68.5%-75.8% through a dual sustained-release system of poly-gamma-glutamic acid-polyethyleneimine graft copolymer and diatomaceous earth, which was 25% lower than that of control groups A (95.2%) and F (93.6%), thus preventing rapid dissipation of the agent. At the same time, the experimental group achieved a scale inhibition efficiency of 96.3%-98.5%, higher than that of control group B (88.3%) without the introduction of a sustained-release carrier and control group F (85.4%) with a traditional nano-load. This indicates that the pH-responsive release characteristics of the bio-based copolymer synergize with the physical adsorption of diatomaceous earth, enabling the agent to continuously chelate calcium and barium ions in high-hardness alkaline water (pH = 9.0), verifying the necessity of the "slow-release-chelation" dual-functional design for long-term scale inhibition.

[0065] 2. After 100 hours of operation, the membrane flux decay rate of the experimental group was only 4.1%-5.5%, and the salt rejection rate remained at 97.9%-98.8%. In contrast, the decay rate of the control groups AF reached 18.6%-32.6%, with the lowest salt rejection rate dropping to 90.3%. Among them, the performance of the control group C (membrane flux decay of 22.5%) without microbial modification and the control group D (decay of 25.7%) without composite system construction was inferior to that of the experimental group, confirming that the bioactive groups induced by microorganisms can reduce particle aggregation through electrostatic repulsion (Zeta potential +25mV), and the cross-linking effect of acrylic polyol enhances the adsorption stability of the membrane surface, preventing clogging of the membrane pores.

[0066] 3. The scale inhibition efficiencies of control group B (lacking diatomaceous earth and copolymer) and control group E (lacking diatomaceous earth) were 88.3% and 94.6%, respectively, both lower than those of the experimental group, confirming the chelating-sustained-release function of the poly-γ-glutamic acid-polyethyleneimine graft copolymer and the synergistic necessity of the diatomaceous earth carrier; control group C (lacking microbial modification) lacked biologically active groups, and the binding force between the agent and the polyol phosphonate was weakened, and the 48-hour release rate was increased by 18% compared with the experimental group, further indicating that microbial induced synthesis is the core technology for constructing the tertiary structure of "modified ATMP-composite network-sustained-release carrier", which can keep the agent stably dispersed in complex water quality.

[0067] In summary, the present invention constructs a pH-responsive micro-nanoscale inhibitor through microbial-induced synthesis and dual-release system design. This agent achieves a scale inhibition efficiency of over 96.3% in high-hardness alkaline water, a 48-hour cumulative release rate controlled within 75.8%, and a 100-hour membrane flux decay rate of only 4.1%-5.5%. This achieves synergistic optimization of long-term scale inhibition and membrane surface protection, thereby improving the application effectiveness of reverse osmosis scale inhibitors in complex water conditions. It effectively addresses the problems of traditional scale inhibitors such as reduced scale inhibition efficiency under alkaline conditions, high agent dosage, insufficient environmental compatibility, and the easy aggregation and clogging of membrane pores caused by nano-loaded agents.

[0068] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. The synthesis process of slow-release micro-nano reverse osmosis scale inhibitor is characterized by: The following steps are involved: S1. Purify and dry amino trimethylene phosphonic acid, polyol phosphonate, acrylic polyol, hydroxy ethylidene diphosphonic acid, and polyacrylamide, respectively. Then, airflow-pulverize and calcine diatomaceous earth to increase the specific surface area and enhance the adsorption performance. Then, dissolve poly-gamma-glutamic acid-polyethyleneimine graft copolymer in deionized water at a mass ratio of 1:10 to prepare a transparent solution with a solid content of 10%; S2. Select a microbial strain and culture it in a culture medium until the logarithmic growth phase to form a culture solution, add the pretreated amino trimethylene phosphonic acid to the culture solution, and transfer it to a shaking incubator for reaction to form modified amino trimethylene phosphonic acid; S3, adding the pretreated polyol phosphonate, acrylic polyol and modified amino tris(methylene phosphonic acid) into a reaction kettle equipped with a temperature control device and mixing to form a preliminary composite, then adding a transparent solution of poly-gamma-glutamic acid-polyethyleneimine graft copolymer, continuing to stir and react, to form a composite system; S4, adding the pretreated hydroxyethylidene diphosphonic acid and polyacrylamide to the composite system, stirring and mixing in a reaction kettle to form a mixed solution; S5. Add the treated diatomaceous earth to the mixed solution, start the reactor and continue mixing to form a scale inhibitor slurry with uniformly dispersed micro-nano particles. Subsequently, transfer the slurry to a plate and frame filter press for filtration to obtain a filter cake, which is then placed in a vacuum drying oven for drying. Finally, the filter cake is pulverized by air flow to obtain a finished reverse osmosis scale inhibitor with a particle size of 80-200 nm.

2. The synthesis process of the slow-release micro-nano reverse osmosis antiscalant according to claim 1, characterized in that: In S1, aminotrimethylenephosphonic acid is dried in a vacuum drying oven at 60°C for 4-4.5 hours, and free amine impurities are removed by ethanol recrystallization for purification; polyol phosphonate is subjected to reduced pressure distillation at -0.08 MPa vacuum and 120°C to remove low-boiling point byproducts, and then adsorption and drying is performed using 3A molecular sieve; acrylic acid polyol is filtered through a 0.22 μm membrane to remove mechanical impurities, and then rotary evaporated at 50°C under nitrogen protection to remove moisture; hydroxyethylidene diphosphonic acid is decolorized by activated carbon adsorption and concentrated under reduced pressure to a moisture content of <0.5%; polyacrylamide is purified by acetone precipitation, vacuum dried, and then ground through an 80-mesh sieve; diatomaceous earth is crushed to D50 = 5 μm and calcined at 150°C for 2 hours to remove organic impurities.

3. The synthesis process of the slow-release micro-nano reverse osmosis antiscalant according to claim 1, characterized in that: In S2, a gene-edited Bacillus subtilis was selected as the microbial strain, an exogenous gene encoding esterase (EstA) was inserted into its genome, and the culture medium used a culture solution containing 20 g / L glucose, 10 g / L yeast powder and 3 g / L potassium dihydrogen phosphate, and the culture was stirred at 37°C and 180 r / min until the turbidity of the bacterial solution reached 0.

8.

4. The synthesis process of the slow-release micro-nano reverse osmosis antiscalant according to claim 1, characterized in that: In S2, the reaction is carried out in the dark for 48-50 hours at 30-35° C. and 180-200 r / min on a shaking platform.

5. The synthesis process of the slow-release micro-nano reverse osmosis antiscalant according to claim 1, characterized in that: In S3, the pretreated polyol phosphonate, acrylic polyol and modified amino tris(methylene phosphonic acid) are mixed in a reactor at a temperature of 60-80° C. and a stirring speed of 240-300 r / min for 2-3 hours, and the poly(gamma-glutamic acid)-polyethyleneimine graft copolymer transparent solution is stirred and reacted in a reactor at 40-50° C. and 150-200 r / min for 1-2 hours.

6. The synthesis process of the slow-release micro-nano reverse osmosis antiscalant according to claim 1, characterized in that: In S4, the pH value in the reactor is controlled to be a mild condition of 7-8, and the hydroxyethylidene diphosphonic acid, polyacrylamide and the composite system are stirred and mixed at a stirring speed of 120-180 r / min for 40-60 minutes.

7. The synthesis process of the slow-release micro-nano reverse osmosis antiscalant according to claim 1, characterized in that: In the step S5, the reactor is stirred at a medium speed of 300-500 r / min for 30-40 minutes.

8. The synthesis process of the slow-release micro-nano reverse osmosis antiscalant according to claim 1, characterized in that: In S5, the plate and frame filter press performs filtration at a pressure of 0.3-0.5 MPa.

9. The synthesis process of the slow-release micro-nano reverse osmosis antiscalant according to claim 1, characterized in that: In the S5, the vacuum drying oven is dried for 4-6 hours at 60-80° C. and a vacuum degree of -0.08 to -0.06 MPa.

10. A sustained-release micro-nano reverse osmosis antiscalant prepared by the synthesis process of the sustained-release micro-nano reverse osmosis antiscalant according to any one of claims 1 to 9, characterized in that: The synthesis process uses the following raw materials: 10-20 parts of aminotrimethylenephosphonic acid, 8-15 parts of polyol phosphonate, 5-10 parts of acrylic polyol, 3-8 parts of poly-γ-glutamic acid-polyethyleneimine graft copolymer, 5-10 parts of hydroxyethylidene diphosphonic acid, 2-5 parts of polyacrylamide and 20-40 parts of diatomaceous earth.

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