A green water treatment agent with scale inhibition, corrosion inhibition and bacteriostasis performance, and a preparation method and application thereof

Abstract

The application discloses a green water treatment agent with scale inhibition, corrosion inhibition and bacteriostasis performance, and a preparation method and application thereof, and has a chemical structure of wherein the ethylenediamine is used as a connecting arm, and the glucose acid is introduced into a polyaspartic acid peptide bond structure by using a graft copolymerization method to synthesize a novel water treatment agent; the water treatment agent can be adsorbed on a metal surface to form a protective film and has good scale inhibition, corrosion inhibition and bacteriostasis performance. The water treatment agent can achieve the best scale inhibition and corrosion inhibition effect by controlling the polymerization degree. Meanwhile, the water treatment agent also has bacteriostasis performance and can inhibit escherichia coli which is a main pollution source of a water environment. Therefore, the water treatment agent realizes efficient improvement of scale inhibition, corrosion inhibition and bacteriostasis performance of polyaspartic acid, reduces application of phosphorus-containing compounds, avoids environmental hazards and is friendly to the environment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of industrial circulating water treatment, and particularly relates to a water treatment agent with scale inhibition, corrosion inhibition and bacteriostasis performance as well as a preparation method and application thereof. BACKGROUND

[0002] Industrial circulating water systems are widely used in industrial production, but the problems such as deposition of water scale, corrosion of pipelines, and metabolism of microorganisms can reduce the heat transfer efficiency and affect the service life of equipment. At present, the most widely used solution is to add a water treatment agent. In the 1970s, organic phosphonate water treatment agents became a research hotspot at that time due to their excellent scale inhibition and corrosion inhibition performance, but long-term use of the water treatment agent can increase the content of phosphorus in water, cause water eutrophication, and destroy water balance, so the research interest has gradually decreased in recent years. In the 1990s, green chemistry was proposed, and green water treatment agents became a research hotspot in the industry, such as biodegradable polyepisuccinimic acid (PESA), polyglutamic acid (PGA), and polyaspartic acid (PASP).

[0003] Among them, polyaspartic acid is cheap and easy to obtain, has certain metal ion chelating ability and dispersing ability, and the peptide chain structure in the polyaspartic acid molecule is easy to be decomposed by microorganisms, so it has attracted more and more attention as a green water treatment agent. Research mainly focuses on modifying the structure of polyaspartic acid to improve its scale inhibition and corrosion inhibition performance. Gluconic acid is easy to degrade like polyaspartic acid, is friendly to the environment, and can form soluble salts with Ca 2+ , Mg 2+ and other metal ions. Literature reports that sodium gluconate salt has certain corrosion inhibition effect, and the compound gluconyl chlorhexidine obtained by salifying chlorhexidine with biuret acid has broad-spectrum bacteriostatic performance as a disinfectant. Based on this, a polyaspartic acid derivative with scale inhibition, corrosion inhibition and bacteriostatic performance is prepared by grafting glucose acid structural units into the side chain of polyaspartic acid through chemical modification with ethylenediamine as a connecting arm. SUMMARY

[0004] In view of the deficiencies in the prior art, the purpose of the present application is to provide a water treatment agent with scale inhibition, corrosion inhibition and bacteriostatic performance as well as a preparation method and application thereof. The water treatment agent provided by the present application is a polyaspartic acid derivative containing effective functional groups such as hydroxyl, carboxyl and amide bond, which can simultaneously have good scale inhibition, corrosion inhibition and bacteriostatic performance.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] The application opens the ring of poly-succinimide under alkaline conditions by N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide, introduces a functional group into the side chain of poly-aspartic acid, and synthesizes a novel water treatment agent (PASP-DGL-ED), the structural formula of which is shown as follows:

[0007]

[0008] Wherein, A represents an unmodified structural unit, the polymerization degree of which is n, B represents a modified structural unit, the polymerization degree of which is m. n+m represents the total polymerization degree, and m / (n+m) x 100% = 40%.

[0009] The application takes poly-succinimide, gluconolactone and ethylenediamine as main raw materials, first reacts the gluconolactone with the ethylenediamine to open the ring to obtain N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide DGL-ED, and then opens the ring of poly-succinimide by N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide under alkaline conditions to obtain the target product PASP-DGL-ED, and the specific reaction route is shown in the following formula:

[0010]

[0011] The method comprises the following steps:

[0012] After the reaction is completed under reflux conditions, the solvent is removed, recrystallization purification is performed, and drying (30-60 DEG C) is performed until the constant weight to obtain the intermediate N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide (DGL-ED).

[0013] The N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide DGL-ED is dissolved in distilled water, poly-succinimide is added, then sodium hydroxide solution is added to adjust the pH value of the reaction solution to weak alkaline, heating and stirring are performed in a 50-80 DEG C water bath for 20-30 h, and the target product PASP-DGL-ED is obtained after separation and purification.

[0014] Specifically, the molar ratio of the gluconolactone to the ethylenediamine is 1: (2-4), the methanol needs to be dried before use, and the concentration of the ethylenediamine in the methanol is 0.1-0.5 mmol / mL.

[0015] Preferably, the reflux temperature in the preparation process of the DGL-ED is 65-70 DEG C.

[0016] Specifically, the molar ratio of monomers to N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide in the polysuccinimide is 1: (2-5), preferably 1:3. The concentration of N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide in distilled water is 0.5-1 mmol / mL.

[0017] Specifically, the concentration of the sodium hydroxide solution used is 1-2 mol / L, the pH value of the reaction solution is adjusted to 8-9 using the NaOH solution, and sodium hydroxide solution is continuously added during the reaction to maintain the pH value of the reaction solution at 8-9.

[0018] Specifically, the separation and purification is to place the solution after the reaction into a dialysis bag and dialyze in distilled water until the conductivity of the distilled water is below 3 muS / cm.

[0019] Preferably, the molecular weight cut-off of the dialysis bag is 500-2000 Da.

[0020] Preferably, the molecular weight of the polysuccinimide is 5000-10000.

[0021] The above water treatment agent with scale inhibition, corrosion inhibition and bacteriostatic properties is used as a water treatment agent, a scale inhibitor, a corrosion inhibitor or a bacteriostatic agent in circulating cooling water.

[0022] Further, the application optimizes the raw material ratio by adjusting the formula and controlling the degree of polymerization, so that the water treatment agent achieves the best scale inhibition effect. When the degree of polymerization of the modified structure unit accounts for 40% of the total degree of polymerization, the water treatment agent can achieve the best scale inhibition effect.

[0023] The application improves the scale inhibition, corrosion inhibition and bacteriostatic properties of polyaspartic acid by introducing a group into the side chain of polyaspartic acid. The application modifies polysuccinimide through ring-opening reaction to prepare a multifunctional polyaspartic acid derivative with scale inhibition, corrosion inhibition and bacteriostatic properties, which can efficiently improve the scale inhibition, corrosion inhibition and bacteriostatic properties of industrial circulating water treatment agents. Compared with the prior art, the application has the following advantages:

[0024] 1) The application introduces gluconic acid into the side chain of polyaspartic acid to synthesize a new type of water treatment agent.

[0025] 2) By adjusting the formula ratio, the degree of polymerization of the modified structure unit accounts for 40% of the total degree of polymerization, and the water treatment agent synthesized under this degree of polymerization has the best scale inhibition performance.

[0026] 3) The structure of the water treatment agent enables it to form a complex with Ca 2+ , Mg 2+The metal ions are complexed to form soluble salt, so as to achieve the scale inhibition effect. Meanwhile, the structure can be adsorbed on the metal surface to form an adsorption film, so as to protect the carbon steel and other metals from corrosion by the atmosphere and harmful substances, and therefore, the structure has the corrosion inhibition effect. In addition, the structure has the bacteriostasis specificity, can inhibit the escherichia coli, and realizes the efficient improvement of the scale inhibition, corrosion inhibition and bacteriostasis performance of the polyaspartic acid.

[0027] 4) The synthesis steps of the present application are simple and green, and the synthesized product is a new green phosphorus-free water treatment agent, which is easy to be degraded by microorganisms and has good biological and environmental compatibility. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 Fig. 2: (a) is the H NMR spectrum of PASP prepared in Example 1 of the present application 1 Fig. 2: (a) is the H NMR spectrum of PASP prepared in Example 1 of the present application 1 Fig. 2: (a) is the H NMR spectrum of PASP prepared in Example 1 of the present application

[0029] Figure 2 Fig. 6: Influence of different concentrations of PASP-DGL-ED and PASP prepared in Example 1 of the present application on CaCO3 scale inhibition;

[0030] Figure 3 Fig. 7: Polarization curves of 3.5% NaCl aqueous solution under different concentrations of PASP-DGL-ED prepared in Example 1 of the present application;

[0031] Figure 4 Fig. 8: Polarization curves of 3.5% NaCl aqueous solution under different concentrations of PASP prepared in Example 1 of the present application;

[0032] Figure 5 Fig. 9: Bacteriostatic circle appearance of escherichia coli under different concentrations of PASP-DGL-ED and PASP prepared in Example 1 of the present application;

[0033] Figure 6 Fig. 10: Influence of different concentrations of PASP-DGL-ED and PASP prepared in Example 1 of the present application on the survival rate of escherichia coli. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0035] Unless otherwise specified, the raw materials used in the following examples and comparative examples are all commercially available products that can be directly purchased or can be prepared using conventional methods in the art.

[0036] The polysuccinimide used in the following examples and comparative examples has a molecular weight of 7000-8000 and was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0037] Example 1

[0038] Synthesis of PASP-DGL-ED

[0039] First, add 30 mmol of ethylenediamine (2 mL) to a round-bottom flask, then add 200 mL of dry MeOH (added to methanol). The molecular sieve was dried overnight, and then 10 mmol of gluconolactone (1.78 g, CAS No. 90-80-2) was added. After reacting under reflux (around 65 °C) for 6 h, the solvent was removed by rotary evaporator. The product was purified by recrystallization with ethanol, filtered, and then dried under vacuum at 40 °C to constant weight to obtain a white solid N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexamethyleneamide (DGL-ED).

[0040] 15 mmol of DGL-ED (3.42 g) and 20 mL of distilled water were added to a round-bottom flask and stirred until clear. Then, 0.492 g of PSI (monomer molar amount of 5 mmol) was added, followed by the addition of 2 mol / L sodium hydroxide aqueous solution to adjust the pH of the reaction solution to 8–9. The mixture was heated and stirred in a 60 °C water bath for 24 h. During the reaction, 2 mol / L NaOH aqueous solution was added as needed to maintain the pH of the reaction solution between 8 and 9. After the reaction was completed, the resulting solution was placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed in distilled water until the conductivity was below 3 μS / cm. The retentate was removed using a rotary evaporator to obtain the target product PASP-DGL-ED.

[0041] PASP Synthesis

[0042] 10 mmol (0.984 g) of polysuccinimide (PSI) was placed in a reaction vessel, and 10 mL of distilled water and 10 mmol (0.4 g) of sodium hydroxide were added. The reaction was continued at 40 °C for 24 h. The resulting solution was placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed in distilled water until the conductivity value was below 3 μS / cm. The retentate was evaporated to dryness using a rotary evaporator to obtain the target product PASP.

[0043] Figure 1 (a) represents PASP 1The H NMR spectrum shows two broad peaks at δ4.49 and δ2.76, which correspond to the hydrogen atoms on -CH- and -CH2- in the PASP structure, respectively.

[0044] like Figure 1 As shown in (b), characteristic peaks of the demethylate of gluconate are observed around δ4.28, δ3.90, δ3.81, and δ3.78.

[0045] The presence of a characteristic peak of the methylene group on gluconic acid at δ3.60 and characteristic peaks of two methylene groups on ethylenediamine at δ3.28 and δ2.73 proves that DGL-ED was successfully synthesized. Figure 1 (c) represents PASP-DGL-ED 1 The 1H NMR spectrum shows typical characteristic peaks of methine and methylene in PASP at δ4.63 and δ2.76, and peaks at δ4.28, δ3.90, δ3.81, δ3.78, δ3.60, δ3.28, and δ

[0046] The presence of characteristic peaks for the methine and methylene groups in the DGL-ED structural fragment at position 2.73 indicates that PASP-DGL-ED was successfully synthesized.

[0047] according to Figure 1 The peak area of ​​-CH- in the gluconolactone structure and -CH- in the PASP-DGL-ED structure in (c) was calculated, and the m / (n+m)×100% of the target product PASP-DGL-ED was 40%.

[0048] Example 2

[0049] The scale inhibition effects of PASP-DGL-ED and PASP prepared in Example 1 were determined using the Chinese National Standard - Determination of Scale Inhibition Performance of Water Treatment Agents (Calcium Carbonate Deposition Method - GB / T 16632-2019).

[0050] First, prepare sodium tetraborate decahydrate (0.010 mol / L), CaCl2(0.15 mol / L) and NaHCO3(0.30 mol / L) solutions, then prepare PASP-DGL-ED and PASP aqueous solutions with a concentration of 1 mg / mL. Take 10 mL of CaCl2solution, 10 mL of sodium tetraborate decahydrate solution, 10 mL of NaHCO3solution and a certain volume of PASP-DGL-ED aqueous solution into a 250 mL conical flask in turn, so that the final concentration of PASP-DGL-ED is 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 mg / L respectively. Then place the conical flask containing the test solution in an 80°C water bath for 10 h. After cooling to room temperature, filter and take 25 mL of the filtrate to determine the Ca 2+ content using a standard EDTA solution (0.010 mol / L), while preparing a test blank sample without water treatment agent as a control. The scale inhibition efficiency (η, %) is obtained from formula (1):

[0051]

[0052] wherein V0 is the volume of EDTA consumed (mL) by the mixed solution of 10 mL CaCl2, 10 mL sodium tetraborate decahydrate and 10 mL NaHCO3 prepared in the previous step at room temperature. V2 is the volume of EDTA consumed after heating in the presence of scale inhibitor; V1 is the volume of EDTA consumed after heating in the absence of scale inhibitor (mL).

[0053] Repeat the above steps to test the scale inhibition effect of PASP as a control.

[0054] The scale inhibition effects of PASP and PASP-DGL-ED at different concentrations are shown in FIG. 1 and FIG. 2. Figure 2 As can be seen from the figures, the scale inhibition effect of PASP-DGL-ED is significantly better than that of PASP. When the concentration is 100 mg / L, the scale inhibition efficiency of PASP-DGL-ED can reach 94.41%.

[0055] Example 3

[0056] The corrosion inhibition effects of PASP-DGL-ED and PASP prepared in Example 1 were determined by using the Chinese Chemical Industry Standard - Determination of Inhibition Performance of Water Treatment Agent (Potentiodynamic Polarization Curve Method - HG / T 4543-2013).

[0057] The electrochemical tests were carried out using CHI660E electrochemical workstation, and the corrosion medium was 3.5% NaCl solution (298K). The corrosion inhibition effect of different concentrations of PASP-DGL-ED and PASP on carbon steel was studied. The reference electrode was saturated calomel electrode, the auxiliary electrode was platinum plate electrode, and the working electrode was 20# carbon steel electrode with a working area of 1cm 2 . Before testing, the working electrode was polished with sandpaper, then cleaned with ethanol, acetone and distilled water, and dried with cold air. At 25℃, first immerse the electrode in 500mL test solution (PASP-DGL-ED is added to 3.5% NaCl solution to prepare 10, 20, 30, 40, 50mg / L PASP-DGL-ED solution) for 60min, then measure the impedance (EIS) and polarization curve after obtaining the stable open circuit potential (OCP). The polarization curve scanning interval is ±250mV (vs. OCP), and the scanning rate is 1mV / s. The inhibition efficiency (η p ) is obtained by formula (2):

[0058]

[0059] In the formula, where is the corrosion current density (A·cm -2 ) of the blank group (blank group: 500mL of 3.5% NaCl solution without PASP-DGL-ED, after 60min of open circuit, impedance and polarization test), and I corr is the corrosion current density (A·cm -2 ) of the experimental group.

[0060] The parameters corresponding to the polarization curve are shown in Table 1, which include corrosion potential (E corr ), corrosion current density (I corr ), and anode and cathode Tafel slope (β α , β c ).

[0061] Example 1 PASP-DGL-ED was prepared into solutions with different concentrations, and the polarization curve was determined by electrochemical method. The polarization curve is shown in the accompanying Figure 3 , and the test results are shown in Table 1:

[0062] Table 1 Potentiodynamic polarization parameters of different concentrations of PASP-DGL-ED in 3.5% NaCl aqueous solution

[0063]

[0064] As can be seen from the results, with the increase of the concentration of example 1 PASP-DGL-ED, the current density I corr decreases significantly, and ηp The inhibition efficiency increased obviously, and the inhibition efficiency of Example 1 PASP-DGL-ED reached the maximum of 41.31% at a concentration of 30 mg / L.

[0065] The polarization curves of PASP at different concentrations were determined by electrochemical method, and the polarization curve diagram is shown in Figure 2. Figure 4 The test results are shown in Table 2.

[0066] Table 2 Potentiodynamic polarization parameters of PASP at different concentrations in 3.5% NaCl aqueous solution

[0067]

[0068] As can be seen from the results, with the increase of the concentration of PASP, the current density I corr decreased, and η p increased, and the inhibition efficiency reached the maximum of 17.84% at a concentration of 20 mg / L.

[0069] Figure 3 The polarization curves of Example 1 PASP-DGL-ED aqueous solution at different concentrations are shown in Figure 3. As can be seen from the figure, compared with the blank concentration, with the increase of the concentration of Example 1 PASP-DGL-ED, the corrosion potential of carbon steel moved to the positive direction, and the moving amplitude of the anodic curve was obviously greater than that of the cathodic curve, which indicated that the water treatment agent added had a significant inhibitory effect on the corrosion of carbon steel. On the other hand, the Tafel curve also moved in the direction of reducing the corrosion current density, and it can be seen that the greater the concentration, the greater the moving amplitude; among them, the moving amplitude of Example 1 PASP-DGL-ED was the greatest at a concentration of 30 mg / L, and then gradually stabilized, and the moving amplitude of the anodic curve was obviously greater than that of the cathode, which indicated that the corrosion inhibition effect of the water treatment agent studied on the cathode was less than that on the anode, indicating that the addition of Example 1 PASP-DGL-ED could significantly inhibit the metal dissolution of the anode, so Example 1 PASP-DGL-ED was an inhibitor mainly inhibiting the anode.

[0070] Figure 4 The polarization curves of the control PASP aqueous solution at different concentrations are shown in Figure 4. Compared with the blank concentration, with the increase of the concentration of the control PASP, the corrosion potential of carbon steel moved to the positive direction, and the moving amplitude of the Tafel anodic curve was greater than that of the cathodic curve, which indicated that the addition of PASP had an inhibitory effect on the corrosion of carbon steel, among them, the moving amplitude of the control PASP was the greatest at a concentration of 20 mg / L, and the moving amplitude of the anodic curve was greater than that of the cathodic curve, which indicated that the corrosion inhibition effect of the water treatment agent studied on the cathode was less than that on the anode, indicating that the addition of the control PASP could inhibit the metal dissolution of the anode, so the control PASP was an inhibitor mainly inhibiting the anode.

[0071] Example 4

[0072] The bacteriostatic effect of PASP-DGL-ED and PASP prepared in Example 1 was determined by the inhibition zone method and the plate spread counting method

[0073] (1) The bacteriostatic effect of PASP-DGL-ED and PASP of Example 1 was determined by the inhibition zone method

[0074] The prepared PASP and PASP-DGL-ED sterilized by ultraviolet light were prepared into solutions with a mass concentration of 50 mg / mL and 100 mg / mL, respectively, using LB medium as the solvent.

[0075] Strain activation: Escherichia coli (E. coli) strains stored in a -80°C refrigerator were streaked on fresh solid LB plates (containing 10 g of tryptone, 5 g of yeast extract, 10 g of NaCl, and 1.6 g of agar powder per 1 liter) and incubated at 30°C for 15 h.

[0076] The single colonies were inoculated in 5 mL of LB liquid medium, and incubated at 30°C and 220 r / min overnight.

[0077] 1 mL of the overnight culture was transferred to 100 mL of LB semi-liquid medium (0.7 g of agar powder), mixed well, and poured into the pre-prepared LB solid plate. After 30 min, sterilized circular filter paper pieces with a diameter of 0.7 mm were laid on the LB medium, and different concentrations of PASP and PASP-DGL-ED were dropped onto the filter paper pieces, with a dosage of 50 μL per filter paper piece, and each sample was repeated three times. After standing for 30 min, the above plate was placed in a 30°C incubator for overnight incubation. The diameter of the inhibition zone was observed and measured. If there is a clear colony inhibition zone around the filter paper piece coated with the agent, it is determined that PASP or PASP-DGL-ED has an inhibitory effect on the tested strain. The bacteriostatic effect of PASP was used as a control group.

[0078] The bacteriostatic effect of PASP was used as a control group. Figure 5 The bacteriostatic circle of E. coli was observed for the PASP and PASP-DGL-ED prepared in Example 1. When the concentration was 50 mg / mL, the bacteriostatic circle diameter of PASP was 8.1 mm, and the bacteriostatic circle diameter of PASP-DGL-ED was 12.3 mm; when the concentration was 100 mg / mL, the bacteriostatic circle diameter of PASP did not change, and the bacteriostatic circle diameter of PASP-DGL-ED was 15.9 mm, indicating that the bacteriostatic ability of PASP-DGL-ED on E. coli was significantly better than that of the control PASP.

[0079] (2) Plate count method to determine the bacteriostatic effect of PASP-DGL-ED and PASP of Example 1

[0080] Strain activation: Take the Escherichia coli (E. coli) strain stored in the refrigerator, inoculate on a fresh solid LB medium (containing 2.5 g of yeast, 2.5 g of NaCl, 5 g of peptone and 7.5 g of agar powder per 500 ml) with a "Z" line, and then put it in a constant temperature shaker for 24 h.

[0081] Select two single colonies on the solid medium and put them into the liquid LB medium, and put them into the constant temperature shaker for 24 h.

[0082] Add 80 μL of the 24 h cultured bacterial solution to the sample sterilized by the ultraviolet lamp and dilute it to 8 mL, so that the mass concentration of the sample is 20, 40, 60, 80, 100 mg / mL respectively. Put the sample with bacterial solution into the constant temperature box at 37℃ for 2 h, take 50 μL of the bacterial solution on the solid LB medium, use a spreader to spread the bacterial solution evenly, and put the spreaded solid medium into the constant temperature incubator at 37℃ for 24 h. Record the number of bacteria on the solid medium after 24 h, and take a digital photo of the experimental results.

[0083] Figure 6 For the influence of different concentrations of PASP and PASP-DGL-ED on the survival rate of E. coli, as the concentration of PASP-DGL-ED increases, the survival rate of E. coli shows a significant downward trend, and as the concentration of PASP increases, the survival rate of E. coli slowly decreases, and overall, the survival rate of E. coli under the action of PASP is higher than that of PASP-DGL-ED, indicating that PASP-DGL-ED has a good inhibitory effect on E. coli, and the higher the concentration, the better the bacteriostatic effect. When the concentration of PASP-DGL-ED is 100 mg / mL, the survival rate of E. coli is only 34%.

[0084] The above examples only express the embodiments of the present application, which are described in more detail and in detail, but cannot be understood as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

[0085] It should be noted that the above examples and control examples belong to the same inventive concept, and the description of the examples and control examples has different focuses. If the description is not detailed in the examples and control examples, reference can be made to the description in other examples and control examples.

Claims

1. A method for preparing a green water treatment agent with scale inhibition, corrosion inhibition, and bacteriostatic properties, characterized in that, Comprising the following steps: (1) After the reaction is completed under reflux conditions using methanol as the solvent and gluconolactone and ethylenediamine as raw materials, the solvent is removed, and the intermediate N-(2-aminoethyl)-2, 3, 4, 5, 6-pentahydroxyhexanamide is purified by recrystallization; (2) N-(2-aminoethyl)-2, 3, 4, 5, 6-pentahydroxyhexanamide is dissolved in distilled water, poly succinimide is added, then the pH value of the reaction solution is adjusted to weak alkaline with sodium hydroxide solution, and the reaction is stirred at 50~80℃ for 20~30 h, and the target product PASP-DGL-ED is obtained after separation and purification; the molar ratio of the repeating units in poly succinimide to N-(2-aminoethyl)-2, 3, 4, 5, 6-pentahydroxyhexanamide is 1: (2~5).

2. The production method according to claim 1, wherein The molar ratio of gluconolactone to ethylenediamine is 1: (2~4), and the methanol needs to be dried before use.

3. The production method according to claim 1, wherein The concentration of the sodium hydroxide solution used is 1 mol / L~2 mol / L, the pH value of the reaction solution is adjusted to 8~9 with NaOH solution, and sodium hydroxide solution is continuously added during the reaction to keep the pH value of the reaction solution at 8~9.

4. The production method according to claim 1, wherein The separation and purification is to dialyze the solution after the reaction in a dialysis bag in distilled water until the conductivity of the distilled water is below 3 μS / cm.

5. The production method according to claim 4, wherein The molecular weight cut-off of the dialysis bag is 500~2000 Da.

6. The water treatment agent with scale inhibition, corrosion inhibition and bacteriostatic performance prepared by the preparation method of any one of claims 1 to 5.

7. The application of the water treatment agent with scale inhibition, corrosion inhibition and bacteriostatic performance of claim 6 as a water treatment agent, scale inhibitor, corrosion inhibitor or bacteriostatic agent in circulating cooling water.

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