Green water treatment agent with scale inhibition, corrosion inhibition and antibacterial properties as well as preparation method and application of green water treatment agent

Abstract

The invention discloses a green water treatment agent with scale inhibition, corrosion inhibition and antibacterial performance and a preparation method and application thereof, the chemical structure of the green water treatment agent is # imgabs0 #, ethidene diamine is used as a connecting arm, gluconic acid is introduced into a polyaspartic acid peptide bond structure by adopting a graft copolymerization method, and the novel water treatment agent is synthesized. The treating agent can be adsorbed on the metal surface to form a protective film, and has good scale inhibition, corrosion inhibition and antibacterial properties. The water treatment agent can achieve the optimal scale inhibition and corrosion inhibition effects by controlling the polymerization degree. Meanwhile, the water treatment agent also has antibacterial activity and can inhibit escherichia coli, and the escherichia coli is a main pollution source of a water environment. Therefore, the water treatment agent realizes efficient improvement of scale inhibition, corrosion inhibition and antibacterial properties of polyaspartic acid, reduces application of phosphorus-containing compounds, avoids environmental hazards, and is environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial circulating water treatment, and specifically relates to a water treatment agent with scale inhibition, corrosion inhibition and antibacterial properties, and a preparation method and application thereof. Background Art

[0002] Industrial circulating water systems are widely used in industrial production, but due to the deposition of scale, corrosion of pipes, metabolism of microorganisms and other problems, the heat transfer efficiency will be reduced and the service life of the equipment will be affected. At present, the most widely used solution is to add water treatment agents. In the 1970s, organic phosphonate water treatment agents became a research hotspot at that time because of their excellent scale and corrosion inhibition properties. However, long-term use of this water treatment agent will increase the phosphorus content in the water body, cause eutrophication of the water body, and destroy the water balance. Therefore, the research enthusiasm has gradually declined 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 polysuccinic epoxy acid (PESA), polyglutamic acid (PGA), polyaspartic acid (PASP), etc.

[0003] Among them, polyaspartic acid is cheap and easy to obtain, has certain metal ion chelating and dispersing capabilities, and the peptide chain structure in the polyaspartic acid molecule is easily decomposed by microorganisms. As a green water treatment agent, it has received more and more attention. Research mainly focuses on structural modification of polyaspartic acid to improve its scale and corrosion inhibition properties. Gluconic acid is as easy to degrade as polyaspartic acid and is environmentally friendly. At the same time, it can react with Ca 2+ Mg 2+ The literature reports that sodium gluconate has a certain corrosion inhibition effect, and the compound chlorhexidine glucose formed by salification with chlorobenzene biguanide has a broad-spectrum antibacterial property as a disinfectant. Based on this, the present invention uses a chemical modification method to graft the gluconic acid structural unit to the polyaspartic acid side chain with ethylenediamine as a connecting arm to prepare a polyaspartic acid derivative with scale inhibition, corrosion inhibition and antibacterial properties. Summary of the invention

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

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention uses N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide to open the ring of polysuccinimide under alkaline conditions, introduces functional groups into the side chain of polyaspartic acid, and synthesizes a new water treatment agent (PASP-DGL-ED), the structural formula of which is as follows:

[0007]

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

[0009] The present invention uses polysuccinimide, gluconolactone and ethylenediamine as main raw materials, firstly, gluconolactone and ethylenediamine are reacted to open the ring to obtain N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide DGL-ED, and then, under alkaline conditions, polysuccinimide is opened with N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide to obtain the target product PASP-DGL-ED. The specific reaction route is shown in the following formula:

[0010]

[0011] The following steps are involved:

[0012] With methanol as solvent, gluconolactone and ethylenediamine as raw materials, after the reaction is completed under reflux conditions, the solvent is removed, the product is recrystallized and purified, and dried (30-60° C.) to constant weight to obtain the intermediate N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide (DGL-ED).

[0013] Dissolve N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide DGL-ED in distilled water, add polysuccinimide, and then adjust the pH value of the reaction solution to weak alkalinity with sodium hydroxide solution, heat and stir the reaction in a water bath at 50-80° C. for 20-30 hours, and separate and purify to obtain the target product PASP-DGL-ED.

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

[0015] Preferably, the reflux temperature during the preparation of DGL-ED is 65-70°C.

[0016] Specifically, the molar ratio of the monomer in the polysuccinimide to N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide 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 mol / L to 2 mol / L, the pH value of the reaction solution is adjusted to 8 to 9 using NaOH solution, and the sodium hydroxide solution is continuously added during the reaction to maintain the pH value of the reaction solution at 8 to 9.

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

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

[0020] Preferably, the molecular weight of polysuccinimide is 5,000-10,000.

[0021] The water treatment agent having the anti-scaling, anti-corrosion and anti-bacterial properties is used as a water treatment agent, anti-scaling agent, anti-corrosion agent or anti-bacterial agent in circulating cooling water.

[0022] Furthermore, the present invention 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 structural unit accounts for 40% of the total degree of polymerization, the water treatment agent can achieve the best scale inhibition effect.

[0023] The present invention not only improves the scale inhibition and corrosion inhibition performance of polyaspartic acid, but also improves the antibacterial performance of polyaspartic acid by introducing a group into the side chain of polyaspartic acid. The present invention modifies polysuccinimide through a ring-opening reaction to prepare a multifunctional polyaspartic acid derivative with scale inhibition, corrosion inhibition and antibacterial performance, which can effectively improve the scale inhibition, corrosion inhibition and antibacterial performance of industrial circulating water treatment agents. Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The present invention 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 polymerization degree of the modified structural unit is controlled to account for 40% of the total polymerization degree. The water treatment agent synthesized under this polymerization degree has the best scale inhibition performance.

[0026] 3) The structure of the water treatment agent allows it to react with Ca 2+ Mg 2+The metal ions are complexed to form soluble salts to achieve the anti-scaling effect. At the same time, the structure can be adsorbed on the metal surface to form an adsorption film to protect carbon steel and other metals from corrosion by the atmosphere and harmful substances, so it has a corrosion inhibition effect. In addition, the structure also has antibacterial specificity and can inhibit Escherichia coli, achieving a high efficiency improvement in the anti-scaling, corrosion inhibition and antibacterial properties of polyaspartic acid.

[0027] 4) The synthesis process of the present invention is simple and green, and the synthesized product is a new type of green phosphorus-free water treatment agent, which is easily degraded by microorganisms and has good biological and environmental compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 (a) is the PASP prepared in Example 1 of the present invention. 1 H NMR spectra; (b) and (c) are DGL-ED and PASP-DDL-ED prepared in Example 1 of the present invention 1 H NMR spectrum;

[0029] Figure 2 The effect of different concentrations of PASP-DGL-ED and PASP prepared in Example 1 of the present invention on CaCO3 scale inhibition;

[0030] Figure 3 Polarization curves of 3.5% NaCl aqueous solution at different concentrations of PASP-DGL-ED prepared in Example 1 of the present invention;

[0031] Figure 4 Polarization curves of 3.5% NaCl aqueous solution at different concentrations of PASP prepared in Example 1 of the present invention;

[0032] Figure 5 The inhibition zone appearance of PASP-DGL-ED and PASP prepared in Example 1 of the present invention at different concentrations against Escherichia coli;

[0033] Figure 6 This is the effect of different concentrations of PASP-DGL-ED and PASP prepared in Example 1 of the present invention on the survival rate of Escherichia coli. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the following examples and comparative examples, unless otherwise specified, the raw materials used are common commercial products that can be directly purchased or can be prepared by conventional methods in the art.

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

[0037] Example 1

[0038] Synthesis of PASP-DGL-ED

[0039] In a round-bottom flask, add 30 mmol of ethylenediamine (2 mL) and 200 mL of dry MeOH (methanol). The mixture was stirred for 2 hours (1 h) and then dried over 400 μm molecular sieves overnight), and then 10 mmol of gluconolactone (1.78 g, CAS No. 90-80-2) was added; the reaction was carried out under reflux conditions (about 65° C.) for 6 hours, and then the solvent was removed by a rotary evaporator. The obtained product was purified by recrystallization with ethanol, filtered, and then dried in vacuo at 40° C. to constant weight to obtain a white solid N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide (DGL-ED).

[0040] Add 15mmol of DGL-ED (3.42g) and 20mL of distilled water to a round-bottom flask, stir until clear, then add 0.492g of PSI (monomer molar weight is 5mmol), then add 2mol / L sodium hydroxide aqueous solution to adjust the pH value of the reaction solution to 8-9, heat and stir in a 60℃ water bath for 24h, and add 2mol / L NaOH aqueous solution in time during the reaction to keep the pH value of the reaction solution between 8 and 9. After the reaction, the obtained solution is loaded into a dialysis bag with a molecular weight cutoff of 1000Da, dialyzed in distilled water until the conductivity value is below 3μS / cm, and the retentate is removed by a rotary evaporator to obtain the target product PASP-DGL-ED.

[0041] Synthesis of PASP

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

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

[0044] like Figure 1 As shown in (b), there are characteristic peaks of methine on gluconic acid at around δ4.28, δ3.90, δ3.81, and δ3.78, characteristic peaks of methylene on gluconic acid at δ3.60, and characteristic peaks of two methylene on ethylenediamine at δ3.28 and δ2.73, proving that DGL-ED was successfully synthesized; Figure 1 (c) for PASP-DGL-ED 1 The H NMR spectrum showed typical characteristic peaks of methine and methylene in PASP at δ4.63 and δ2.76, and characteristic peaks of methine and methylene in the DGL-ED structural fragment at δ4.28, δ3.90, δ3.81, δ3.78, δ3.60, δ3.28 and δ2.73, respectively, indicating that PASP-DGL-ED was successfully synthesized.

[0045] according to Figure 1 Based on the calculation of the peak areas of -CH- in the gluconolactone structure and -CH- of PASP in the PASP-DGL-ED structure in (c), the m / (n+m)×100% of the synthetic target product PASP-DGL-ED is 40%.

[0046] Example 2

[0047] The scale inhibition effect of PASP-DGL-ED and PASP prepared in Example 1 was determined using the Chinese National Standard - Determination of Scale Inhibition Performance of Water Treatment Agents (Calcium Carbonate Deposition Method - GB / T 16632-2019)

[0048] First, prepare sodium tetraborate decahydrate (0.010 mol / L), CaCl2 (0.15 mol / L) and NaHCO3 (0.30 mol / L) solutions, and then prepare aqueous solutions of PASP-DGL-ED and PASP at a concentration of 1 mg / mL, respectively. Take 10 mL of CaCl2 solution, 10 mL of sodium tetraborate decahydrate solution, 10 mL of NaHCO3 solution and a certain volume of PASP-DGL-ED aqueous solution and add them to a 250 mL conical flask in sequence, so that the final concentrations of PASP-DGL-ED are 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 mg / L, respectively. Then place the conical flask containing the test solution in an 80°C water bath and heat for 10 hours. After cooling to room temperature, filter, take 25 mL of the filtrate, and calibrate Ca with a standard EDTA solution (0.010 mol / L). 2+The content of water treatment agent was calculated, and a blank sample without water treatment agent was prepared as a control. The scale inhibition efficiency (η, %) is obtained by formula (1):

[0049]

[0050] Where V0 is the volume (mL) of EDTA consumed by the mixed solution of 10mL CaCl2, 10mL sodium tetraborate decahydrate and 10mL NaHCO3 prepared in the previous step at room temperature. V2 is the volume of EDTA consumed after heating in the presence of a scale inhibitor; V1 is the volume (mL) of EDTA consumed after heating in the absence of a scale inhibitor.

[0051] The above steps were repeated to test the scale inhibition effect of PASP as a control.

[0052] The scale inhibition effects of PASP and PASP-DGL-ED at different concentrations are shown in the attached Figure 2 It can be seen from the figure that 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%.

[0053] Example 3

[0054] The corrosion inhibition effects of PASP-DGL-ED and PASP prepared in Example 1 were determined using the Chinese Chemical Industry Standard - Determination of Corrosion Inhibition Performance of Water Treatment Agents (Potentiometric Polarization Curve Method - HG / T4543-2013).

[0055] The electrochemical test was carried out using a CHI660E electrochemical workstation. The corrosion medium was a 3.5% NaCl solution (298K). The corrosion inhibition effect of PASP-DGL-ED and PASP at different concentrations on carbon steel was studied. The reference electrode was a saturated calomel electrode, the auxiliary electrode was a platinum electrode, the working electrode was a 20# carbon steel electrode, and the working area was 1 cm 2 . Before the test, the working electrode was polished with sandpaper, then cleaned with ethanol, acetone and distilled water, and blown dry with cold air. At 25°C, the electrode was first immersed in 500mL of the test solution (PASP-DGL-ED was added to 3.5% NaCl solution to prepare 10, 20, 30, 40, and 50mg / L PASP-DGL-ED solutions) for 60min. After obtaining a stable open circuit potential (OCP), impedance (EIS) and polarization curve measurements were performed. The polarization curve scanning interval was ±250mV (vs.OCP), and the scanning rate was 1mV / s. Corrosion inhibition efficiency (η p ) is obtained from formula (2):

[0056]

[0057] In the formula: The corrosion current density (A·cm) of the blank group (blank group: 500 mL of 3.5% NaCl solution without PASP-DGL-ED, open circuit for 60 minutes, and then impedance and polarization tests) -2 ), I corr is the corrosion current density of the experimental group (A·cm -2 )).

[0058] The parameters corresponding to the polarization curves are presented in Table 1, including the corrosion potential (E corr ), corrosion current density (I corr ) and the anodic and cathodic Tafel slopes (β α , β c ).

[0059] The PASP-DGL-ED of Example 1 was prepared into solutions of different concentrations, and the polarization curves were measured by electrochemical method. The polarization curves are shown in the attached Figure 3 , the test results are shown in Table 1:

[0060] Table 1 Potentiodynamic polarization parameters of PASP-DGL-ED at different concentrations in 3.5% NaCl aqueous solution

[0061]

[0062] From the results, it can be seen that with the increase of the concentration of PASP-DGL-ED in Example 1, the current density I corr Significantly reduced, η p The corrosion inhibition efficiency of PASP-DGL-ED in Example 1 increased significantly, reaching a maximum of 41.31% when the concentration was 30 mg / L.

[0063] PASP was prepared at different concentrations and the polarization curve was determined by electrochemical method. The polarization curve is shown in the attached figure. Figure 4 , the test results are shown in Table 2:

[0064] Table 2 Potentiodynamic polarization parameters of different concentrations of PASP in 3.5% NaCl aqueous solution

[0065]

[0066] From the results, it can be seen that with the increase of PASP concentration, the current density I corr Reduce, η p The maximum corrosion inhibition efficiency was 17.84% when the concentration was 20 mg / L.

[0067] Figure 3The polarization curves of the aqueous solution of PASP-DGL-ED of Example 1 with different concentrations are shown in the figure. As can be seen from the figure, compared with the blank concentration, with the increase of the concentration of PASP-DGL-ED of Example 1, the corrosion potential of carbon steel moves in the positive direction, and the movement amplitude of the anode curve is significantly greater than that of the cathode curve. The results show that the added water treatment agent has a significant inhibitory effect on the corrosion of carbon steel. On the other hand, the Tafel curve is also moving in the direction of decreasing the corrosion current density. It can be seen that the greater the concentration, the greater the movement amplitude; among them, the movement amplitude of PASP-DGL-ED of Example 1 is the largest when the concentration is 30 mg / L, and then gradually stabilizes, and the movement amplitude of the anode curve is significantly greater than that of the cathode, which indicates that the corrosion inhibition effect of the water treatment agent studied on the cathode is smaller than that on the anode, indicating that the addition of PASP-DGL-ED of Example 1 can significantly inhibit the metal dissolution of the anode, so PASP-DGL-ED of Example 1 is a corrosion inhibitor mainly for inhibiting the anode.

[0068] Figure 4 Figure 3 is the polarization curve of the control PASP aqueous solution with different concentrations. Compared with the blank concentration, with the increase of the control PASP concentration, the corrosion potential of carbon steel moves in the positive direction, and the movement amplitude of the Tafel anode curve is greater than that of the cathode curve. The results show that the added PASP has an inhibitory effect on the corrosion of carbon steel. The movement amplitude of the control PASP is the largest when the concentration is 20 mg / L, and the movement amplitude of the anode curve is greater than that of the cathode curve. This shows that the corrosion inhibition effect of the water treatment agent on the cathode is smaller than that on the anode, indicating that the addition of the control PASP can inhibit the metal dissolution at the anode. Therefore, the control PASP is a corrosion inhibitor mainly for inhibiting the anode.

[0069] Example 4

[0070] The antibacterial effect of PASP-DGL-ED and PASP prepared in Example 1 was determined by the inhibition zone method and the plate coating counting method.

[0071] (1) Determination of the antibacterial effect of PASP-DGL-ED and PASP in Example 1 by the inhibition zone method

[0072] Using LB culture medium as solvent, the prepared PASP and PASP-DGL-ED sterilized by ultraviolet light were prepared into solutions with mass concentrations of 50 mg / mL and 100 mg / mL, respectively.

[0073] Activation of bacterial strains: Take the Escherichia coli (E. coli) strain stored in a -80°C refrigerator, streak it on a fresh solid LB plate (containing 10g tryptic peptone, 5g yeast extract, 10g NaCl and 1.6g agar powder per 1 liter), and culture it at a constant temperature of 30°C for 15h.

[0074] A single colony was inoculated into 5 mL LB liquid medium and cultured overnight at 30°C and 220 r / min.

[0075] Take 1mL of overnight culture solution and transfer it to 100mL LB semi-liquid medium (0.7g agar powder), mix well, and pour it into the LB solid plate prepared in advance. After 30 minutes, spread the sterilized circular filter paper with a diameter of 0.7mm on the LB medium, and drop different concentrations of PASP and PASP-DGL-ED agents on the filter paper. The agent dosage on each filter paper is 50μL, and each sample is repeated three times. After standing for 30 minutes, the above plate is placed in a 30℃ constant temperature incubator for overnight culture. Observe and measure the diameter of the inhibition zone. If there is an obvious colony inhibition zone around the filter paper coated with the agent, it can be determined that PASP or PASP-DGL-ED has an inhibitory effect on the tested strain. Among them, the antibacterial effect of PASP is used as the control group.

[0076] The antibacterial effect of PASP was used as the control group. Figure 5 The inhibition zone appearance of PASP and PASP-DGL-ED against E. coli prepared in Example 1. When the concentration was 50 mg / mL, the diameter of the inhibition zone of PASP was 8.1 mm, and the diameter of the inhibition zone of PASP-DGL-ED was 12.3 mm; when the concentration was 100 mg / mL, the diameter of the inhibition zone of PASP did not change, and the diameter of the inhibition zone of PASP-DGL-ED was 15.9 mm, indicating that the antibacterial ability of PASP-DGL-ED against E. coli was significantly better than that of the control PASP.

[0077] (2) Determination of the antibacterial effects of PASP-DGL-ED and PASP in Example 1 by plate spread counting method

[0078] Activation of bacterial strains: Take the Escherichia coli (E. coli) strain stored in the refrigerator, inoculate it in a "Z" shape on fresh solid LB medium (containing 2.5g yeast, 2.5g NaCl, 5g peptone and 7.5g agar powder per 500ml), and then place it in a constant temperature shaking incubator for 24h.

[0079] Two single colonies on the solid culture medium were selected and placed in liquid LB culture medium, and then cultured in a constant temperature shaking incubator for 24 hours.

[0080] After sterilization with UV light, add 80 μL of bacterial solution cultured for 24 hours to the samples respectively and dilute them to 8 mL, so that the mass concentration of the samples is 20, 40, 60, 80, and 100 mg / mL respectively. Place the sample with bacterial solution in a constant temperature incubator at 37°C for 2 hours, take 50 μL of bacterial solution on the solid LB medium, use a coating rod to spread the bacterial solution evenly, and place the coated solid medium in a constant temperature incubator at 37°C for 24 hours. After 24 hours, record the number of colonies on the solid medium and take digital photos of the experimental results.

[0081] Figure 6 The figure shows the effect of different concentrations of PASP and PASP-DGL-ED on the survival rate of Escherichia coli. With the increase of PASP-DGL-ED concentration, the survival rate of Escherichia coli showed a significant downward trend. With the increase of PASP concentration, the survival rate of Escherichia coli slowly decreased. Overall, the survival rate of Escherichia coli under the action of PASP was higher than that of PASP-DGL-ED, indicating that PASP-DGL-ED has a good inhibitory effect on Escherichia coli, and the higher the concentration, the better the antibacterial effect. When the concentration of PASP-DGL-ED is 100 mg / mL, the survival rate of Escherichia coli is only 34%.

[0082] The above-mentioned embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0083] It should be noted that the above embodiments and control examples all belong to the same inventive concept, and the descriptions of the embodiments and control examples have different emphases. For matters not described in detail in the embodiments and control examples, reference may be made to the descriptions in other embodiments and control examples.

Claims

1. A method for preparing a green water treatment agent with scale inhibition, corrosion inhibition and antibacterial properties, characterized in that: The following steps are involved: (1) Using methanol as solvent, gluconolactone and ethylenediamine as raw materials, after the reaction is completed under reflux conditions, the solvent is removed, and the product is purified by recrystallization to obtain the intermediate N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide; (2) Dissolve N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide in distilled water, add polysuccinimide, and then adjust the pH value of the reaction solution to weak alkalinity with sodium hydroxide solution. Stir the reaction at 50-80°C for 20-30 h, and separate and purify to obtain the target product PASP-DGL-ED.

2. The preparation method according to claim 1, characterized in that The molar ratio of gluconolactone to ethylenediamine is 1:(2~4), and methanol needs to be dried before use.

3. The preparation method according to claim 1, characterized in that: The molar ratio of the monomer to N-(2-aminoethyl)-2,3,4,5,6-pentahydroxyhexanamide in polysuccinimide is 1:(2~5).

4. The preparation method according to claim 1, characterized in that: The concentration of the sodium hydroxide solution used is 1 mol / L~2 mol / L, and the pH value of the reaction solution is adjusted to 8~9 using NaOH solution. During the reaction, the sodium hydroxide solution is continuously added to maintain the pH value of the reaction solution at 8~9.

5. The preparation method according to claim 1, characterized in that: The separation and purification is to put the solution after the reaction into a dialysis bag and dialyze it in distilled water until the conductivity of the distilled water is below 3 μS / cm.

6. The preparation method according to claim 5, characterized in that: The molecular weight cut-off of the dialysis bag is 500~2000 Da.

7. A water treatment agent having scale inhibition, corrosion inhibition and antibacterial properties obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the water treatment agent with anti-scaling, anti-corrosion and anti-bacterial properties as claimed in claim 7 as a water treatment agent, anti-scaling agent, anti-corrosion agent or anti-bacterial agent in circulating cooling water.

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