Antifouling agent, its preparation method and application

Abstract

The application provides a scale inhibitor and a preparation method and application thereof. The preparation method of the scale inhibitor comprises the following steps: mixing inulin, alkali and water to obtain an alkali solution of inulin; mixing N-hydroxyethyl acrylamide, isopropyl alcohol and water to obtain an isopropyl alcohol aqueous solution of N-hydroxyethyl acrylamide; mixing itaconic acid, sodium hypophosphite, alkali and water to obtain a mixed alkali solution of itaconic acid and sodium hypophosphite; adding a redox initiator into the alkali solution of inulin, and then performing a first reaction under a deoxygenated atmosphere to obtain an activated alkali solution of inulin; mixing the activated alkali solution of inulin with the isopropyl alcohol aqueous solution of N-hydroxyethyl acrylamide and the mixed alkali solution of itaconic acid and sodium hypophosphite, and then performing a second reaction under a deoxygenated atmosphere to obtain a copolymer solution; and performing purification treatment on the copolymer in the copolymer solution, so that the obtained copolymer is the scale inhibitor.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemical agents, specifically relating to a scale inhibitor, its preparation method, and its application. Background Technology

[0002] During oilfield development, especially in the later stages of extraction, increased water content, changes in pressure and temperature, and incompatibility between the injected fluid and reservoir fluid, as well as between the injected fluid and the reservoir solid phase composition, lead to scale formation. Large amounts of scale can cause significant damage to normal oilfield production, severely impacting its operation.

[0003] Currently, an increasing number of scale inhibition technologies have emerged, mainly categorized as follows: physical scale inhibition technology, chemical scale inhibition technology, and process scale inhibition technology. Physical scale inhibition technology uses physical methods to prevent scale-forming ions from adsorbing onto equipment walls and forming scale. Chemical scale inhibition technology adds scale inhibitors, allowing the inhibitor to interact with scale-forming ions, thereby altering the crystal structure of the scale-forming substances, dispersing scale-forming ions evenly, or combining with scale-forming ions, thus preventing scale formation. Process scale inhibition technology prevents scale formation by controlling or altering process conditions. Comparatively, chemical scale inhibition technology has a wider inhibition area, is easier to operate, and has a larger effective range; therefore, most oilfields adopt chemical scale inhibition technology for scale prevention.

[0004] The development of scale inhibitors has evolved from inorganic and organic to polymeric, and from single to compound formulations. Currently, commonly used scale inhibitors mainly include organophosphate scale inhibitors, synthetic polymer scale inhibitors, natural polymer scale inhibitors, and small organic molecule scale inhibitors, each with different application ranges. Among them, organophosphate scale inhibitors are the most widely used in the field. Inorganic phosphate scale inhibitors, as the mainstream scale inhibitors used in the early stages, have good chemical stability, are not easily hydrolyzed, are temperature and salt resistant, and have a certain inhibitory effect on calcium carbonate scale. To reduce the phosphorus content in scale inhibitors, organophosphate scale inhibitors and polyacrylic acid scale inhibitors have been developed. However, organophosphate scale inhibitors can form insoluble substances with metal ions in water. These insoluble substances and calcium phosphate precipitates not only reduce the performance of the scale inhibitor itself but also cause the formation of other types of scale; in addition, the large-scale use of phosphorus-containing polymers can have a certain impact on the ecological environment. Based on this, synthetic polymer scale inhibitors and natural polymer scale inhibitors have gradually become the main research directions in the field of oilfield scale prevention. However, existing synthetic polymer scale inhibitors and natural polymer scale inhibitors generally have problems, such as complex synthesis processes, long synthesis time, high cost, poor sulfate scale inhibition effect, poor field adaptability, and the need for compounding.

[0005] In summary, there is still a need to research scale inhibitors that are simple to synthesize, have short synthesis time, low cost, good sulfate scale inhibition effect, good field adaptability, and do not require compounding. Summary of the Invention

[0006] The purpose of this invention is to provide a scale inhibitor that is low in cost, has good sulfate scale inhibition effect, good field adaptability, and does not require compounding.

[0007] To achieve the above objectives, the present invention provides the following three technical solutions.

[0008] In a first aspect, the present invention provides a method for preparing a scale inhibitor, comprising the following steps:

[0009] Inulin, alkali, and water are mixed to obtain an alkaline solution of inulin; N-hydroxyethylacrylamide, isopropanol, and water are mixed to obtain an isopropanol aqueous solution of N-hydroxyethylacrylamide; itaconic acid, sodium hypophosphite, alkali, and water are mixed to obtain a mixed alkaline solution of itaconic acid and sodium hypophosphite.

[0010] After adding a redox initiator to an alkaline solution of inulin, the first reaction is carried out under a deoxygenation atmosphere to obtain an activated alkaline solution of inulin.

[0011] The activated inulin alkali solution was mixed with an isopropanol aqueous solution of N-hydroxyethylacrylamide, itaconic acid and sodium hypophosphite, and then a second reaction was carried out under a deoxygenation atmosphere to obtain a copolymer solution.

[0012] The copolymer in the copolymer solution is purified to obtain the scale inhibitor.

[0013] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the redox initiator includes at least one of ammonium persulfate and potassium persulfate.

[0014] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the alkali used in the alkaline solution of inulin includes at least one of sodium hydroxide and potassium hydroxide.

[0015] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the alkali used in the mixed alkaline solution of itaconic acid and sodium hypophosphite includes at least one of sodium hydroxide and potassium hydroxide. First aspect

[0016] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the molar ratio of inulin, N-hydroxyethylacrylamide and itaconic acid is 1:(1-2):(1.5-2).

[0017] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the mass of sodium hypophosphite is 5%-10% of the combined mass of inulin, N-hydroxyethylacrylamide, and itaconic acid.

[0018] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the redox initiator is 5-10% of the total mass of inulin, N-hydroxyethylacrylamide, itaconic acid and sodium hypophosphite.

[0019] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the mass of isopropanol is 3-8% of the total mass of inulin, N-hydroxyethylacrylamide, itaconic acid and sodium hypophosphite.

[0020] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, in the alkaline solution of inulin, the mass ratio of inulin, alkali and water is 1:(0.03-0.05):(2-3).

[0021] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, in the mixed alkaline solution of itaconic acid and sodium hypophosphite, the molar ratio of itaconic acid to alkali is (2-3):1.

[0022] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the ratio of the mass of inulin to the mass of deionized water in the alkaline solution of inulin, the isopropanol aqueous solution of N-hydroxyethylacrylamide, and the mixed alkaline solution of itaconic acid and sodium hypophosphite is 1:(4-6).

[0023] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the temperature of the first reaction is 40°C-50°C.

[0024] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the time of the first reaction is 20-50 min.

[0025] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the temperature of the second reaction is 70°C-90°C.

[0026] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the time for the second reaction is 3-4 hours.

[0027] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the activated inulin alkali solution is mixed with an isopropanol aqueous solution of N-hydroxyethylacrylamide, itaconic acid, and a mixed alkali solution of sodium hypophosphite in the following manner:

[0028] The isopropanol aqueous solution of N-hydroxyethylacrylamide, the itaconic acid and the sodium hypophosphite mixed alkaline solution were added dropwise to the activated inulin alkaline solution.

[0029] The isopropanol aqueous solution of N-hydroxyethylacrylamide was added dropwise over 0.5-1 hour.

[0030] The mixed alkaline solution of itaconic acid and sodium hypophosphite was added dropwise over 0.5-1 hour.

[0031] In one specific embodiment, the mixed alkaline solution of N-hydroxyethylacrylamide in isopropanol aqueous solution, itaconic acid, and sodium hypophosphite is added dropwise over 0.5-1 hour;

[0032] More preferably, during the process of adding the isopropanol aqueous solution of N-hydroxyethylacrylamide, the itaconic acid and the sodium hypophosphite mixed alkaline solution dropwise to the activated inulin alkali solution, the temperature of the activated inulin alkali solution is maintained at the temperature of the second reaction.

[0033] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, in the process of carrying out the first reaction under a deoxygenation atmosphere, a nitrogen atmosphere is used for deoxygenation.

[0034] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, in the process of carrying out the second reaction under a deoxygenation atmosphere, a nitrogen atmosphere is used for deoxygenation.

[0035] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, during the process of adding a redox initiator to the alkaline solution of inulin, the temperature of the alkaline solution of inulin is maintained at the temperature of the first reaction.

[0036] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, during the process of adding a redox initiator to the alkaline solution of inulin, the temperature of the alkaline solution of inulin is maintained at the temperature of the first reaction.

[0037] According to a preferred embodiment of the technical solution provided in the first aspect of the present invention, the copolymer in the copolymer solution is purified to obtain a scale inhibitor comprising:

[0038] The copolymer solution was dialyzed, and the dialysate was freeze-dried to obtain the copolymer.

[0039] Secondly, the present invention provides a scale inhibitor that is a copolymer of inulin, N-hydroxyethylacrylamide, itaconic acid and sodium hypophosphite.

[0040] According to a preferred embodiment of the technical solution provided in the second aspect of the present invention, the scale inhibitor can be prepared by the method for preparing the scale inhibitor provided in the first aspect of the present invention.

[0041] The scale inhibitor prepared according to the method for preparing the scale inhibitor provided in the first aspect of the present invention is presumably to have the following structure:

[0042]

[0043] Wherein, q:m:p is preferably (1-2):(0.3-0.8):(1.5-2); q is preferably 4-6; m is preferably 1-3; p is preferably 6-8; and n is preferably 1-30.

[0044] Thirdly, the present invention provides the application of the scale inhibitor provided in the second aspect of the present invention in scale inhibition in water bodies.

[0045] The scale inhibitor provided by this invention is a modified inulin copolymer obtained by introducing difunctional or multifunctional small molecules into the inulin molecular chain through free radical polymerization, using inulin as the monomer. Compared with the prior art, the technical solution provided by this invention has the following beneficial effects:

[0046] 1. The scale inhibitor provided by this invention has strong electronegativity and a strong ability to chelate metals. The scale inhibitor provided by this invention has good ability to inhibit sulfate scaling, good field adaptability, and does not require compounding.

[0047] 2. The scale inhibitor preparation method provided by this invention has mild reaction conditions, stable system temperature fluctuations, and easy process control, and belongs to the technology of preparing polymer compounds through amidation reaction.

[0048] 3. The scale inhibitor prepared by this invention is prepared using natural high molecular weight monomer inulin as the main reactant. The scale inhibitor prepared by this invention has good biodegradability and can reduce the impact on the environment.

[0049] 4. The preparation method of this invention involves graft copolymerization via an amidation reaction under alkaline conditions. Under alkaline conditions, the hydroxyl groups on polyhydroxy sugars are more reactive and condense with carboxyl groups, thereby improving the solubility of inulin. Attached Figure Description

[0050] Figure 1 The infrared spectrum of the scale inhibitor prepared in Example 1 of this invention. Detailed Implementation

[0051] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0052] Example 1

[0053] This embodiment provides a scale inhibitor, the preparation method of which includes the following steps:

[0054] Take appropriate amounts of HEAA (N-hydroxyethylacrylamide), isopropanol, NaOH, sodium hypophosphite, itaconic acid, inulin (CAS: 9005-80-5), ammonium persulfate, and deionized water.

[0055] Take a portion of deionized water and dissolve HEAA (N-hydroxyethylacrylamide) and isopropanol in the deionized water to prepare an isopropanol aqueous solution of N-hydroxyethylacrylamide. Transfer the isopropanol aqueous solution of N-hydroxyethylacrylamide to a constant pressure funnel for later use. The molar ratio of inulin to HEAA is 1:2, the mass ratio of HEAA to deionized water is 3:4, and the isopropanol is 3% of the total mass of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

[0056] Take another portion of deionized water and dissolve NaOH, sodium hypophosphite, and itaconic acid sequentially in this portion of deionized water (cool the deionized water to room temperature before dissolving each substance) to prepare a mixed alkaline solution of itaconic acid and sodium hypophosphite. Transfer the mixed alkaline solution of itaconic acid and sodium hypophosphite to a constant pressure funnel for later use. The molar ratio of inulin to itaconic acid is 1:2, the molar ratio of NaOH to itaconic acid is 1:2, the mass ratio of NaOH to deionized water is 1:4, and the mass of sodium hypophosphite is 10% of the sum of the masses of inulin, N-hydroxyethylacrylamide, and itaconic acid.

[0057] Under air conditions, inulin was placed in a three-necked flask equipped with a thermometer and a stirrer. Then, deionized NaOH aqueous solution was added to the flask. The mixture was heated and stirred at 50°C for 30 minutes to fully dissolve the inulin in the NaOH aqueous solution, yielding an alkaline inulin solution. The molar ratio of inulin to NaOH was 5:2, and the mass ratio of inulin to deionized water was 3:6. Next, the alkaline inulin solution was maintained at 50°C, and ammonium persulfate was added. The mixture was stirred at 50°C and reacted under nitrogen for 30 minutes to prepare an activated alkaline inulin solution. The mass of ammonium persulfate was 10% of the combined mass of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

[0058] The activated inulin alkali solution was heated to 65°C, and the above-mentioned N-hydroxyethyl acrylamide isopropanol aqueous solution and a mixed alkali solution of itaconic acid and sodium hypophosphite were added dropwise simultaneously under a nitrogen atmosphere. The addition was completed in about 1 hour. Then the temperature was raised to 90°C, and the grafting reaction was carried out under a nitrogen atmosphere for 4 hours. After the reaction was completed, the solution was cooled to room temperature to obtain a yellow copolymer solution.

[0059] After weighing the yellow copolymer solution, it was dialyzed through a 2000 Da dialysis membrane to remove unreacted monomers. The dialysate was freeze-dried for 48 hours to obtain the purified copolymer product, which is the scale inhibitor.

[0060] The molecular weight of the prepared scale inhibitor was tested, and the number average molecular weight of the prepared scale inhibitor was 2359 g / mol.

[0061] The infrared spectrum of the prepared scale inhibitor was tested, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the prepared scale inhibitor has a density of 3376 cm⁻¹. -1 2931cm -1 1640cm -1 1558cm -1 1397cm -1 1131cm -1 1035cm -1 936cm -1 719cm -1 The characteristic absorption peak is at 719 cm⁻¹. -1 The characteristic absorption peak is caused by the in-plane bending vibration of the long-chain methylene group, at 936 cm⁻¹. -1 The characteristic absorption peak is caused by the symmetric stretching vibration of the furan ring, at 1035 cm⁻¹. -1 The characteristic absorption peak is caused by the overlap of stretching vibrations of CO and PO, at 1131 cm⁻¹. -1 The characteristic absorption peak is caused by the stretching vibration of P=O, and most importantly, it is at 1558 cm⁻¹. -1 The characteristic absorption peak is caused by secondary amide, at 1640 cm⁻¹. -1 The characteristic absorption peak is caused by the conjugation of carbonyl groups in multiple carboxylic acids, at 2931 cm⁻¹. -1 The characteristic absorption peak is caused by the stretching vibration of the methylene group, at 3376 cm⁻¹. -1 The characteristic absorption peaks are multiple absorption peaks resulting from the overlapping of the OH stretching vibration and NH stretching vibration of intermolecular bonding. This indicates that inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite have been copolymerized.

[0062] It is speculated that the grafting reaction is as follows:

[0063]

[0064] The prepared scale inhibitor is presumably to have the following structure:

[0065]

[0066] Where n = 1, q = 4, m = 3, p = 8.

[0067] Example 2

[0068] This embodiment provides a scale inhibitor, the preparation method of which includes the following steps:

[0069] Take appropriate amounts of HEAA (N-hydroxyethylacrylamide), isopropanol, NaOH, sodium hypophosphite, itaconic acid, inulin (CAS: 9005-80-5), ammonium persulfate, and deionized water.

[0070] Take a portion of deionized water, dissolve HEAA (N-hydroxyethylacrylamide) and isopropanol in the deionized water to prepare an isopropanol aqueous solution of N-hydroxyethylacrylamide. Transfer the isopropanol aqueous solution of N-hydroxyethylacrylamide to a constant pressure funnel for later use. The molar ratio of inulin to HEAA is 1:1, the mass ratio of HEAA to deionized water is 3:5, and the isopropanol is 5% of the total mass of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

[0071] Take another portion of deionized water and dissolve NaOH, sodium hypophosphite, and itaconic acid sequentially in this portion of deionized water (cool the deionized water to room temperature before dissolving each substance) to prepare a mixed alkaline solution of itaconic acid and sodium hypophosphite. Transfer the mixed alkaline solution of itaconic acid and sodium hypophosphite to a constant pressure funnel for later use. The molar ratio of inulin to itaconic acid is 1:1.5, the molar ratio of NaOH to itaconic acid is 1:2, the mass ratio of NaOH to deionized water is 1:5, and the mass of sodium hypophosphite is 5% of the sum of the masses of inulin, N-hydroxyethylacrylamide, and itaconic acid.

[0072] Under air conditions, inulin was placed in a three-necked flask equipped with a thermometer and a stirrer. Then, deionized NaOH aqueous solution was added to the flask. The mixture was heated and stirred at 50°C for 30 minutes to fully dissolve the inulin in the NaOH aqueous solution, yielding an alkaline inulin solution. The molar ratio of inulin to NaOH was 5:3, and the mass ratio of inulin to deionized water was 3:8. Next, the alkaline inulin solution was maintained at 50°C, and ammonium persulfate was added. The mixture was stirred at 50°C and reacted under nitrogen for 30 minutes to prepare an activated alkaline inulin solution. The mass of ammonium persulfate was 10% of the combined mass of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

[0073] The activated inulin alkali solution was heated to 65°C, and the above-mentioned N-hydroxyethyl acrylamide isopropanol aqueous solution and a mixed alkali solution of itaconic acid and sodium hypophosphite were added dropwise simultaneously under a nitrogen atmosphere. The addition was completed in about 1 hour. Then the temperature was raised to 80°C, and the grafting reaction was carried out under a nitrogen atmosphere for 4 hours. After the reaction was completed, the solution was cooled to room temperature to obtain a yellow copolymer solution.

[0074] After weighing the yellow copolymer solution, it was dialyzed through a 2000 Da dialysis membrane to remove unreacted monomers. The dialysate was freeze-dried for 48 hours to obtain the purified copolymer product, which is the scale inhibitor.

[0075] The molecular weight of the prepared scale inhibitor was tested, and the number average molecular weight of the prepared scale inhibitor was 3502 g / mol.

[0076] The prepared scale inhibitor is presumably to have the following structure:

[0077]

[0078] Where n = 4, q = 4, m = 3, p = 6.

[0079] Example 3

[0080] This embodiment provides a scale inhibitor, the preparation method of which includes the following steps:

[0081] Take appropriate amounts of HEAA (N-hydroxyethylacrylamide), isopropanol, NaOH, sodium hypophosphite, itaconic acid, inulin (CAS: 9005-80-5), potassium persulfate, and deionized water.

[0082] Take a portion of deionized water, dissolve HEAA (N-hydroxyethylacrylamide) and isopropanol in the deionized water to prepare an isopropanol aqueous solution of N-hydroxyethylacrylamide. Transfer the isopropanol aqueous solution of N-hydroxyethylacrylamide to a constant pressure funnel for later use. The molar ratio of inulin to HEAA is 1:1, the mass ratio of HEAA to deionized water is 3:5, and the isopropanol is 8% of the total mass of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

[0083] Take another portion of deionized water and dissolve NaOH, sodium hypophosphite, and itaconic acid sequentially in this portion of deionized water (cool the deionized water to room temperature before dissolving each substance) to prepare a mixed alkaline solution of itaconic acid and sodium hypophosphite. Transfer the mixed alkaline solution of itaconic acid and sodium hypophosphite to a constant pressure funnel for later use. The molar ratio of inulin to itaconic acid is 1:1.5, the molar ratio of NaOH to itaconic acid is 1:2, the mass ratio of NaOH to deionized water is 1:5, and the mass of sodium hypophosphite is 5% of the sum of the masses of inulin, N-hydroxyethylacrylamide, and itaconic acid.

[0084] Under air conditions, inulin was placed in a three-necked flask equipped with a thermometer and a stirrer. Then, deionized NaOH aqueous solution was added to the flask. The mixture was heated and stirred at 50°C for 10 minutes to fully dissolve the inulin in the NaOH aqueous solution, yielding an alkaline inulin solution. The molar ratio of inulin to NaOH was 5:3, and the mass ratio of inulin to deionized water was 3:8. Next, the alkaline inulin solution was maintained at 50°C, and potassium persulfate was added. The mixture was stirred at 50°C and reacted under nitrogen for 50 minutes to prepare an activated alkaline inulin solution. The mass of potassium persulfate was 5% of the combined mass of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

[0085] The activated inulin alkali solution was heated to 60°C, and the above-mentioned N-hydroxyethyl acrylamide isopropanol aqueous solution and a mixed alkali solution of itaconic acid and sodium hypophosphite were added dropwise simultaneously under a nitrogen atmosphere. The addition was completed in about 0.5 hours. Then the temperature was raised to 70°C, and the grafting reaction was carried out under a nitrogen atmosphere for 3 hours. After the reaction was completed, the solution was cooled to room temperature to obtain a pale yellow copolymer solution.

[0086] The pale yellow copolymer solution was weighed and then dialyzed through a 2000 Da dialysis membrane to remove unreacted monomers. The dialysate was freeze-dried for 48 hours to obtain the purified copolymer product, which is the scale inhibitor.

[0087] The molecular weight of the prepared scale inhibitor was tested, and the number average molecular weight of the prepared scale inhibitor was 7313 g / mol.

[0088] The prepared scale inhibitor is presumably to have the following structure:

[0089]

[0090] Where n = 11, q = 5, m = 3, p = 7.

[0091] Example 4

[0092] This embodiment provides a scale inhibitor, the preparation method of which includes the following steps:

[0093] Take appropriate amounts of HEAA (N-hydroxyethylacrylamide), isopropanol, NaOH, sodium hypophosphite, itaconic acid, inulin (CAS: 9005-80-5), ammonium persulfate, and deionized water.

[0094] Take a portion of deionized water, dissolve HEAA (N-hydroxyethylacrylamide) and isopropanol in the deionized water to prepare an isopropanol aqueous solution of N-hydroxyethylacrylamide. Transfer the isopropanol aqueous solution of N-hydroxyethylacrylamide to a constant pressure funnel for later use. The molar ratio of inulin to HEAA is 1:2, the mass ratio of HEAA to deionized water is 3:4, and the isopropanol is 5% of the total mass of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

[0095] Take another portion of deionized water and dissolve NaOH, sodium hypophosphite, and itaconic acid sequentially in this portion of deionized water (cool the deionized water to room temperature before dissolving each substance) to prepare a mixed alkaline solution of itaconic acid and sodium hypophosphite. Transfer the mixed alkaline solution of itaconic acid and sodium hypophosphite to a constant pressure funnel for later use. The molar ratio of inulin to itaconic acid is 1:2, the molar ratio of NaOH to itaconic acid is 1:2, the mass ratio of NaOH to deionized water is 1:4, and the mass of sodium hypophosphite is 5% of the sum of the masses of inulin, N-hydroxyethylacrylamide, and itaconic acid.

[0096] Under air conditions, inulin was placed in a three-necked flask equipped with a thermometer and a stirrer. Then, deionized NaOH aqueous solution was added to the flask. The mixture was heated and stirred at 50°C for 20 minutes to fully dissolve the inulin in the NaOH aqueous solution, yielding an alkaline inulin solution. The molar ratio of inulin to NaOH was 5:2, and the mass ratio of inulin to deionized water was 3:6. Next, the alkaline inulin solution was maintained at 50°C, and ammonium persulfate was added. The mixture was stirred at 50°C and reacted under nitrogen for 20 minutes to prepare an activated alkaline inulin solution. The mass of ammonium persulfate was 5% of the combined mass of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

[0097] The activated inulin alkali solution was heated to 60°C, and the above-mentioned N-hydroxyethyl acrylamide isopropanol aqueous solution and a mixed alkali solution of itaconic acid and sodium hypophosphite were added dropwise simultaneously under a nitrogen atmosphere. The addition was completed in about 0.5 hours. Then the temperature was raised to 70°C, and the grafting reaction was carried out under a nitrogen atmosphere for 3 hours. After the reaction was completed, the solution was cooled to room temperature to obtain a pale yellow copolymer solution.

[0098] The pale yellow copolymer solution was weighed and then dialyzed through a 2000 Da dialysis membrane to remove unreacted monomers. The dialysate was freeze-dried for 48 hours to obtain the purified copolymer product, which is the scale inhibitor.

[0099] The molecular weight of the prepared scale inhibitor was tested, and the number average molecular weight of the prepared scale inhibitor was 10865 g / mol.

[0100] The prepared scale inhibitor is presumably to have the following structure:

[0101]

[0102] Where n = 18, q = 4, m = 3, p = 6.

[0103] Experimental Example 1:

[0104] The scale inhibitors provided in Examples 1-4, as well as commercial scale inhibitors 1 (AD43-4) and 2 (sw-15), were tested for sulfate scale inhibition performance.

[0105] Barium sulfate scale inhibition performance test:

[0106] Accurately weigh 0.50g of the scale inhibitor to be tested, dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute it to the 250mL mark to obtain the scale inhibitor solution;

[0107] Take 200 mL of deionized water into a 250 mL volumetric flask, add the pre-prepared BaCl2 solution and mix, so that the BaCl2 concentration in the mixed solution is high. 2+ The content is 2.8 mg·mL-1 Add 3.75 mL of scale inhibitor solution, let stand for 10 minutes, then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is neutralized. 2- The content is 2.06 mg·mL -1 Dilute with deionized water to 250mL and then transfer to a ground glass joint Erlenmeyer flask.

[0108] The ground glass joint Erlenmeyer flask was placed in a water bath at 50℃±1℃ for half an hour until the temperature stabilized. After standing for 24 hours, the flask was removed and cooled to room temperature. The supernatant from the flask was filtered using medium-speed qualitative filter paper. 10.00 ml of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration.

[0109] To determine the scale inhibition rate of barium sulfate, a blank control experiment was conducted. The only difference between the blank control experiment and the barium sulfate scale inhibition performance test was that pure water was used instead of barium sulfate as the scale inhibitor solution. The barium sulfate scale inhibition rate of each scale inhibitor was calculated based on the test results of the blank control experiment.

[0110] Calcium sulfate scale inhibition performance test:

[0111] Accurately weigh 0.50g of the scale inhibitor to be tested, dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute it to the 250mL mark to obtain the scale inhibitor solution;

[0112] Take 200 mL of deionized water into a 250 mL volumetric flask, add the pre-prepared CaCl2 solution and mix, so that the Ca in the mixed solution is concentrated. 2+ The content is 30g·mL -1 Add 3.75 mL of scale inhibitor solution, let stand for 10 minutes, then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is neutralized. 2- The content is 2.06 mg·mL -1 Dilute with deionized water to 250mL and then transfer to a ground glass joint Erlenmeyer flask.

[0113] The ground glass joint Erlenmeyer flask was placed in a water bath at 50℃±1℃ for half an hour until the temperature stabilized. After standing for 24 hours, the flask was removed and cooled to room temperature. The supernatant from the flask was filtered using medium-speed qualitative filter paper. 10.00 ml of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration.

[0114] To determine the scale inhibition rate of calcium sulfate, a blank control experiment was conducted. The only difference between the blank control experiment and the calcium sulfate scale inhibition performance test was that pure water was used instead of pure water as the scale inhibitor solution. The calcium sulfate scale inhibition rate of each scale inhibitor was calculated based on the test results of the blank control experiment.

[0115] The test results are shown in Table 1.

[0116] Table 1

[0117] Scale inhibitor dosage (mg / L) Barium sulfate scale inhibition rate % Calcium sulfate scale inhibition rate % Example 1 Scale inhibitor 30 95.5 82.6 Example 2 Scale Inhibitor 30 90.3 87.3 Example 3 Scale inhibitor 30 75.4 54.2 Example 4 Scale inhibitor 30 73.5 55.6 AD43-4 scale inhibitor 30 47.2 63.4 SW-15 scale inhibitor 30 65.7 57.1

[0118] As shown in Table 1, the water-soluble grafted polymer scale inhibitor obtained by using inulin as the matrix and itaconic acid and HEAA as modifying monomers, and utilizing persulfate and alkali activation initiation, exhibits excellent scale inhibition performance against barium sulfate and calcium sulfate through free radical polymerization in aqueous solution. When the scale inhibitor dosage is 30 mg / L, the inhibition rate against barium sulfate is 73.5%-95.5%, and the inhibition rate against calcium sulfate is 54.2%-82.6%. Furthermore, the above results show that the scale inhibitor provided by this invention has a significantly better scale inhibition effect than commercial AD43-4 and commercial SW-15 scale inhibitors. Example 1 of this invention provides the best scale inhibition effect, indicating that using the scale inhibitor prepared according to the ratio of HEAA (N-hydroxyethylacrylamide), isopropanol, alkali, sodium hypophosphite, itaconic acid, inulin, initiator, and water shown in Example 1 results in a product with a higher scale inhibition rate.

[0119] Experimental Example 2:

[0120] Based on the scale inhibitor in Implementation Example 1, the scale inhibition efficiency of scale inhibitors with different concentrations was determined.

[0121] Barium sulfate scale inhibition efficiency test:

[0122] 1) Accurately weigh 0.50g of the scale inhibitor to be tested, dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute it to the 250mL mark to obtain the scale inhibitor solution;

[0123] Take 200 mL of deionized water into a 250 mL volumetric flask, add the pre-prepared BaCl2 solution and mix, so that the BaCl2 concentration in the mixed solution is high. 2+ The content is 2.8 mg·mL -1 Add 3.75 mL of scale inhibitor solution, let stand for 10 minutes, then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is neutralized. 2- The content is 2.06 mg·mL -1 Dilute with deionized water to 250mL and then transfer to a ground glass joint Erlenmeyer flask.

[0124] The ground glass joint Erlenmeyer flask was placed in a water bath at 50℃±1℃ for half an hour until the temperature stabilized. After standing for 24 hours, the flask was removed and cooled to room temperature. The supernatant from the flask was filtered using medium-speed qualitative filter paper. 10.00 ml of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0125] 2) Repeat step 1), except that the volume of scale inhibitor solution added to the volumetric flask is 5.00 ml instead of 3.75 ml;

[0126] 3) Repeat step 1), except that the volume of scale inhibitor solution added to the volumetric flask is 7.50 ml instead of 3.75 ml;

[0127] 4) Repeat step 1), except that the volume of scale inhibitor solution added to the volumetric flask is 12.50 ml instead of 3.75 ml;

[0128] 5) Repeat step 1), except that the volume of scale inhibitor solution added to the volumetric flask is 15.00 ml instead of 3.75 ml.

[0129] To determine the scale inhibition rate of barium sulfate, a blank control experiment was conducted. The only difference between the blank control experiment and the barium sulfate scale inhibition performance test was that pure water was used instead of barium sulfate as the scale inhibitor solution. The barium sulfate scale inhibition rate of each scale inhibitor was calculated based on the test results of the blank control experiment.

[0130] Calcium sulfate scale inhibition performance test:

[0131] 1) Accurately weigh 0.50g of the scale inhibitor to be tested, dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute it to the 250mL mark to obtain the scale inhibitor solution;

[0132] Take 200 mL of deionized water into a 250 mL volumetric flask, add the pre-prepared CaCl2 solution and mix, so that the Ca in the mixed solution is concentrated. 2+ The content is 30g·mL -1 Add 3.75 mL of scale inhibitor solution, let stand for 10 minutes, then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is neutralized. 2- The content is 2.06 mg·mL -1 Dilute with deionized water to 250mL and then transfer to a ground glass joint Erlenmeyer flask.

[0133] The ground glass joint Erlenmeyer flask was placed in a water bath at 50℃±1℃ for half an hour until the temperature stabilized. After standing for 24 hours, the flask was removed and cooled to room temperature. The supernatant from the flask was filtered using medium-speed qualitative filter paper. 10.00 ml of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0134] 2) Repeat step 1), except that the volume of scale inhibitor solution added to the volumetric flask is 5.00 ml instead of 3.75 ml;

[0135] 3) Repeat step 1), except that the volume of scale inhibitor solution added to the volumetric flask is 7.50 ml instead of 3.75 ml;

[0136] 4) Repeat step 1), except that the volume of scale inhibitor solution added to the volumetric flask is 12.50 ml instead of 3.75 ml;

[0137] 5) Repeat step 1), except that the volume of scale inhibitor solution added to the volumetric flask is 15.00 ml instead of 3.75 ml.

[0138] To determine the scale inhibition rate of calcium sulfate, a blank control experiment was conducted. The only difference between the blank control experiment and the calcium sulfate scale inhibition performance test was that pure water was used instead of pure water as the scale inhibitor solution. The calcium sulfate scale inhibition rate of each scale inhibitor was calculated based on the test results of the blank control experiment.

[0139] The test results are shown in Table 2.

[0140] Table 2

[0141]

[0142] As shown in Table 2, in Example 1, the scale inhibitor concentration above 30 ppm can achieve a scale inhibition rate of over 95% for barium sulfate and 82.6% for calcium sulfate. As the scale inhibitor concentration increases, the scale inhibition effect first increases and then tends to decrease.

[0143] Experimental Example 3:

[0144] The scale inhibitor provided in Example 1, commercial scale inhibitor 1 (AD43-4), and commercial scale inhibitor 2 (sw-15) were subjected to scale inhibition effect evaluation experiments to test the scale inhibition efficiency of the scale inhibitor in the field produced water.

[0145] Water samples were selected from the site; Water sample A: mineralization 1.22 mg / L, sodium sulfate type; Water sample B: mineralization 44.2 g / L, calcium chloride type; Compatibility analysis was performed on water samples A and B. When the volume ratio of water sample A to water sample B was 1:1, the amount of calcium carbonate scale was about 200 mg / L and the amount of barium sulfate scale was 50 mg / L.

[0146] Accurately weigh 0.50g of the scale inhibitor provided in Example 1, dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute to the 250mL mark to obtain scale inhibitor solution A; accurately weigh 0.50g of commercial scale inhibitor 1 (AD43-4), dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute to the 250mL mark to obtain scale inhibitor solution B; accurately weigh 0.50g of commercial scale inhibitor 2 (sw-15), dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute to the 250mL mark to obtain scale inhibitor solution C;

[0147] Take two 50ml water samples A and place them in two 100ml volumetric flasks respectively. Dilute with distilled water to a final volume of 100mL to obtain solution A. Then take two 50ml water samples B and place them in two 100ml volumetric flasks respectively. Dilute with distilled water to a final volume of 100mL to obtain solution B.

[0148] Experimental Group 1: 50 ml of solution A was placed in a 100 ml ground glass bottle, 1.5 ml of scale inhibitor solution A was added, and the mixture was allowed to stand for 10 min. Then, 50 ml of solution B was added, and the mixture was shaken well. The bottle was then placed in a water bath at 50℃±1℃ for half an hour until the temperature remained constant. After standing for 24 h, the ground glass bottle was removed and cooled to room temperature. The clear liquid at the top of the ground glass bottle was filtered using medium-speed qualitative filter paper. 10.00 ml of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0149] Experimental Group 2: 50 ml of solution A was placed in a 100 ml ground glass bottle, 3.0 ml of scale inhibitor solution A was added, and the mixture was allowed to stand for 10 min. Then, 50 ml of solution B was added, and the mixture was shaken well. The bottle was then placed in a water bath at 50℃±1℃ for half an hour and allowed to stand for 24 h. After cooling to room temperature, the ground glass bottle was removed and the liquid from the top of the bottle was filtered using medium-speed qualitative filter paper. 10.00 ml of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0150] Experimental Group 3: Take 50 ml of solution A and place it in a 100 ml ground glass bottle. Add 3.0 ml of scale inhibitor solution B and let it stand for 10 min. Then add another 50 ml of solution B, shake well, and place it in a 50℃±1℃ water bath for half an hour. After standing for 24 h, remove the ground glass bottle and cool it to room temperature. Filter the clear liquid from the top of the ground glass bottle using medium-speed qualitative filter paper. Transfer 10.00 ml of the filtrate to an Erlenmeyer flask and titrate it with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0151] Experimental Group 4: Take 50 ml of solution A and place it in a 100 ml ground glass bottle. Add 3.0 ml of scale inhibitor solution C and let it stand for 10 min. Then add 50 ml of solution B, shake well, and place it in a 50℃±1℃ water bath for half an hour. After standing for 24 h, remove the ground glass bottle and cool it to room temperature. Filter the clear liquid from the top of the ground glass bottle using medium-speed qualitative filter paper. Transfer 10.00 ml of the filtrate to an Erlenmeyer flask and titrate it with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration.

[0152] The scale inhibition rate of each experimental group was calculated based on the compatibility analysis results of water sample A and water sample B.

[0153] The test results are shown in Table 3.

[0154] Table 3

[0155] experimental group Scale inhibitor dosage (mg / L) Barium sulfate scale inhibition rate % 1 30 88.6 2 60 93.8 3 60 51.6 4 60 62.5

[0156] As shown in Table 3, in water samples with barium sulfate as the main scaling system, when the dosage of the scale inhibitor provided in Example 1 is 60 mg / L, the scale inhibition rate reaches 93.8%, which is significantly better than that of commercial AD43-4 scale inhibitor and commercial SW-15 scale inhibitor.

[0157] Experimental Example 4:

[0158] An experiment was conducted to evaluate the effect of iron ions on scale inhibition on the scale inhibitor provided in Example 1, commercial scale inhibitor 1 (AD43-4), and commercial scale inhibitor 2 (sw-15).

[0159] Accurately weigh 0.50g of the scale inhibitor provided in Example 1, dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute to the 250mL mark to obtain scale inhibitor solution A; accurately weigh 0.50g of commercial scale inhibitor 1 (AD43-4), dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute to the 250mL mark to obtain scale inhibitor solution B; accurately weigh 0.50g of commercial scale inhibitor 2 (sw-15), dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute to the 250mL mark to obtain scale inhibitor solution C; prepare a ferrous ammonium sulfate solution with a concentration of 20g / L;

[0160] Experimental Group 1: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add 0 mL of ferrous ammonium sulfate solution, then add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Then add 3.75 ml of scale inhibitor solution A, let stand for 10 minutes, and then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is reduced.2- The content is 2.06 mg·mL -1 Dilute with deionized water to a final volume of 250 mL and transfer to a ground-glass stoppered Erlenmeyer flask. Place the flask in a 50℃±1℃ water bath for half an hour until the temperature stabilizes, then let it stand for 24 hours. Remove the flask and cool to room temperature. Filter the supernatant from the flask using medium-speed qualitative filter paper. Transfer 10.00 mL of the filtrate to an Erlenmeyer flask and titrate with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0161] Experimental Group 2: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add 0.12 mL of ferrous ammonium sulfate solution, then add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Then add 3.75 ml of scale inhibitor solution A, let stand for 10 minutes, and then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is reduced. 2- The content is 2.06 mg·mL -1 Dilute with deionized water to a final volume of 250 mL and transfer to a ground-glass stoppered Erlenmeyer flask. Place the flask in a 50℃±1℃ water bath for half an hour until the temperature stabilizes, then let it stand for 24 hours. Remove the flask and cool to room temperature. Filter the supernatant from the flask using medium-speed qualitative filter paper. Transfer 10.00 mL of the filtrate to an Erlenmeyer flask and titrate with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0162] Experimental Group 3: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add 0.62 mL of ferrous ammonium sulfate solution, then add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Then add 3.75 ml of scale inhibitor solution A, let stand for 10 minutes, and then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is reduced. 2- The content is 2.06 mg·mL -1 Dilute with deionized water to a final volume of 250 mL and transfer to a ground-glass stoppered Erlenmeyer flask. Place the flask in a 50℃±1℃ water bath for half an hour until the temperature stabilizes, then let it stand for 24 hours. Remove the flask and cool to room temperature. Filter the supernatant from the flask using medium-speed qualitative filter paper. Transfer 10.00 mL of the filtrate to an Erlenmeyer flask and titrate with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0163] Experimental Group 4: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add 0.62 mL of ferrous ammonium sulfate solution, then add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Then add 3.75 ml of scale inhibitor solution B, let stand for 10 minutes, and then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is reduced. 2- The content is 2.06 mg·mL -1 Dilute with deionized water to a final volume of 250 mL and transfer to a ground-glass stoppered Erlenmeyer flask. Place the flask in a 50℃±1℃ water bath for half an hour until the temperature stabilizes, then let it stand for 24 hours. Remove the flask and cool to room temperature. Filter the supernatant from the flask using medium-speed qualitative filter paper. Transfer 10.00 mL of the filtrate to an Erlenmeyer flask and titrate with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0164] Experimental Group 5: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add 0.62 mL of ferrous ammonium sulfate solution, then add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Then add 3.75 ml of scale inhibitor solution C, let stand for 10 minutes, and then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is reduced. 2- The content is 2.06 mg·mL -1 Dilute with deionized water to a final volume of 250 mL and transfer to a ground-glass stoppered Erlenmeyer flask. Place the flask in a 50℃±1℃ water bath for half an hour until the temperature stabilizes, then let it stand for 24 hours. Remove the flask and cool to room temperature. Filter the supernatant from the flask using medium-speed qualitative filter paper. Transfer 10.00 mL of the filtrate to an Erlenmeyer flask and titrate with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration.

[0165] To determine the scale inhibition rate, a blank control experiment was conducted. The only difference between the blank control experiment and experimental group 1 was that the scale inhibitor solution was replaced with pure water. The scale inhibition rate of each scale inhibitor was calculated based on the test results of the blank control experiment.

[0166] The test results are shown in Table 4.

[0167] Table 4

[0168] experimental group Scale inhibitor concentration (mg / L) Iron ion concentration (mg / L) Scale inhibition rate % 1 30 0 95.5％ 2 30 10 88.9 3 30 50 70.6 4 30 50 21.5 5 30 50 15.3

[0169] As shown in Table 4, the iron ion content has a certain impact on the scale inhibition effect. As the iron ion content increases, the scale inhibition efficiency tends to decrease. The scale inhibitor provided in Example 1 has better iron resistance compared with commercial AD43-4 scale inhibitor and commercial SW-15 scale inhibitor.

[0170] Experimental Example 5:

[0171] An experiment was conducted to evaluate the effect of pH on the scale inhibition effect of the scale inhibitor provided in Example 1.

[0172] Accurately weigh 0.50g of the scale inhibitor provided in Example 1, dissolve it in a small amount of pure water, transfer it to a 250mL volumetric flask, and dilute it to the 250mL mark to obtain a scale inhibitor solution; prepare a ferrous ammonium sulfate solution with a concentration of 20g / L.

[0173] Experimental Group 1: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Add 7.5 ml of scale inhibitor solution, let stand for 10 minutes, then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is neutralized. 2- The content is 2.06 mg·mL -1 The pH of the solution was then adjusted and diluted to 250 mL with deionized water to obtain a solution with a pH of 3. The solution in the volumetric flask was transferred to a ground glass joint Erlenmeyer flask, which was then placed in a water bath at 50℃±1℃ for half an hour until the temperature stabilized. After standing for 24 hours, the flask was removed and cooled to room temperature. The supernatant from the ground glass joint Erlenmeyer flask was filtered using medium-speed qualitative filter paper. 10.00 mL of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0174] Experimental Group 2: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Add 7.5 ml of scale inhibitor solution, let stand for 10 minutes, then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is neutralized. 2- The content is 2.06 mg·mL -1The pH of the solution was then adjusted and diluted to 250 mL with deionized water to obtain a solution with a pH of 4. The solution in the volumetric flask was transferred to a ground glass joint Erlenmeyer flask, which was then placed in a 50℃±1℃ water bath for half an hour until the temperature stabilized. After standing for 24 hours, the flask was removed and cooled to room temperature. The supernatant from the ground glass joint Erlenmeyer flask was filtered using medium-speed qualitative filter paper. 10.00 mL of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0175] Experimental Group 3: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Add 7.5 ml of scale inhibitor solution, let stand for 10 minutes, then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is neutralized. 2- The content is 2.06 mg·mL -1 The pH of the solution was then adjusted and diluted to 250 mL with deionized water to obtain a solution with a pH of 5. The solution in the volumetric flask was transferred to a ground glass joint Erlenmeyer flask, which was then placed in a 50℃±1℃ water bath for half an hour until the temperature stabilized. After standing for 24 hours, the flask was removed and cooled to room temperature. The supernatant from the ground glass joint Erlenmeyer flask was filtered using medium-speed qualitative filter paper. 10.00 mL of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0176] Experimental Group 4: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Add 7.5 ml of scale inhibitor solution, let stand for 10 minutes, then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is neutralized. 2- The content is 2.06 mg·mL -1 The pH of the solution was then adjusted and diluted to 250 mL with deionized water to obtain a solution with a pH of 6. The solution in the volumetric flask was transferred to a ground glass joint Erlenmeyer flask, which was then placed in a water bath at 50℃±1℃ for half an hour until the temperature stabilized. After standing for 24 hours, the flask was removed and cooled to room temperature. The supernatant from the ground glass joint Erlenmeyer flask was filtered using medium-speed qualitative filter paper. 10.00 mL of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0177] Experimental Group 5: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Add 7.5 ml of scale inhibitor solution, let stand for 10 minutes, then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is neutralized. 2- The content is 2.06 mg·mL -1 The pH of the solution was then adjusted and diluted to 250 mL with deionized water to obtain a solution with a pH of 7. The solution in the volumetric flask was transferred to a ground glass joint Erlenmeyer flask, which was then placed in a 50℃±1℃ water bath for half an hour until the temperature stabilized. After standing for 24 hours, the flask was removed and cooled to room temperature. The supernatant from the ground glass joint Erlenmeyer flask was filtered using medium-speed qualitative filter paper. 10.00 mL of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration;

[0178] Experimental Group 6: Take 50 ml of distilled water and place it in a 250 ml volumetric flask. Add the pre-prepared BaCl2 solution and mix. The resulting solution should contain BaCl2. 2+ The content is 2.8 mg·mL -1 Add 7.5 ml of scale inhibitor solution, let stand for 10 minutes, then add the pre-prepared Na2SO4 solution while shaking to mix, so that the SO4 in the mixed solution is neutralized. 2- The content is 2.06 mg·mL -1 The pH of the solution was then adjusted and diluted to 250 mL with deionized water to obtain a solution with a pH of 10. The solution in the volumetric flask was transferred to a ground glass joint Erlenmeyer flask, which was then placed in a water bath at 50℃±1℃ for half an hour until the temperature stabilized. After standing for 24 hours, the flask was removed and cooled to room temperature. The supernatant from the ground glass joint Erlenmeyer flask was filtered using medium-speed qualitative filter paper. 10.00 mL of the filtrate was transferred to an Erlenmeyer flask and titrated with EDTA standard solution (sodium ethylenediaminetetraacetate) to determine Ba. 2+ The concentration.

[0179] To determine the scale inhibition rate, a blank control experiment was conducted. The only difference between the blank control experiment and experimental group 1 was that the scale inhibitor solution was replaced with pure water. The scale inhibition rate of each scale inhibitor was calculated based on the test results of the blank control experiment.

[0180] The test results are shown in Table 5.

[0181] Table 5

[0182] experimental group Scale inhibitor concentration (mg / L) Iron ion concentration (mg / L) Scale inhibition rate % 1 60 3 60.9 2 60 4 75.0 3 60 5 86.4 4 60 6 97.5 5 60 7 98.6 6 60 10 87.0

[0183] As shown in Table 5, the scale inhibitor provided in Example 1 exhibits the best scale inhibition effect at neutral pH. Under slightly acidic and alkaline conditions, the scale inhibition rate can still reach over 85%, indicating that the scale inhibitor has good acid and alkali resistance.

[0184] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings are not necessarily shown in a specific order or sequence to achieve the desired result.

Claims

1. A method for preparing a scale inhibitor, comprising the following steps: Inulin, alkali, and water are mixed to obtain an alkaline solution of inulin; N-hydroxyethylacrylamide, isopropanol, and water are mixed to obtain an isopropanol aqueous solution of N-hydroxyethylacrylamide; itaconic acid, sodium hypophosphite, alkali, and water are mixed to obtain a mixed alkaline solution of itaconic acid and sodium hypophosphite. After adding a redox initiator to an alkaline solution of inulin, the first reaction is carried out under a deoxygenation atmosphere to obtain an activated alkaline solution of inulin. The activated inulin alkali solution was mixed with an isopropanol aqueous solution of N-hydroxyethylacrylamide, itaconic acid and sodium hypophosphite, and then a second reaction was carried out under a deoxygenation atmosphere to obtain a copolymer solution. The copolymer in the copolymer solution is purified to obtain the scale inhibitor.

2. The method for preparing the scale inhibitor according to claim 1, wherein, Redox initiators include at least one of ammonium persulfate and potassium persulfate.

3. The method for preparing the scale inhibitor according to claim 1, wherein, The alkali used in the alkaline solution of inulin includes at least one of sodium hydroxide and potassium hydroxide; The base used in the mixed alkaline solution of itaconic acid and sodium hypophosphite includes at least one of sodium hydroxide and potassium hydroxide.

4. The method for preparing the scale inhibitor according to claim 1, wherein, The molar ratio of inulin, N-hydroxyethylacrylamide, and itaconic acid is 1:(1-2):(1.5-2).

5. The method for preparing the scale inhibitor according to claim 1, wherein, The mass of sodium hypophosphite is 5%-10% of the combined mass of inulin, N-hydroxyethylacrylamide, and itaconic acid.

6. The method for preparing the scale inhibitor according to claim 1, wherein, The redox initiator accounts for 5-10% of the combined mass of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

7. The method for preparing the scale inhibitor according to claim 1, wherein, The mass of isopropanol is 3-8% of the combined mass of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

8. The method for preparing the scale inhibitor according to claim 1, wherein, In an alkaline solution of inulin, the mass ratio of inulin, alkali, and water is 1:(0.03-0.05):(2-3). In a mixed alkaline solution of itaconic acid and sodium hypophosphite, the molar ratio of itaconic acid to alkali is (2-3):1; The ratio of the mass of inulin to the mass of deionized water in the alkaline solution of inulin, the aqueous solution of N-hydroxyethylacrylamide in isopropanol, and the mixed alkaline solution of itaconic acid and sodium hypophosphite is 1:(4-6).

9. The method for preparing the scale inhibitor according to claim 1, wherein, The temperature of the first reaction is 40℃-50℃; The first reaction time is 20-50 minutes.

10. The method for preparing the scale inhibitor according to claim 1, wherein, The temperature for the second reaction is 70℃-90℃; The second reaction takes 3-4 hours.

11. A scale inhibitor, wherein, The scale inhibitor is a copolymer of inulin, N-hydroxyethylacrylamide, itaconic acid, and sodium hypophosphite.

12. The scale inhibitor according to claim 11, wherein, The scale inhibitor can be prepared by the method for preparing the scale inhibitor according to any one of claims 1-11.

13. The application of the scale inhibitor according to claim 11 or 12 in scale inhibition in water bodies.

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