An antibacterial corrosion inhibitor for oilfield sewage and its preparation method

Abstract

The invention relates to the technical field of sewage treatment, and in particular to an antibacterial corrosion inhibitor for oilfield sewage and a preparation method thereof. The invention comprises the following steps: using dimethylaminoethyl methacrylate and biphenyl dichlorobenzyl to synthesize a high-temperature-resistant biphenyl corrosion inhibitor; then using 1,3,5-benzenetricarboxylic acid as an organic ligand to synthesize a copper-zinc bimetallic organic framework as a carrier; and utilizing a negative pressure method to load the biphenyl corrosion inhibitor into the bimetallic organic framework; using the synthesized composite corrosion inhibitor as a core layer raw material, using modified cellulose nanocrystals as a core layer dispersant and a synergistic antibacterial agent, selecting cationic monomers, long carbon chain alkyl hydrophobic monomers, acrylamide, and sodium p-styrene sulfonate as raw materials, and synthesizing a shell structure with antibacterial and hydrophobic effects on the surfaces of the modified nanofiber crystals and the composite corrosion inhibitor under the action of an initiator, thereby improving the treatment rate of oilfield sewage.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, in particular to an antibacterial corrosion inhibitor for oil field sewage and a preparation method thereof. Background Art

[0002] With the continuous improvement of oil production technology, the large-scale use of water injection, polymer injection and other extraction technologies has caused the water content of crude oil to continue to increase, which has increased the workload of subsequent oilfield wastewater treatment. Because crude oil contains a large amount of corrosive components, the composition of oilfield wastewater is complex, including dissolved gases such as carbon dioxide and hydrogen disulfide, which have a relatively serious corrosion effect on wastewater treatment equipment, and may cause pipeline perforation, equipment failure, pipeline cracking and other accidents, and even affect the normal production of the oil field.

[0003] Therefore, corrosion inhibitors are added during oilfield wastewater treatment to improve the corrosiveness of oilfield wastewater to equipment. However, traditional corrosion inhibitors need to be added frequently and in large quantities, resulting in problems such as waste of resources. In addition, they have poor antibacterial properties and cannot effectively improve the properties of oilfield wastewater. Summary of the Invention

[0004] The object of the present invention is to provide an antibacterial corrosion inhibitor for oilfield sewage and a preparation method thereof, which requires few equipments and has high efficiency.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for preparing an antibacterial corrosion inhibitor for oilfield sewage comprises the following steps:

[0007] S1: Preparation of composite corrosion inhibitor using biphenyl corrosion inhibitor and bimetallic organic framework by negative pressure process;

[0008] S2: A capsule corrosion inhibitor with a core-shell structure is prepared using a composite corrosion inhibitor and modified cellulose nanocrystals as the core layer, i.e., an antibacterial corrosion inhibitor for oilfield wastewater.

[0009] Furthermore, the preparation of the composite corrosion inhibitor includes the following steps: mixing the bimetallic organic framework, biphenyl corrosion inhibitor, and acetone, transferring the mixture to a vacuum drying oven and placing the mixture for 20-30 minutes, reducing the pressure of the vacuum drying oven to 0.05-0.08 MPa, centrifuging the mixture, and continuing to disperse the mixture into the biphenyl corrosion inhibitor and acetone. The operation is repeated 3-5 times to obtain the composite corrosion inhibitor.

[0010] Furthermore, the preparation of the biphenyl corrosion inhibitor includes the following steps: mixing dimethylaminoethyl methacrylate and acetone, adding a mixture of biphenyl dichlorobenzyl and acetone, keeping warm at 55-60° C. for 7-8 hours, separating the acetone, washing with ether, and drying to obtain the biphenyl corrosion inhibitor.

[0011] Furthermore, the preparation of the bimetallic organic framework includes the following steps: mixing zinc nitrate hexahydrate, copper nitrate trihydrate, anhydrous ethanol, and deionized water, adding a mixture of 1,3,5-benzenetricarboxylic acid, anhydrous ethanol, and deionized water, ultrasonically stirring for 10-20 minutes, transferring to a reactor and keeping it at 105-110°C for 17-18 hours, centrifuging, washing, drying, and grinding to obtain the bimetallic organic framework.

[0012] Furthermore, the preparation of the capsule corrosion inhibitor includes the following steps: under a nitrogen atmosphere, mixing a composite corrosion inhibitor, modified cellulose nanocrystals, and deionized water, adding disodium ethylenediaminetetraacetic acid, an azo initiator, and adding a mixture of methacryloyloxyethyl hexadecyldimethylammonium bromide, octadecyl acrylate, acrylamide, sodium p-styrenesulfonate, dimethylaminoethyl methacrylate, and deionized water, keeping the mixture at 10° C. for 3-4 hours, heating to 40-45° C., adding acrylamide and a redox initiator, and keeping the mixture for 3-4 hours to obtain the capsule corrosion inhibitor.

[0013] Furthermore, the azo initiator is 2,2-azobis(2-methylpropylimidazole) dihydrochloride; and the redox initiator is a mixture of ammonium persulfate and sodium bisulfite in a mass ratio of 2:1.

[0014] Furthermore, the raw material composition of the capsule corrosion inhibitor is, in parts by mass: 0.4-0.6 parts of composite corrosion inhibitor, 0.2-0.4 parts of modified cellulose nanocrystals, 0.02-0.05 parts of disodium ethylenediaminetetraacetic acid, 0.5-0.7 parts of azo initiator, 11-13 parts of methacryloyloxyethyl hexadecyldimethylammonium bromide, 2-5 parts of octadecyl acrylate, 26-28 parts of acrylamide, 3-5 parts of sodium p-styrenesulfonate, 3-5 parts of dimethylaminoethyl methacrylate, 50-60 parts of deionized water, and 0.1-0.3 parts of redox initiator.

[0015] Furthermore, the preparation of modified cellulose nanocrystals includes the following steps:

[0016] (1) Mixing sugarcane pith raw material and NaOH, transferring them to a sealed reaction tank, keeping them at 115-120°C for 3-4 hours, introducing 0.5 MPa oxygen into the reaction tank, and the oxygenation frequency is 3-6 times, each time for 2-4 minutes, cooling to 18-25°C, separating the solid and liquid, freezing, rinsing with clean water until neutral, passing through a 200-mesh sieve, and dispersing them in deionized water to prepare a fiber suspension with a mass concentration of 0.25 wt.%, ultrasonically treating for 50-60 minutes, centrifuging, and drying to obtain cellulose nanocrystals;

[0017] (2) Under an argon atmosphere, cellulose nanocrystals and deionized water are mixed, heated to 45-50°C, a mixture of potassium persulfate and deionized water is added, stirred for 20-30 minutes, heated to 70-75°C, methyl allyl polyoxyethylene ether and deionized water are added, and the temperature is kept warm for 2-3 hours. Isopropyl alcohol is added, and the mixture is transferred to isopropyl alcohol, allowed to stand for 1-2 hours, filtered, ethanol is added, stirred and allowed to stand for 1-2 hours, filtered, methanol is added, stirred thoroughly, filtered, extracted, dried, and ground to obtain grafted cellulose nanocrystals;

[0018] (3) Methacryloyloxyethyl hexadecyldimethylammonium bromide and deionized water are mixed, and a mixture of grafted cellulose nanocrystals and deionized water is added, stirred for 30-40 minutes, allowed to stand for 44-48 hours, filtered, washed with deionized water for 3-5 times, and dried to obtain modified cellulose nanocrystals.

[0019] Furthermore, the preparation of methacryloyloxyethyl hexadecyldimethylammonium bromide includes the following steps: mixing dimethylaminoethyl acrylate, hexadecane bromide, and acetone, keeping the mixture in a water bath at 48-52° C. for 40-42 hours, washing with petroleum ether 3-5 times, and drying to obtain methacryloyloxyethyl hexadecyldimethylammonium bromide.

[0020] Beneficial effects of the present invention:

[0021] The present invention provides an antibacterial corrosion inhibitor for oilfield sewage and a preparation method thereof. By adjusting the process and raw materials, a coated long-acting slow-release corrosion inhibitor with a core-shell structure is prepared, which effectively improves the treatment capacity of oilfield sewage.

[0022] A high-temperature-resistant biphenyl corrosion inhibitor was first synthesized using dimethylaminoethyl methacrylate and biphenyl dichlorobenzyl. A copper-zinc bimetallic organic framework (BOF) synthesized with 1,3,5-benzenetricarboxylic acid as an organic ligand was then used as a carrier. The BFOF, which has excellent antibacterial properties, thermal stability, a large specific surface area, and a regular pore structure, was loaded with the high-temperature-resistant biphenyl corrosion inhibitor using a negative pressure method to obtain a composite corrosion inhibitor, thereby effectively improving the antibacterial and long-lasting properties of the corrosion inhibitor.

[0023] In order to prolong the effectiveness of the composite corrosion inhibitor in oilfield wastewater, the synthesized composite corrosion inhibitor was used as the core layer raw material, and modified cellulose nanocrystals were used as the core layer dispersant and synergistic antibacterial agent. The shell layer raw material with antibacterial and hydrophobic effects was synthesized on the surface of the composite corrosion inhibitor and modified cellulose nanocrystals.

[0024] The present invention uses green raw material sugarcane pith fiber as raw material, and obtains cellulose nanocrystals through oxygen-alkali cooking and ultrasonic treatment, thereby simplifying the preparation process of the cellulose nanocrystals and achieving the purpose of cost saving. Then, methyl allyl polyoxyethylene ether is used as a monomer and potassium persulfate is used as an initiator to synthesize grafted cellulose nanocrystals, effectively improving the hydrophilicity of the cellulose nanocrystals. Then, methacryloyloxyethyl hexadecyldimethylammonium bromide synthesized from dimethylaminoethyl acrylate and hexadecane bromide is introduced into the side chains of the grafted cellulose nanocrystal structure through electrostatic self-assembly. The introduction of hydrophilic polyether and hydrophobic long-chain alkyl groups into the cellulose nanocrystals helps to enhance their dispersion properties, thereby improving the dispersion uniformity and antibacterial durability of the composite corrosion inhibitor, and further enhancing the treatment capacity of oilfield wastewater.

[0025] The present invention selects cationic monomer methacryloyloxyethyl hexadecyldimethylammonium bromide, long carbon chain alkyl hydrophobic monomer octadecyl acrylate, acrylamide, and sodium p-styrene sulfonate as raw materials. Under the action of an initiator, a shell structure with antibacterial and hydrophobic effects is synthesized on the surfaces of modified nanofiber crystals and a composite corrosion inhibitor. The sodium p-styrene sulfonate can effectively improve the temperature and salt resistance of the sustained-release agent, and while extending the effect of the sustained-release agent, utilizes the high relative molecular weight and large positive charge density of the shell layer to achieve higher flocculation efficiency through stronger charge neutralization, adsorption bridging, and hydrophobic association, thereby improving the treatment rate of oilfield wastewater. DETAILED DESCRIPTION

[0026] The following will provide a clear and complete description of the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] It should be noted that if the embodiments of the present invention involve directional indications such as up, down, left, right, front, and back, such directional indications are only used to explain a specific posture, such as the relative position relationship between components, movement, etc. If the specific posture changes, the directional indication will also change accordingly. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0028] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0029] Example 1: A method for preparing an antibacterial corrosion inhibitor for oilfield sewage, comprising the following steps:

[0030] S1: Preparation of composite corrosion inhibitor using biphenyl corrosion inhibitor and bimetallic organic framework by negative pressure process;

[0031] The preparation of the composite corrosion inhibitor comprises the following steps: mixing 200 mg of a bimetallic organic framework, 800 mg of a biphenyl corrosion inhibitor, and 20 mL of acetone, transferring the mixture to a sealed vacuum drying oven and placing the mixture for 20 minutes, reducing the vacuum oven pressure to 0.05 MPa, centrifuging the mixture, and dispersing the mixture into a mixture of 800 mg of the biphenyl corrosion inhibitor and 20 mL of acetone, repeating the operation three times to obtain the composite corrosion inhibitor;

[0032] The preparation of the biphenyl corrosion inhibitor comprises the following steps: mixing 6.3 g of dimethylaminoethyl methacrylate and 30 mL of acetone, adding a mixture of 5 g of biphenyl dichlorobenzyl and 30 mL of acetone, keeping the mixture at 55° C. for 8 h, separating the acetone, washing with ether, and drying to obtain the biphenyl corrosion inhibitor;

[0033] The preparation of the bimetallic organic framework comprises the following steps: mixing 2 mmol of zinc nitrate hexahydrate, 8 mmol of copper nitrate trihydrate, 25 mL of anhydrous ethanol, and 25 mL of deionized water, adding a mixture of 7 mmol of 1,3,5-benzenetricarboxylic acid, 25 mL of anhydrous ethanol, and 25 mL of deionized water, ultrasonically stirring the mixture for 10 minutes, transferring the mixture to a reactor and keeping the mixture at 105° C. for 18 hours, centrifuging, washing, drying, and grinding to obtain the bimetallic organic framework;

[0034] S2: A capsule corrosion inhibitor with a core-shell structure is prepared using a composite corrosion inhibitor and modified cellulose nanocrystals as the core layer and a hydrophobic antibacterial copolymer as the shell layer, i.e., an antibacterial corrosion inhibitor for oilfield wastewater;

[0035] The preparation of the capsule corrosion inhibitor comprises the following steps: in a nitrogen atmosphere, in parts by mass, mixing 0.4 parts of a composite corrosion inhibitor, 0.2 parts of modified cellulose nanocrystals, and 10 parts of deionized water; adding 0.02 parts of disodium ethylenediaminetetraacetic acid, 0.5 parts of 2,2-azobis(2-methylpropylimidazole) dihydrochloride; adding a mixture of 11 parts of methacryloyloxyethyl hexadecyldimethylammonium bromide, 2 parts of octadecyl acrylate, 13 parts of acrylamide, 3 parts of sodium p-styrenesulfonate, 3 parts of dimethylaminoethyl methacrylate, and 40 parts of deionized water; keeping the mixture at 10° C. for 3 hours; heating the mixture to 40° C.; adding 13 parts of acrylamide and 0.1 parts of a redox initiator, wherein the redox initiator is a mixture of ammonium persulfate and sodium bisulfite in a mass ratio of 2:1; and keeping the mixture warm for 3 hours to obtain the capsule corrosion inhibitor;

[0036] The preparation of modified cellulose nanocrystals includes the following steps:

[0037] (1) 40 g of sugarcane pith raw material and 200 mL of NaOH were mixed and transferred to a sealed reaction tank. The mixture was kept at 115° C. for 4 h. 0.5 MPa of oxygen was introduced into the reaction tank for 3 times, each time for 4 min. The mixture was cooled to 18° C., solid-liquid separation was performed, and the mixture was frozen. The mixture was rinsed with clean water until neutral, passed through a 200-mesh sieve, and dispersed in deionized water to prepare a fiber suspension with a mass concentration of 0.3 wt.%. The mixture was ultrasonically treated at a power of 2000 W for 50 min. The mixture was centrifuged and dried to obtain cellulose nanocrystals.

[0038] (2) Under argon atmosphere, 5 g of cellulose nanocrystals and 25 mL of deionized water were mixed, heated to 45 °C, and a mixture of 0.4 g of potassium persulfate and 20 mL of deionized water was added, stirred for 20 min, heated to 70 °C, 2.2 g of methyl allyl polyoxyethylene ether and 20 mL of deionized water were added, and the mixture was kept warm for 2 h. 1 mL of isopropanol was added, and the mixture was transferred to 250 mL of isopropanol, allowed to stand for 1 h, filtered, and 100 mL of ethanol was added. After stirring, the mixture was allowed to stand for 1 h, filtered, and 150 mL of methanol was added. The mixture was fully stirred and filtered. Acetone and acetic acid were used as extractants and the mixture was extracted using a Soxhlet extractor for 5 h. The mixture was dried and ground to obtain grafted cellulose nanocrystals.

[0039] (3) 0.8 g of methacryloyloxyethyl hexadecyldimethylammonium bromide and 20 mL of deionized water were mixed, and a mixture of 1 g of grafted cellulose nanocrystals and 20 mL of deionized water was added, stirred for 30 min, allowed to stand for 44 h, filtered, washed with deionized water 3-5 times, and dried to obtain modified cellulose nanocrystals;

[0040] The preparation of methacryloyloxyethyl hexadecyldimethylammonium bromide comprises the following steps: mixing 1 mmol of dimethylaminoethyl acrylate, 1 mmol of hexadecane bromide, and 20 mL of acetone, keeping the mixture in a 50° C. water bath for 40 hours, washing the mixture three times with petroleum ether, and drying the mixture to obtain methacryloyloxyethyl hexadecyldimethylammonium bromide.

[0041] Example 2: A method for preparing an antibacterial corrosion inhibitor for oilfield sewage, comprising the following steps:

[0042] S1: Preparation of composite corrosion inhibitor using biphenyl corrosion inhibitor and bimetallic organic framework by negative pressure process;

[0043] The preparation of the composite corrosion inhibitor comprises the following steps: mixing 200 mg of a bimetallic organic framework, 800 mg of a biphenyl corrosion inhibitor, and 20 mL of acetone, transferring the mixture to a sealed vacuum drying oven and placing the mixture for 20 minutes, reducing the vacuum oven pressure to 0.06 MPa, centrifuging the mixture, and dispersing the mixture into a mixture of 800 mg of the biphenyl corrosion inhibitor and 20 mL of acetone, repeating the operation four times to obtain the composite corrosion inhibitor;

[0044] The preparation of the biphenyl corrosion inhibitor comprises the following steps: mixing 6.3 g of dimethylaminoethyl methacrylate and 30 mL of acetone, adding a mixture of 5 g of biphenyl dichlorobenzyl and 30 mL of acetone, keeping the mixture at 58° C. for 7.5 hours, separating the acetone, washing with ether, and drying to obtain the biphenyl corrosion inhibitor;

[0045] The preparation of the bimetallic organic framework comprises the following steps: mixing 2 mmol of zinc nitrate hexahydrate, 8 mmol of copper nitrate trihydrate, 25 mL of anhydrous ethanol, and 25 mL of deionized water, adding a mixture of 7 mmol of 1,3,5-benzenetricarboxylic acid, 25 mL of anhydrous ethanol, and 25 mL of deionized water, stirring the mixture ultrasonically for 15 minutes, transferring the mixture to a reactor and keeping the temperature at 108° C. for 17.5 hours, centrifuging, washing, drying, and grinding to obtain the bimetallic organic framework;

[0046] S2: A capsule corrosion inhibitor with a core-shell structure is prepared using a composite corrosion inhibitor and modified cellulose nanocrystals as the core layer and a hydrophobic antibacterial copolymer as the shell layer, i.e., an antibacterial corrosion inhibitor for oilfield wastewater;

[0047] The preparation of the capsule corrosion inhibitor comprises the following steps: in a nitrogen atmosphere, in parts by mass, mixing 0.5 parts of a composite corrosion inhibitor, 0.3 parts of modified cellulose nanocrystals, and 10 parts of deionized water; adding 0.04 parts of disodium ethylenediaminetetraacetate, 0.6 parts of 2,2-azobis(2-methylpropylimidazole) dihydrochloride; adding a mixture of 12 parts of methacryloyloxyethyl hexadecyldimethylammonium bromide, 3 parts of octadecyl acrylate, 13.5 parts of acrylamide, 4 parts of sodium p-styrenesulfonate, 4 parts of dimethylaminoethyl methacrylate, and 45 parts of deionized water; keeping the mixture at 10° C. for 3.5 hours; heating the mixture to 42° C.; adding 13.5 parts of acrylamide and 0.2 parts of a redox initiator, wherein the redox initiator is a mixture of ammonium persulfate and sodium bisulfite in a mass ratio of 2:1; and keeping the mixture warm for 3.5 hours to obtain the capsule corrosion inhibitor;

[0048] The preparation of modified cellulose nanocrystals includes the following steps:

[0049] (1) 40 g of sugarcane pith raw material and 200 mL of NaOH were mixed and transferred to a sealed reaction tank. The mixture was kept at 118° C. for 3.5 h. 0.5 MPa of oxygen was introduced into the reaction tank for 4 times, each for 3 min. The mixture was cooled to 20° C., solid-liquid separation was performed, and the mixture was frozen. The mixture was rinsed with clean water until neutral, passed through a 200-mesh sieve, and dispersed in deionized water to prepare a fiber suspension with a mass concentration of 0.3 wt.%. The mixture was ultrasonically treated at a power of 2000 W for 55 min. The mixture was centrifuged and dried to obtain cellulose nanocrystals.

[0050] (2) Under argon atmosphere, 5 g of cellulose nanocrystals and 25 mL of deionized water were mixed, heated to 48 °C, and a mixture of 0.4 g of potassium persulfate and 20 mL of deionized water was added, stirred for 25 min, heated to 72 °C, 2.2 g of methyl allyl polyoxyethylene ether and 20 mL of deionized water were added, and the mixture was kept warm for 2.5 h. 1 mL of isopropanol was added, and the mixture was transferred to 250 mL of isopropanol, allowed to stand for 1.5 h, filtered, and 100 mL of ethanol was added. After stirring, the mixture was allowed to stand for 1.5 h, filtered, and 150 mL of methanol was added. The mixture was fully stirred and filtered. The mixture was extracted with acetone and acetic acid as the extractant and extracted with a Soxhlet extractor for 5 h. The mixture was dried and ground to obtain grafted cellulose nanocrystals.

[0051] (3) 0.8 g of methacryloyloxyethyl hexadecyldimethylammonium bromide and 20 mL of deionized water were mixed, and a mixture of 1 g of grafted cellulose nanocrystals and 20 mL of deionized water was added, stirred for 35 min, allowed to stand for 46 h, filtered, washed four times with deionized water, and dried to obtain modified cellulose nanocrystals;

[0052] The preparation of methacryloyloxyethyl hexadecyldimethylammonium bromide comprises the following steps: mixing 1 mmol of dimethylaminoethyl acrylate, 1 mmol of hexadecane bromide, and 20 mL of acetone, keeping the mixture in a 50° C. water bath for 41 hours, washing the mixture four times with petroleum ether, and drying the mixture to obtain methacryloyloxyethyl hexadecyldimethylammonium bromide.

[0053] Example 3: A method for preparing an antibacterial corrosion inhibitor for oilfield sewage, comprising the following steps:

[0054] S1: Preparation of composite corrosion inhibitor using biphenyl corrosion inhibitor and bimetallic organic framework by negative pressure process;

[0055] The preparation of the composite corrosion inhibitor comprises the following steps: mixing 200 mg of a bimetallic organic framework, 800 mg of a biphenyl corrosion inhibitor, and 20 mL of acetone, transferring the mixture to a sealed vacuum drying oven and placing the mixture for 30 minutes, reducing the vacuum oven pressure to 0.08 MPa, centrifuging the mixture, and dispersing the mixture into a mixture of 800 mg of the biphenyl corrosion inhibitor and 20 mL of acetone, repeating the operation five times to obtain the composite corrosion inhibitor;

[0056] The preparation of the biphenyl corrosion inhibitor comprises the following steps: mixing 6.3 g of dimethylaminoethyl methacrylate and 30 mL of acetone, adding a mixture of 5 g of biphenyl dichlorobenzyl and 30 mL of acetone, keeping the mixture at 60° C. for 7 h, separating the acetone, washing with ether, and drying to obtain the biphenyl corrosion inhibitor;

[0057] The preparation of the bimetallic organic framework comprises the following steps: mixing 2 mmol of zinc nitrate hexahydrate, 8 mmol of copper nitrate trihydrate, 25 mL of anhydrous ethanol, and 25 mL of deionized water, adding a mixture of 7 mmol of 1,3,5-benzenetricarboxylic acid, 25 mL of anhydrous ethanol, and 25 mL of deionized water, stirring the mixture ultrasonically for 20 minutes, transferring the mixture to a reactor and keeping the temperature at 110° C. for 17 hours, centrifuging, washing, drying, and grinding to obtain the bimetallic organic framework;

[0058] S2: A capsule corrosion inhibitor with a core-shell structure is prepared using a composite corrosion inhibitor and modified cellulose nanocrystals as the core layer and a hydrophobic antibacterial copolymer as the shell layer, i.e., an antibacterial corrosion inhibitor for oilfield wastewater;

[0059] The preparation of the capsule corrosion inhibitor comprises the following steps: in a nitrogen atmosphere, in parts by mass, mixing 0.6 parts of a composite corrosion inhibitor, 0.4 parts of modified cellulose nanocrystals, and 10 parts of deionized water; adding 0.05 parts of disodium ethylenediaminetetraacetic acid, 0.7 parts of 2,2-azobis(2-methylpropylimidazole) dihydrochloride; adding a mixture of 13 parts of methacryloyloxyethyl hexadecyldimethylammonium bromide, 5 parts of octadecyl acrylate, 14 parts of acrylamide, 5 parts of sodium p-styrenesulfonate, 5 parts of dimethylaminoethyl methacrylate, and 50 parts of deionized water; keeping the mixture at 10° C. for 4 hours, heating to 45° C., adding 14 parts of acrylamide and 0.3 parts of a redox initiator, wherein the redox initiator is a mixture of ammonium persulfate and sodium bisulfite in a mass ratio of 2:1; and keeping the mixture warm for 4 hours to obtain the capsule corrosion inhibitor;

[0060] The preparation of modified cellulose nanocrystals includes the following steps:

[0061] (1) 40 g of sugarcane pith raw material and 200 mL of NaOH were mixed and transferred to a sealed reaction tank. The mixture was kept at 120° C. for 3 h. 0.5 MPa of oxygen was introduced into the reaction tank for 6 times, each time for 2 min. The mixture was cooled to 25° C., solid-liquid separation was performed, and the mixture was frozen. The mixture was rinsed with clean water until neutral, passed through a 200-mesh sieve, and dispersed in deionized water to prepare a fiber suspension with a mass concentration of 0.3 wt.%. The mixture was ultrasonically treated at a power of 2000 W for 60 min. The mixture was centrifuged and dried to obtain cellulose nanocrystals.

[0062] (2) Under argon atmosphere, 5 g of cellulose nanocrystals and 25 mL of deionized water were mixed, heated to 50 °C, and a mixture of 0.4 g of potassium persulfate and 20 mL of deionized water was added, stirred for 30 min, heated to 75 °C, 2.2 g of methyl allyl polyoxyethylene ether and 20 mL of deionized water were added, and the mixture was kept warm for 3 h. 1 mL of isopropanol was added, and the mixture was transferred to 250 mL of isopropanol, allowed to stand for 2 h, filtered, and 100 mL of ethanol was added. After stirring, the mixture was allowed to stand for 2 h, filtered, and 150 mL of methanol was added. The mixture was fully stirred and filtered. The mixture was extracted with acetone and acetic acid as the extractant and extracted with a Soxhlet extractor for 5 h. The mixture was dried and ground to obtain grafted cellulose nanocrystals.

[0063] (3) 0.8 g of methacryloyloxyethyl hexadecyldimethylammonium bromide and 20 mL of deionized water were mixed, and a mixture of 1 g of grafted cellulose nanocrystals and 20 mL of deionized water was added, stirred for 40 min, allowed to stand for 44 h, filtered, washed with deionized water 5 times, and dried to obtain modified cellulose nanocrystals;

[0064] The preparation of methacryloyloxyethyl hexadecyldimethylammonium bromide comprises the following steps: mixing 1 mmol of dimethylaminoethyl acrylate, 1 mmol of hexadecane bromide, and 20 mL of acetone, keeping the mixture in a 50° C. water bath for 42 hours, washing the mixture five times with petroleum ether, and drying the mixture to obtain methacryloyloxyethyl hexadecyldimethylammonium bromide.

[0065] Comparative Example 1: Taking Example 3 as the control group, the composite corrosion inhibitor was replaced by biphenyl corrosion inhibitor, and the other processes were normal.

[0066] Comparative Example 2: Taking Example 3 as the control group, the modified nanofiber crystals were replaced by grafted nanofiber crystals, and the other processes were normal.

[0067] Comparative Example 3: Taking Example 3 as the control group, the modified nanofiber crystals were replaced by cellulose nanocrystals, and the other processes were normal.

[0068] Comparative Example 4: Example 3 was used as the control group, but methacryloyloxyethyl hexadecyldimethylammonium bromide was not prepared, and the other processes were normal.

[0069] Comparative Example 5: Taking Example 3 as the control group, 0.6 parts of composite corrosion inhibitor, 0.4 parts of modified cellulose nanocrystals, and 10 parts of deionized water were mixed in S2, 20 parts of polyvinyl alcohol were added, the temperature was raised to 90°C, 0.6 g of glutaraldehyde was added, and the temperature was kept for 1 hour to obtain a capsule corrosion inhibitor. The other processes were normal.

[0070] Source of raw materials:

[0071] Sugarcane pith raw material (40-50 mesh): Guangxi Laibin Dongtang Paper Co., Ltd.; methyl allyl polyoxyethylene ether 188998: Shanghai Koraman Reagent Co., Ltd.; dimethylaminoethyl methacrylate D111129, biphenyl dichloride B102156, zinc nitrate hexahydrate Z111703, copper nitrate trihydrate C573328, 1,3,5-benzenetricarboxylic acid T109692, disodium ethylenediaminetetraacetic acid E116431, 2,2-azobis(2-methylpropylimidamide) dihydrochloride A101386, octadecyl acrylate S161395, acrylamide A108465, sodium p-styrenesulfonate S107000, hexadecane bromide B108899: Aladdin reagent; acetone, ether, anhydrous ethanol, NaOH, potassium persulfate, isopropyl alcohol, methanol, acetic acid, petroleum ether, analytical grade: Sinopharm Group reagent.

[0072] Performance test: sustained release: the corrosion inhibition performance test was carried out with reference to SY-T5273-2000 "Performance Evaluation Method of Corrosion Inhibitors for Oilfield Produced Water". The simulated water quality was: sodium chloride 29 g / L, potassium chloride 0.37 g / L, calcium chloride 210 g / L, magnesium chloride 21 g / L, sodium bicarbonate 0.12 g / L, sodium sulfate 0.09 g / L, the amount of corrosion inhibitor added was 200 mg / L, and the rotating coupon method was used for testing. The parameters were: temperature 60°C, rotation shaft speed 150 r / min, test piece linear speed 0.5 m / s, and the simulated water quality was changed every three days. A3 steel sheet with a size of 50 mm × 13 mm × 1.5 mm was selected. Antibacterial property: the prepared corrosion inhibitor was kept at 120°C for 4 h and its antibacterial property was tested after cooling. Escherichia coli and Staphylococcus aureus were selected as bacterial species and the plate method was used for testing. The results are shown in Table 1.

[0073] Table 1

[0074]

[0075] The present invention provides an antibacterial corrosion inhibitor for oilfield sewage and a preparation method thereof. As shown in Table 1, the corrosion inhibition rates of the corrosion inhibitors prepared according to Examples 1, 2, and 3 of the present invention reach 91.1-91.7% after 18 days, indicating that the inhibitors have excellent long-term sustained-release performance. In addition, after the corrosion inhibitors prepared according to Examples 1, 2, and 3 are kept at 120° C. for 4 hours, the anti-Escherichia coli rates reach 100%, and the anti-Staphylococcus aureus rates are 99.9-100%, indicating that the inhibitors have excellent high temperature resistance, can maintain excellent antibacterial ability at high temperatures, and effectively improve the treatment capacity of the inhibitors for oilfield sewage in practical applications.

[0076] Comparing Comparative Example 1 with Example 3, it can be seen that a high-temperature resistant biphenyl corrosion inhibitor is first synthesized using dimethylaminoethyl methacrylate and biphenyl dichlorobenzyl. Then, a copper-zinc bimetallic organic framework synthesized using 1,3,5-benzenetricarboxylic acid as an organic ligand is used as a carrier. The high-temperature resistant biphenyl corrosion inhibitor is loaded into the bimetallic organic framework having good antibacterial properties, thermal stability, a large specific surface area, a regular pore structure, etc. using a negative pressure method to obtain a composite corrosion inhibitor, thereby effectively improving the antibacterial and long-term effects of the corrosion inhibitor.

[0077] Comparing Comparative Examples 2, 3, and 4 with Example 3, it can be seen that in the present invention, green raw material sugarcane pith fiber is used as the raw material, and cellulose nanocrystals are obtained through oxygen-alkali cooking and ultrasonic treatment, thereby simplifying the preparation process of the cellulose nanocrystals and achieving the purpose of cost savings. Then, methyl allyl polyoxyethylene ether is used as a monomer and potassium persulfate is used as an initiator to synthesize grafted cellulose nanocrystals, effectively improving the hydrophilicity of the cellulose nanocrystals. Then, methacryloyloxyethyl hexadecyldimethylammonium bromide synthesized from dimethylaminoethyl acrylate and hexadecane bromide is introduced into the side chains of the grafted cellulose nanocrystal structure through electrostatic self-assembly. The introduction of hydrophilic polyether and hydrophobic long-chain alkyl groups into the cellulose nanocrystals helps to enhance their dispersion properties, thereby improving the dispersion uniformity and antibacterial durability of the composite corrosion inhibitor, and further improving the treatment capacity of oilfield wastewater.

[0078] Comparing Comparative Example 5 with Example 3, it can be seen that the present invention adopts a polymerization method, selects cationic monomer methacryloyloxyethyl hexadecyldimethylammonium bromide, long carbon chain alkyl hydrophobic monomer octadecyl acrylate, acrylamide, and sodium p-styrene sulfonate as raw materials, and synthesizes a shell structure with antibacterial and hydrophobic effect on the surface of modified nanofiber crystals and composite corrosion inhibitor under the action of an initiator. Among them, sodium p-styrene sulfonate can effectively improve the temperature and salt resistance of the sustained-release agent, while extending the effectiveness of the sustained-release agent. While utilizing the high relative molecular mass and large positive charge density of the shell, it can achieve higher flocculation efficiency through stronger charge neutralization, adsorption bridging, and hydrophobic association, thereby improving the treatment rate of oilfield wastewater.

[0079] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention specification under the inventive concept of the present invention, or any direct / indirect application in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing an antibacterial corrosion inhibitor for oilfield sewage, characterized in that: The following steps are involved: S1: Preparation of composite corrosion inhibitor using biphenyl corrosion inhibitor and bimetallic organic framework by negative pressure process; S2: A capsule corrosion inhibitor with a core-shell structure is prepared using a composite corrosion inhibitor and modified cellulose nanocrystals as the core layer, i.e., an antibacterial corrosion inhibitor for oilfield wastewater; The preparation of the composite corrosion inhibitor comprises the following steps: mixing a bimetallic organic framework, a biphenyl corrosion inhibitor, and acetone, transferring the mixture to a sealed vacuum drying oven and placing the mixture for 20-30 minutes, reducing the vacuum oven pressure to 0.05-0.08 MPa, centrifuging the mixture, and continuing to disperse the mixture into the biphenyl corrosion inhibitor and acetone, repeating the operation 3-5 times to obtain the composite corrosion inhibitor; The preparation of the biphenyl corrosion inhibitor comprises the following steps: mixing dimethylaminoethyl methacrylate and acetone, adding a mixture of biphenyl dichlorobenzyl and acetone, keeping the mixture at 55-60° C. for 7-8 hours, separating the acetone, washing with ether, and drying to obtain the biphenyl corrosion inhibitor; The preparation of the bimetallic organic framework comprises the following steps: mixing zinc nitrate hexahydrate, copper nitrate trihydrate, anhydrous ethanol, and deionized water, adding a mixture of 1,3,5-benzenetricarboxylic acid, anhydrous ethanol, and deionized water, ultrasonically stirring for 10-20 minutes, transferring to a reaction kettle and keeping the temperature at 105-110° C. for 17-18 hours, centrifuging, washing, drying, and grinding to obtain the bimetallic organic framework; The preparation of the capsule corrosion inhibitor comprises the following steps: under a nitrogen atmosphere, mixing a composite corrosion inhibitor, modified cellulose nanocrystals, and deionized water, adding disodium ethylenediaminetetraacetic acid, an azo initiator, and adding a mixture of methacryloyloxyethyl hexadecyldimethylammonium bromide, octadecyl acrylate, acrylamide, sodium p-styrenesulfonate, dimethylaminoethyl methacrylate, and deionized water, keeping the mixture at 10° C. for 3-4 hours, heating the mixture to 40-45° C., adding acrylamide and a redox initiator, and keeping the mixture for 3-4 hours to obtain the capsule corrosion inhibitor; The preparation of the modified cellulose nanocrystals comprises the following steps: (1) Mixing sugarcane pith raw material and NaOH, transferring them to a sealed reaction tank, keeping them at 115-120°C for 3-4 hours, introducing 0.5 MPa oxygen into the reaction tank, and the oxygenation times are 3-6 times, each time for 2-4 minutes, cooling to 18-25°C, separating the solid and liquid, freezing, rinsing with clean water until neutral, passing through a 200-mesh sieve, dispersing in deionized water to prepare a fiber suspension, ultrasonically treating for 50-60 minutes, centrifuging, and drying to obtain cellulose nanocrystals; (2) Under an argon atmosphere, cellulose nanocrystals and deionized water are mixed, heated to 45-50°C, a mixture of potassium persulfate and deionized water is added, stirred for 20-30 minutes, heated to 70-75°C, methyl allyl polyoxyethylene ether and deionized water are added, and the temperature is kept warm for 2-3 hours. Isopropyl alcohol is added, and the mixture is transferred to isopropyl alcohol, allowed to stand for 1-2 hours, filtered, ethanol is added, stirred and allowed to stand for 1-2 hours, filtered, methanol is added, stirred thoroughly, filtered, extracted, dried, and ground to obtain grafted cellulose nanocrystals; (3) Methacryloyloxyethyl hexadecyldimethylammonium bromide and deionized water are mixed, and a mixture of grafted cellulose nanocrystals and deionized water is added, stirred for 30-40 minutes, allowed to stand for 44-48 hours, filtered, washed with deionized water for 3-5 times, and dried to obtain modified cellulose nanocrystals.

2. The method for preparing an antibacterial corrosion inhibitor for oilfield sewage according to claim 1, wherein: In the preparation of the capsule corrosion inhibitor, the azo initiator is 2,2-azobis(2-methylpropylimidazole) dihydrochloride; the redox initiator is a mixture of ammonium persulfate and sodium bisulfite in a mass ratio of 2:

1.

3. The method for preparing an antibacterial corrosion inhibitor for oilfield sewage according to claim 1, wherein: The raw material composition of the capsule corrosion inhibitor is as follows, in parts by mass: 0.4-0.6 parts of composite corrosion inhibitor, 0.2-0.4 parts of modified cellulose nanocrystals, 0.02-0.05 parts of disodium ethylenediaminetetraacetic acid, 0.5-0.7 parts of azo initiator, 11-13 parts of methacryloyloxyethyl hexadecyldimethylammonium bromide, 2-5 parts of octadecyl acrylate, 26-28 parts of acrylamide, 3-5 parts of sodium p-styrenesulfonate, 3-5 parts of dimethylaminoethyl methacrylate, 50-60 parts of deionized water, and 0.1-0.3 parts of redox initiator.

4. The method for preparing an antibacterial corrosion inhibitor for oilfield sewage according to claim 1, wherein: The preparation of methacryloyloxyethyl hexadecyldimethylammonium bromide comprises the following steps: mixing dimethylaminoethyl acrylate, hexadecane bromide and acetone, keeping the mixture in a water bath at 48-52° C. for 40-42 hours, washing with petroleum ether for 3-5 times, and drying to obtain methacryloyloxyethyl hexadecyldimethylammonium bromide.

5. An antibacterial corrosion inhibitor for oilfield sewage, characterized by: Prepared according to any one of the preparation methods described in claims 1-4.

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