Preparation method of modified polyether sulfone ultrafiltration membrane for fuel ethanol separation
Patent Information
- Application Number
- CN202611069252.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-17
- Publication Date
- 2026-08-21
AI Technical Summary
然而，PES膜表面呈疏水性，在过滤含有蛋白质、多糖及胶体等物质的燃料乙醇发酵液时，易发生严重的膜污染，导致通量急剧衰减
[0028]与现有技术相比，本公开的有益效果是：本公开制备得到了一种兼具耐乙醇溶胀性和抗有机污染的改性聚醚砜超滤膜；其可以用于燃料乙醇分离。
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Figure CN122605360A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of ultrafiltration membranes, and more specifically to a method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation. Background Technology
[0002] Polyethersulfone (PES) ultrafiltration membranes are widely used in separation applications due to their excellent heat resistance, chemical stability, and mechanical strength. However, the hydrophobic surface of PES membranes makes them prone to severe membrane fouling when filtering fuel ethanol fermentation broth containing proteins, polysaccharides, and colloids, leading to a sharp decline in flux. Furthermore, the fuel ethanol system is an aqueous ethanol environment, and existing hydrophilic modified layers (such as dopamine coatings or simple amino acid grafts) are prone to swelling, peeling, or chain relaxation in this organic solvent environment, causing the modified layer to fail and making it difficult to balance high flux with long-term stability.
[0003] In the prior art, although there are studies on grafting polyvinyl alcohol-based compounds to modify PES membranes to improve hydrophilicity and antifouling ability, such modifications are mainly aimed at aqueous systems, and their aliphatic flexible chains swell severely in ethanol systems.
[0004] In 2007, Lee et al. first proposed that dopamine can form a polymeric dopamine coating layer on the surface of many substrates through an oxidation-self-polymerization process. This coating layer can serve as an intermediate active layer, fixing substances with amino (-NH2) or thiol (-SH) groups onto the substrate surface. Based on this discovery, many researchers have used polymeric dopamine as a grafting intermediate to graft compounds with -NH2 or -SH groups onto the membrane surface, thereby endowing the membrane surface with more properties. Jiang et al. (2010) successfully prepared modified membranes by grafting heparin onto a polymeric dopamine coating layer on the surface of a porous polyethylene (PE) membrane, thereby increasing the filtration flux, reducing the permeation pressure, and increasing the membrane's resistance to protein adsorption. Zhu et al. (2011) grafted bovine serum albumin (BSA) onto a polymeric dopamine coating layer on the surface of a porous PE membrane and found that the modified membrane exhibited better hydrophilicity and blood compatibility. Chen et al. (2009) coated chitosan onto a polymeric dopamine layer on a PES porous membrane and found that the composite membrane had a stable structure and high permeation flux. McCloskey et al. (2012) grafted amino polyethylene glycol (mPEG-NH2) onto the surface of an ultrafiltration membrane through a polymeric dopamine coating and found that the modified membrane had a certain improvement in its resistance to fouling in oil-water separation applications.
[0005] Therefore, developing a modified PES ultrafiltration membrane with solvent swelling resistance suitable for fuel ethanol separation has become a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0006] This disclosure provides a method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation, thereby addressing the shortcomings of related technologies.
[0007] According to a first aspect of the present disclosure, a method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation is provided, the method comprising the following steps: Step 1: Prepare amino-containing compound A; Step 2: React compound A obtained in step 1 with polyvinyl alcohol to obtain polyvinyl alcohol grafted with compound A; Step 3: Provide a polyethersulfone ultrafiltration membrane, and use a dopamine solution to coat and modify the polyethersulfone ultrafiltration membrane to obtain a coated and modified polyethersulfone ultrafiltration membrane; Step 4: The coated modified polyethersulfone ultrafiltration membrane prepared in step 3 is placed upside down in a solution containing polyvinyl alcohol grafted with compound A. After reaction, it is rinsed and dried to obtain the modified polyethersulfone ultrafiltration membrane for fuel ethanol separation.
[0008] In one aspect of this disclosure, compound A has a structural formula represented by the following formula IA:
[0009] Ar1 is selected from substituted or unsubstituted C6-C30 aryl groups, or substituted or unsubstituted 5-30 heteroaryl groups; R1 is selected from hydrogen, nitro, hydroxyl, halogen atom, carboxyl, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy, or ;where R 11 Selected from substituted or unsubstituted C1-C30 alkyl groups and substituted or unsubstituted C1-C30 alkoxy groups; R2 is selected from substituted or unsubstituted C1-C30 alkylene groups. , ,or Among them, R 21 and R 22 Each is independently selected from substituted or unsubstituted C1-C30 alkylene groups.
[0010] In one aspect of the embodiments of this disclosure, compound A has a structural formula represented by the following formula II-A:
[0011] Wherein, R1 is selected from hydrogen, nitro, hydroxyl, carboxyl, C1-C10 alkyl, C1-C10 alkoxy, or ;where R 11 Selected from C1-C10 alkyl and C1-C10 alkoxy groups; R2 is selected from C1-C15 alkylene groups. , ,or Among them, R 21 and R 22 Each is independently selected from C1-C15 alkylene groups.
[0012] In one aspect of the embodiments of this disclosure, compound A has a structural formula represented by the following formula III-A:
[0013] Wherein, R2 is selected from C1-C5 alkylene groups, or Among them, R 21 and R 22 Each is independently selected from C1-C5 alkylene groups.
[0014] In one aspect of the embodiments of this disclosure, compound A is selected from compounds A-1 or A-2: , .
[0015] In one aspect of the embodiments of this disclosure, compound A-2 is prepared by the following steps: Step 1-a: Using ethyl 3-(3-nitrophenyl)-3-oxopropionate as a raw material, ethyl 3-(3-aminophenyl)-3-oxopropionate is obtained by reduction with iron powder;
[0016] Step 2-a: The ethyl 3-(3-aminophenyl)-3-oxopropionate obtained in step 1-a is reduced by palladium on carbon to obtain the intermediate product of step 2-a;
[0017] Step 3-a: The intermediate product of step 2-a is reacted with hydroxylamine hydrochloride and chloral hydrate to generate the intermediate product of step 3-a;
[0018] Step 4-a: React the intermediate product of step 3-a with concentrated sulfuric acid to generate the intermediate product of step 4-a;
[0019] Step 5-a: The intermediate product from step 4-a is reacted with sodium hydroxide to obtain compound A-2; .
[0020] In one aspect of this disclosure, step 2 includes: Step 1-b: Compound A and polyvinyl alcohol are dissolved in dimethyl sulfoxide and reacted for 8-12 hours under acid catalysis and stirring and heating conditions; Step 2-b: After the reaction is complete, acetone is added to precipitate the polyvinyl alcohol grafted with compound A obtained from the reaction. The precipitate is purified by dissolution and precipitation method to obtain the polyvinyl alcohol grafted with compound A.
[0021] In one aspect of the embodiments of this disclosure, preferably, the compound A used in step 1-b is compound A-2; and the polyvinyl alcohol grafted with compound A is polyvinyl alcohol grafted with compound A-2.
[0022] In one aspect of this disclosure, step 3 includes: Step 1-c: Fix the polyethersulfone ultrafiltration membrane in the reaction tank and pour the dopamine solution into the reaction tank; Step 2-c: Place the reaction tank on a decolorizing shaker and react at room temperature and under aerobic conditions for 0.5-2 hours; Step 3-c: After the reaction is complete, rinse the membrane surface with deionized water to remove residual dopamine solution; immerse the membrane in anhydrous ethanol for 10-40 minutes to remove loosely adhered polymeric dopamine, and obtain the coated modified polyethersulfone ultrafiltration membrane.
[0023] In one aspect of this disclosure, step 4 includes: Step 1-d: The coated modified polyethersulfone ultrafiltration membrane is inverted in a modified solution containing polyvinyl alcohol grafted with compound A, prepared with Tris buffer; Step 2-d: React at 50-70°C for 1-3 hours; after the reaction is complete, remove the membrane and rinse it with pure water; dry the rinsed membrane to obtain the modified polyethersulfone ultrafiltration membrane for fuel ethanol separation.
[0024] In one aspect of the embodiments of this disclosure, preferably, the polyvinyl alcohol grafted with compound A used in step 1-d is polyvinyl alcohol grafted with compound A-2.
[0025] In one aspect of this disclosure, in step 1-d, the concentration of polyvinyl alcohol grafted with compound A in the modified solution is 1-10 mg / mL.
[0026] The polyethersulfone ultrafiltration membrane feedstock used in this disclosure has a molecular weight cutoff of 50,000-150,000 Da, preferably 80,000-120,000 Da; more preferably 100,000 Da. This molecular weight cutoff range is suitable for the clarification and pretreatment of fuel ethanol fermentation broth, effectively retaining yeast cell debris, polysaccharide colloids, and protein aggregates, while allowing ethanol, water, and small molecule pigments to permeate, thus achieving both high throughput and antifouling performance.
[0027] According to a second aspect of the present disclosure, a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation is provided, the modified polyethersulfone ultrafiltration membrane being prepared by the aforementioned preparation method.
[0028] Compared with the prior art, the beneficial effects of this disclosure are: this disclosure prepares a modified polyethersulfone ultrafiltration membrane that has both resistance to ethanol swelling and resistance to organic pollution; it can be used for fuel ethanol separation. Attached Figure Description
[0029] Figure 1 This is a flowchart illustrating the preparation process of Embodiment 1 of this disclosure. Detailed Implementation
[0030] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.
[0031] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. The embodiments described herein are illustrative in nature and are used to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.
[0032] For the sake of brevity, this article only discloses a few specific numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.
[0033] In this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0034] In this description, unless otherwise stated, "above" and "below" include the stated number.
[0035] Unless otherwise stated, the terms used in this disclosure have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the values of the parameters mentioned in this disclosure can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this disclosure).
[0036] The term "about" is used to describe and indicate small variations. When used in conjunction with an event or situation, the term may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately. For example, when used in conjunction with numerical values, the term may refer to a range of variation less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. Additionally, quantities, ratios, and other numerical values are sometimes presented in range format herein. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only numerical values explicitly specified as range limits but also all individual numerical values or subranges covered within the range, as if each numerical value and subrange were explicitly specified.
[0037] The list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single component or multiple components. Item B may contain a single component or multiple components. Item C may contain a single component or multiple components.
[0038] In this disclosure, the term "alkyl" refers to an aliphatic hydrocarbon group, which can be straight-chain or branched. Branched refers to one or more lower alkyl groups, such as methyl, ethyl, or propyl, that link a linear alkyl chain. "Lower alkyl" refers to a group containing about 1 to about 6 carbon atoms in the chain, which can be straight-chain or branched.
[0039] In this disclosure, the term "aryl" refers to an aromatic monocyclic or polycyclic ring system. An aryl group may optionally be substituted with one or more "cyclic substituents," which may be the same or different, as defined herein. Non-limiting examples of suitable aryl groups include phenyl and naphthyl.
[0040] In this disclosure, the term "heteroaryl" refers to an aromatic monocyclic or polycyclic ring system, wherein one or more ring atoms are elements other than carbon, such as nitrogen, oxygen, or sulfur, either individually or in combination, and preferably a heteroaryl contains about 5 to about 6 ring atoms. A "heteroaryl" may optionally be substituted by one or more "cyclic substituents," which may be the same or different, as defined herein. The prefixes azido, oxa, or thiado preceding the name of a heteroaryl root indicate that at least one nitrogen, oxygen, or sulfur atom is present as a ring atom, respectively. The nitrogen atom of a heteroaryl may optionally be oxidized to the corresponding N-oxide. Suitable, non-limiting examples of heteroaryl groups include pyridyl, pyrazinyl, furanyl, phenylthio, pyrimidinyl, isoxazolyl, isothiazolyl, oxazolyl, thiazolyl, pyrazolyl, furazanyl, pyrroleyl, pyrazolyl, triazolyl, 1,2,4-thiadiazolyl, pyrazinyl, pyridazinyl, quinoxalinyl, 2,3-diazanaphthyl, imidazo[1,2-a]pyridyl, imidazo[2,1-b]thiazolyl, benzofurazanyl, indoleyl, azaindoleyl, benzimidazolyl, benzothiopheneyl, quinolinyl, imidazolyl, thienopyridyl, quinazolinyl, thienopyrimidinyl, pyrrolopyridyl, imidazopyridyl, isoquinolinyl, benzoazaindoleyl, 1,2,4-triazinyl, benzothiazolyl, etc.
[0041] In this disclosure, the term "amino" refers to the -NR′R′′ group. The amino group may optionally be substituted. In an unsubstituted amino group, R′ and R′′ are hydrogen. In a substituted amino group, R′ and R′′ may each independently be, but not limited to, hydrogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkylcycloalkyl, alkylheterocycloalkyl, alkoxy, sulfonyl, alkenyl, alkanoyl, aryl, arylalkyl, or heteroaryl, provided that R′ and R′′ are not both hydrogen. In a substituted amino group, R′ and R′′ may cyclize to form a cyclic amino group, such as pyrrolidinyl or piperidinyl. Such cyclic amino groups may incorporate other heteroatoms, for example, to form piperazine or morpholine groups. Such cyclic amino groups may optionally be substituted, for example, by an amino, hydroxyl, or oxo group.
[0042] In this disclosure, the term "alkoxy" refers to -O-alkyl. Alkoxy can refer to a straight-chain, branched, or cyclic, saturated or unsaturated oxy-hydrocarbon chain, including, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy, tert-butoxy, and pentoxy. Alkoxy may optionally be substituted by one or more alkoxy substituents ("substituted alkoxy").
[0043] The present disclosure will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present disclosure are obtained through conventional commercial means. Unless otherwise specified, all contents mentioned below are mass contents. Unless otherwise specified, it is understood that the process is carried out at room temperature.
[0044] Example Example 1: Example 1 includes the following steps: 1. Preparation of compound A-2: Add 50 mL of water, 5 mL of concentrated hydrochloric acid, and 1 g of ammonium chloride to a 250 mL three-necked flask equipped with a mechanical stirrer; stir and heat to 80 °C, then add 10 g of reduced iron powder in batches; then heat to 95 °C and activate for 10 min; then dissolve 7.2 g of ethyl 3-(3-nitrophenyl)-3-oxopropionate in 30 mL of anhydrous ethanol and slowly add it dropwise to the three-necked flask over 1.5 h. After the addition is complete, keep the reaction at the temperature for 2 h; then filter while hot to remove the iron powder, and then let the filtrate stand and cool. A large amount of brown crystals precipitate out. Filter, dissolve the resulting filter cake in chloroform, filter to remove insoluble matter, and then dry with anhydrous sodium sulfate and recrystallize with ethyl acetate to obtain intermediate product 1;
[0045] 4.9 g of intermediate product 1, 30 mL of glacial acetic acid, and 0.8 g of 10% palladium on carbon were added to a 100 mL three-necked flask. The reaction flask was sealed, purged with nitrogen three times, then with hydrogen three times, followed by hydrogen purging. The mixture was stirred and heated to 65 °C for 24 h. The reaction was then stopped, cooled to room temperature, and the palladium on carbon was recovered by filtration under nitrogen protection. The solvent in the filtrate was evaporated to obtain a gel-like substance, which was dissolved in 5% (mass fraction) sodium hydroxide solution. The insoluble matter was removed by filtration, and the pH of the filtrate was adjusted to neutral with hydrochloric acid. Water was evaporated, and the resulting solid was dissolved in methanol. The insoluble inorganic salts were removed by filtration, the solvent was evaporated, and the solid was recrystallized from ethyl acetate to obtain intermediate product 2.
[0046] In a 250 mL three-necked flask, add 105 mL of water, 1.4 mL of 37% (w / w) concentrated hydrochloric acid, and 3.25 g of intermediate product 2. Stir at room temperature until the solid dissolves. Then, heat to 100°C and add 3.10 g of chloral hydrate, 4.48 g of anhydrous sodium sulfate, and 3.80 g of hydroxylamine hydrochloride. Incubate at this temperature for 2 hours with stirring. Stop the reaction, concentrate the reaction solution to remove water, and obtain a solid. Dissolve the obtained solid in chloroform, filter to remove insoluble matter, and then rotary evaporate the filtrate. Recrystallize the filtrate with anhydrous ethanol to obtain intermediate product 3. The above steps can be repeated multiple times to prepare sufficient amounts of intermediate product 3 for subsequent reactions.
[0047] In a 250 mL three-necked flask, 50 mL of 98% concentrated sulfuric acid was added, and the temperature was raised to 30°C. 6.9 g of intermediate product 3 was slowly added over 1 hour with stirring, while maintaining the reaction temperature at 30-35°C. After the addition was complete, the temperature was raised to 60°C and the reaction was allowed to proceed for 2.5 hours. The reaction was then stopped, and the mixture was cooled to room temperature. The pH was adjusted to 8 with 10% (mass fraction) sodium hydroxide solution while the mixture was being stirred in an ice bath. The solvent was then evaporated, and the resulting solid was dissolved in chloroform. The insoluble matter was removed by filtration, and the filtrate was evaporated to dryness and recrystallized from anhydrous ethanol to obtain intermediate product 4.
[0048] In a 250 mL three-necked flask, add 2 g of sodium hydroxide and 50 mL of distilled water, stir to dissolve, and cool to below 30°C. Add 2.5 g of intermediate product 4 and stir to dissolve. Then cool in an ice bath to below 15°C, and add 3.5 g of 30% hydrogen peroxide aqueous solution dropwise, controlling the dropping rate to maintain the temperature at 15-20°C. After the addition is complete, continue stirring the reaction at 20-25°C for 3 hours. Under ice-water bath cooling, slowly add 2 mol / L hydrochloric acid until the pH is approximately 5.2. The water was then evaporated, the resulting solid was dissolved in chloroform, the insoluble matter was removed by filtration, the filtrate was evaporated to dryness, and recrystallized from anhydrous ethanol to give compound A-2; ¹H NMR (400 MHz): δ 2.63 (2H, t, J = 7.4 Hz), 3.05 (2H, t, J = 7.4 Hz), 6.69 (1H, dd, J = 7.8, 1.5 Hz), 7.16 (1H, dd, J = 7.8, 7.8 Hz), 7.41 (1H, dd, J = 7.8, 1.5 Hz). The above steps can be repeated multiple times to prepare a sufficient amount of compound A-2 for subsequent reactions.
[0049]
[0050] 2. Preparation of polyvinyl alcohol grafted with compound A-2: 10.0 g of polyvinyl alcohol (PVA, degree of polymerization 1800) and 6.0 g of compound A-2 were added to a 250 mL three-necked flask equipped with a mechanical stirrer and reflux condenser. 100 mL of dimethyl sulfoxide (DMSO) was added, and the mixture was heated to 80°C and stirred to dissolve. After complete dissolution, 1.0 mL of concentrated sulfuric acid was added dropwise as a catalyst, and the mixture was then heated to 90°C and stirred for 10 h under nitrogen protection. During the reaction, the aliphatic carboxyl group at the end of compound A-2 preferentially underwent esterification with the hydroxyl group of the PVA side chain under acid catalysis. The ortho-aromatic carboxyl group on the benzene ring, influenced by intramolecular hydrogen bonds formed by the ortho-amino group and steric hindrance, essentially did not participate in esterification, thus avoiding intermolecular crosslinking of PVA; as shown below:
[0051] After the reaction was complete, the reaction solution was cooled to room temperature and slowly poured into 500 mL of acetone, stirring constantly to precipitate the product. The precipitate was collected by filtration, redissolved in 50 mL of DMSO, and then slowly poured into 300 mL of acetone for a second precipitation. This dissolution-precipitation process was repeated three times to remove unreacted compound A-2 and small molecule byproducts. Finally, the purified precipitate was placed in a Soxhlet extractor and extracted with anhydrous ethanol for 24 h to completely displace and remove residual DMSO and acetone. After extraction, the product was vacuum dried to constant weight to obtain polyvinyl alcohol grafted with compound A-2.
[0052] 3. Preparation of modified polyethersulfone ultrafiltration membrane: A polyethersulfone ultrafiltration membrane (molecular weight cutoff 100,000) was fixed in a clamped reaction vessel. Dopamine hydrochloride was dissolved in 10 mM Tris-HCl buffer (pH approximately 8.5) to prepare a dopamine solution with a concentration of 8 mg / mL. The dopamine solution was poured into the reaction vessel to completely submerge the membrane. The reaction vessel was placed on a decolorizing shaker and reacted at room temperature under aerobic conditions for 1 hour. After the reaction was completed, the membrane surface was rinsed with deionized water to remove residual dopamine solution. Subsequently, the membrane was immersed in anhydrous ethanol for 20 minutes to remove loosely adhered polymerized dopamine, resulting in a coated modified polyethersulfone ultrafiltration membrane, which was stored in deionized water for later use.
[0053] The polyvinyl alcohol grafted with compound A-2 prepared above was dissolved in 10 mM Tris-HCl buffer (pH approximately 8.5) to prepare a modified solution with a concentration of 2 mg / mL. The modified polyethersulfone ultrafiltration membrane prepared above was inverted in the modified solution, ensuring full contact between the membrane surface and the solution. The reaction system was placed in a constant temperature water bath and reacted at 60°C for 1 h. After the reaction was completed, the membrane was removed and thoroughly rinsed with deionized water to remove the polyvinyl alcohol grafted with compound A-2 present on the membrane surface due to physical adsorption. The rinsed membrane was dried in a vacuum drying oven at 40°C to constant weight to obtain the modified polyethersulfone ultrafiltration membrane of this embodiment. The steps and... Figure 1 As shown.
[0054] Example 2: Example 2 includes the following steps: 1. Preparation of polyvinyl alcohol grafted with 3-amino-4-(2-hydroxyphenyl)butyric acid: 10.0 g of polyvinyl alcohol (PVA, degree of polymerization 1800) and 6.2 g of 3-amino-4-(2-hydroxyphenyl)butyric acid (commercially available, Anage Chemicals) were added to a 250 mL three-necked flask equipped with a mechanical stirrer and reflux condenser. 100 mL of dimethyl sulfoxide (DMSO) was added, and the mixture was heated to 80°C and stirred until dissolved. After complete dissolution, 1.0 mL of concentrated sulfuric acid was added dropwise as a catalyst, and the mixture was then heated to 90°C and stirred for 10 h under nitrogen protection. The chemical formula of 3-amino-4-(2-hydroxyphenyl)butyric acid is shown below:
[0055] 2. Preparation of modified polyethersulfone ultrafiltration membrane: A polyethersulfone ultrafiltration membrane (molecular weight cutoff 100,000) was fixed in a clamped reaction vessel. Dopamine hydrochloride was dissolved in 10 mM Tris-HCl buffer to prepare a dopamine solution with a concentration of 8 mg / mL. The dopamine solution was poured into the reaction vessel to completely submerge the membrane. The reaction vessel was placed on a decolorizing shaker and reacted at room temperature under aerobic conditions for 1 hour. After the reaction was completed, the membrane surface was rinsed with deionized water to remove residual dopamine solution. The membrane was then immersed in anhydrous ethanol for 20 minutes to remove loosely adhered polymerized dopamine, resulting in a coated modified polyethersulfone ultrafiltration membrane, which was stored in deionized water for later use.
[0056] The 3-amino-4-(2-hydroxyphenyl)butyric acid-grafted polyvinyl alcohol prepared above was dissolved in 10 mM Tris-HCl buffer to prepare a modified solution with a concentration of 2 mg / mL. The coated modified polyethersulfone ultrafiltration membrane prepared above was inverted in the above modified solution to ensure full contact between the membrane surface and the solution. The reaction system was placed in a constant temperature water bath and reacted at 60°C for 1 h. After the reaction was completed, the membrane was removed and thoroughly rinsed with deionized water to remove the 3-amino-4-(2-hydroxyphenyl)butyric acid-grafted polyvinyl alcohol present on the membrane surface due to physical adsorption. The rinsed membrane was dried in a vacuum drying oven at 40°C to constant weight to obtain the modified polyethersulfone ultrafiltration membrane of this embodiment.
[0057] Example 3: Example 3 includes the following steps: 1. Preparation of glycine-grafted polyvinyl alcohol: 10.0 g of polyvinyl alcohol (PVA, degree of polymerization 1800) and 2.15 g of glycine were added to a 250 mL three-necked flask equipped with a mechanical stirrer and reflux condenser. 100 mL of dimethyl sulfoxide (DMSO) was added, and the mixture was heated to 80°C and stirred to dissolve. After complete dissolution, 1.0 mL of concentrated sulfuric acid was added dropwise as a catalyst, and the mixture was then heated to 90°C and stirred for 10 h under nitrogen protection. The reaction is shown below:
[0058] 2. Preparation of modified polyethersulfone ultrafiltration membrane: A polyethersulfone ultrafiltration membrane (molecular weight cutoff 100,000) was fixed in a clamped reaction vessel. Dopamine hydrochloride was dissolved in 10 mM Tris-HCl buffer to prepare a dopamine solution with a concentration of 8 mg / mL. The dopamine solution was poured into the reaction vessel to completely submerge the membrane. The reaction vessel was placed on a decolorizing shaker and reacted at room temperature under aerobic conditions for 1 hour. After the reaction was completed, the membrane surface was rinsed with deionized water to remove residual dopamine solution. The membrane was then immersed in anhydrous ethanol for 20 minutes to remove loosely adhered polymerized dopamine, resulting in a coated modified polyethersulfone ultrafiltration membrane, which was stored in deionized water for later use.
[0059] The glycine-grafted polyvinyl alcohol prepared above was dissolved in 10 mM Tris-HCl buffer to prepare a modified solution with a concentration of 2 mg / mL. The coated modified polyethersulfone ultrafiltration membrane prepared above was inverted in the modified solution to ensure full contact between the membrane surface and the solution. The reaction system was placed in a constant temperature water bath and reacted at 60°C for 1 h. After the reaction was completed, the membrane was removed and thoroughly rinsed with deionized water. The rinsed membrane was dried in a vacuum drying oven at 40°C to constant weight to obtain the modified polyethersulfone ultrafiltration membrane of this embodiment.
[0060] Example 4: The preparation process of Example 4 is basically the same as that of Example 3, except that an equimolar amount of salicylic acid is used instead of glycine.
[0061] Comparative Example 1: Comparative Example 1 did not modify the polyethersulfone ultrafiltration membrane (molecular weight cutoff 100,000); it was simply cleaned and dried before use.
[0062] Comparative Example 2: A polyethersulfone ultrafiltration membrane (molecular weight cutoff 100,000) was fixed in a clamped reaction vessel. Dopamine hydrochloride was dissolved in 10 mM Tris-HCl buffer to prepare a dopamine solution with a concentration of 8 mg / mL. The dopamine solution was poured into the reaction vessel to completely submerge the membrane. The reaction vessel was placed on a decolorizing shaker and reacted at room temperature under aerobic conditions for 1 h. After the reaction was completed, the membrane surface was rinsed with deionized water to remove residual dopamine solution. Subsequently, the membrane was immersed in anhydrous ethanol for 20 min to remove loosely adhered polymerized dopamine, thus obtaining the coated modified polyethersulfone ultrafiltration membrane of this comparative example.
[0063] Comparative Example 3: Comparative Example 3 includes the following steps: 1. Preparation of compound A-2: The steps here are the same as in Example 1.
[0064] 2. Preparation of modified polyethersulfone ultrafiltration membrane: A polyethersulfone ultrafiltration membrane (molecular weight cutoff 100,000) was fixed in a clamped reaction vessel. Dopamine hydrochloride was dissolved in 10 mM Tris-HCl buffer to prepare a dopamine solution with a concentration of 8 mg / mL. The dopamine solution was poured into the reaction vessel to completely submerge the membrane. The reaction vessel was placed on a decolorizing shaker and reacted at room temperature under aerobic conditions for 1 hour. After the reaction was completed, the membrane surface was rinsed with deionized water to remove residual dopamine solution. The membrane was then immersed in anhydrous ethanol for 20 minutes to remove loosely adhered polymerized dopamine, resulting in a coated modified polyethersulfone ultrafiltration membrane, which was stored in deionized water for later use.
[0065] The compound A-2 prepared above was dissolved in DMSO to prepare a solution with a concentration of 6 mg / mL. The coated modified polyethersulfone ultrafiltration membrane prepared above was inverted in the above solution, ensuring full contact between the membrane surface and the solution. The reaction system was placed in a constant temperature water bath and reacted at 60°C for 1 h. After the reaction was completed, the membrane was removed and thoroughly rinsed with deionized water. The rinsed membrane was dried in a vacuum drying oven at 40°C to constant weight to obtain the modified polyethersulfone ultrafiltration membrane of this comparative example.
[0066] Comparative Example 4: Comparative Example 4 includes the following steps: 1. Preparation of compound A-2: The steps here are the same as in Example 1.
[0067] 2. Preparation of polyvinyl alcohol grafted with compound A-2: The steps here are the same as in Example 1.
[0068] 3. Preparation of modified polyethersulfone ultrafiltration membrane: The polyvinyl alcohol grafted with compound A-2 prepared above was dissolved in 10 mM Tris-HCl buffer to prepare a modified solution with a concentration of 2 mg / mL. The washed polyethersulfone ultrafiltration membrane (molecular weight cutoff 100,000) was inverted in the modified solution to ensure full contact between the membrane surface and the solution. The reaction system was placed in a constant temperature water bath and reacted at 60°C for 1 h. After the reaction was complete, the membrane was removed and thoroughly rinsed with deionized water. The rinsed membrane was dried in a vacuum drying oven at 40°C to constant weight to obtain the modified polyethersulfone ultrafiltration membrane of this comparative example.
[0069] Performance testing: Ethanol swelling stability test: The films of Examples 1-4 and Comparative Examples 1-4 were immersed in a 70% (volume fraction) ethanol aqueous solution, left to stand at 25°C for 72 hours, then removed, rinsed with deionized water and dried. The water contact angle was measured again, and the change in contact angle Δθ was calculated. The values are shown in Table 1.
[0070] Membrane flux and antifouling stability testing: A full-volume filtration device (Millipore ultrafiltration cup, effective membrane area 12.6 cm²) was used. 2 The operating pressure was 0.1 MPa, and the stirring speed was 200 r / min. The feed liquid was a simulated fuel ethanol fermentation broth containing 0.5 g / L peptone (simulating fermentation source proteins and peptides), 0.5 g / L dextran T-500, 5.0 g / L glucose, 0.5 g / L sodium chloride, 0.2 g / L potassium dihydrogen phosphate, 0.3 g / L acetic acid (simulating fermentation by-product organic acids), and 10% (volume fraction) ethanol. The initial flux and the stable flux after 5 h were tested, and the results are shown in Table 2.
[0071] Table 1
[0072] Table 2
[0073] The results above show that the overall performance of Example 1 is significantly better than all other samples. This is because (1) the benzene ring of compound A-2 is embedded in the PVA graft chain to form a rigid structure, which effectively inhibits the swelling and relaxation of the PVA flexible chain segments in the ethanol environment and maintains the long-term stability of the membrane pore size and surface microstructure. (2) the amino group of compound A-2 undergoes a covalent Schiff base / Michael addition reaction with the dopamine coating layer to form a chemical bond, which keeps the graft layer intact under long-term use. (3) the 2-aromatic carboxyl group of compound A-2 is partially ionized in the weakly acidic simulated fermentation broth and works synergistically with the protonation of the 3-position amino group to build a zwitterionic charge barrier on the membrane surface. This barrier generates Donnan repulsion against negatively charged peptone, polysaccharide colloids and acetate and other fermentation source pollutants, which significantly reduces irreversible adsorption, thereby greatly improving the 5-hour stable flux compared with other examples and comparative examples.
[0074] Furthermore, the results above also show that in Example 4, because salicylic acid does not contain amino groups, it cannot be covalently grafted with the dopamine layer. Therefore, the PVA copolymer gradually swells and detaches from the membrane surface, leaving only a dopamine coating on the membrane surface. Thus, its performance is similar to that of Comparative Example 2. Additionally, it can be seen that the contact angle of Comparative Example 1 remains almost unchanged, indicating that the PES matrix itself is resistant to ethanol swelling (but lacks resistance to organic contamination). Moreover, the results above also show that Comparative Example 4 does not include a dopamine coating step, and the PES membrane surface is hydrophobic and lacks active reactive sites, therefore the PVA copolymer cannot form a bond with it; thus, its performance is similar to that of Comparative Example 1.
[0075] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein.
Claims
1. A method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation, characterized in that, The preparation method includes the following steps: Step 1: Prepare amino-containing compound A; Step 2: React compound A obtained in step 1 with polyvinyl alcohol to obtain polyvinyl alcohol grafted with compound A; Step 3: Provide a polyethersulfone ultrafiltration membrane, and use a dopamine solution to coat and modify the polyethersulfone ultrafiltration membrane to obtain a coated and modified polyethersulfone ultrafiltration membrane; Step 4: The coated modified polyethersulfone ultrafiltration membrane prepared in step 3 is placed upside down in a solution containing polyvinyl alcohol grafted with compound A. After reaction, it is rinsed and dried to obtain the modified polyethersulfone ultrafiltration membrane for fuel ethanol separation.
2. The method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation according to claim 1, characterized in that, The compound A has the following structural formula represented by formula IA: Ar1 is selected from substituted or unsubstituted C6-C30 aryl groups, or substituted or unsubstituted 5-30 heteroaryl groups; R1 is selected from hydrogen, nitro, hydroxyl, halogen atom, carboxyl, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy, or ;where R 11 Selected from substituted or unsubstituted C1-C30 alkyl groups and substituted or unsubstituted C1-C30 alkoxy groups; R2 is selected from substituted or unsubstituted C1-C30 alkylene groups. , ,or Among them, R 21 and R 22 Each is independently selected from substituted or unsubstituted C1-C30 alkylene groups.
3. The method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation according to claim 2, characterized in that, The compound A has the following structural formula, represented by formula II-A: Wherein, R1 is selected from hydrogen, nitro, hydroxyl, carboxyl, C1-C10 alkyl, C1-C10 alkoxy, or ;where R 11 Selected from C1-C10 alkyl and C1-C10 alkoxy groups; R2 is selected from C1-C15 alkylene groups. , ,or Among them, R 21 and R 22 Each is independently selected from C1-C15 alkylene groups.
4. The method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation according to claim 3, characterized in that, The compound A has the following structural formula, represented by formula III-A: Wherein, R2 is selected from C1-C5 alkylene groups, or Among them, R 21 and R 22 Each is independently selected from C1-C5 alkylene groups.
5. The method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation according to claim 4, characterized in that, Compound A is selected from the following compounds A-1 or A-2: 、 。 6. The method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation according to claim 5, characterized in that, Compound A-2 was prepared by the following steps: Step 1-a: Using ethyl 3-(3-nitrophenyl)-3-oxopropionate as a raw material, ethyl 3-(3-aminophenyl)-3-oxopropionate is obtained by reduction with iron powder; Step 2-a: The ethyl 3-(3-aminophenyl)-3-oxopropionate obtained in step 1-a is reduced by palladium on carbon to obtain the intermediate product of step 2-a; Step 3-a: The intermediate product of step 2-a is reacted with hydroxylamine hydrochloride and chloral hydrate to generate the intermediate product of step 3-a; Step 4-a: React the intermediate product of step 3-a with concentrated sulfuric acid to generate the intermediate product of step 4-a; Step 5-a: The intermediate product from step 4-a is reacted with sodium hydroxide to obtain compound A-2; 。 7. The method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation according to claim 1, characterized in that, Step 2 includes: Step 1-b: Compound A and polyvinyl alcohol are dissolved in dimethyl sulfoxide and reacted for 8-12 hours under acid catalysis and stirring and heating conditions; Step 2-b: After the reaction is complete, acetone is added to precipitate the polyvinyl alcohol grafted with compound A obtained from the reaction. The precipitate is purified by dissolution and precipitation method to obtain the polyvinyl alcohol grafted with compound A.
8. The method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation according to claim 1, characterized in that, Step 3 includes: Step 1-c: Fix the polyethersulfone ultrafiltration membrane in the reaction tank and pour the dopamine solution into the reaction tank; Step 2-c: Place the reaction tank on a decolorizing shaker and react at room temperature and under aerobic conditions for 0.5-2 hours; Step 3-c: After the reaction is complete, rinse the membrane surface with deionized water to remove residual dopamine solution; immerse the membrane in anhydrous ethanol for 10-40 minutes to obtain the coated modified polyethersulfone ultrafiltration membrane.
9. The method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation according to claim 1, characterized in that, Step 4 includes: Step 1-d: The coated modified polyethersulfone ultrafiltration membrane is inverted in a modified solution containing polyvinyl alcohol grafted with compound A, prepared with Tris buffer; Step 2-d: React at 50-70°C for 1-3 hours; after the reaction is complete, remove the membrane and rinse it with pure water; dry the rinsed membrane to obtain the modified polyethersulfone ultrafiltration membrane for fuel ethanol separation.
10. The method for preparing a modified polyethersulfone ultrafiltration membrane for fuel ethanol separation according to claim 9, characterized in that, In step 1-d, the concentration of polyvinyl alcohol grafted with compound A in the modified solution is 1-10 mg / mL.