Anion exchange resin based on a tertiary amine type nitrogen-containing polysaccharide derivative and a preparation method thereof

Abstract

The application discloses anion exchange resin based on tertiary amine type nitrogen-containing polysaccharide derivatives and a preparation method thereof, and the anion exchange resin has the following general structure formula: [A(B) i ] n -(CL) j -D; in the formula, [A(B) i ] n is a tertiary amine type nitrogen-containing polysaccharide derivative, A is a polysaccharide unit residue, B is a substituent group on the polysaccharide unit residue, and the degree of substitution is i; D is a compound with multiple hydroxyl groups, carboxyl groups or primary amine groups; (CL) j is a crosslinking agent with a functionality of j, which can occur crosslinking reaction with A and D; the resin of the application is insoluble porous double-network tertiary amine polysaccharide derivative formed by simultaneous crosslinking of the tertiary amine type nitrogen-containing polysaccharide derivative and the compound with multiple hydroxyl groups, carboxyl groups or primary amine groups, which has adjustable porous morphology and can effectively improve the adsorption of the material, the double crosslinking network structure can improve the crosslinking density of the material, and meanwhile, the reversible cycle of adsorption and desorption can be realized, and the material has high environmental and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of fine chemical application technology, and more specifically, to an anion exchange resin based on a tertiary amine-type nitrogen-containing polysaccharide derivative and its preparation method. Background Technology

[0002] Ion exchange resins are currently the most researched and widely used ion exchange adsorbents. However, traditional ion exchange resins, such as polystyrene resins and polyacrylate resins, are petroleum-based synthetic polymers, which consume large amounts of fossil resources, and the waste resins are difficult to degrade, causing secondary pollution. Therefore, there is an urgent need to develop a renewable and environmentally friendly new material as a substitute for synthetic resins.

[0003] Biomass polysaccharides, as an abundant renewable resource in nature, are of great significance for achieving sustainable development and promoting green transformation through scientific research and technological development. Among cationic adsorbents, tertiary amine nitrogen-containing polysaccharide derivatives exhibit great potential and application value, mainly due to the fact that the tertiary amine group enables reversible conversion of the hydrophilicity / hydrophobicity and electrophoresis of tertiary amine polysaccharides, thereby allowing for controllable adsorption and desorption. Invention patent ZL201910695375.7 discloses a tertiary amine nitrogen-containing polysaccharide derivative that utilizes the reaction of monochlorotriazine containing a double tertiary amine group with the hydroxyl group on the polysaccharide unit to efficiently introduce double tertiary amine at one site. It has excellent bridging adsorption capacity for negatively charged particles, and the hydrophobicity of the triazine structure further promotes adsorption. By controlling the degree of substitution (Carbohydr.Polym. 2012, 88, 132-138.), molecular weight (Langmuir 2024, 40, 3231-3240.), and hydrophobicity (Environ.Res. 2021, 201, 111489.) of amino polysaccharides, the flocculation and adsorption capacity of amino polysaccharide derivatives were significantly improved. Furthermore, thermosensitive tertiary amine polysaccharide derivatives (Chem.Eng.J. 2021, 413, 127410.) and amphoteric polysaccharide derivatives containing tertiary amines (RSC Adv. 2018, 8, 1274-1280.) can be applied to a wider range of environments. However, the hydrophilic hydroxyl groups and protonable amine groups on the polysaccharides result in poor water resistance of tertiary amine polysaccharides. Easily soluble or highly swollen polysaccharide derivatives are clearly unfavorable for heterogeneous adsorption processes, therefore they cannot be directly used as ion exchange resins.

[0004] Insoluble polysaccharide products can be prepared by forming a three-dimensional network from tertiary amine polysaccharide derivatives through appropriate cross-linking (ZL202210428406.4). Introducing a second cross-linking network into a single cross-linking network can further increase the cross-linking density and reduce the swelling rate (Carbohydr. Polym. 2020, 242, 116320.). On the other hand, the adsorption capacity of ion exchange resins is also affected by the adsorption surface area; ion exchange resins with high adsorption capacity can be prepared by increasing their adsorption surface area through physical pore formation.

[0005] However, there are currently no reports on the preparation of porous and swelling-resistant ion exchange resins using biomass polysaccharide derivatives via a one-step cross-linking method. Therefore, the development of new green and environmentally friendly polysaccharide-based ion exchange resins is of great significance for promoting the high-value utilization of biomass resources and accelerating green transformation. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned defects in the prior art and provide an anion exchange resin based on a tertiary amine nitrogen-containing polysaccharide derivative and its preparation method. The method involves simultaneously crosslinking and pore-forming a water-soluble tertiary amine nitrogen-containing polysaccharide derivative with a compound having multiple hydroxyl, carboxyl, or primary amine groups as a second network in an emulsion template to obtain an insoluble porous double-network tertiary amine polysaccharide derivative. This derivative has an adjustable number of weakly basic amine groups and hydrophobic groups, and its porous morphology with adjustable pore size greatly increases the number of adsorption sites. The double-crosslinked network structure improves the structural stability and water resistance of the material. Furthermore, the electrical properties of the tertiary amine groups on the material can be adjusted according to the environmental pH, enabling reversible cycles of adsorption and desorption.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] An anion exchange resin based on a tertiary amine-type nitrogen-containing polysaccharide derivative, wherein the general structural formula of the anion exchange resin is shown in Formula I:

[0009] [A(B) i ] n -(CL) j -D(Ⅰ)

[0010] In formula I, [A(B)] i ] n It is a tertiary amine type nitrogenous polysaccharide derivative, wherein A is a polysaccharide unit residue, B is a substituent on the polysaccharide unit residue, and the degree of substitution is i; D is a compound having multiple hydroxyl, carboxyl, or primary amine groups; (CL) j It is a crosslinking agent with functionality j, which can undergo crosslinking reactions with both A and D;

[0011] The anion exchange resin is an insoluble porous double-network tertiary amine polysaccharide derivative formed by crosslinking a tertiary amine-type nitrogen-containing polysaccharide derivative and a compound having polyhydroxy, carboxyl or primary amine groups simultaneously.

[0012] Optionally, the pore diameter of the anion exchange resin based on the tertiary amine-type nitrogen-containing polysaccharide derivative is 0.1 μm to 1.0 μm; the porosity of the anion exchange resin based on the tertiary amine-type nitrogen-containing polysaccharide derivative is 17% to 67%.

[0013] Optionally, in formula I, the glycan unit residue A includes one or more of starch, cellulose, hemicellulose, chitin, guar gum, chitosan, xylan, glucomannan, cyclodextrin or polysaccharide unit residues prepared by acid hydrolysis, oxidation, crosslinking.

[0014] Optionally, in formula I, the substituent B on the glycan unit residue has a diamino group with a triazine ring as a bridge group, which can randomly replace the H on -OH or -NH2 at any position on the polysaccharide unit, and the substitution degree 0 < i ≤ 3, preferably, the substitution degree is 0.6 to 0.8. It has the structural general formula shown in formula I-1:

[0015]

[0016] In formula I-1, R1, R2, R3, R4 are each independently selected from -H, C1-C 11 alkyl, C1-C 11 aryl, C1-C8 carboxylic acid, C1-C8 alcohol, C1-C8 thiol or C1-C8 alkoxymethyl. Preferably, R1, R2, R3, R4 are each independently selected from -H, C1-C3 alkyl, C1-C2 aryl, C1-C4 carboxylic acid, C1-C4 alcohol, C1-C4 thiol or C1-C4 alkoxymethyl.

[0017] Optionally, in formula I, the compound D having polyhydroxy, carboxyl or primary amine groups is selected from one or more of C1-C8 polyols, C1-C8 polycarboxylic acids, C1-C8 polyprimary amines and polymers containing hydroxyl, carboxyl, primary amine groups.

[0018] Optionally, the polymers containing hydroxyl, carboxyl, primary amine groups include one or more of polyethylenepolyamine, polyvinyl alcohol, polyethylene glycol, polyacrylic acid, carboxymethyl starch and hydroxyethyl cellulose with a molecular weight of 1000 to 67000, preferably with a molecular weight of 60000 to 67000; the total number of hydroxyl, carboxyl and primary amine groups on the molecular chain of the compound D having polyhydroxy, carboxyl or primary amine groups ≥ 2.

[0019] Optionally, in formula I, the tertiary amine-type nitrogen-containing polysaccharide derivative [A(B) i n ​The mass ratio of compound D, which has multiple hydroxyl, carboxyl, or primary amine groups, to the compound is 1:0.02 to 1:0.2. Preferably, the mass ratio is 1:0.08 to 1:0.1.

[0020] Optionally, in Formula I, the crosslinking agent (CL) j It is a compound containing j alkoxy methyl groups with melamine as a bridging group, wherein the alkoxy groups can be randomly substituted by -OH or amino groups containing active hydrogen on A and D, and it has the general structural formula shown in Formula I-2:

[0021]

[0022] In Equation I-2, R5~R 10 Each of the following is independently selected from -H, -CH2OH, -CH2OCH3, -CH2OCH2CH3, -CH2O(CH2)2CH3 or -CH2O(CH2)3CH3, and R5~R 10 The total number of -H and -CH2OH in the middle is <5.

[0023] Optionally, in Formula I, the tertiary amine type nitrogenous polysaccharide derivative [A(B)] i ] n With crosslinking agent (CL) j The mass ratio is 1:0.05 to 1:0.4. Preferably, the mass ratio is 1:0.2 to 1:0.4.

[0024] This invention also discloses a method for preparing anion exchange resin based on tertiary amine-type nitrogen-containing polysaccharide derivatives as described above, comprising the following steps:

[0025] Tertiary amine-type nitrogenous polysaccharide derivatives [A(B)] i ] n Compound D, which has multiple hydroxyl, carboxyl or primary amine groups, is added to water, and the pH of the solution is adjusted to 2-6 to dissolve it. Then, the oil phase is added for high-speed emulsification to obtain an emulsion template.

[0026] A crosslinking agent (CL) is added to the emulsion template. j After mixing, the mixture is reacted in a closed environment at 20℃~60℃ for 0h~24h. After drying and washing away the oil droplets, the anion exchange resin based on the tertiary amine type nitrogen-containing polysaccharide derivative is obtained.

[0027] Optional, tertiary amine-type nitrogenous polysaccharide derivatives [A(B)] i ] nThe preparation method includes the following steps: a diamino compound containing a monochlorotriazine structure and a polysaccharide are added to a solvent at a molar ratio of 0.1–10:1–10, wherein the polysaccharide is calculated as polysaccharide units. The mixture is stirred and stirred until homogeneous. The reaction is carried out at 0℃–200℃ for 0.1 h–24 h. After the reaction is complete, the polysaccharide is precipitated in methanol or deionized water, filtered, washed with anhydrous methanol, dried, and pulverized to obtain a tertiary amine-type nitrogen-containing polysaccharide derivative [A(B)]. i ] n .

[0028] Optional solvents include water, ethanol, isopropanol, butanol, DMF, or DMSO.

[0029] Optionally, the tertiary amine-type nitrogenous polysaccharide derivative [A(B)] i ] n The mass ratio of water to the feed is 1:1 to 1:20. Preferably, the mass ratio is 1:5 to 1:7.

[0030] Optionally, the oil phase includes one or more of the following: vegetable oil, gasoline, paraffin oil, n-hexane, cyclohexane, toluene, and ethyl acetate.

[0031] Optionally, the volume ratio of the oil phase to water is 1:0.5 to 1:5. Preferably, the volume ratio is 1:3.

[0032] Implementing the embodiments of the present invention will have the following beneficial effects:

[0033] This invention develops a novel tertiary amine-type biomass polysaccharide-based anion exchange resin with a porous, double-crosslinked network structure. The material uses tertiary amine-type biomass polysaccharides as the matrix and main component. The presence of the tertiary amine allows for adsorption under acidic conditions and desorption in alkaline solutions, thus enabling the recycling of the ion exchange resin. Furthermore, the double-crosslinked network structure of this invention has a higher crosslinking density compared to a single-network structure. Simultaneously, the double-crosslinked network structure and the hydrophobic triazine groups improve the water resistance of this ion exchange resin, making it insoluble in water and exhibiting low swelling, thus facilitating its application in various scenarios. The porous structure increases the adsorption specific surface area, thereby enhancing the material's adsorption capacity. Moreover, the product is low in toxicity or non-toxic, biodegradable, and possesses high environmental and economic benefits, making it a highly efficient biomass-based ion exchanger. Attached Figure Description

[0034] Figure 1 a is a flowchart of the preparation of starch-based ion exchange resin in Example 1, and it is also applicable to all examples; Figure 1 b is the reaction equation for preparing starch-based ion exchange resin in Example 1.

[0035] Figure 2a is the infrared spectrum of the starch-based ion exchange resin obtained in Example 1; Figure 2 b is the starch-based ion exchange resin obtained in Example 1. 13 C solid-state nuclear magnetic resonance spectrum; Figure 2 c is the thermogravimetric curve of the starch-based ion exchange resin obtained in Example 1.

[0036] Figure 3 a is a scanning electron microscope image of the non-porous starch-based ion exchange resin obtained in Comparative Example 2. Figure 3 b and 3c are scanning electron microscope images and pore size distribution charts of the porous starch-based ion exchange resin obtained in Example 1. Figure 3 d and 3e are pore size distribution diagrams of the product obtained in Example 1, measured by high-pressure mercury intrusion porosimetry.

[0037] Figure 4 a represents the effect of the degree of substitution of tertiary amine starch on the elastic modulus and viscous modulus of the resulting wet product; Figure 4 b represents the effect of PVA molecular weight on the elastic modulus of the wet product; Figure 4 c represents the effect of PVA67000 addition on the elastic modulus of the wet product; Figure 4 d represents the effect of the amount of crosslinking agent added on the elastic modulus of the wet product.

[0038] Figure 5 a, b, and c are scanning electron microscope images of the porous products obtained when the oil-to-water volume ratio of the emulsion is 1:2, 1:3, and 1:4, respectively. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0040] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0041] The tertiary amine nitrogen-containing starch derivatives #1, #2, and #3 exemplified in the following examples have the following general structural formula:

[0042]

[0043] The above-mentioned tertiary amine nitrogen-containing starch derivatives 1#, 2#, and 3# were prepared according to the method of patent ZL201910695375.7: a diamino compound containing a monochlorotriazine structure was added to starch at a molar ratio of 0.8:1, wherein the starch was calculated as polysaccharide units, and stirred and mixed evenly. The mixture was reacted at 110°C for 8 hours. After the reaction was completed, the starch was precipitated in deionized water, filtered, washed with anhydrous methanol, dried, and pulverized to obtain the above-mentioned tertiary amine nitrogen-containing starch derivatives 1#, 2#, and 3#.

[0044] Example 1

[0045] 2.5g of a tertiary amine-type nitrogen-containing starch derivative (degree of substitution 0.6) and 0.35g of polyvinyl alcohol (PVA67000) with a molecular weight of 67000 Da were mixed and dissolved in 15ml of water. The pH was adjusted to 2 with hydrochloric acid, and 5ml of soybean oil was added. The mixture was then rapidly emulsified using an emulsifier. 0.5g of a crosslinking agent (R5~R5 in structural formula I-2) was added to the emulsion. 10 All components were -CH2OCH3. The mixture was stirred until a gel formed, sealed, and reacted at 40°C for 12 hours. The water was then dried, and oil droplets were washed away with ethyl acetate to obtain a porous anion exchange resin based on 1# tertiary amine-type nitrogen-containing starch. This resin did not swell in pure water, but its swelling rate was 15% after 24 hours in an HCl solution at pH 2.5.

[0046] Figure 1 a is a schematic diagram of the preparation process in Example 1, and 1b is the reaction equation. Figure 2 This is a structural characterization of the product, where 2a is the infrared spectrum and 2b is... 13 The C-type solid-state NMR spectrum is shown, and 2c is the thermogravimetric curve of the product. In the infrared spectrum, the product is observed at 1583 and 810 cm⁻¹. -1 The peak at 1020-1160 cm⁻¹ is a characteristic peak of the triazine ring, while the peak at 1020-1160 cm⁻¹ is a characteristic peak of the triazine ring. -1 The significantly enhanced COC stretching vibration peak at this location indicates the formation of new cross-linked ether bonds. 13 In the C10 NMR spectrum, the C6 peak on the starch polysaccharide unit appears at 58-65 ppm, while in the product this peak is significantly shifted to a lower field, indicating that the -OH on starch C6 forms an ether bond and a cross-linked structure, proving that the target product has been obtained.

[0047] Comparative Example 1

[0048] The only difference between this comparative example and Example 1 is that PVA67000 is not used to construct the second network during the crosslinking process, resulting in an ion exchange resin with a single crosslinked starch network.

[0049] The preparation method was the same as in Example 1. It was found that the resin prepared in Comparative Example 1 did not swell in pure water, but its swelling rate in an HCl aqueous solution with pH=2.5 was 550% after 24 hours. This indicates that the dual-network resin has a tighter cross-linking and better water resistance than the single-network resin.

[0050] Comparative Example 2

[0051] The only difference between this comparative example and Example 1 is that: no emulsion is used as a pore-forming template, that is, no oil phase is added to prepare an oil-in-water emulsion, and the preparation method is the same as in Example 1, thereby obtaining a non-porous tertiary amine starch-based ion exchange resin.

[0052] Figure 3 a and 3b are scanning electron microscope (SEM) images of the starch-based ion exchange resins prepared in Comparative Example 2 and Example 1, respectively. The product of Comparative Example 2 consists of solid, blocky particles, while the product obtained in Example 1 has dense pores and... Figure 3 The CE diagram shows that the pore size of the porous structure is about 1 μm, thus increasing the specific surface area of ​​the resin by creating pores.

[0053] Examples 2-9

[0054] The method is the same as in Example 1, that is, the tertiary amine type nitrogenous polysaccharide derivative [A(B)] i ] n The polysaccharide unit residue A in the resin can be replaced with one of the polysaccharide unit residues from cellulose, hemicellulose, chitin, guar gum, chitosan, xylan, glucomannan, or cyclodextrin to obtain anion exchange resins with different biomass polysaccharide bases.

[0055] Example 10

[0056] 2.5g of a tertiary amine-type nitrogen-containing starch derivative (2#, degree of substitution 0.6) and 0.35g of PVA67000 were dissolved in 15ml of water. The pH was adjusted to 2 with hydrochloric acid, and 5ml of soybean oil was added. The mixture was then rapidly emulsified using an emulsifier. 0.5g of a crosslinking agent (R5~R5 in structural formula I-2) was added to the emulsion. 10 All components were -CH2OCH3. The mixture was stirred until a gel formed, sealed, and reacted at 40°C for 12 hours. The water was then dried, and the oil droplets were washed away with ethyl acetate to obtain a porous, highly hydrophobic anion exchange resin based on a 2# tertiary amine-type nitrogen-containing starch derivative.

[0057] Examples 11-18

[0058] The method is the same as in Example 10, except that the starch polysaccharide unit residues in the 2# tertiary amine type nitrogen-containing starch derivative are replaced with one of the polysaccharide unit residues of cellulose, hemicellulose, chitin, guar gum, chitosan, xylan, glucomannan, or cyclodextrin to obtain highly hydrophobic anion exchange resins with different biomass polysaccharide bases.

[0059] Example 19

[0060] Dissolve 2.5g of a tertiary amine-type nitrogen-containing starch derivative (3#) with a degree of substitution of 0.6 and 0.35g of PVA67000 in 15ml of water. Adjust the pH to 1.5 with hydrochloric acid, add 5ml of soybean oil, and emulsify rapidly using an emulsifier. Add 0.5g of a crosslinking agent (R5~R5 in structural formula I-2) to the emulsion. 10 All components were -CH2OCH3. The mixture was stirred until a gel formed, sealed, and reacted at 40°C for 12 hours. The water was then dried, and the oil droplets were washed away with ethyl acetate to obtain a porous zwitterionic exchange resin based on 3# tertiary amine-type nitrogen-containing starch.

[0061] Examples 20-27

[0062] The method is the same as in Example 19, except that the starch polysaccharide unit residues in the 3# tertiary amine type nitrogen-containing starch derivative are replaced with one of the polysaccharide unit residues of cellulose, hemicellulose, chitin, guar gum, chitosan, xylan, glucomannan, or cyclodextrin to obtain zwitterionic exchange resins with different biomass polysaccharide bases.

[0063] Examples 28-30

[0064] The method was the same as in Example 1, except that the 1# tertiary amine nitrogen-containing starch derivative with a degree of substitution of 0.6 was replaced with 1# tertiary amine nitrogen-containing starch derivatives with degrees of substitution of 0.2, 0.4, and 0.8, respectively, to obtain tertiary amine starch-based anion exchange resins with different total exchange capacities. The elastic modulus G' of the crosslinked wet product was measured using an advanced rheometer, as shown in the figure. Figure 4 As shown in Figure a, the elastic modulus of the wet product gradually decreases with the increase of the degree of substitution. This indicates that the increase of substituent B leads to the increase of steric hindrance of the -OH group on the polysaccharide, which is not conducive to the cross-linking process.

[0065] Examples 31-34

[0066] By using PVA of different molecular weights, namely PVA30000, PVA10000, PVA5000, and PVA1000 (alternative to PVA67000 in Example 1), crosslinked products with different strengths were obtained. The elastic modulus G' of the wet crosslinked products was characterized using an advanced rheological instrument. Figure 4 As shown in b, the higher the molecular weight of PVA, the higher the wet product G', indicating that there are physical interactions such as chain entanglement and interpenetration between PVA and the polysaccharide chain. Therefore, the crosslinking strength can be controlled by adjusting the molecular weight of PVA.

[0067] Examples 35-39

[0068] The method is the same as in Example 1, except that the amount of PVA67000 added is changed. Specifically, 3.0 wt%, 6.7 wt%, 11.2 wt%, 14.7 wt%, and 19.1 wt% of PVA67000 are added respectively, resulting in wet products with different elastic moduli G'. Figure 4 As shown in Figure c, this indicates that the amount of PVA added has a significant impact on the strength of the product.

[0069] Examples 40-45

[0070] By replacing PVA67000 in Example 1 with ethylenediamine, diethylenetriamine, polyethylene glycol, polyacrylic acid, carboxymethyl starch, and hydroxyethyl cellulose, a dual-network starch-based anion exchange resin with different second networks was obtained.

[0071] Example 46

[0072] 2.5g of a tertiary amine-type nitrogen-containing starch derivative (degree of substitution 0.6) and 0.35g of oxalic acid were dissolved in 15ml of water. Oxalic acid, acting as an acidifier and second network, reduces the use of hydrochloric acid. Then, 5ml of soybean oil was added and emulsified rapidly using an emulsifier. 0.5g of a crosslinking agent (R5-R5 in structural formula I-2) was added to the emulsion. 10 All components were -CH2OCH3. The mixture was stirred until a gel formed, sealed, and reacted at 40°C for 12 hours. The water was then dried, and the oil droplets were washed away with ethyl acetate to obtain a porous anion exchange resin based on a 1# tertiary amine-type nitrogen-containing starch derivative.

[0073] Examples 47-48

[0074] The method is the same as in Example 46, except that oxalic acid is replaced with malonic acid and citric acid, thereby obtaining an anion exchange resin based on a 1# tertiary amine nitrogen-containing starch derivative that contains ester groups.

[0075] Examples 49-50

[0076] The method is the same as in Example 46, except that the volume ratio of oil to water in the emulsion is changed from 1:3 to 1:2 and 1:4, respectively, to obtain porous starch-based ion exchange resins with different pore morphologies and porosities. Figure 5 These are scanning electron microscope images of the products obtained with different oil-to-water volume ratios. It can be seen that the products all have a dense porous structure.

[0077] Example 51

[0078] 2.5g of a tertiary amine-type nitrogen-containing starch derivative (substitution degree 0.6) and 0.35g of PVA67000 were dissolved in 15ml of water. The pH was adjusted to 2 with hydrochloric acid, and 5ml of cyclohexane was added. The mixture was then rapidly emulsified using an emulsifier. 0.5g of a crosslinking agent (R5-R5 in structural formula I-2) was added to the emulsion. 10 All components were -CH2OCH3. The mixture was stirred until a gel formed, sealed, and reacted at 40°C for 12 hours. The water was then dried, and the cyclohexane was washed away with ethanol to obtain a porous anion exchange resin based on a 1# tertiary amine-type nitrogen-containing starch derivative.

[0079] Examples 52-53

[0080] The method is the same as in Example 51, except that cyclohexane is replaced with n-hexane and ethyl acetate is used as the oil phase of the emulsion template, and a porous starch-based ion exchange resin is obtained in the same way.

[0081] Examples 54-58

[0082] The method is the same as in Example 51, except that the amount of crosslinking agent added is changed to account for 9 wt%, 19 wt%, 25 wt%, 30 wt%, and 40 wt% of the total mass fraction of the reactants. Starch-based ion exchange resins with different degrees of crosslinking are obtained. The elastic modulus G' of the wet product is as follows: Figure 4 As shown in d, the highest degree of crosslinking and elastic modulus are achieved when the amount of crosslinking agent is 25wt%.

[0083] Examples 59-60

[0084] The method is the same as in Example 51, except that the highly methylated crosslinking agent (R5~R in Formula I-2) is used. 10 All of them (-CH2OCH3) were replaced with crosslinking agents with high imino content (R5~R5 of Formula I-2). 10 (At least 1-3 of them are -H, the rest are -CH2OCH3) and crosslinking agents with high hydroxymethyl content (R5~R5 of formula I-2) 10 At least 1-3 of them are -CH2OH, and the rest are -CH2OCH3), to obtain tertiary amine starch-based anion exchange resins with different degrees of crosslinking.

[0085] Test Example 1

[0086] First, prepare 100 ml of a 2 g / L reactive brilliant blue X-BR dye solution in an Erlenmeyer flask and adjust the pH to 2.0. Weigh 0.1 g of the starch-based ion exchanger prepared in Example 1 and add it to the Erlenmeyer flask, then shake it in a constant-temperature shaker at 25°C to ensure sufficient adsorption. After 2 hours, take the supernatant and measure the remaining dye concentration on a UV-Vis microscope to calculate the adsorption capacity. The results show that the maximum adsorption capacity of this ion exchanger is 1560 mg / g. Under the same conditions, the adsorption capacity of the non-porous starch-based ion exchanger obtained in Comparative Example 3 is only 200 mg / g.

[0087] The adsorbed ion exchanger was filtered and collected, and then desorbed using a Na₂CO₃ solution containing 20%–50% ethanol. The desorption rate increased from 67% to 95% with increasing ethanol concentration. The desorbed ion exchanger was subjected to ten cycles of adsorption and desorption. After ten cycles, the adsorption capacity of the exchanger was 1390 mg / g.

[0088] The remaining embodiments of this invention have the same effect as Embodiment 1.

[0089] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An anion exchange resin based on a tertiary amine-type nitrogen-containing polysaccharide derivative, characterized in that, The general structural formula of the anion exchange resin is shown in Formula I: [A(B) i ] n -(CL) j -D(Ⅰ) In formula I, [A(B)] i ] n It is a tertiary amine type nitrogenous polysaccharide derivative, wherein A is a polysaccharide unit residue, B is a substituent on the polysaccharide unit residue, and the degree of substitution is i; D is a compound having multiple hydroxyl, carboxyl, or primary amine groups; (CL) j It is a crosslinking agent with functionality j, which can undergo crosslinking reactions with both A and D; The anion exchange resin is an insoluble porous double-network tertiary amine polysaccharide derivative formed by cross-linking a tertiary amine type nitrogen-containing polysaccharide derivative with a compound having multiple hydroxyl, carboxyl or primary amine groups. In Formula I, the substituent B on the polysaccharide unit residue has a diamine group with a triazine ring as a bridging group, which can randomly replace the H on the -OH or -NH2 at any position on the polysaccharide unit, with a degree of substitution of 0. In Formula I, the compound D having multiple hydroxyl, carboxyl or primary amine groups is selected from polymers containing hydroxyl, carboxyl or primary amine groups. In Equation I-1, R1, R2, R3, and R4 are each independently selected from -H or C1~C 11 alkyl; The polymers containing hydroxyl, carboxyl, and primary amine groups include one or more of polyethylene polyamine, polyvinyl alcohol, polyethylene glycol, polyacrylic acid, carboxymethyl starch, and hydroxyethyl cellulose. The total number of hydroxyl, carboxyl, and primary amine groups on the molecular chain of compound D, which has multiple hydroxyl, carboxyl, or primary amine groups, is ≥2. The anion exchange resin based on tertiary amine nitrogen-containing polysaccharide derivatives has a pore size of 0.1 μm to 1.0 μm and a porosity of 17% to 67%. In Formula I, the crosslinking agent (CL) j It is a compound containing j alkoxy methyl groups with melamine as a bridging group, wherein the alkoxy groups can be randomly substituted by -OH or amino groups containing active hydrogen on A and D, and it has the general structural formula shown in Formula I-2: In Equation I-2, R5~R 10 Each of the following is independently selected from -H, -CH2OH, -CH2OCH3, -CH2OCH2CH3, -CH2O(CH2)2CH3 or -CH2O(CH2)3CH3, and R5~R 10 The total number of -H and -CH2OH groups is <5; In Formula I, the tertiary amine-type nitrogenous polysaccharide derivative [A(B)] i ] n The mass ratio of compound D, which has multiple hydroxyl, carboxyl, or primary amine groups, to compound D is 1:0.02 to 1:0.

2. In Formula I, the tertiary amine-type nitrogenous polysaccharide derivative [A(B)] i ] n With crosslinking agent (CL) j The mass ratio is 1:0.05~1:0.

4.

2. The anion exchange resin based on a tertiary amine-type nitrogen-containing polysaccharide derivative according to claim 1, characterized in that, In Formula I, the polysaccharide unit residue A includes one or more of the following: starch, cellulose, hemicellulose, chitin, guar gum, chitosan, xylan, glucomannan, cyclodextrin, or polysaccharide unit residues prepared by acid hydrolysis, oxidation, or cross-linking.

3. The anion exchange resin based on a tertiary amine-type nitrogen-containing polysaccharide derivative according to claim 1, characterized in that, Includes the following steps:

4. A method for preparing anion exchange resin based on a tertiary amine-type nitrogen-containing polysaccharide derivative as described in any one of claims 1-3, characterized in that, The oil phase includes one or more of the following: vegetable oil, gasoline, paraffin oil, n-hexane, cyclohexane, toluene, and ethyl acetate; Tertiary amine-type nitrogenous polysaccharide derivatives [A(B)] i ] n Compound D, which has multiple hydroxyl, carboxyl or primary amine groups, is added to water, and the pH of the solution is adjusted to 2-6 to dissolve it. Then, the oil phase is added for high-speed emulsification to obtain an emulsion template. A crosslinking agent (CL) is added to the emulsion template. j After mixing, the mixture is reacted in a closed environment at 20℃~60℃ for 12h~24h, dried and washed to remove oil droplets, to obtain the anion exchange resin based on the tertiary amine type nitrogen-containing polysaccharide derivative.

5. The preparation method according to claim 4, characterized in that, The tertiary amine-type nitrogenous polysaccharide derivative [A(B)] i ] n The mass ratio of water to water is 1:1 to 1:20; The volume ratio of the oil phase to water is 1:0.5 to 1:

5. ​

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