Preparation method and application of high-affinity MOFs boron affinity molecularly imprinted hydrogel adsorbent

Abstract

The invention discloses a preparation method and application of a high-affinity MOFs (Metal-Organic Frameworks) boron affinity molecularly imprinted hydrogel adsorbent. According to the invention, MOFs are modified by cellulose nanocrystals so as to enhance the surface functionalization of the MOFs; preparing a sulfydryl functionalized covalent organic framework microsphere; the preparation method comprises the following steps: by taking hybrid MOFs as Pickering particles, preparing a high-affinity MOFs-based boron affinity imprinted hydrogel adsorbent by combining emulsion interface crosslinking with an RAFT (reversible addition fragmentation chain transfer) imprinting strategy; the adsorbent is applied to selective adsorption of NRG in agricultural wastewater. The polymer with the boron affinity imprinting cavity is synthesized through the RAFT emulsion microreactor, rich sites are provided for selective adsorption, the mass transfer rate is remarkably increased, and the adsorption capacity of the polymer is improved. It is worthy of notice that the adsorbent shows a remarkable specific advantage in NRG adsorption and separation links, and an adsorption material with a good application prospect is provided for promoting the industrial separation process of NRG.

Description

Technical Field

[0001] This invention belongs to the field of environmental materials technology. It innovatively integrates the multi-interface crosslinking strategy of green Piktarin high internal phase emulsion with one-step RAFT technology, and uses hybrid solid particles as stabilizers to successfully prepare a high-affinity MOF boron affinity molecularly imprinted hydrogel adsorbent, which is then applied to the purification process of naringin in agricultural environmental waste. Background Technology

[0002] Naringin (NRG), a high-value bioactive compound, is widely found in citrus fruit processing byproducts, with significant differences in content across different parts of the pomelo—approximately 70% of the total content in the peel. It possesses excellent biomedical and industrial properties, including antioxidant, antitumor, anti-inflammatory, and ability to improve diabetes and its complications. However, efficient extraction of naringin from agricultural waste remains a key research challenge. Traditional extraction techniques, such as adsorption, Soxhlet extraction, and reflux extraction, generally suffer from high energy consumption, large amounts of organic solvents, long extraction times, and lack of reusability, leading to high costs, poor selectivity, and environmental pollution, failing to meet the demands for efficient and green extraction. The molecular structure of naringin promotes the development of borate affinity, forming a specific reversible covalent bond with the cis-dihydroxy structure of naringin (NRG). This innovative method opens up new possibilities for the preparation of boron affinity adsorbents for NRG separation. Meanwhile, molecularly imprinted polymers (MIPs) have attracted much attention in the field of separation technology due to their ability to accurately recognize target molecules, excellent stability, and wide range of applications. Combining boron affinity with MIPs can fully leverage two major technical advantages: firstly, relying on boric acid affinity imprinting recognition sites, high specificity and selectivity for naringin can be achieved; secondly, rapid mass transfer kinetics ensure that the adsorbent efficiently and rapidly captures target molecules, perfectly suited for the selective separation of naringin. Furthermore, the rapid mass transfer kinetics enable boron affinity imprinted polymers to capture molecules efficiently and rapidly, making them very suitable for NRG selective separation applications. Developed affinity materials include cellulose nanocrystals, silica, and carbon nanotubes. However, most materials share common defects: small specific surface area leading to insufficient adsorption sites, slow mass transfer rate affecting extraction efficiency, and unreachable effective contact sites reducing recognition accuracy, ultimately resulting in poor adsorption performance and failing to overcome the bottlenecks of traditional extraction technologies.

[0003] Metal-organic frameworks (MOFs) are a novel class of porous coordination polymers formed by coordination interactions between metal ions and organic ligands. They possess characteristics such as tunable pore size, ultra-large specific surface area, high porosity, and large pore volume, making them a research hotspot in the field of separation technology. Two-dimensional porous MOF nanosheets, in particular, not only have excellent chemical composition and ultra-large specific surface area but also allow for adjustable pore size, demonstrating enormous application potential in the separation field. Cellulose nanocrystals (CNCs) are condensation polymers with advantages such as low cost, biodegradability, recyclability, and non-toxicity, perfectly meeting the dual requirements of environmental protection and economy in green extraction technology. Therefore, this invention prepares a boron affinity-imprinted adsorbent by combining MOFs and CNCs to form CNCs / MOFs hybrid solid particles.

[0004] Pickering high internal phase emulsions, as novel emulsion systems, have been widely used in the preparation of functional separation materials. High internal phase emulsions are defined as emulsions where the dispersed phase volume accounts for more than 74.5% of the total volume. Traditional high internal phase emulsions have significant limitations: to suppress droplet flocculation and maintain system stability, they typically require the addition of 5-50 wt% high-concentration surfactants, which poses potential environmental risks. Therefore, this invention focuses on Pickering high internal phase emulsions as an alternative system. In the Pickering high internal phase emulsion system, natural solid particles can spontaneously and irreversibly adsorb at the liquid-liquid interface, forming a dense interfacial protective film. This structure significantly improves the overall stability of the emulsion. Summary of the Invention

[0005] This invention utilizes a Pickering high internal phase emulsion as a microreactor to prepare boron affinity molecularly imprinted polymer adsorbents via molecular imprinting technology and emulsion template method, which are then used for the specific separation and enrichment of naringin molecules. Specifically, firstly, CNCs@DDMAT with RAFT initiation function are reacted with MIL-101 (Fe) via a solvothermal reaction to obtain hybrid MOF solid particles (MCNCs@DDMAT). To achieve NRG enrichment under neutral conditions, a novel ionic liquid, boric acid (ILB), is introduced. Then, using Artemisia argyi oil (AAO) as the oil phase, NRG as the template molecule, and ILB as the functional monomer, a high affinity MOF boron affinity molecularly imprinted adsorbent (PHs@ILB-MIPs) is prepared via one-step RAFT emulsion polymerization and used for the selective separation and purification of NRG molecules.

[0006] A method for preparing a high-affinity MOF boron affinity molecularly imprinted hydrogel adsorbent includes the following steps:

[0007] (1) Preparation of Pickering stable particles MCNCs@DDMAT:

[0008] Cellulose nanocrystals (CNCs) were added to deionized water under a nitrogen atmosphere. Then, isophorone diisocyanate and HO-NAGA-OH were injected into the solution using a syringe. The reaction system was then subjected to a first reaction at 60°C for 24 hours. After the reaction, the mixture was centrifuged, dialyzed with deionized water, and freeze-dried. The crude product was then dispersed in chloroform along with 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid. Ethylenediaminetetraacetic acid (EDC) and dimethylcarbamate (DMAP) were added under magnetic stirring, and a second reaction was carried out at 35–45°C for 3–5 days. The solvent was then removed, and a yellow precipitate was obtained by rotary evaporation. This precipitate was dialyzed in deionized water to remove unreacted substances. Finally, the product was obtained by freeze-drying and named CNCs@DDMAT.

[0009] Ferric chloride hexahydrate was dispersed in N,N-dimethylformamide and subjected to ultrasonic treatment to obtain solution A;

[0010] Then, phthalic acid was dispersed in N,N-dimethylformamide and ultrasonically treated to obtain solution B;

[0011] CNCs@DDMAT was added to solution B, and the mixture was magnetically stirred to ensure thorough dispersion. Solution A was then added. Finally, the mixture was transferred to a Teflon-coated stainless steel autoclave and subjected to a third heating reaction at 100–110 °C for 20–32 h. After cooling to room temperature, the product was centrifuged to obtain a yellow precipitate. This precipitate was washed several times with N,N-dimethylformamide and ethanol, and dried at 80 °C for 12 h to obtain the final product, named MCNCs@DDMAT.

[0012] In step (1), the ratio of cellulose nanocrystals, isophorone diisocyanate, HO-NAGA-OH, 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid, ethylenediaminetetraacetic acid (EDC), and dimethylcarbamate (DMAP) is 200 mg: 20 mg: 40 mg: 100 mg: 0.68 g: 1.4 g;

[0013] In step (1), the ratio of ferric chloride hexahydrate, phthalic acid and CNCs@DDMAT is 198.6 mg: 62.3 mg: 30 mg;

[0014] (2) Preparation of 3-(4-boronbenzyl)-1-vinyl-1H-imidazol-3-bromoionic liquid boric acid (ILB)

[0015] 4-(bromoethyl)phenylboronic acid was added to acetonitrile and sonicated. Then, 1-vinylimidazole was added dropwise. The mixture was then placed in an oil bath at 80-90°C and stirred and refluxed for 18 h. After the reaction was completed, anhydrous diethyl ether was added. A white solid precipitate was formed and the crude product was collected. Finally, the product was dried at 60°C for 6 h to obtain the final product, which was named ILB.

[0016] In step (2), the ratio of 4-(bromoethyl)phenylboronic acid, acetonitrile and 1-vinylimidazole is 10 mmol: 80 mL: 40 mmol;

[0017] (3) Preparation of porous imprinted and non-imprinted hydrogels (PHs@ILB-MIPs and PHs@ILB-NIPs)

[0018] First, MCNCs@DDMAT, 3-(4-boronbenzyl)-1-vinyl-1H-imidazol-3-bromoionic liquid borate ILB and template molecule naringin NRG were dispersed in deionized water. Then, acrylamide, N,N'-methylenebisacrylamide and potassium persulfate were added to the above aqueous phase to obtain an aqueous phase.

[0019] Subsequently, Artemisia argyi oil (oil phase) and Tween 80 were added to the aqueous phase and stirred evenly using a high-speed stirrer. The resulting O / W emulsion was then transferred to a mold, and nitrogen gas was purged for 15-20 minutes. The polymerization reaction was carried out at 60-65°C for 24-36 hours. After the reaction, the eluent was eluted in a methanol / acetic acid mixed solution until no naringin NRG was found in the eluent. Then, the unreacted oil phase was eluted with pure ethanol. Finally, the crude product was dried at 40°C for 24 hours to obtain the final product, a high-affinity MOF boron affinity molecularly imprinted hydrogel adsorbent, named PHs@ILB-MIPs.

[0020] Non-imprinted materials were prepared using the same synthesis process as imprinted polymers, except that the template molecule NRG was not added to the reaction system. After elution and drying, the final product was obtained and named PHs@ILB-NIPs.

[0021] In step (3),

[0022] The ratio of MCNCs@DDMAT, ILB, NRG, deionized water, acrylamide, N,N'-methylenebisacrylamide and potassium persulfate is 100 mg: 0.1 mmol: 0.025 mmol: 1.0 mL: 200 mg: 20 mg: 10 mg;

[0023] The ratio of ILB, Artemisia argyi oil, and Tween 80 used was 0.1 mmol: 4 mL: 0.1 mL;

[0024] In the methanol / acetic acid mixed solution, the volume ratio of methanol to acetic acid is 7:3;

[0025] The high affinity MOFs boron affinity molecularly imprinted hydrogel adsorbent prepared in this invention is used for the selective separation of the flavonoid compound naringin NRG.

[0026] The high-affinity MOFs boron affinity molecularly imprinted hydrogel adsorbent prepared in this invention was used for the selective separation of the o-dihydroxyflavone compound naringin NRG.

[0027] The above technical solution is only one optimal and feasible technical solution shown in this invention. The scope of protection of this invention is not limited to this. Those skilled in the art can reasonably adjust the technical design according to actual needs.

[0028] The adsorption principle of this invention is:

[0029] The adsorbent of this invention can selectively capture NRG from agricultural waste solutions containing various cis-dihydroxy interfering substances. Specifically, adjacent hydroxyl groups in NRG specifically form stable five- or six-membered cyclic esters with boric acid groups in the adsorbent, while other interfering substances remain in the original solution. Therefore, NRG can specifically bind to the imprinted cavity of the adsorbent, achieving highly selective adsorption of NRG in agricultural wastewater through covalent / non-covalent interactions; while other interfering substances remain in the waste solution because they cannot enter the imprinted cavity, thereby enhancing the selective adsorption capacity of NRG in agricultural wastewater.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) The present invention prepares a MOF boron affinity molecularly imprinted hydrogel adsorbent based on emulsion polymerization. The adsorbent has a large specific surface area, which can effectively improve the specific adsorption capacity of the adsorbent, and also has excellent emulsification properties.

[0032] (2) The adsorbent of the present invention has the characteristics of high mass transfer efficiency, fast adsorption rate, excellent dispersibility, high utilization rate of effective sites, strong mechanical stability, resistance to loss and low leakage.

[0033] (3) The adsorbent of the present invention uses commercially available raw materials, the preparation process is simple and easy to carry out, and it has a wide adaptability to different working conditions and good industrial production adaptability. Attached Figure Description

[0034] To more clearly illustrate the technical path of the present invention, the accompanying drawings used in the embodiments (Embodiment 1, Embodiment 2, Embodiment 3) will be described below. The accompanying drawings described below are now used as embodiments of the present invention, and those skilled in the art can obtain the drawings according to their needs without creative effort. Wherein:

[0035] Figure 1 These are TEM images of CNCs (Fig. a1) and CNCs@DDMAT (Fig. a2) in Example 1;

[0036] Figure 2 SEM scans of MIL-101(Fe) (Figure a1) and MCNCs@DDMAT (Figure a2) prepared in Example 1;

[0037] Figure 3 SEM scans of PHs@ILB-MIPs (Fig. a1, Fig. a2) and PHs@ILB-NIPs (Fig. b1, Fig. b2) prepared in Example 1;

[0038] Figure 4 The image shows the EDS energy dispersive spectroscopy (EDS) analysis of the PHs@ILB-MIPs adsorbent prepared in Example 1.

[0039] Figure 5 The infrared spectra of PHs@ILB-MIPs and PHs@ILB-NIPs prepared in Example 1 are shown below.

[0040] Figure 6 The adsorption kinetic fitting curves of PHs@ILB-MIPs (Figure a) and PHs@ILB-NIPs (Figure b) prepared in Example 2 are shown.

[0041] Figure 7 This is the adsorption isotherm curve of the MOFs boron affinity molecularly imprinted adsorbent (PHs@ILB-MIPs) in Example 2;

[0042] Figure 8 This is a bar graph showing the competitive adsorption of the adsorbents (PHs@ILB-MIPs and PHs@ILB-NIPs) in Example 3. Detailed Implementation

[0043] To make the research objectives, features, and results of this invention more easily understood, the following detailed explanation of examples of this invention is provided in conjunction with the specification.

[0044] Example 1

[0045] A method for preparing a high-affinity MOF boron affinity molecularly imprinted hydrogel adsorbent includes the following steps:

[0046] (1) Preparation of Pickering stable particles MCNCs@DDMAT:

[0047] Preparation of CNCs@NAGA particles:

[0048] 0.20 g of cellulose nanocrystals (CNCs) were placed in a 100 mL three-necked round-bottom flask under a nitrogen atmosphere. Then, 40 mL of deionized water was added to the system. Next, 0.02 g of isophorone diisocyanate and 0.04 g of HO-NAGA-OH (dissolved in 1.0 mL of water) were injected into the solution using a syringe, and the reaction system was then incubated at 60 °C for 24 hours. After centrifugation, the mixture was dialyzed against deionized water with a molecular weight cutoff of 12000 Daltons for 2 days. Finally, the product was freeze-dried for 24 hours and named CNCs@NAGA.

[0049] Preparation of CNCs@DDMAT particles:

[0050] 0.20 g of CNCs@NAGA nanocomposite material was dispersed with 0.1 g of 2-(dodecyltrithiocarbonate)-2-methylpropionic acid in 60 mL of chloroform. Then, 0.68 g of ethylenediaminetetraacetic acid (EDC) and 1.4 g of dimethylcarbamate (DMAP) were added under magnetic stirring, and the reaction was carried out at 35 °C for 3 days. The solvent was then removed, and a yellow precipitate was obtained by rotary evaporation. This precipitate was dialyzed against deionized water with a molecular weight cutoff of 12,000 Daltons for 3 days to remove unreacted substances. Finally, the final product, named CNCs@DDMAT, was obtained by freeze-drying for 24 hours.

[0051] Preparation of Pickering Stable Particles MCNCs@DDMAT:

[0052] 198.6 mg of ferric chloride hexahydrate was dispersed in 2 mL of N,N-dimethylformamide and sonicated for 2 min. Then, 62.3 mg of phthalic acid was dispersed in 2.5 mL of DMF and sonicated for 3 min. 30 mg of CNCs@DDMAT was added to the N,N-dimethylformamide solution containing phthalic acid, and the mixture was magnetically stirred for 3 h to ensure thorough dispersion of CNCs@DDMAT in the N,N-dimethylformamide. The ferric chloride hexahydrate and phthalic acid N,N-dimethylformamide solutions were then mixed under high-speed magnetic stirring. Finally, the mixture was transferred to a Teflon stainless steel autoclave and heated at 110 °C for 20 h. After cooling to 25 °C, the product was centrifuged to obtain a yellow precipitate. The precipitate was washed three times with N,N-dimethylformamide and ethanol, and dried at 80 °C for 12 h to obtain the final product, named MCNCs@DDMAT.

[0053] In contrast, MIL-101(Fe) was prepared separately:

[0054] 198.6 mg of ferric chloride hexahydrate was dispersed in 2 mL of N,N-dimethylformamide and sonicated for 2 min to obtain solution A; 62.3 mg of phthalic acid was dispersed in 2.5 mL of N,N-dimethylformamide and sonicated for 3 min to obtain solution B; then solutions A and B were mixed and stirred thoroughly with a high-speed magnetic stirrer. Finally, the mixture was transferred to a reactor and polymerized at 110 °C for 20 h. After cooling the product to 25 °C, centrifugation yielded a yellow precipitate. The precipitate was washed three times with N,N-dimethylformamide and ethanol, and dried at 80 °C for 12 h to obtain the product, named MIL-101(Fe).

[0055] (2) Preparation of 3-(4-boronbenzyl)-1-vinyl-1H-imidazol-3-bromoionic liquid boric acid (ILB):

[0056] 10 mmol of 4-(bromoethyl)phenylboronic acid was placed in a round-bottom flask, and 80 mL of acetonitrile was added. The mixture was sonicated for 3 minutes. Then, 40 mmol of 1-vinylimidazole was added dropwise, and the flask was placed in an oil bath at 80 °C, stirred, and refluxed for 18 h. After the reaction was complete, anhydrous diethyl ether was added, and a white solid precipitate was collected. Finally, the crude product was dried at 60 °C for 6 h to obtain the final product, named ILB.

[0057] (3) Preparation of porous imprinted and non-imprinted hydrogels (PHs@ILB-MIPs and PHs@ILB-NIPs):

[0058] First, 100 mg MCNCs@DDMAT, 0.1 mmol ILB, and 0.025 mmol naringin were dispersed in 1.0 mL of deionized water. Then, 200 mg acrylamide, 20 mg N,N'-methylenebisacrylamide, and 10 mg potassium persulfate were added to the aqueous phase. Subsequently, 4 mL of Artemisia argyi oil (oil phase) and 0.1 mL of Tween 80 were added to the aqueous phase, and the mixture was stirred uniformly for 3 minutes using a high-speed stirrer. The resulting O / W emulsion was transferred to a mold, purged with nitrogen for 15 minutes, and polymerized at 60 °C for 24 h. After the reaction was complete, the template molecules (NRG) were eluted with a methanol / acetic acid (7 / 3, v / v) mixture until no NRG remained in the eluent. The unreacted oil phase was then eluted with pure ethanol to obtain the crude product. Finally, the crude product was dried at 40 °C for 24 h to obtain the final product, named PHs@ILB-MIPs.

[0059] Non-imprinted materials were prepared using the same synthesis process as imprinted polymers, except that the template molecule NRG was not added to the reaction system. After elution and drying, the final product was obtained and named PHs@ILB-NIPs.

[0060] like Figure 1 As shown in the transmission spectrum of CNCs (Fig. a1), it can be clearly observed that the original CNCs have a typical needle-like structure and a smooth surface. After surface modification, as can be seen from Fig. a2, the average diameter of CNCs@DDMAT has increased compared to the original CNCs, which is due to the successful modification of the RAFT initiator.

[0061] like Figure 2 As shown in Figure a1, the MIL-101 (Fe) with a uniform octahedral shape has a smooth surface. In contrast, it is easy to see from Figure a2 that the MCNCs@DDMAT have uniform rod-shaped CNCs attached to their rough surfaces, indicating that the CNCs were successfully grown in situ in the MOF.

[0062] like Figure 3 As shown in Figures a1-a2 and b1-b2, PHs@ILB-MIPs and PHs@ILB-NIPs exhibit abundant macroporous structures and rough surfaces. This is because adsorbents with boron affinity-imprinted cavities were synthesized via a RAFT emulsion microreactor.

[0063] like Figure 4 As shown in the EDS spectra, six main characteristic peaks of C, N, O, B, S and Fe were detected, which proves that the RAFT initiator CNCs@DDMAT was successfully grafted onto MIL-101 (Fe), and stable particles MCNCs@DDMAT were synthesized.

[0064] like Figure 5 As shown in the infrared spectrum, it is clear that the spectra of PHs@ILB-MIPs and PHs@ILB-NIPs are close to each other at 1340 cm⁻¹. -1 The presence of a BO characteristic peak indicates that the present invention successfully integrates boron affinity recognition sites into the porous network structure of the hydrogel through a one-step RAFT emulsion polymerization method.

[0065] Example 2

[0066] Weigh 5.0 mg of PHs@ILB-MIPs and 5.0 mg of PHs@ILB-NIPs, and add them to 5 mL of NRG solution with a concentration of 35 mg / L and a pH of 6.0, respectively. The solutions are then shaken in a 308 K water bath. The contact time between the adsorbent and the solution ranges from 5 to 160 min. The residual NRG concentration at each time point is determined by UV-Vis method, and the adsorption capacity is calculated based on the results. Figure 6As shown, PHs@ILB-MIPs exhibited rapid adsorption characteristics from 0 to 30 minutes, likely due to the high initial concentration of NRG solution and the porous structure of the hydrogel adsorbent with abundant boric acid binding sites. The adsorption rate gradually slowed down over time, reaching adsorption equilibrium at 160 minutes. This is because, with increasing time, the imprinted cavities were gradually occupied by target molecules, leading to a continuous increase in adsorption capacity until equilibrium was reached. Furthermore, compared to PHs@ILB-MIPs, the non-imprinted adsorbent (PHs@ILB-NIPs) exhibited slower adsorption kinetics and lower adsorption capacity due to the lack of specific recognition cavities.

[0067] Weigh 5 mg of PHs@ILB-MIPs and add them to 5 mL of NRG solutions (pH=6.0) at different concentrations (10, 15, 25, 35, 50 mg / L), respectively. Incubate in constant temperature water baths at 298 K, 303 K, and 308 K for 160 minutes each. After the adsorption reaction is complete, the residual concentration of NRG is determined using UV-Vis, and the adsorption capacity is calculated based on the measured data. The adsorption capacity of PHs@ILB-MIPs is calculated using the same method. Figure 7 As shown, under different initial concentrations and temperatures, the adsorption capacity of PHs@ILB-MIPs gradually increases with increasing temperature, indicating that the adsorption reaction of NRG in PHs@ILB-MIPs is an endothermic reaction.

[0068] Example 3

[0069] 5.0 mg of PHs@ILB-MIPs and 5.0 mg of PHs@ILB-NIPs were each immersed in 5.0 mL of an aqueous solution of the aforementioned hydroxyl compounds (pH=7.0, concentration 35 mg / L). These compounds included naringin, hydroquinone, catechol, luteolin, and o-nitrophenol. The mixture was then subjected to adsorption in a 308 K water bath for 160 minutes. After adsorption, the supernatant was separated by centrifugation, and the concentration of competing molecules was determined using UV-Vis. Figure 8 As shown, PHs@ILB-MIPs exhibit significantly stronger adsorption capacity for NRG compared to other competitors, which is attributed to the abundant imprinted recognition sites on its surface, indicating that the material has a significant specific recognition ability for NRG.

Claims

1. A method for preparing a high-affinity MOF boron affinity molecularly imprinted hydrogel adsorbent, characterized in that, Includes the following steps: (1) Preparation of Pickering stable particles MCNCs@DDMAT: Cellulose nanocrystals (CNCs) were added to deionized water under a nitrogen atmosphere. Then, isophorone diisocyanate and HO-NAGA-OH were injected into the solution using a syringe, followed by the first reaction. After the reaction was completed, the mixture was centrifuged, dialyzed against deionized water, and freeze-dried. The crude product was then dispersed in chloroform with 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid. Subsequently, ethylenediaminetetraacetic acid (EDC) and dimethylcarbamate (DMAP) were added under magnetic stirring for the second reaction. The solvent was then removed, and a yellow precipitate was obtained by rotary evaporation. This precipitate was dialyzed against deionized water to remove unreacted substances. Finally, the product was obtained by freeze-drying and named CNCs@DDMAT. Ferric chloride hexahydrate was dispersed in N,N-dimethylformamide and subjected to ultrasonic treatment to obtain solution A; Then, phthalic acid was dispersed in N,N-dimethylformamide and ultrasonically treated to obtain solution B; CNCs@DDMAT was added to solution B and magnetically stirred to fully disperse it. Solution A was then added. Finally, the mixture was transferred to a Teflon stainless steel autoclave for a third heating reaction. After the product was cooled to room temperature, it was centrifuged to obtain a yellow precipitate, which was washed several times with N,N-dimethylformamide and ethanol, dried, and the final product was obtained, named MCNCs@DDMAT. (2) Preparation of 3-(4-boronbenzyl)-1-vinyl-1H-imidazol-3-bromoionic liquid borate ILB: 4-(bromoethyl)phenylboronic acid was added to acetonitrile and sonicated. Then 1-vinylimidazolium was added dropwise. The mixture was then placed in an oil bath, stirred, concentrated, and refluxed. After the reaction was completed, anhydrous diethyl ether was added. A white solid precipitate was formed, and the crude product was collected, dried, and the final product was obtained, named ILB. (3) Preparation of porous imprinted hydrogels PHs@ILB-MIPs: First, MCNCs@DDMAT, 3-(4-boronbenzyl)-1-vinyl-1H-imidazol-3-bromoionic liquid borate ILB and template molecule naringin NRG were dispersed in deionized water. Then, acrylamide, N,N'-methylenebisacrylamide and potassium persulfate were added to the above aqueous phase to obtain an aqueous phase. Subsequently, the oil phase Artemisia argyi oil and Tween 80 were added to the aqueous phase and stirred evenly using a high-speed stirrer. Then, the obtained O / W emulsion was transferred to a mold, and nitrogen gas was introduced for polymerization. After the reaction was completed, the emulsion was eluted in a methanol / acetic acid mixed solution until no naringin NRG was found in the emulsion. Then, the unreacted oil phase was eluted with pure ethanol. Finally, the crude product was dried to obtain the final product, a high-affinity MOF boron affinity molecularly imprinted hydrogel adsorbent, named PHs@ILB-MIPs.

2. The preparation method according to claim 1, characterized in that, In step (1), the ratio of cellulose nanocrystals, isophorone diisocyanate, HO-NAGA-OH, 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid, ethylenediaminetetraacetic acid (EDC), and dimethylcarbamate (DMAP) is 200 mg: 20 mg: 40 mg: 100 mg: 0.68 g: 1.4 g.

3. The preparation method according to claim 1, characterized in that, In step (1), the ratio of ferric chloride hexahydrate, phthalic acid and CNCs@DDMAT is 198.6 mg: 62.3 mg: 30 mg.

4. The preparation method according to claim 1, characterized in that, In step (1), The first reaction was carried out at a temperature of 60°C for 24 hours. The second reaction is carried out at a temperature of 35-45℃ for 3-5 days. The third heating reaction was carried out at a temperature of 100-110℃ for 20-32 hours.

5. The preparation method according to claim 1, characterized in that, In step (2), the ratio of 4-(bromoethyl)phenylboronic acid, acetonitrile and 1-vinylimidazole is 10 mmol: 80 mL: 40 mmol.

6. The preparation method according to claim 1, characterized in that, In step (2), the oil bath temperature is 80~90℃ and the reflux time is 18 h; the drying temperature is 60 ℃ and the time is 6 h.

7. The preparation method according to claim 1, characterized in that, In step (3), the ratio of MCNCs@DDMAT, ILB, NRG, deionized water, acrylamide, N,N'-methylenebisacrylamide and potassium persulfate is 100 mg, 0.1 mmol: 0.025 mmol: 1.0 mL: 200 mg: 20 mg: 10 mg.

8. The preparation method according to claim 1, characterized in that, In step (3), the ratio of ILB, Artemisia argyi oil, and Tween 80 is 0.1 mmol: 4 mL: 0.1 mL.

9. The preparation method according to claim 1, characterized in that, In step (3), the nitrogen gas is passed for 15-20 minutes, the polymerization temperature is 60-65℃, and the time is 24-36 hours; the drying time is 40℃ and the time is 24 hours; in the methanol / acetic acid mixed solution, the volume ratio of methanol to acetic acid is 7:

3.

10. The application of the high-affinity MOF boron affinity molecularly imprinted hydrogel adsorbent prepared by the preparation method according to any one of claims 1 to 9 for the selective separation of the flavonoid compound naringin NRG.

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