CN111318264A

CN111318264A - Preparation method of boron affinity molecular imprinting stirring rod and application of stirring rod in adsorption separation of catechol

Info

Publication number: CN111318264A
Application number: CN202010094277.0A
Authority: CN
Inventors: 沈丹青; 潘建明; 陈学平
Original assignee: Jiangsu University
Current assignee: Hefei Jiuzhou Longteng Scientific And Technological Achievement Transformation Co ltd
Priority date: 2020-02-15
Filing date: 2020-02-15
Publication date: 2020-06-23
Anticipated expiration: 2040-02-15
Also published as: CN111318264B

Abstract

The invention belongs to the technical field of preparation of separation functional materials, and relates to a preparation method of a boron affinity molecular imprinting stirring rod, which comprises the following steps: soaking a capillary glass tube containing iron wires in the piranha solution, and removing impurities; diluting 3-aminopropyltriethoxysilane in ethanol, uniformly mixing, adding glacial acetic acid, and soaking the pretreated capillary glass tube at 50-80 ℃ for 2-5 h to obtain an amination-modified capillary glass tube; then soaking in glutaraldehyde solution, storing in dark place, washing with distilled water and ethanol in sequence, and vacuum drying; preparing a solution according to the proportion of ultrasonically dispersing 0.2g of boron affinity imprinted nano-sheets in 10-20 mL of water, soaking a capillary glass tube in the solution, and reacting for 5-8 h in a dark place to obtain the boron affinity imprinted nano-sheets. According to the invention, the boron affinity imprinting nano sheet is grafted on the outer surface of the glass capillary tube containing the iron core, so that the boron affinity imprinting nano sheet can rotate automatically under an external magnetic field and is suspended in a solution to be adsorbed, and the loss of imprinting materials caused by the contact with the bottom of a container is reduced. It can be used for separating and adsorbing catechol.

Description

Preparation method of boron affinity molecular imprinting stirring rod and application of stirring rod in adsorption separation of catechol

Technical Field

The invention belongs to the technical field of preparation of separation functional materials, relates to a functionalized molecularly imprinted stirring rod, and particularly relates to a preparation method of a boron-affinity molecularly imprinted stirring rod and application of the boron-affinity molecularly imprinted stirring rod in adsorption separation of catechol.

Background

Catechol (cathechol), also known as Catechol, is one of the typical compounds with a cis-dihydroxy. Catechol is found in nature in many derivatives, and was first obtained by distillation of protocatechuic acid or the extract of catechu. It has wide application, is an important chemical intermediate, and can be used for manufacturing rubber additives, electroplating additives, hair dyes, photographic developers, bactericides, insecticides, light stabilizers, antioxidants, spices, dyes and the like; is also an important medical intermediate, and can be used for preparing antitussive, berberine, isoproterenol, etc.; elements such as titanium, molybdenum, tungsten, vanadium, iron, cerium and the like can also be determined through chromogenic reaction or colorimetric reaction analysis.

The catechol is used as an important chemical raw material, and has important significance in separation and purification during production of chemical products and recycling after adsorption separation and pollution in waste water. The industrial production of catechol has many methods, and currently, more methods are used, namely an ortho-chlorophenol alkaline hydrolysis method and a phenol hydroxylation method, wherein the ortho-chlorophenol alkaline hydrolysis method and the phenol hydroxylation method are used, wherein the ortho-chlorophenol alkaline hydrolysis method and the phenol hydroxylation method use recycled butyl acetate as an extraction liquid, and then a product is obtained by a rectifying tower. The latter is to hydroxylate the ortho-position and para-position of phenol under the condition of catalyst to obtain catechol and hydroquinone, and then to distill hydroxylation liquid containing a large amount of water by using dehydration distillation process to separate catechol. The method has simple flow and mild operation, is beneficial to continuous production, and has vigorous industrial demand for the hydroquinone as a byproduct. But the separation of the catechol and the hydroquinone is difficult to operate, and the high-concentration hydrogen peroxide reduces the safety factor of the scheme. In addition, the two methods realize separation by a distillation method, and the catechol has high boiling point, heat sensitivity and thermal instability, is easy to polymerize or decompose at a specific temperature, can cause oxidation after being heated for a long time, and brings more energy consumption and yield loss to the separation process.

The molecular imprinting stirring rod is a selective separation material which has a structure and a shape similar to a stirring rod (son) and is modified with an imprinting polymer layer on the outer surface. The general preparation method is as follows: firstly, carrying out active group modification on the surface of a glass rod containing a magnetic inner core, and then wrapping the surface with a imprinted polymer layer with a certain thickness. The molecular imprinting stirring rod can automatically rotate under an external magnetic field, so that the recognition and adsorption functions of a target object in a solution system are accelerated. However, a thicker imprinted polymeric layer may result in some embedding of the imprinted sites. Meanwhile, due to the uncertainty of the glass thickness, the magnet quality and the like of the stirring rod, the adsorption effect and the performance of the molecular imprinting stirring rod are difficult to accurately know. Furthermore, the traditional molecularly imprinted stirring rod is similar to a magneton when in use and is positioned on the bottom wall of the container, the imprinted polymer layer is damaged and falls off due to long-time rotation, and the fallen polymer layer cannot be reversibly repaired.

Disclosure of Invention

The invention discloses a preparation method of a boron affinity molecular imprinting stirring rod, aiming at solving the problems of low imprinting recognition site, small binding capacity, poor selective adsorption on catechol and the like introduced in the prior art.

The technical scheme is as follows:

a preparation method of a boron affinity molecular imprinting stirring rod comprises the following steps:

A. soaking a capillary glass tube containing iron wires in a piranha solution for 8-15 h at 60-80 ℃ to remove surface impurities, taking out, washing with ethanol and distilled water respectively, drying, and soaking in ethanol for later use;

diluting 3-Aminopropyltriethoxysilane (APTES) in ethanol, uniformly mixing, adding glacial acetic acid, soaking the pretreated capillary glass tube at 50-80 ℃ for 2-5 h, preferably at 60 ℃ for 2h, and modifying the surface of the capillary glass tube with amino functional groups; taking out, washing with ethanol, and drying to obtain an aminated capillary glass tube, wherein the volume ratio of the 3-Aminopropyltriethoxysilane (APTES) to the ethanol to the glacial acetic acid is 2-5 mL: 50-150 mL: 300-500 muL;

C. soaking the aminated capillary glass tube in a glutaraldehyde solution, storing for 5-8 h, preferably 6h, in a dark place, reacting the modified amino with aldehyde at one end of glutaraldehyde to expose aldehyde functional groups at the other end of the surface of the capillary tube, washing with distilled water and ethanol in sequence after the reaction is finished, and drying in vacuum;

D. and C, preparing a solution according to the proportion that 0.2g of boron affinity imprinted nano sheet (NS-2-MIPs) is ultrasonically dispersed in 10-20 mL of water, soaking the capillary tube obtained in the step C in the solution, reacting for 5-8 hours in a dark place, enabling the surface of the NS-2-MIPs nano sheet with the amino group to be attached to the surface of the aldehyde group modified capillary tube, and exposing one surface of the imprinted polymer to the external environment to obtain the boron affinity molecular imprinting stirring rod.

In the preferred embodiment of the invention, the volume ratio of 3-Aminopropyltriethoxysilane (APTES) to ethanol to glacial acetic acid in step B is 4mL to 100mL to 400. mu.L.

In the preferred embodiment of the present invention, the concentration of the glutaraldehyde solution in step C is 25%.

The boron affinity imprinted nano sheet (NS-2-MIPs) in the step D of the invention comprises the following preparation steps:

(A) under the protection of nitrogen, adding catechol and 4-vinylbenzene boric acid into a mixed solution of acetonitrile and toluene, and performing self-assembly for 3-6 h in a dark place to obtain a self-assembly solution, wherein the mass-to-volume ratio of the catechol, the 4-vinylbenzene boric acid, the mixed solution of acetonitrile and toluene is 50-100 mg: 100-250 mg: 80-150 mL;

(B) adding anisotropic nanosheets (NS-2), Ethylene Glycol Dimethacrylate (EGDMA) and Azobisisobutyronitrile (AIBN) into the self-assembly liquid, ultrasonically mixing uniformly, carrying out magnetic stirring polymerization at 50-80 ℃ for 7-14 h, preferably carrying out polymerization at 60 ℃ for 12h, centrifuging, washing with ethanol for more than 3 times, eluting the template with a mixed solution of glacial acetic acid and methanol, washing the product with ethanol, and carrying out vacuum drying at 45 ℃ to obtain boron affinity imprinted nanosheets (NS-2-MIPs), wherein the mass-volume ratio of the anisotropic nanosheets (NS-2), the Ethylene Glycol Dimethacrylate (EGDMA) and the Azobisisobutyronitrile (AIBN) is 80-150 mg: 0.5-1 muL: 10-50 mg.

In a preferred embodiment of the invention, the mass-to-volume ratio of the mixed solution of catechol, 4-vinylphenylboronic acid, acetonitrile and toluene in step (A) is 96mg:120mg:100 mL; the volume ratio of the acetonitrile to the toluene is 3: 1.

In the above preferred embodiment, the volume ratio of glacial acetic acid to methanol in step (B) is 9: 1.

For comparison, the procedure for preparing non-imprinted nanoplates (NS-2-NIPs) was consistent with boron affinity imprinted nanoplates (NS-2-MIPs) except that no template molecule catechol was added.

The anisotropic nanosheet (NS-2) in step (B) above, having a preparation step comprising:

(1) diluting polystyrene-maleic anhydride (HSMA) into an aqueous solution with distilled water, ultrasonically dispersing and uniformly mixing, slowly dropwise adding an HCl solution, and continuously stirring until white flocculent precipitates disappear, wherein the volume ratio of the HSMA to the aqueous solution to the HCl solution is 10-20 mL: 50-200 mL: 1-2 mL;

(2) adding alkane into the solution system, emulsifying at a high speed of 8000-14000 rpm to form emulsion droplets, dropwise adding 3- (methacryloyloxy) propyl trimethoxy silane, Tetraethoxysilane (TEOS) and 3-Aminopropyltriethoxysilane (APTES), the volume ratio of the alkane, the 3- (methacryloyloxy) propyltrimethoxysilane, the Tetraethoxysilane (TEOS) and the 3-Aminopropyltriethoxysilane (APTES) is 10-15 mL: 200-500 μ L: 2-5 mL, continuously stirring for 10-20 min, transferring to a water bath at 40-80 ℃, standing for reaction for 8-20 h, preferably reacting for 12h at 60 ℃, centrifugally collecting, washing with water and ethanol, removing oil-water two phases, and mixing the obtained white solid with a weight-volume ratio of 1g:20mL of the solution was dispersed in ethanol, ultrasonically crushing for 5-15 min, centrifuging, and drying in vacuum at 45 ℃ to obtain an anisotropic nanosheet (NS-2); wherein the alkane is n-decane, dodecane, or n-tridecane.

In a preferred embodiment of the present invention, the volume ratio of the HSMA, the aqueous solution and the HCl solution in step (1) is 15mL:85mL:1 mL.

In the preferred embodiment of the invention, the concentration of the HCl solution in the step (1) is 2 mol/L.

In the preferred embodiment of the invention, the volume ratio of the alkane, the 3- (methacryloyloxy) propyltrimethoxysilane, the Tetraethoxysilane (TEOS) and the 3-Aminopropyltriethoxysilane (APTES) in the step (2) is 4mL: 85. mu.L: 1mL: 85. mu.L.

In the preferred embodiment of the invention, the alkane in the step (2) is n-decane.

In the preferred embodiment of the present invention, the polystyrene-maleic anhydride (HSMA) in step (1) is synthesized according to the prior art (e.g., Chen Y, Liang F, Yang H, et al. Janus nanosheets of polymer-inorganic layered compositions [ J ]. Macromolecules,2012,45(3): 1460-:

(a) mixing toluene, styrene (St), Maleic Anhydride (MA) and Azobisisobutyronitrile (AIBN) and intermittently ultrasonically dispersing, wherein the volume mass ratio of the toluene to the styrene to the maleic anhydride to the azobisisobutyronitrile is 100-200 mL: 4-8 mL: 3-8 g: 0.01-0.02 g, introducing nitrogen for 20-40 min after uniform dispersion, heating to 60-100 ℃, carrying out stirring reflux reaction on magnetons for 2-5 h, centrifuging, washing a solid phase with toluene for 3-5 times, and carrying out vacuum drying at 60 ℃ to obtain a white granular styrene-maleic anhydride copolymer (SMA);

(b) dissolving a styrene-maleic anhydride copolymer (SMA) in distilled water, and adding sodium hydroxide, wherein the mass volume ratio of the styrene-maleic anhydride copolymer (SMA), the distilled water and the sodium hydroxide is 3-6 g: 30-70 mL: 1-2 g, stirring at 70-90 ℃ for 1-3 h, preferably stirring at 80 ℃ for 3h, so as to obtain the polystyrene-maleic anhydride (HSMA).

In a preferred embodiment of the invention, the volume-to-mass ratio of the toluene, the styrene, the maleic anhydride and the azobisisobutyronitrile in the step (a) is 150mL to 5.8mL to 5g to 0.01 g.

In the preferred embodiment of the invention, nitrogen is introduced for 30min in the step (a), and the reflux reaction is carried out for 3.0h at 85 ℃ under the condition of magneton stirring.

In a preferred embodiment of the invention, the mass-to-volume ratio of the styrene-maleic anhydride copolymer (SMA) in the step (b), the distilled water and the sodium hydroxide is 4g:34mL:1 g.

In the preferred embodiment, the concentration of the polystyrene-maleic anhydride (HSMA) solution obtained in step (b) is 10%.

The invention adopts an anisotropic emulsion method to prepare the product with amino (NH) on one surface₂-) a functional group, a silicon nanosheet (NS-2) bearing a carbon-carbon double bond (-C ═ C-) functional group on one side; then introducing a boric acid imprinted polymer at one side with a carbon-carbon double bond functional group through precipitation polymerization reaction to obtain boron affinity imprinted nano sheets (NS-2-MIPs); then through Schiff base reaction, theNS-2-MIPs are modified on the surface of the aldehyde group activated magnetic core capillary tube to form a molecular imprinting stirring rod with specific adsorption effect on catechol. The size is controllable, the function can be designed and the stirring rod can be repaired. The selectivity and the reusability of the boron affinity imprinting nano-sheet (Ns-2-MIP) are greatly improved by adopting a molecular imprinting technology and a boron affinity technology. In addition, the invention carries out strict combination experiments to detect the adsorption performance of the anisotropic nanosheets, and shows that the performance is good.

The invention also aims to apply the prepared boron affinity molecular imprinting stirring rod to the adsorption and separation of catechol.

And (3) placing the prepared boron affinity molecular imprinting stirring rod in 100mL of 20mg/L catechol solution for adsorption at the environment of 25 ℃, adding an external magnetic field to enable the stirring rod to rotate automatically, taking out the stirring rod after 2 hours, and testing the concentration of the adsorbed solution.

Adsorption capacity calculation formula:

Q_e(μmol/g) represents the equilibrium adsorption capacity; c₀(mg/L) represents the original concentration of catechol in the solution; c_e(mg/L) represents the concentration of catechol in the solution at equilibrium; v (mL) represents the volume of the adsorption solution; m (g) represents the mass of the adsorbent, and M represents the relative molecular mass of catechol (M ═ 110.11).

The discrimination performance evaluation of the present invention was performed by the following method:

static adsorption experiment: adding 5mg of the adsorbents (NS-2-MIPs and NS-2-NIPs) prepared according to the method into 5.0mL of test solution (the concentration value is 20mg/L) with the initial pH value of 5.5-9.5, measuring the content of the adsorbed catechol by using an ultraviolet-visible spectrophotometer, and calculating the adsorption capacity according to the result; after saturated adsorption, selecting other substances with the same structure as catechol as competitive adsorbates to research the selective recognition performance of NS-2-MIPs and NS-2-NIPs; the adsorption effects of NS-2-MIPs and NS-2-NIPs are researched through the adsorption amounts of a plurality of different concentrations; the recycling capacity of the adsorbent was determined by adsorption-desorption experiments.

Advantageous effects

According to the invention, boron affinity imprinted nano sheets (NS-2-MIPs) are grafted on the outer surface of a glass capillary tube containing an iron core to obtain a molecular imprinted stirring rod, so that the stirring rod can rotate automatically under an external magnetic field and is suspended in a solution to be adsorbed, and the loss of imprinted materials due to contact with the bottom of a container is reduced. Can separate catechol from the high-purity catechol, and has great potential in industrial application.

Drawings

FIG. 1 SEM pictures of the unfractured NS-2(A), NS-2(a), NS-2-MIPs (B) and NS-2-MIPs magnified region (b) prepared in example 1;

FIG. 2 is a graph of infrared spectra of NS-2 and NS-2-MIPs prepared in example 1 and example 3, which were analyzed for functional groups;

FIG. 3 XPS test spectra of NS-2 and NS-2-MIPs prepared in example 1 and example 3;

FIG. 4 is a thermogravimetric analysis of NS-2 and NS-2-MIPs prepared in examples 1 and 3;

FIG. 5 is an SEM image of the glass rod (A) before modification of NS-2-MIPs and the glass rod (B, B) after modification of NS-2-MIPs prepared in example 6;

FIG. 6 is a graph showing the effect of pH conditions on the adsorption capacity of NS-2-MIPs and NS-2-NIPs;

FIG. 7 adsorption kinetics and model fitting curves for NS-2-MIPs and NS-2-NIPs;

FIG. 8 shows the selective adsorption capacity and the validation results of NS-2-MIPs and NS-2-NIPs in the test solution;

FIG. 9 shows the results of verification of the regeneration ability of NS-2-MIPs and NS-2-NIPs.

Detailed Description

The present invention will be described in detail below with reference to examples to enable those skilled in the art to better understand the present invention, but the present invention is not limited to the following examples.

Example 1

Synthesis of anisotropic nanoplatelets (NS-2):

diluting 15mL of polystyrene-maleic anhydride (HSMA) to 150mL with distilled water, ultrasonically dispersing and uniformly mixing, slowly dropwise adding 1mL of 2MHCl solution, and continuously stirring until white flocculent precipitate disappears. Then, n-decane was added to the aqueous solution, and emulsified at 10000rpm to form emulsion droplets. Then 510. mu.L of 3- (methacryloyloxy) propyltrimethoxysilane, 4mL of tetraethyl orthosilicate (TEOS) and 510. mu.L of 3-Aminopropyltriethoxysilane (APTES) were added dropwise, and after stirring was continued for 15min, the mixture was transferred to a 60 ℃ water bath and allowed to stand. After 15h of reaction, the product was collected using centrifugation and washed with water and ethanol to remove both the oil and water phases. Dispersing the obtained white solid in ethanol, performing ultrasonic disruption for 10min by using a cell wall breaking instrument, collecting the product by centrifugation, and performing vacuum drying at 45 ℃ for later use.

Fig. 1A is an SEM image of the thin-layer hollow silicon spheres prepared in this example under incomplete ultrasound, and it can be found that the diameter of the silicon spheres is about 5-10 μm, the thickness of the shell layer is about 10-20nm, and the outer surface and the inner surface of the sphere shell are smooth and rough.

FIG. 1a is an SEM image of the shell of the thin hollow silicon spheres prepared in this example, which is broken and collapsed by strong ultrasound, and the shell material is completely broken by further ultrasound.

Example 2

Synthesis of anisotropic nanoplatelets (NS-2):

diluting 15mL of polystyrene-maleic anhydride (HSMA) to 150mL with distilled water, ultrasonically dispersing and uniformly mixing, slowly dropwise adding 1mLHCl solution, and continuously stirring until white flocculent precipitate disappears. Dodecane was further added to the above aqueous solution, and emulsified at 10000rpm to form emulsion droplets. Then 510. mu.L of 3- (methacryloyloxy) propyltrimethoxysilane, 4mL of tetraethyl orthosilicate (TEOS) and 510. mu.L of 3-Aminopropyltriethoxysilane (APTES) were added dropwise, and after stirring was continued for 15min, the mixture was transferred to a 60 ℃ water bath and allowed to stand. After 15h of reaction, the product was collected using centrifugation and washed with water and ethanol to remove both the oil and water phases. Dispersing the obtained white solid in ethanol, performing ultrasonic disruption for 10min by using a cell wall breaking instrument, collecting the product by centrifugation, and performing vacuum drying at 45 ℃ for later use.

Example 3

Synthesis of anisotropic nanoplatelets (NS-2):

diluting 15mL of polystyrene-maleic anhydride (HSMA) to 150mL with distilled water, ultrasonically dispersing and uniformly mixing, slowly dropwise adding 1mLHCl solution, and continuously stirring until white flocculent precipitate disappears. And adding n-tridecane into the aqueous solution, and emulsifying at 10000rpm to form emulsion droplets. Then 510. mu.L of 3- (methacryloyloxy) propyltrimethoxysilane, 4mL of tetraethyl orthosilicate (TEOS) and 510. mu.L of 3-Aminopropyltriethoxysilane (APTES) were added dropwise, and after stirring was continued for 15min, the mixture was transferred to a 60 ℃ water bath and allowed to stand. After 15h of reaction, the product was collected using centrifugation and washed with water and ethanol to remove both the oil and water phases. Dispersing the obtained white solid in ethanol, performing ultrasonic disruption for 10min by using a cell wall breaking instrument, collecting the product by centrifugation, and performing vacuum drying at 45 ℃ for later use.

Fig. 1B shows that after the NS-2SEM image prepared in this example is subjected to precipitation polymerization to graft a boron affinity imprinted polymer, the roughness of the surface with double bonds is significantly increased, the surface has a granular feel, the thickness of the nanosheet is also increased, and the smooth surface with amino groups is not changed.

FIG. 1b is an SEM image of an enlarged region of NS-2-MIPs, and a nano-sized boron affinity imprinted polymer is grown on the surface of the nanosheets, and the particle size is about 100 nm.

FIG. 2 is a chart of the infrared spectra of the functional groups of NS-2 and NS-2-MIPs analyzed in example 1 and this example. The use of FT-IR shows that NS-2 and NS-2-MIPs are 1082cm^-1Obvious characteristic peaks of Si-O-Si appear at the positions, which indicates that the frameworks of 2 materials are all silicon dioxide. At 1712cm^-1The absorption peak which occurs can be attributed to the tensile vibration of C ═ O, 704cm^-1The absorption peak at (a) is derived from the C-H out-of-plane bending vibration. Compared with NS-2, NS-2-MIPs are 1342cm^-1An absorption peak generated by B-O stretching vibration appears, which indicates that the NS-2 surface successfully modifies the boron affinity imprinted polymer.

FIG. 3 is a XPS test spectrum of NS-2 and NS-2-MIPs of example 1 and this example, showing that characteristic peaks of Si 2s and Si 2p appear at 152.9eV and 102.8eV, a characteristic peak of C1 s appears at 284.7eV, a characteristic peak at 398.9eV is attributable to N1 s, and a characteristic peak of O1 s appears at 531.6eV, and these results reveal the presence of carbon-and nitrogen-containing functional groups in NS-2 and confirm that the functionalized silane coupling agent has reacted at the oil-water interface. In addition, NS-2-MIPs showed a peak of B1 s at 180.9eV compared to NS-2, indicating that the boron affinity imprinted polymer was grafted to the surface of NS-2 by precipitation polymerization, which is consistent with the FT-IR results.

FIG. 4 is a thermogravimetric analysis of NS-2 and NS-2-MIPs of example 1 and this example, showing that the weight loss of NS-2 is 7.88% as the temperature is increased from 30 ℃ to 100 ℃. The second significant weight loss phase of NS-2 started at 350 ℃, which was caused by the thermal decomposition of the functional groups in NS-2, with a weight loss of 48.42%. In the range of 30-800 ℃, NS-2-MIPs have two weight loss stages in total, the weight loss rate is 7.66% before 100 ℃, the weight loss reason is the same as NS-2, and the weight loss is the evaporation of water in the material. Weight loss rates of up to 80.08% occurred in the temperature range of 300-450 ℃, mainly due to decomposition of the imprinted polymer. From the comparison of the results of thermogravimetric analysis of NS-2 and NS-2-MIPs, the mass specific gravity of the imprinted polymer grafted by precipitation polymerization reached 31.44%.

Example 4

Boron affinity imprinted nanosheet (NS-2-MIPs) synthesis:

catechol (96mg) and 4-vinylphenylboronic acid (120mg) were added to a 150mL mixed solution of acetonitrile and toluene (V: V ═ 3: 1), and self-assembled for 3 hours under nitrogen protection in the dark to obtain a self-assembled solution. NS-2(100mg), EGDMA (0.4. mu.L) and AIBN (20mg) were then added to the above solution. After ultrasonic mixing, the mixture is magnetically stirred and reacted for 10 hours at 70 ℃ (the whole process is carried out under the protection of nitrogen). After the polymerization reaction, the product was centrifuged and washed three more times with ethanol. The template was eluted with a mixed solution of glacial acetic acid and methanol (V: V ═ 9: 1), and the product was washed with ethanol and dried under vacuum at 45 ℃.

Example 5

Boron affinity imprinted nanosheet (NS-2-MIPs) synthesis:

catechol (96mg) and 4-vinylphenylboronic acid (200mg) were added to a 150mL mixed solution of acetonitrile and toluene (V: V ═ 3: 1), and self-assembled for 3 hours under nitrogen protection in the dark to obtain a self-assembled solution. NS-2(100mg), EGDMA (0.4. mu.L) and AIBN (20mg) were then added to the above solution. After ultrasonic mixing, the mixture is magnetically stirred and reacted for 10 hours at 70 ℃ (the whole process is carried out under the protection of nitrogen). After the polymerization reaction, the product was centrifuged and washed three more times with ethanol. The template was eluted with a mixed solution of glacial acetic acid and methanol (V: V ═ 9: 1), and the product was washed with ethanol and dried under vacuum at 45 ℃.

Example 6

inserting a small section of iron wire into a capillary glass tube, soaking the glass tube containing the iron wire in a piranha solution (concentrated sulfuric acid: 30% hydrogen peroxide: 7:3), and placing the tube in a drying oven at 60-80 ℃ for 12 hours to remove surface impurities; taking out, washing with ethanol and distilled water for several times, washing to remove residual piranha washing liquid, drying in clean place, and soaking in ethanol;

diluting 4.0mL of APTES in 100mL of ethanol, uniformly mixing, adding 400 mu L of glacial acetic acid, soaking the capillary glass tube at 60 ℃ for more than 2.0h to modify the surface of the capillary glass tube with amino functional groups, taking out the capillary glass tube after modification, washing the capillary glass tube with ethanol and drying to obtain a glass tube with a surface rich in amino;

soaking the amination-modified glass tube in 25% glutaraldehyde solution, storing for more than 3h at normal temperature in a dark place to react the modified amino group with aldehyde group at one end of glutaraldehyde and expose aldehyde functional group at the other end of the surface of the glass tube, washing with distilled water and ethanol respectively after the reaction is finished, and vacuum drying;

adding a proper amount of NS-2-MIPs into 10mL of water, ultrasonically dispersing for 15min, immersing the glass tube in the water, reacting for 3h in a dark place, enabling one surface of the NS-2-MIPs nanosheet with the amino group to be attached to the surface of the aldehyde-modified glass tube, and exposing one surface of the imprinted polymer to the external environment to obtain the imprinted polymer.

FIG. 5 is SEM images of glass rods (A) before modification of NS-2-MIPs and glass rods (B, B) after modification of NS-2-MIPs, which are prepared in this example, and it can be seen that the surface of the glass tube without NS-2-MIPs functionalization is smooth as shown in FIG. (A), while the surface of the glass tube with NS-2-MIPs attached to the surface of the glass tube by reaction is rough, and it can be seen from the detail view (B) that NS-2-MIPs show a snowflake pattern on the surface of the glass tube.

Example 7

5mg of the adsorbents prepared as described in example 5 (NS-2-MIPs and NS-2-NIPs) were added to 5.0mL of catechol test solutions (concentration value 20mg/L) formulated at pH 6.5, 7.4, 8.5 and 9.2, and the final catechol concentration was measured by UV-visible spectrophotometer at 276 nm.

The experiment was performed three times to balance the adsorption capacity.

The results show that the adsorption capacities of NS-2-MIPs and NS-2-NIPs are pH 8.5>pH 9.2>pH 7.4>pH 6.5, when the system acidity is increased, the pH value is not greater than pK of boric acid functional group in phenylboronic acid_aThe binding effect was not good and the adsorption effect was weak. This shows that the optimum adsorption conditions are at a pH of 8.5 (results are shown in FIG. 6).

The adsorption capacities of the nodes NS-2-MIPs and NS-2-NIPs at different times are considered, and then the data are fitted by utilizing the quasi-primary and quasi-secondary dynamics models, and dynamics and a fitting curve thereof are drawn (as shown in figure 7). The NS-2-MIPs and the NS-2-NIPs realize rapid adsorption balance in the adsorption process, and the NS-2-MIPs reach more than 98 percent of the balance adsorption amount in 30min, which can be attributed to the introduction of effective imprinting sites. The equilibrium adsorption capacity of NS-2-MIPs is 2.73 times that of NS-2-NIPs, which indicates that the number of effective imprinted sites in NS-2-MIPs is much higher than that of non-imprinted sites.

The selectivity test was performed by comparing the amount of rebinding of catechol-like molecular structures, and the selection was compared to the amount of adsorption of Quercetin (QRT), 2,4, 6-Trichlorophenol (TCP), Hydroquinone (HDQ). As a result, it was found that NS-2-MIPs have adsorption capacities of 67.49. mu. mol/g, 3.20. mu. mol/g, 9.384. mu. mol/g and 3.695. mu. mol/g in the order of catechol, TCP, QRT and HDQ, and NS-2-NIPs have adsorption capacities of 23.90. mu. mol/g, 2.542. mu. mol/g, 9.093. mu. mol/g and 3.558. mu. mol/g, respectively. The adsorption capacity of NS-2-MIPs on catechol is much larger than that of TCP, QRT and HDQ, and the trend is more remarkable than that of NS-2-NIPs. This result indicates that NS-2-MIPs have better specific recognition ability for catechol (the results are shown in FIG. 8).

The regeneration capacity of NS-2-MIPs and NS-2-NIPs was tested by seven consecutive adsorption-desorption cycles, after 7 regeneration cycle periods, the adsorption capacity of NS-2-MIPs to catechol was 63.89. mu. mol/g, which is 95.36% of the initial adsorption capacity, while the adsorption capacity of NS-2-NIPs after seven cycles was 22.19. mu. mol/g, which is 92.45% of the initial adsorption capacity. The results show that NS-2-MIPs can be repeatedly utilized, the adsorption performance is stable, and the stability is better than NS-2-NIPs (the results are shown in figure 9).

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present invention or directly or indirectly applied to other related technical fields are included in the scope of the present invention.

Claims

1. A preparation method of a boron affinity molecular imprinting stirring rod is characterized by comprising the following steps:

B. diluting 3-aminopropyltriethoxysilane in ethanol, uniformly mixing, adding glacial acetic acid, soaking the pretreated capillary glass tube at 50-80 ℃ for 2-5 h, taking out, washing with ethanol, and drying to obtain an amination-modified capillary glass tube, wherein the volume ratio of the 3-aminopropyltriethoxysilane to the ethanol to the glacial acetic acid is 2-5 mL: 50-150 mL: 300-500 uL;

C. soaking the aminated capillary glass tube in a glutaraldehyde solution, storing for 5-8 h in a dark place, washing with distilled water and ethanol in sequence after the reaction is finished, and drying in vacuum;

D. and D, preparing a solution according to the proportion of ultrasonically dispersing 0.2g of boron affinity imprinted nano-sheets NS-2-MIPs in 10-20 mL of water, soaking the capillary glass tube obtained in the step C in the solution, and reacting for 5-8 hours in a dark place to obtain the boron affinity molecular imprinting stirring rod.

2. The method for preparing the boron affinity molecular imprinting stirring rod according to claim 1, characterized in that: and D, diluting the 3-aminopropyltriethoxysilane in the ethanol, uniformly mixing, adding glacial acetic acid, and soaking the pretreated capillary glass tube at 60 ℃ for 2 hours.

3. The method for preparing the boron affinity molecular imprinting stirring rod according to claim 1, characterized in that: and in the step B, the volume ratio of the 3-aminopropyltriethoxysilane to the ethanol to the glacial acetic acid is 4mL to 100mL to 400 uL.

4. The method for preparing the boron affinity molecular imprinting stirring rod according to claim 1, characterized in that: and D, soaking the amination-modified capillary glass tube in the step C in a glutaraldehyde solution, and storing for 6 hours in a dark place.

5. The method for preparing the boron affinity molecular imprinting stirring rod according to claim 1, characterized in that: the concentration of the glutaraldehyde solution in step C is 25%.

6. A preparation method of the boron affinity imprinted nano-sheet NS-2-MIPs is characterized by comprising the following steps:

(B) adding anisotropic nanosheet NS-2, ethylene glycol dimethacrylate and azobisisobutyronitrile into the self-assembly liquid, ultrasonically mixing uniformly, performing magnetic stirring polymerization at 50-80 ℃ for 7-14 h, preferably performing polymerization at 60 ℃ for 12h, centrifuging, washing with ethanol for more than 3 times, eluting the template with a mixed solution of glacial acetic acid and methanol, washing the product with ethanol, and performing vacuum drying at 45 ℃ to obtain the boron affinity imprinted nanosheet NS-2-MIPs, wherein the mass-to-volume ratio of the anisotropic nanosheet NS-2, the ethylene glycol dimethacrylate and the azobisisobutyronitrile is 80-150 mg: 0.5-1 muL: 10-50 mg.

7. The method for preparing NS-2-MIPs from boron affinity imprinted nanosheets according to claim 6, wherein: the mass volume ratio of the catechol to the mixed solution of the 4-vinylphenylboronic acid and the acetonitrile and the toluene in the step (A) is 96mg to 120mg to 100 mL; the volume ratio of the acetonitrile to the toluene is 3: 1.

8. The method for preparing NS-2-MIPs from boron affinity imprinted nanosheets according to claim 6, wherein: the volume ratio of the glacial acetic acid to the methanol in the step (B) is 9: 1.

9. A stirring rod for boron affinity molecular imprinting prepared according to the method of any one of claims 1 to 5.

10. Use of a boron affinity molecular imprinting stir-rod according to claim 9, characterized in that: it is applied to the adsorption separation of catechol.