阅读说明：本技术 一种用于检测诺氟沙星的MOFs型分子印迹聚合物及其制备方法 (MOFs type molecularly imprinted polymer for detecting norfloxacin and preparation method thereof ) 是由 董燕珊 彭健伟 彭志华 刘婉琼 桂成毅 于 2021-09-02 设计创作，主要内容包括：本发明公开了一种用于检测诺氟沙星的MOFs型分子印迹聚合物的制备方法,包括以下步骤：S1：制备UiO-66-NH-(2)作为分子印迹的载体；S2：通过酸酐和氨基的反应,在UiO-66-NH-(2)表面接枝双键,合成UiO-66-M；S3：通过自由基聚合将NOR压印在UiO-66-M表面,合成UiO-66@MIP。该荧光传感器阵列可以同时识别水中三种氨基糖苷类抗生素和三种重金属离子,实现有机/无机污染物的同时区分检测。该分子印迹聚合物具有高吸附能力、高选择性以及高稳定性,将其用于诺氟沙星的分离检测中,有效降低了检测成本和操作难度,同时提高了检测效率。(The invention discloses a preparation method of MOFs type molecularly imprinted polymer for detecting norfloxacin, which comprises the following steps: s1: preparation of UiO-66-NH 2 As a carrier for molecular imprinting; s2: by reaction of acid anhydrides and amino groups in UiO-66-NH 2 Grafting double bonds on the surface to synthesize UiO-66-M; s3: the UO-66 @ MIP was synthesized by imprinting NOR onto the surface of the UO-66-M by free radical polymerization. The fluorescent sensor array can identify simultaneouslyThree aminoglycoside antibiotics and three heavy metal ions in water realize the simultaneous distinguishing and detection of organic/inorganic pollutants. The molecularly imprinted polymer has high adsorption capacity, high selectivity and high stability, and is used for separating and detecting norfloxacin, so that the detection cost and the operation difficulty are effectively reduced, and the detection efficiency is improved.)

1. A preparation method of MOFs type molecularly imprinted polymer for detecting norfloxacin is characterized by comprising the following steps: the method comprises the following steps:

s1: preparation of UiO-66-NH₂As moleculesA support for blotting;

s2: by reaction of acid anhydrides and amino groups in UiO-66-NH₂Grafting double bonds on the surface to synthesize UiO-66-M;

s3: the UO-66 @ MIP was synthesized by imprinting NOR onto the surface of the UO-66-M by free radical polymerization.

2. The method of claim 1, wherein: step S2 includes the following steps: the UiO-66-NH prepared in the step S1₂Dispersing in dichloromethane, carrying out ultrasonic treatment for 20 minutes, adding methacrylic anhydride into the solution, and continuously reacting for 96 hours at 25 ℃; after the reaction is finished, centrifuging at 9000rpm, collecting the precipitate, and washing with dichloromethane for 3 times; and (3) drying the product at 45 ℃ in vacuum to obtain UiO-66-M.

3. The method of claim 1, wherein: step S3 includes the following steps: mixing the UiO-66-M prepared in the step S2 with acetonitrile, ultrasonically dispersing for 10 minutes, adding NOR and MAA, and stirring the mixture for 2 hours at room temperature; heating the mixture to 60 ℃, adding EGDMA and AIBN, and reacting the mixture at 60 ℃ for 24 hours; after the reaction is finished, centrifuging at 9000rpm to collect precipitates, and then washing by using an eluant until the template is removed; and finally, drying the product at 60 ℃ in vacuum to obtain the [email protected] MIP.

4. The method of claim 2, wherein: in step S2, UiO-66-NH₂The ratio of the amount of methylene chloride to the amount of methacrylic anhydride was 1g:15mL:2.6 mL.

5. The production method according to claim 3, characterized in that: in step S3, UiO-66-M, acetonitrile, NOR, MAA, EGDMA and AIBN were used in a ratio of 80mg:50mL:51mg: 68. mu.L: 400. mu.L: 70 mg.

6. The method of claim 1, wherein: step S1 includes the following steps: reacting ZrCl₄And acetic acid was dissolved in DMF by ultrasonic waves for 5 minutes; then will beDissolving 2-amino terephthalic acid in the solution, carrying out ultrasonic treatment for 5 minutes, and adding deionized water into the solution; transferring the mixed solution into a polytetrafluoroethylene reactor, heating to 120 ℃, keeping for 24 hours, and then cooling to room temperature; the product was washed repeatedly with DMF and ethanol and then dried under vacuum at 60 ℃.

7. The method of claim 6, wherein: in step S1, ZrCl₄The ratio of the amounts of acetic acid, DMF, 2-aminoterephthalic acid and deionized water was 0.78g:5.55mL:80mL:0.58g:0.24 mL.

8. The production method according to claim 3, characterized in that: the eluent described in step S3 is a methanol/acetic acid solution.

9. The method of claim 8, wherein: the volume ratio of methanol to acetic acid in the methanol/acetic acid solution is 9: 1.

10. A MOFs type molecularly imprinted polymer for detecting norfloxacin, which is characterized in that: the method according to any one of claims 1 to 9.

Technical Field

The invention belongs to the field of antibiotic detection, and particularly relates to an MOFs (metal-organic frameworks) type molecularly imprinted polymer for detecting norfloxacin and a preparation method thereof.

Background

Norfloxacin (NOR) is one of quinolone antibiotics, and is widely used in human and animal products for disease treatment and control as a broad-spectrum, inexpensive antibiotic. According to incomplete statistics, the usage amount of antibiotics in China exceeds 50% of the total usage amount in the world, thereby causing a plurality of problems. Since it is only partially metabolized, a large amount of antibiotics are discharged to the environment with feces and urine, and therefore, it is not uncommon to detect antibiotics in lakes and rivers. And long-term drinking of water containing antibiotics can cause the reduction of human immunity, the imbalance of intestinal flora, even carcinogenesis and teratogenesis. Therefore, the development of a low-cost, simple and efficient norfloxacin separation and detection method is urgent. Currently, Solid Phase Extraction (SPE) or QuEChERS is widely used for extracting norfloxacin from water, but has the problems of high cost, low adsorption capacity, no selectivity and the like. Therefore, these methods still have room for improvement.

Molecularly Imprinted Polymers (MIPs), commonly known as artificial antibodies, are polymers that can selectively bind template targets through a key and lock mechanism. Due to low cost, high stability and high selectivity, molecular imprinting is a common method for improving material selectivity. The high-selectivity polymer needs to be attached to a nano material with a certain specific surface area to exert the highest performance, so that a method for compounding the molecularly imprinted polymer on the surface of the nano material needs to be established.

In recent years, Metal Organic Frameworks (MOFs) have been the focus of much research. Due to the large accessible surface area, uniform and adjustable pore size, chemical modularity, fluorescence and catalytic activity, MOFs and composite materials thereof are widely applied to the fields of separation, enrichment, analysis and detection. In these fields, however, the properties exhibited by MOFs are well documented as having the potential to be combined with molecular imprinting.

Disclosure of Invention

An object of the present invention is to provide a MOFs type molecularly imprinted polymer for detecting norfloxacin with high adsorption capacity, high selectivity and high stability and a preparation method thereof, aiming at the technical problems to be solved.

In order to achieve the above object, the present invention provides a method for preparing MOFs type molecularly imprinted polymer for detecting norfloxacin, comprising: the method comprises the following steps:

s1: preparation of UiO-66-NH₂As a carrier for molecular imprinting;

s2: by reaction of acid anhydrides and amino groups in UiO-66-NH₂Grafting double bonds on the surface to synthesize UiO-66-M;

s3: the UO-66 @ MIP was synthesized by imprinting NOR onto the surface of the UO-66-M by free radical polymerization.

Compared with the prior art, the method combines the molecular imprinting technology with MOFs, and selects the UiO-66-NH with high stability₂As a carrier for molecular imprinting, by the reaction of acid anhydride and amino group, in UiO-66-NH₂After surface grafting of double bonds, NOR was imprinted on the MOFs surface by free radical polymerization to form [email protected] MIP. The molecularly imprinted polymer has high adsorption capacity, high selectivity and high stability, and is used for separating and detecting norfloxacin, so that the detection cost and the operation difficulty are effectively reduced, and the detection efficiency is improved.

Preferably, step S2 includes the steps of: the UiO-66-NH prepared in the step S1₂Dispersing in dichloromethane, carrying out ultrasonic treatment for 20 minutes, adding methacrylic anhydride into the solution, and continuously reacting for 96 hours at 25 ℃; inverse directionAfter the reaction is finished, centrifuging at 9000rpm, collecting the precipitate, and washing with dichloromethane for 3 times; and (3) drying the product at 45 ℃ in vacuum to obtain UiO-66-M.

Preferably, step S3 includes the steps of: mixing the UiO-66-M prepared in the step S2 with acetonitrile, ultrasonically dispersing for 10 minutes, adding NOR and MAA, and stirring the mixture for 2 hours at room temperature; heating the mixture to 60 ℃, adding EGDMA and AIBN, and reacting the mixture at 60 ℃ for 24 hours; after the reaction is finished, centrifuging at 9000rpm to collect precipitates, and then washing by using an eluant until the template is removed; and finally, drying the product at 60 ℃ in vacuum to obtain the [email protected] MIP.

Preferably, in step S2, UiO-66-NH₂The ratio of the amount of methylene chloride to the amount of methacrylic anhydride was 1g:15mL:2.6 mL.

Preferably, in step S3, UiO-66-M, acetonitrile, NOR, MAA, EGDMA and AIBN are used in a ratio of 80mg:50mL:51mg:68 μ L:400 μ L:70 mg.

Preferably, step S1 includes the steps of: reacting ZrCl₄And acetic acid was dissolved in DMF by ultrasonic waves for 5 minutes; dissolving 2-amino terephthalic acid in the solution, carrying out ultrasonic treatment for 5 minutes, and adding deionized water into the solution; transferring the mixed solution into a polytetrafluoroethylene reactor, heating to 120 ℃, keeping for 24 hours, and then cooling to room temperature; the product was washed repeatedly with DMF and ethanol and then dried under vacuum at 60 ℃.

Preferably, in step S1, ZrCl₄The ratio of the amounts of acetic acid, DMF, 2-aminoterephthalic acid and deionized water was 0.78g:5.55mL:80mL:0.58g:0.24 mL.

Preferably, the eluent described in step S3 is a methanol/acetic acid solution.

Preferably, the methanol/acetic acid solution has a methanol to acetic acid volume ratio of 9: 1.

The invention also provides the MOFs type molecularly imprinted polymer for detecting norfloxacin, which is prepared by the preparation method and has high adsorption capacity, high selectivity and high stability.

Drawings

FIG. 1 shows UiO-66-NH prepared in example 1₂Infrared characterization of UiO-66-M and [email protected] MIP

FIG. 2 shows UiO-66-NH prepared in example 1₂XRD profiles of UiO-66-M and [email protected] MIP

FIG. 3 shows UiO-66-NH prepared in example 1₂Thermogravimetric characterization of UiO-66-M and [email protected] MIP

FIG. 4 shows UiO-66-NH prepared in example 1₂Nitrogen adsorption and desorption curve and aperture distribution diagram with UiO-66-M

FIG. 5 is a graph showing the nitrogen desorption curve and the pore size distribution of [email protected] MIP prepared in example 1

FIG. 6 shows UiO-66-NH prepared in example 1₂TEM image of

FIG. 7 is a TEM image of UiO-66-M obtained in example 1

FIG. 8 is a TEM image of [email protected] MIP prepared in example 1

FIG. 9 is a TEM image of [email protected] NIP obtained in comparative example

FIG. 10 is a bar graph of the effect of template to functional monomer ratio on adsorption capacity in [email protected] MIP

FIG. 11 is a bar graph of the effect of the ratio of functional monomer to crosslinker in [email protected] MIP on adsorption capacity

FIG. 12 is a bar graph of the effect of pH on adsorption capacity under adsorption conditions

FIG. 13 is a graph showing the static adsorption profiles of [email protected] MIP prepared in example 1 and [email protected] NIP prepared in comparative example

FIG. 14 is a Scatchard plot of [email protected] MIP prepared in example 1

FIG. 15 is a Scatchard plot of [email protected] NIP prepared by a comparative example

FIG. 16 is a graph showing the dynamic adsorption profiles of [email protected] MIP prepared in example 1 and [email protected] NIP prepared in comparative example

FIG. 17 is a bar graph of the results of the selectivity test of [email protected] MIP prepared in example 1 versus [email protected] NIP prepared in comparative example

FIG. 18 is a histogram of the reusability test of [email protected] MIP prepared in example 1

FIG. 19 is a working curve for HPLC of norfloxacin

FIG. 20 is a comparison graph of HPLC chromatograms of an actual water sample and a [email protected] MIP adsorption elution solution in an effect test example

Detailed Description

The present invention will be further described with reference to the following examples. It should be understood that the following examples are illustrative of the present invention only, and are not intended to limit the scope of the present invention.

The instruments used in the following examples, test examples and test examples are shown in Table 1, and the reagents are shown in Table 2.

TABLE 1 Experimental instruments

TABLE 2 Experimental reagent Table

Example 1: preparation of MOFs type molecularly imprinted polymer [email protected] MIP for detecting norfloxacin

The MOFs type molecularly imprinted polymer [email protected] MIP for detecting norfloxacin is prepared according to the following steps:

s1: preparation of UiO-66-NH₂As a carrier for molecular imprinting: 0.78g of ZrCl₄And 5.55mL of acetic acid was dissolved in 80mL of DMF by sonication for 5 minutes. Then, 0.58g of 2-amino terephthalic acid was dissolved in the solution. After another 5 minutes of sonication, 0.24mL of deionized water was added to the solution. The mixed solution was transferred to a polytetrafluoroethylene reactor, heated to 120 ℃ for 24 hours, and then cooled to room temperature. The product was washed repeatedly with DMF and ethanol and then under vacuum at 60 deg.CAnd (5) drying.

S2: by reaction of acid anhydrides and amino groups in UiO-66-NH₂Grafting double bonds on the surface to synthesize UiO-66-M: 1g of UiO-66-NH prepared in step S1₂Dispersed in 15mL dichloromethane. After 20 minutes of sonication, 2.6mL of methacrylic anhydride was added to the solution. The entire reaction was continued at 25 ℃ for 96 hours. After the reaction was completed, the precipitate was collected by centrifugation at 9000rpm and washed 3 times with methylene chloride. The product was dried under vacuum at 45 ℃.

S3: imprinting NOR on the surface of UiO-66-M by radical polymerization, to synthesize [email protected] MIP: 80mg of UiO-66-M and 50mL of acetonitrile were charged to a 100mL flask. After 10 minutes of sonication, 51mg NOR and 68. mu.L MAA were added to the flask. The mixture was stirred at room temperature for 2 hours. After the reaction system was heated to 60 ℃, 400. mu.L of EGDMA and 70mg of AIBN were added. The mixture was reacted at 60 ℃ for 24 hours. After the reaction was completed, the precipitate was collected by centrifugation at 9000rpm, and then washed with methanol/acetic acid (90:10, v/v) until the template was removed. Finally the product was dried under vacuum at 60 ℃.

Comparative example: synthesis of [email protected] NIP

The preparation method of [email protected] NIP is substantially the same as that of [email protected] MIP in example 1, except that NOR is not added in step S3. Specifically, [email protected] NIP is prepared according to the following steps:

s1: preparation of UiO-66-NH₂As a carrier for molecular imprinting: 0.78g of ZrCl₄And 5.55mL of acetic acid was dissolved in 80mL of DMF by sonication for 5 minutes. Then, 0.58g of 2-amino terephthalic acid was dissolved in the solution. After another 5 minutes of sonication, 0.24mL of deionized water was added to the solution. The mixed solution was transferred to a polytetrafluoroethylene reactor, heated to 120 ℃ for 24 hours, and then cooled to room temperature. The product was washed repeatedly with DMF and ethanol and then dried under vacuum at 60 ℃.

S2: by reaction of acid anhydrides and amino groups in UiO-66-NH₂Grafting double bonds on the surface to synthesize UiO-66-M: 1g of UiO-66-NH prepared in step S1₂Dispersed in 15mL dichloromethane. After 20 minutes of sonication, 2.6mL of methacrylic anhydride was added to the solution. The entire reaction was continued at 25 ℃ for 96 hours. Reaction ofAfter completion, the precipitate was collected by centrifugation at 9000rpm and washed 3 times with dichloromethane. The product was dried under vacuum at 45 ℃.

S3: synthesis of [email protected] NIP: 80mg of UiO-66-M and 50mL of acetonitrile were charged to a 100mL flask. After 10 minutes of ultrasonic dispersion, 68 μ L of MAA was added to the flask. The mixture was stirred at room temperature for 2 hours. After the reaction system was heated to 60 ℃, 400. mu.L of EGDMA and 70mg of AIBN were added. The mixture was reacted at 60 ℃ for 24 hours. After the reaction was completed, the precipitate was collected by centrifugation at 9000rpm, and then washed with methanol/acetic acid (90:10, v/v) until the template was removed. Finally the product was dried under vacuum at 60 ℃.

Test example: structural characterization of several materials from example 1 and comparative examples

Test example 1: infrared (FT-IR) characterization

FT-IR spectroscopy is used as a means of demonstrating the composition of materials to help demonstrate the success of the synthesis of the relevant materials. 3461cm as shown in FIG. 1^-1And 3351cm^-1The absorption corresponds to symmetric and asymmetric N-H vibration. The N-H bending vibration and the C-N stretching can be 1572cm^-1To 1385cm^-1Are found in (a). With UiO-66-NH₂Compared with the FT-IR spectrum of the product, UiO-66-M is 1673cm^-1There was a new absorption peak due to the characteristic absorption peak of C ═ C, indicating the successful synthesis of UiO-66-M. Due to the formation of the molecularly imprinted layer, the FT-IR spectrum of [email protected] MIP mainly consists of 2950cm^-1C-H absorption Peak and 1716cm^-1C ═ O absorption peak composition, demonstrating that UiO-66-M and [email protected] MIP have been successfully synthesized.

Test example 2: powder X-ray diffraction (PXRD) characterization

To demonstrate whether the material remains stable before and after modification and polymerization, it is stable to UiO-66-NH₂Powder X-ray diffraction (PXRD) was performed for UiO-66-M and [email protected] MIP. As shown in fig. 2, the black line peaks at 2 θ ═ 7.36, 8.48, 17.08, 22.25, and 33.12 ° correspond to the characteristic diffraction peaks of UiO-66s for (110), (200), (022), (115), and (137), respectively. UiO-66-NH₂After the reaction with methacrylic anhydride, the diffraction peak of UiO-66-M is consistent with that of the original UiO-66, which indicates that the chemical reaction does not destroy the crystalA bulk structure. Due to the modification of molecular imprinting, the PXRD pattern of [email protected] MIP has a higher baseline, so that the obtained data are subjected to background subtraction and baseline correction. The obtained pattern peak is compared with the original UiO-66-NH₂The peaks are the same, indicating that the original crystal structure is maintained even after polymerization.

Test example 3: thermogravimetric characterization

FIG. 3 is a thermogravimetric characterization of the material, UiO-66-NH₂Approximately similar to the thermogravimetric curve of UiO-66-M, the mass reduction before 100 ℃ is attributed to the loss of solvent and moisture in the material, which begins to be digested to CO, when the temperature rises to around 270 ℃₂And zirconia. In terms of combustion residues, UiO-66-NH₂Slightly above UiO-66-M, it can also be seen that the double bond modification was successful. The thermogravimetric curve of MIP @ UiO-66 (same as [email protected] MIP) is obviously different from that of the former two, and the combustion residue is much less, which proves that norfloxacin is successfully imprinted into UiO-66-NH₂Of (2) is provided.

Test example 4: nitrogen adsorption and desorption experiment

FIGS. 4 to 5 show experimental data of nitrogen adsorption and desorption of relevant materials. UiO-66-NH₂Typical type I adsorption curves are compared with UiO-66-M, which proves that the adsorption curves are microporous structures, wherein UiO-66-NH₂The Langmuir specific surface area of 943, and a comparison of the pore volume distributions shows that the pore diameter of UiO-66-M is slightly reduced and the pore volume is smaller than that of the original UiO-66-NH₂. The [email protected] MIP is a type IV adsorption curve, and the material has a new pore size due to imprinting of a molecular imprinting layer.

Test example 5: characterization of scanning Electron microscope

FIGS. 6 to 9 are TEM images of several materials from which UiO-66-NH can be observed₂Presents a typical octahedral structure with a size of about 100nm, consistent with the crystal structure synthesized by others. The crystal structure of UiO-66-M did not change after reaction with methacrylic anhydride. This result corresponds to the previous XRD results. Due to the modification of the molecularly imprinted layer, [email protected] MIP is converted from the original octahedron to the diameterIrregular spheres of 250nm size.

Test example 1: ratio optimization test

The ratio of the functional monomer to the cross-linking agent plays an important role in the adsorption capacity of the molecularly imprinted material. To obtain a [email protected] MIP with a larger adsorption capacity, the ratio of functional Monomer (MAA) to cross-linker (EGDMA) and the ratio of functional Monomer (MAA) to template (NOR) were optimized. In discussing the ratio of MAA to EGDMA, the molar ratio of MAA to NOR was fixed at 5:1, and the amount of EGDMA was varied to synthesize [email protected] MIP in accordance with step S3. As a result, as shown in FIGS. 10 to 11, when the ratio is too low, the imprinted polymer cannot be formed, and when the ratio is too high, the polymerization process becomes vigorous and the pores of the imprinted polymer are adversely affected. The results show that [email protected] MIP possesses the best adsorption capacity when synthesized at a ratio of 1:2.5 MAA to EGDMA. In studying the ratio of MAA to NOR, the molar ratio of MAA to EGDMA was fixed at 1:2.5, and the amount of NOR was varied to synthesize [email protected] MIP according to step S3. When the amount of MAA is too small, complete prepolymerization with the template is not possible, resulting in a low adsorption capacity. When the MAA increases, it also leads to more non-specific adsorption, which also affects the adsorption capacity of [email protected] MIP. As can be seen from the figure, [email protected] MIP has better adsorption performance when the ratio of MAA to NOR is 5: 1.

Test example 2: adsorption condition optimization test

Since the external conditions have a certain influence on the adsorption capacity of the [email protected] MIP, the experiment example focuses on the influence of pH and temperature on the adsorption capacity of the [email protected] MIP. Norfloxacin is a typical amphoteric compound, and thus pH has a great influence on the state of norfloxacin. Norfloxacin has pKa1 and pKa2 of 6.20 and 8.70, respectively. Norfloxacin exists primarily in anionic form at pH greater than 8.70 and in cationic form at pH less than 6.20, i.e., norfloxacin and recognition sites of the molecular imprint would electrostatically repel and hinder its interaction with [email protected] MIP at pH greater than 8.7 or less than 6.2 in solution. In contrast, norfloxacin is in a neutral state when the pH is between 6.2 and 8.7, and therefore interacts more easily with the material through hydrogen bonds. The pH condition is the same as the daily water environment, and the application requirements in real life are met. As can be seen from FIG. 12, the adsorption capacity of [email protected] MIP is stronger in this pH range.

Test example 3: static adsorption experiment

NOR was prepared in standard solutions at concentrations of 10mg/L to 500 mg/L. Then adding the NOR standard solution into a centrifuge tube, and respectively adding the [email protected] MIP and the [email protected] NIP. The mixture was incubated on a shaker at 500rpm for 24 hours. The supernatant was collected by centrifugation. The supernatant was examined with an ultraviolet spectrophotometer at 277nm and the concentration of NOR was calculated from the standard curve of NOR.

The adsorption capacities (Q, mg/g) of [email protected] MIP and [email protected] NIP were respectively calculated by the following formulas:

Q＝(C₀-C)*V/m

wherein C is₀(mg/L) is the initial concentration of the NOR standard solution, C (mg/L) is the concentration of the solution after completion of adsorption, V (ml) is the volume of the NOR standard solution added, and m is the mass to which [email protected] MIP or [email protected] NIP is added.

The imprinting factor (α) and the selectivity factor (β) are important criteria for measuring the performance of molecularly imprinted polymers and non-molecularly imprinted polymers, which can be calculated by the following formula:

α＝Q_MIP/Q_NIP

β＝α₁/α₂

wherein QMIPP and QNIP are the adsorption capacities of [email protected] MIP and [email protected] NIP, respectively. Alpha is alpha₁Is a selection factor of NOR, and alpha₂Is a selection factor for other test objectives.

In this test example, a static adsorption curve study was conducted on [email protected] MIP and [email protected] NIP at norfloxacin concentrations of 0 to 450 mg/L. As shown in FIG. 13, due to the absence of the imprinted sites, the [email protected] NIP adsorption capacity reached saturation at 200mg/L, and the saturated adsorption capacity was about 25.9 mg/g. In contrast, when norfloxacin concentration exceeded 300mg/L, the adsorption capacity of [email protected] MIP gradually approached equilibrium, and the imprinted sites on [email protected] MIP were still saturated, with a saturated adsorption of about 53.1 mg/g.

The Scatchard equation is an important criterion for evaluating the static adsorption of [email protected] MIP and [email protected] NIP.

Q/C_e＝(Q_m-Q)/K_d

Wherein Q_mDenotes the maximum adsorption capacity, K, of the material_dIs the dissociation constant, C_eIs the equilibrium concentration of norfloxacin in the solution at equilibrium for adsorption. FIG. 14 shows a Scatchard plot of [email protected] MIP consisting of two different linear equations, illustrating that the MIP has two different binding sites. The Scatchard plot (FIG. 15) for the [email protected] NIP has only one straight line segment compared to the [email protected] MIP.

Test example 4: dynamic adsorption experiment

The [email protected] MIP was weighed into a centrifuge tube. Then 3ml of 150mg/L NOR solution was added thereto. The mixture was incubated on a shaker at 500rpm for 1 to 50 minutes, respectively. The supernatant was collected by centrifugation and detected by UV spectrophotometer at 277 nm.

Dynamic adsorption curves of [email protected] MIP and [email protected] NIP are shown in FIG. 16, and when the initial concentration of norfloxacin is 120mg/L, the [email protected] MIP reaches the adsorption equilibrium at 30 min. Compared with [email protected] MIP, [email protected] NIP achieves adsorption equilibrium, and the adsorption capacity is lower than that of [email protected] MIP, because specific binding sites are not available.

Test example 5: selective adsorption experiment

2mL of NOR, CIP, SD and TC solutions at a concentration of 200mg/L were mixed with [email protected] MIP and [email protected] NIP. All of these were incubated on a shaker at 500rpm for 60 minutes. After filtering off the precipitate, a clear liquid was collected for testing.

The selectivity of [email protected] MIP was evaluated by selecting the antibiotic Sulfadiazine (SD) and Tetracycline (TC) in combination with Norfloxacin (NOR), its structural analog Ciprofloxacin (CIP) and other classes. As shown in FIG. 17, [email protected] MIP shows an ultra-high selectivity in adsorbing other types of antibiotics. In contrast, [email protected] NIP showed significant non-specific adsorption to these antibiotics due to the lack of a molecularly imprinted recognition site. However, due to the small difference in the structures of ciprofloxacin and norfloxacin, when [email protected] MIP interacts with ciprofloxacin, it preferentially occupies the binding site, resulting in a higher adsorption capacity, but adsorption capacityStill lower than the [email protected] MIP used for norfloxacin. The results are consistent with the experimental results reported previously. As mentioned above, [email protected] MIP has imprinting factors (. alpha.) of 2.09,1.86, 0.94,1.07 for NOR, CIP, SD and TC, respectively, while [email protected] NIP has selectivity factors (. beta.) of 1.12,2.22,1.95 for CIP, SD and TC, respectively. In other words, the selectivity experiments demonstrated in UiO-66-NH₂The surface creates molecularly imprinted sites.

Test example 6: reusability experiment of [email protected] MIP

The reusability of [email protected] MIP is an important index for measuring whether the material can be applied to practical detection. To evaluate reusability, [email protected] MIP was mixed with 3ml norfloxacin solution at 90mg/L for 30 minutes at 450 rpm. After adsorption, the supernatant was collected by a centrifuge, and the concentration of norfloxacin remaining in the solution was measured by an ultraviolet spectrophotometer. The NOR on the [email protected] MIP was eluted using a methanol/acetic acid (90:10, v/v) solution. After completion, the above process is repeated. As shown in fig. 18, after 5 cycles, the [email protected] MIP still maintained a high adsorption efficiency, which was only a 12% reduction compared to the first. The results show that the material has excellent stability and reusability.

Comparative effect example: compared with the prior adsorbing materials

TABLE 3 comparison of the effectiveness of the adsorption Material

As shown in Table 3, according to the existing published literature data, compared with the existing several adsorbing materials, the [email protected] MIP adsorbing capacity provided by the invention is obviously improved, the recovery rate is higher, and the comprehensive adsorbing effect is excellent.

Effect test example: actual water sample detection

The norfloxacin standard solution of 215mg/L is diluted to a series of concentrations of 43.0mg/L, 21.5mg/L, 14.3mg/L, 10.8mg/L, 5.4mg/L, 2.2mg/L, 1.1mg/L, 0.54mg/L, 0.27mg/L and 0.1mg/L, the series of norfloxacin standard solutions are detected by determined liquid chromatography conditions, and a standard curve of norfloxacin is drawn by using peak areas of obtained data, as shown in FIG. 19.

3ml of the actual water sample was taken into a centrifuge tube and 10mg of [email protected] MIP was added thereto. The mixture was incubated on a shaker at 500rpm for 40 minutes and the supernatant removed by centrifugation. Then, 3ml of the eluent (methanol/acetic acid ═ 9:1) was added to the centrifuge tube, and the eluent was collected after ultrasonic centrifugation. The eluent is enriched by a nitrogen blowing instrument and then is added with water to reach the constant volume of 3 ml. The aqueous solution is detected by high performance liquid chromatography.

The above liquid chromatography conditions were as follows: with C₁₈The column was stationary and the mobile phase was 0.8ml in 0.025mol/L phosphoric acid solution (pH adjusted to 3.0 with triethylamine) -acetonitrile (80:20), and the wavelength of the PDA detector was set at 277 nm. The dead time is used to characterize the material and the peak area integral is used to quantify.

After the actual water sample is processed by the steps, the obtained eluent is detected by high performance liquid chromatography after being processed by liquid phase, an HPLC chromatogram is shown in figure 20, and the peak area is substituted into a standard curve to calculate to obtain norfloxacin with the concentration of 0.51mg/L in the water sample.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

The above description is only a partial example of the present invention, and does not limit the embodiments and the protection scope of the present invention, therefore, it should be recognized that the present invention is covered by the protection scope of the present invention by the equivalent substitution and obvious change made by the description of the present invention for those skilled in the art.