Preparation method of nicotine molecularly imprinted composite material

Abstract

The application provides a preparation method of a nicotine molecular imprinting composite material, and the preparation method comprises the following steps: (1) preparing a CS / PANI prepolymer; (2) preparing a CS / PANI- GO composite material containing nicotine on the basis; and (3) eluting the composite material to prepare a CS / PANI- GO nicotine molecular imprinting composite material. The nicotine molecular imprinting composite material prepared by the application has the performances of high adsorption capacity, high adsorption efficiency and high nicotine selective adsorption.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of nicotine adsorption materials, in particular to a preparation method of a nicotine molecular imprinting composite material. BACKGROUND

[0002] The content (mass fraction) of total plant alkaloids (nicotine) in tobacco is usually more than 1%, and nicotine is easily soluble in solvents such as water, ethanol, diethyl ether, chloroform and petroleum ether. Conventional methods all need to perform complex pretreatment on samples, and are time-consuming. A molecular imprinting sensor provides a new means for rapid and accurate determination of nicotine, and a polymer molecular imprinting is a new type of high polymer material with specific recognition function. The specific recognition of the template molecule is mainly due to the functional groups in the imprinting cavities. Therefore, the polymer molecular imprinting has a binding site matched with the target in the functional groups and the spatial structure, is simple to prepare, has good stability, and can be used in harsh environments such as acid, alkali, high temperature and high pressure. SUMMARY

[0003] The application aims to provide a preparation method of a nicotine molecular imprinting composite material, and the prepared material is a composite material with high adsorption capacity, high adsorption efficiency and high selective adsorption for nicotine.

[0004] To solve the above technical problems, the application adopts the following technical scheme:

[0005] A preparation method of a nicotine molecular imprinting composite material comprises the following steps:

[0006] S1: a certain amount of CS is dissolved in a N,N-dimethylformamide solution with PANI to prepare a CS / PANI prepolymer by stirring;

[0007] S2: nicotine, epichlorohydrin and GO are added to the CS / PANI prepolymer for further crosslinking;

[0008] S3: the solution obtained in S2 is poured into a tubular mold to react to obtain a gelatinous CS / PANI-GO composite material, and the composite material is heated in an oven;

[0009] S4: the hydrogel is washed with an acetonitrile solution to remove the template molecule nicotine;

[0010] S5: the CS / PANI-GO hydrogel is washed with deionized water, and the washing is stopped when the pH value of the deionized water after washing is 7, and the washing is performed in a flowing deionized water mode;

[0011] S6: the CS / PANI-GO hydrogel is freeze-dried to prepare a CS / PANI-GO nicotine molecular imprinting composite material.

[0012] Further: in the step S1, the amount of CS added is 0.5%, 1%, 2%, 3%, 4% of the sum of the mass of PANI and GO.

[0013] Further: in the step S1, the stirring time is 9-14 hours, and the stirring speed is 200 revolutions / minute.

[0014] Further: in the step S2, the crosslinking time is 1-5 hours, and the temperature is 30-70 DEG C.

[0015] Further: in the step S3, the heating time in the oven is 4-10 hours, and the temperature is 30-60 DEG C.

[0016] Further: in the step S4, the washing time is 5-20 minutes, and the washing method is repeated washing with acetonitrile.

[0017] Note: CS is chitosan;

[0018] PANI is polyaniline;

[0019] GO is graphene oxide;

[0020] CS / PANI is chitosan / graphene oxide composite material;

[0021] CS / PANI-GO is nicotine molecularly imprinted polymer;

[0022] CS2 / PANI-GO is nicotine molecularly imprinted polymer with 2% CS content;

[0023] NIM-CS2 / PANI-GO is non-imprinted polymer;

[0024] PANI-GO is polyaniline / graphene oxide composite material.

[0025] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0026] (1) Because GO with high specific surface area and functional molecules are added in the hydrogel, it has higher adsorption capacity and adsorption efficiency.

[0027] (2) The template molecule nicotine is introduced in the process of preparing the hydrogel, so that it has imprinted cavities with nicotine specific recognition, and thus has the ability of selective adsorption of nicotine. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 FTIR spectra of GO, CS and CS2 / PANI-GO of the present application.

[0029] Figure 2For the present application, the effects of pH on the adsorption of nicotine by GO, PANI-GO and CS2 / PANI-GO (a); the effects of adsorption time on the adsorption of nicotine by PANI-GO and CS2 / PANI-GO (b); the pseudo-first-order kinetic model (c); and the pseudo-second-order kinetic model (d).

[0030] Figure 3 For the present application, the adsorption thermodynamic curve of CS2 / PANI-GO (a) and the Langmuir model (b).

[0031] Figure 4 For the present application, the adsorption performance of nicotine, nornicotine and anatabine on the imprinted polymer and the non-imprinted polymer. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0033] Example 1:

[0034] A preparation method of a nicotine molecular imprinting composite material, comprising the following steps:

[0035] S1: A certain amount of CS is stirred in a 1g PANI solution in 50mL N,N-dimethylformamide solution to prepare a CS / PANI prepolymer;

[0036] S2: 1mmol of nicotine, 1mmol of epichlorohydrin and 0.1g of GO are added to the CS / PANI prepolymer for further crosslinking;

[0037] S3: The solution obtained in S2 is poured into a tubular mold for reaction to obtain a gel-like CS / PANI-GO composite material, and heating in an oven;

[0038] S4: The hydrogel is washed with acetonitrile solution to remove the template molecule nicotine;

[0039] S5: The CS / PANI-GO hydrogel is rinsed with deionized water, and the rinsing is stopped when the pH value of the rinsed deionized water is 7, and the rinsing is performed by flowing deionized water.

[0040] S6: The CS / PANI-GO hydrogel is freeze-dried to prepare a CS / PANI-GO nicotine molecular imprinting composite material.

[0041] In the step S1, the amount of CS added is 0.5% of the sum of the mass of PANI and GO.

[0042] The stirring time in the step S1 is 9 hours, and the stirring speed is 200 revolutions / minute.

[0043] The crosslinking time in the step S2 is 1 hour, and the temperature is 30 DEG C.

[0044] The heating time in the step S3 is 4 hours in an oven, and the temperature is 30 DEG C.

[0045] The washing time in the step S4 is 5 minutes, and the washing mode is repeated washing with acetonitrile.

[0046] The preparation of a nicotine molecularly imprinted composite material is realized.

[0047] Example 2:

[0048] A preparation method of a nicotine molecularly imprinted composite material comprises the following steps:

[0049] S1: A certain amount of CS is stirred with 1g PANI in 50mL N,N-dimethylformamide solution to prepare a CS / PANI prepolymer;

[0050] S2: 1mmol of nicotine, 1mmol of epichlorohydrin and 0.1g of GO are added to the CS / PANI prepolymer for further crosslinking;

[0051] S3: The solution obtained in S2 is poured into a tubular mold to obtain a gel-like CS / PANI-GO composite material, and heated in an oven;

[0052] S4: The hydrogel is washed with acetonitrile solution to remove the template molecule nicotine;

[0053] S5: The CS / PANI-GO hydrogel is rinsed with deionized water, and the rinsing is stopped when the pH value of the deionized water after rinsing is 7, and the rinsing mode is deionized water flowing rinsing;

[0054] S6: The CS / PANI-GO hydrogel is freeze-dried to prepare a CS / PANI-GO nicotine molecularly imprinted composite material.

[0055] In the step S1, the added amount of CS is 4% of the sum of the mass of PANI and GO.

[0056] The stirring time in the step S1 is 14 hours, and the stirring speed is 200 revolutions / minute.

[0057] The crosslinking time in the step S2 is 5 hours, and the temperature is 70 DEG C.

[0058] The heating time in the step S3 is 10 hours in an oven, and the temperature is 60 DEG C.

[0059] The step S4, the washing time is 20 minutes, the washing method is repeatedly washed with acetonitrile.

[0060] The preparation of a nicotine molecular imprinting composite material is realized.

[0061] Embodiment 3:

[0062] A preparation method of a nicotine molecular imprinting composite material, comprising the following steps:

[0063] S1: a certain amount of CS is dissolved in 50 mL of N, N-dimethylformamide solution with 1g PANI to prepare a CS / PANI prepolymer;

[0064] S2: 1mmol of nicotine, 1mmol of epichlorohydrin and 0.1g of GO are added to the CS / PANI prepolymer for further crosslinking;

[0065] S3: the solution obtained in S2 is poured into a tubular mold to obtain a gel-like CS / PANI-GO composite material, and heated in an oven;

[0066] S4: the hydrogel is washed with acetonitrile solution to remove the template molecule nicotine;

[0067] S5: the CS / PANI-GO hydrogel is washed with deionized water, and the washing is stopped when the pH value of the deionized water after washing is 7, and the washing method is deionized water flow washing;

[0068] S6: the CS / PANI-GO hydrogel is freeze-dried to prepare a CS / PANI-GO nicotine molecular imprinting composite material.

[0069] In the step S1, the amount of CS added is 2% of the total mass of PANI and GO.

[0070] In the step S1, the stirring time is 12 hours, and the stirring speed is 200 revolutions per minute.

[0071] In the step S2, the crosslinking time is 2 hours, and the temperature is 60°C.

[0072] In the step S3, the heating time in the oven is 8 hours, and the temperature is 45°C.

[0073] In the step S4, the washing time is 10 minutes, and the washing method is repeatedly washed with acetonitrile.

[0074] The preparation of a nicotine molecular imprinting composite material is realized.

[0075] The following is the characterization of the molecular imprinting composite material obtained in Example 3.

[0076] Molecularly imprinted polymer CS / PANI-GO characterization

[0077] The anti-swelling CS / PANI-GO nicotine molecularly imprinted polymer was prepared by cross-linking chitosan (CS) and polyaniline (PANI) with graphene oxide (GO). The successful synthesis of CS / PANI-GO material was verified by FTIR, and the results are shown in Figure 1 As can be seen from the FTIR spectrum of GO, the strong and broad absorption peak at 1745 cm -1 belongs to the stretching vibration of C=0 in the structure of graphene oxide. The broad and strong absorption peak at 3380 cm -1 corresponds to the stretching vibration of -OH in the structure of graphene oxide. The absorption peak at 1250 cm -1 is attributed to the stretching vibration of C-O-C. The broad and strong absorption peak at 3380 cm -1 of the FTIR spectrum of CS corresponds to the stretching vibration of -OH and -NH2 in the structure. The stretching vibration absorption peak of C-N in the structure of CS appears at 1428 cm -1 . Compared with the FTIR of GO and CS, the appearance of the stretching vibration peaks at 3380 and 3340 cm -1 and the C-N stretching vibration peak at 1428 cm -1 indicates the successful preparation of CS / PANI-GO composite material.

[0078] Adsorption performance of CS2 / PANI-GO nicotine molecularly imprinted composite material

[0079] The pH value plays a key role in evaluating the adsorption performance of adsorbent materials. As can be seen from Figure 2 a, the adsorption capacity of GO increases with the increase of pH value when pH=3-6. When the pH is higher than 6, the adsorption capacity of GO decreases with the increase of pH value. Compared with GO, the adsorption capacity of PANI-GO and CS2 / PANI-GO materials increases with the increase of pH value. When pH=8, the CS2 / PANI-GO hydrogel material reaches the maximum adsorption capacity, and the adsorption capacity of nicotine reaches 198 mg g -1 . This is because the deprotonation of the amino groups in the structure of PANI and CS releases a large number of adsorption active sites on the surface of the material with the increase of pH value. With the increase of pH, H +The decrease in ion concentration and more active sites on PANI-GO and CS2 / PANI-GO hydrogel materials for binding nicotine result in an increase in adsorption capacity. At the same time, the network structure formed by PANI-GO and CS2 / PANI-GO increases the probability of functional groups combining with nicotine. With the increase of pH from 8 to 10, the adsorption capacity of PANI-GO and CS2 / PANI-GO decreases, which is mainly due to the fact that it is difficult for nicotine to combine with the active sites in PANI-GO and CS2 / PANI-GO materials under alkaline conditions. In addition, the adsorption capacity of CS2 / PANI-GO adsorbent is greater than that of PANI-GO and GO, indicating that the introduction of PANI and CS enriches the adsorption active sites of GO for adsorbing nicotine.

[0080] The adsorption behavior of the adsorbent was explored, and the contact time and adsorption kinetics were studied when the initial nicotine concentration was 0.1 mg mL -1 . The kinetic mechanism is controlled by the mass transfer process, including the equilibrium time and the physical and chemical properties of the adsorbent. As can be seen from Figure 2 b, the adsorption capacity of PANI-GO and CS2 / PANI-GO materials for nicotine increases significantly with time until the adsorption capacity of the adsorbent does not change significantly with time after the adsorbent reaches the equilibrium time. The adsorption equilibrium time of CS2 / PANI-GO (80 min) composite material is lower than that of PANI-GO (120 min), which is due to the introduction of CS reducing the swelling of the material. At the same time, the adsorption capacity of PANI-GO and CS2 / PANI-GO after reaching adsorption equilibrium is 180 mg·g -1 and 198 mg·g -1 , respectively. This result shows that the introduction of PANI and CS increases the adsorption active sites and the anti-swelling property of the gel, improves the combination probability of the material and nicotine, and thus increases the adsorption capacity and adsorption efficiency of graphene oxide. The adsorption time and adsorption capacity data of PANI-GO and CS2 / PANI-GO adsorbents were fitted with pseudo-first-order kinetics and pseudo-second-order kinetics models Figure 2 c, d) to illustrate its adsorption behavior. As can be seen from the fitted curves, the adsorption kinetics of PANI-GO and CS2 / PANI-GO both conform to the pseudo-second-order kinetics model, rather than the pseudo-first-order kinetics model. This conclusion shows that the adsorption rate of the organic functional groups in the interlayer spacing of PANI-GO and CS2 / PANI-GO and nicotine adsorption is mainly determined by the rate of nicotine combining with the material surface.

[0081] The thermodynamic adsorption behavior of CS2 / PANI-GO adsorbent material was studied and the maximum adsorption capacity of the material was evaluated. The adsorption performance of the adsorbent material at different nicotine concentrations at 25°C, 35°C and 45°C was investigated, and the results are as follows Figure 3 a. As can be seen from the figure, the adsorption capacity of CS2 / PANI-GO increases with the increase of nicotine concentration. On the one hand, the increase of nicotine concentration in the solution makes more active sites in the adsorbent for adsorption; on the other hand, the increase of temperature increases the chaotic degree of nicotine in the solution and increases the collision probability with the material surface. From the fitting curve Figure 3 b) it can be seen that the thermodynamics of CS2 / PANI-GO conforms to the Langmuir model, indicating that the adsorption of nicotine on the adsorption sites on the surface of CS2 / PANI-GO is uniform and monolayer, and the binding energy on the entire surface of the material is uniformly distributed.

[0082] Selectivity of CS2 / PANI-GO nicotine molecularly imprinted composite material

[0083] The selectivity of CS2 / PANI-GO molecularly imprinted composite material was investigated by selective adsorption experiments with cotinine and nornicotine as competitive molecules. The adsorption results of the molecularly imprinted composite material and the non-molecularly imprinted composite material show that Figure 4 ), the molecularly imprinted polymer CS2 / PANI-GO has very good selective adsorption of nicotine, and the adsorption selectivity coefficients of nornicotine and cotinine are 2.9 and 2.4, respectively. This shows that it is effective to construct selective recognition sites in the molecularly imprinted composite material. The results show that the prepared molecularly imprinted cavity has high recognition ability for nicotine.

[0084] Although the present application has been described herein with reference to a number of illustrative embodiments, it should be understood that various other modifications and implementations can be devised by those skilled in the art without departing from the principles and spirit of the disclosure. More specifically, many variations and modifications of the subject combination arrangement can be made to the components thereof and / or the arrangement itself within the scope of the disclosure. Other uses will be apparent to those skilled in the art.

Claims

1. A method for preparing a nicotine molecularly imprinted composite material, characterized in that: Includes the following steps: S1: A certain amount of chitosan (CS) and polyaniline (PANI) were dissolved in N,N-dimethylformamide solution and stirred to prepare a CS / PANI prepolymer; S2: Nicotine, epichlorohydrin and graphene oxide (GO) are added to the CS / PANI prepolymer for further crosslinking; S3: Pour the solution obtained in S2 into a tubular mold to react and obtain a gel-like CS / PANI-GO composite material, and heat it in an oven; S4: Wash the hydrogel with acetonitrile solution to remove the template molecule nicotine; S5: Rinse the CS / PANI-GO hydrogel with deionized water. Stop rinsing when the pH of the rinsed deionized water is 7. The rinsing method is to rinse with flowing deionized water. S6: Freeze-dry the CS / PANI-GO hydrogel to prepare the CS / PANI-GO nicotine molecularly imprinted composite material.

2. The method for preparing a nicotine molecularly imprinted composite material according to claim 1, characterized in that: The amount of CS added is 0.5%, 1%, 2%, 3%, or 4% of the sum of the masses of PANI and GO.

3. The method for preparing a nicotine molecularly imprinted composite material according to claim 1, characterized in that: In step S1, the stirring time is 9-14 hours and the stirring speed is 200 rpm.

4. The method for preparing a nicotine molecularly imprinted composite material according to claim 1, characterized in that: In step S2, the crosslinking time is 1-5 hours and the temperature is 30-70°C.

5. The method for preparing a nicotine molecularly imprinted composite material according to claim 1, characterized in that: In step S3, the heating time in the oven is 4-10 hours, and the temperature is 30-60°C.

6. The method for preparing a nicotine molecularly imprinted composite material according to claim 1, characterized in that: In step S4, the washing time is 5-20 minutes, and the rinsing method is repeated rinsing with acetonitrile.

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