CN108031453A - Microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material - Google Patents

Abstract

The present invention relates to the separation adsorbing domain of p-nitrophenol, is specifically a kind of preparation method and applications of microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material.The preparation method includes the preparation of magnetic flyash, the synthesis of microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram material and the elution of template molecule.The made microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material of the present invention, there are a large amount of holes for belonging to avtive spot on its surface, adsorption activity is strong, fast selective absorption can be carried out to template molecule and is easy to elute, for Solid Phase Extraction can fast and efficiently making choice property of p-nitrophenol separation, enrichment, by with efficient liquid-phase chromatography method combination can realize in environmental water sample p-nitrophenol quick separating detect.

Description

Microwave-assisted magnetic fly ash loaded p-nitrophenol molecularly imprinted solid-phase extraction material

technical field

The invention relates to the field of separation and adsorption of p-nitrophenol, in particular to a preparation method and application of a microwave-assisted magnetic fly ash loaded p-nitrophenol molecularly imprinted solid-phase extraction material.

Background technique

P-Nitrophenol (PNP) is a phenolic organic pollutant, slightly soluble in water, not easy to volatilize with steam, and is a dangerous substance with enrichment effect, which will seriously endanger the environment and the health of organisms. The U.S. Environmental Protection Agency (EPA) has listed it as one of the priority pollutants, and stipulated that its concentration in natural water bodies should be limited to below 10ng/L. my country has also included it in the blacklist of 68 priority pollutants in water. As one of the methods for treating p-nitrophenol, the adsorption method has low treatment cost, does not introduce other pollutants when separating pollutants, and can realize rapid and effective separation of pollutants and water environment and is effective.

Molecularly imprinted materials are polymers synthesized by molecular imprinting technology that can selectively recognize template molecules. They have active sites that match the size, shape and functional groups of template molecules, thus enabling selective separation of specific molecules. In the preparation of molecularly imprinted polymers, the microwave-assisted reaction method can not only shorten the reaction time, make the synthesized polymer particles more uniform, and improve the adsorption capacity of imprinted materials; but the addition of surface imprinting technology can make the active sites of molecularly imprinted materials Located on the surface of the material, it is more conducive to the adsorption, so the microwave surface molecularly imprinted material can be used as a new type of adsorbent to effectively separate and adsorb pollutants.

Solid-phase extraction is a sample pretreatment technology developed in recent years, which is mainly used for the separation, purification and enrichment of samples. However, the traditional solid-phase extraction column packing is usually dominated by non-specific selective materials. It is easy to adsorb the interfering substances together, which will eventually make the sample purification incomplete and affect the detection results. Molecularly imprinted solid phase extraction, that is, using selective molecularly imprinted materials as solid phase extraction agents, combining solid phase extraction technology with the advantages of molecularly imprinted materials, can greatly improve the extraction and purification effect of solid phase extraction columns, so as to achieve Effective separation, enrichment and rapid detection of pollutants.

Contents of the invention

The purpose of the present invention is to provide a simple, economical and effective preparation method of microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid phase extraction material and a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid phase extraction method. Phase extraction column, so as to realize the rapid and efficient selective separation and detection of p-nitrophenol.

The present invention is achieved through the following technical scheme: a preparation method of a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction material, comprising the following steps:

(1) Preparation of magnetic fly ash:

Take fly ash and disperse it in distilled water by ultrasonication for 10-40min, add FeCl ₃ 6H ₂ O and continue stirring for 0.5-1.5h, then add FeSO ₄ 7H ₂ O under nitrogen protection and stir at 30-80°C for 10-40min , then add ammonia water to make the pH of the solution ≥ 10, continue to stir for 2 to 4 hours to obtain a black precipitate, use a permanent magnet to collect the product and wash it with deionized water to neutrality to obtain magnetic fly ash;

(2) Synthesis of microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted materials:

Weigh p-nitrophenol and dissolve it in an organic solvent, heat and stir in a water bath at 40-80°C for 20-60 minutes, add a monomer soluble in an organic solvent into the p-nitrophenol solution and continue stirring for 0.5-1.5 hours , then add magnetic fly ash, disperse evenly, add initiator and crosslinking agent, stir and react by microwave heating for 5-15min to obtain molecularly imprinted material microspheres;

(3) Elution of template molecules:

The product was repeatedly eluted with an acid solution until no PNP molecules were detected in the filtrate, and then vacuum-dried at 40-60°C to obtain a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction material.

As a further improvement of the technical solution of the present invention, the fly ash is subjected to pretreatment and activation before step (1) ultrasonic dispersion, and the steps of pretreatment and activation are as follows: the fly ash is passed through a 100-200 mesh sieve, and deionized water is used to Wash for 3 to 4 times, stir with a mixer at a speed of 80 to 120r/min, then precipitate to remove the upper layer of turbid liquid, put it in an oven to dry for 24 to 36 hours, and stir several times during this period to prevent agglomeration; put the dried fly ash into Stir in 1-6mol/L HCL at 40-70°C for 6-10 hours, then filter, wash repeatedly with distilled water until neutral, and then dry at 30-60°C.

As a further improvement of the technical solution of the present invention, the molar ratio of FeCl ₃ ·6H ₂ O to FeSO ₄ ·7H ₂ O is (1.5-2):1.

As a further improvement of the technical solution of the present invention, the monomer is one of γ-ureidopropyltrimethoxysilane and γ-ureidopropyltriethoxysilane or a mixture mixed in any proportion; The initiator is one or more of azobisisobutyronitrile, azobisisoheptanonitrile and dimethyl azobisisobutyrate.

As a further improvement of the technical solution of the present invention, the crosslinking agent is one or more of ethylene glycol dimethacrylate, epichlorohydrin, and N,N-methylenebisacrylamide.

As a further improvement of the technical solution of the present invention, the molar ratio of the PNP, monomer, crosslinking agent, and initiator is 1: (3-5): (2-4): (0.15-0.3), and the crosslinking agent, The volume ratio of the organic solvent is 1:(15-35).

As a further improvement of the technical solution of the present invention, the acid solution is 0.5-1.5 mol/L hydrochloric acid or methanol and acetic acid with a volume ratio of 9:1.

The present invention further provides a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid phase extraction material prepared by any of the above microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction materials. Application in the adsorption separation of p-nitrophenol pollutants.

The present invention further provides a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column. Preparation method of extraction material The prepared microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction material is used as filler.

Further, the method for using the extraction column includes the following steps:

(1) After filling the solid-phase extraction column, activate the solid-phase extraction column with methanol and distilled water successively;

(2) Adjust the pH of the sample solution to 2-10 and add it to the column;

(3) Carry out leaching and elution with the eluent to the solid-phase extraction column after loading the sample, measure the p-nitrophenol content in the eluent with high performance liquid chromatography, and the eluent is methanol, (1- 9): 1 methanol: one of acetic acid solution, acetic acid, and distilled water.

The microwave-assisted magnetic fly ash loaded p-nitrophenol molecularly imprinted solid-phase extraction material prepared by the present invention uses industrial waste slag fly ash as a carrier after modification, which embodies the principle of technical economy by turning harm into benefit. The synthesis process is simple and the reaction is simple. The conditions are mild and have high stability; the material has the advantages of strong adsorption activity, good selectivity and easy elution because of its large number of specific active sites on the surface. It is used for solid phase extraction and combined with high performance liquid chromatography. The rapid separation, enrichment and detection process of p-nitrophenol in environmental water samples can be realized.

Description of drawings

Fig. 1 is a SEM image of the microwave-assisted magnetic fly ash loaded p-nitrophenol molecularly imprinted solid-phase extraction material of the present invention.

Detailed ways

The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings.

A method for preparing a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction material, comprising the following steps:

(1) Preparation of magnetic fly ash:

Take 0.3~1g of fly ash and disperse it in distilled water by ultrasonication for 10~40min, add FeCl ₃ 6H ₂ O and stir for 0.5~1.5h, then add FeSO ₄ 7H ₂ O under the protection of nitrogen and stir at 30~80℃ for 10~ After 40 minutes, add ammonia water to make the pH of the solution ≥ 10, and continue to stir for 2-4 hours to obtain a black precipitate, which is collected by a permanent magnet and washed with deionized water until neutral. Wherein, the fly ash is pretreated and activated before ultrasonic dispersion, and the specific steps include: passing the fly ash through a 100-200 mesh sieve, washing it with deionized water for 3-4 times, at a speed of 80-120r/min After stirring with a mixer, precipitate and remove the upper layer of turbid liquid, put it in an oven to dry for 24-36 hours, and stir several times during this period to prevent agglomeration; put the dried fly ash into 1-6mol/L HCL, and dry it at 40-70 After stirring for 6-10 hours, filter, wash repeatedly with distilled water until neutral, and then dry at 30-60°C.

Specifically, the molar ratio of FeCl ₃ ·6H ₂ O to FeSO ₄ ·7H ₂ O is (1.5～2):1 (for example, 1.5:1 or 2:1); the amount of FeSO ₄ ·7H ₂ O added is 2～ 5mmol.

(2) Synthesis of microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted materials:

Dissolve p-nitrophenol in an organic solvent, heat and stir in a water bath at 40-80°C for 20-60 minutes, then add the monomer dissolved in the organic solvent and continue stirring for 0.5-1.5 hours, then add magnetic fly ash, disperse Add an initiator and a cross-linking agent after uniformity, stir and react by microwave heating for 5-15 minutes to obtain molecularly imprinted material microspheres.

Specifically, the monomer is selected from one or a mixture of γ-ureidopropyltrimethoxysilane and γ-ureidopropyltriethoxysilane; the initiator is azobisisobutyronitrile, azobis One or more of isoheptanonitrile and dimethyl azobisisobutyrate; the crosslinking agent is selected from ethylene glycol dimethacrylate, epichlorohydrin, and N,N-methylenebisacrylamide one or more of .

During specific implementation, the mol ratio of PNP, monomer, cross-linking agent and initiator is 1: (3-5): (2-4): (0.15-0.3) in the described method, the ratio of cross-linking agent, organic solvent The volume ratio is 1:(15-35). The molar ratio of described PNP, monomer, linking agent, initiator can be 1:3:2:0.15, 1:5:2:0.3, 1:4:3:0.2, 1:3:4:0.15 or 1:5:4:0.3.

During specific implementation, the microwave reaction power is 80-240w.

(3) Elution of template molecules:

The product was repeatedly eluted with an acid solution until no PNP molecules were detected in the filtrate, and then vacuum-dried at 40-60°C to obtain a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction material (MIP).

Specifically, the acid solution is 0.5-1.5 mol/L hydrochloric acid or methanol:acetic acid with a volume ratio of 9:1.

Application of a microwave-assisted magnetic fly ash loaded p-nitrophenol molecularly imprinted solid-phase extraction material prepared by the invention in selective adsorption and separation of p-nitrophenol pollutants.

The present invention provides a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid phase extraction column. The solid-phase extraction column is prepared by the microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid phase The extraction material is a filler.

Specifically, the volume of the solid-phase extraction column was selected as 1 mL, and the mass of the solid-phase extraction material loaded with microwave-assisted magnetic fly ash loaded with p-nitrophenol molecular imprinting was 100 mg.

The method for using the microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column of the present invention is used for the selective separation and enrichment of p-nitrophenol solution and the detection of p-nitrophenol, and the specific steps include: :

(1) Before loading the sample, activate the solid-phase extraction column with methanol and distilled water in sequence;

(2) Adjust the pH of the sample solution to 2-10 and add it to the column;

(3) Carry out leaching and elution with the solid-phase extraction column of eluent pair, measure p-nitrophenol content in eluent with high performance liquid chromatography (HPLC), described eluent is methyl alcohol, (1- 9): 1 methanol: one of acetic acid, acetic acid, and distilled water, with a volume of 1-5 mL.

Example 1

A method for preparing a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction material, comprising the following steps:

(1) Pretreatment and activation of fly ash:

Pass the fly ash through a 100-mesh sieve, wash it three times with deionized water, stir it with a mixer at a speed of 800r/min for 25 minutes, then settle to remove the upper layer of turbid liquid, put it in an oven to dry for 36 hours, and stir several times during this period to prevent agglomeration. Put 30g of dried fly ash into 200mL of 1mol/L HCL, stir at 60°C for 6h, filter, wash repeatedly with distilled water until neutral, and then dry at 30°C.

(2) Preparation of magnetic fly ash:

Take 0.3g activated fly ash and ultrasonically disperse in distilled water within 10min, add 4mmol FeCl ₃ 6H ₂ O and continue to stir for 1h, then add 2mmol FeSO ₄ 7H ₂ O under nitrogen protection and stir at 30°C for 40min, then Ammonia water was added to make the pH of the solution ≥ 10, and the stirring was continued for 4 h. The product was collected with a magnet and washed with deionized water until neutral.

(3) Synthesis of microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted materials:

Dissolve 0.0042mol of PNP in 30mL of methanol and transfer it into a three-necked flask, heat and stir in a water bath at 40°C for 60min, dissolve 0.0126mol of γ-ureidopropyltriethoxysilane in 26mL of methanol and add it to the three-necked flask and continue to stir for 0.5 h, then add 3.5g of magnetic fly ash, disperse evenly, add 0.0006mol of azobisisoheptyl cyanide and 1.6mL of ethylene glycol dimethacrylate (EGDMA) and stir for 50min, then heat and react with 80w microwave for 15min to obtain Molecularly imprinted material microspheres.

(4) Elution of template molecules:

The obtained product was repeatedly eluted with 0.5mol/L HCL solution until no PNP molecules were detected in the filtrate, and then dried in a vacuum oven at 40°C to obtain microwave-assisted magnetic fly ash-loaded p-nitrophenol molecules Blot solid-phase extraction material.

Example 2

A method for preparing a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction material, comprising the following steps:

(1) Pretreatment and activation of fly ash:

Pass the fly ash through a 200-mesh sieve, wash it with deionized water for 4 times, stir it with a mixer at a speed of 120r/min for 40 minutes, then settle to remove the upper layer of turbid liquid, put it in an oven to dry for 36 hours, and stir several times during this period to prevent agglomeration. Put 30g of dried fly ash into 200mL of 6mol/L HCL, stir at 70°C for 6h, filter, wash repeatedly with distilled water until neutral, and then dry at 50°C.

(2) Preparation of magnetic fly ash:

Take 1g of activated fly ash and ultrasonically disperse in distilled water within 40min, add 7.5mmol FeCl ₃ 6H ₂ O and continue to stir for 1h, then add 5mmol FeSO ₄ 7H ₂ O under nitrogen protection and stir at 80°C for 40min, then Ammonia water was added to make the pH of the solution ≥ 10, and the stirring was continued for 4 h. The product was collected with a magnet and washed with deionized water until neutral.

(3) Synthesis of microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted materials:

Dissolve 0.0042mol of PNP in 25mL of methanol and transfer it into a three-necked flask, heat and stir in a water bath at 70°C for 20min, dissolve 0.021mol of γ-ureidopropyltrimethoxysilane in 20mL of methanol and add it to the three-necked flask and continue to stir for 1.5h , then add 4g of magnetic fly ash, disperse evenly, add 0.0012mol azobisisobutyronitrile dimethyl ester, add 0.0084mol N,N-methylene bisacrylamide dissolved in 3mL methanol, stir for 50min, and then use 240w Molecularly imprinted material microspheres were obtained after microwave heating for 5 min.

(4) Elution of template molecules:

The obtained product was repeatedly eluted with 1.5mol/L HCL solution until no PNP molecules were detected in the filtrate, and dried in a vacuum oven at 60°C to obtain microwave-assisted magnetic fly ash loaded p-nitrophenol molecules Blot solid-phase extraction material.

Example 3

A method for preparing a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction material, comprising the following steps:

(1) Pretreatment and activation of fly ash:

Pass the fly ash through a 200-mesh sieve, wash it three times with deionized water, stir it with a mixer at a speed of 100r/min for 30 minutes, then settle to remove the upper layer of turbid liquid, put it in an oven to dry for 24 hours, and stir several times during this period to prevent agglomeration. Put 30g of dried fly ash into 200mL of 1mol/L HCL, stir at 50°C for 8h, filter, wash repeatedly with distilled water until neutral, and then dry at 50°C.

(2) Preparation of magnetic fly ash:

Take 0.5g activated fly ash and ultrasonically disperse in distilled water within 30min, add 3mmol FeCl ₃ 6H ₂ O and continue stirring for 1h, then add 1.5mmol FeSO ₄ 7H ₂ O under nitrogen protection and stir at 80°C for 30min, Then ammonia water was added to make the pH of the solution ≥ 10, and the stirring was continued for 3 h. The product was collected with a magnet and washed with deionized water until neutral.

(3) Synthesis of microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted materials:

Weigh 0.0042mol of PNP, dissolve it in 26mL of methanol and transfer it into a three-necked flask, heat and stir in a water bath at 60°C for 30min, dissolve 0.0168mol of γ-ureidopropyltrimethoxysilane in 20mL of methanol, add it to the three-necked flask and continue stirring for 1h , then add 3g of magnetic fly ash, disperse evenly, add 0.007mol of azobisisobutyronitrile and 2.3mL of ethylene glycol dimethacrylate (EGDMA) and stir for 30min, and react with 80w microwave for 10min to obtain the molecularly imprinted material Microspheres.

(4) Elution of template molecules:

The obtained product was repeatedly eluted with 1:9 acetic acid:methanol solution until no PNP molecules were detected in the filtrate, and then dried in a vacuum drying oven at 50°C to obtain a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid phase Extraction material (MIP).

Example 4

A method for preparing a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction material, comprising the following steps:

(1) Pretreatment and activation of fly ash:

Pass the fly ash through a 100-mesh sieve, wash it three times with deionized water, stir it with a mixer at a speed of 100r/min for 40 minutes, then settle to remove the upper layer of turbid liquid, put it in an oven to dry for 36 hours, and stir it several times during this period to prevent agglomeration. Put 30g of dried fly ash into 200mL of 3mol/L HCL, stir at 40°C for 6h, filter, wash repeatedly with distilled water until neutral, and then dry at 50°C.

(2) Preparation of magnetic fly ash:

Take 0.7g activated fly ash and ultrasonically disperse in distilled water within 40min, add 4.5mmol FeCl ₃ 6H ₂ O and continue stirring for 1.5h, then add 3mmol FeSO ₄ 7H ₂ O under nitrogen protection and stir at 50°C for 1h , and then add ammonia water to make the pH of the solution ≥ 10, continue to stir for 4h, collect the product with a magnet and wash it with deionized water until neutral.

(3) Synthesis of microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted materials:

Dissolve 0.0042mol of PNP in 25mL of methanol and transfer it into a three-necked flask, heat and stir in a water bath at 60°C for 50min, respectively add 0.0084mol of γ-ureidopropyltrimethoxysilane and 0.0084mol of γ-ureidopropyltrimethoxysilane Dissolve ethoxysilane in 20.5mL of methanol, add the two monomers into a three-necked flask and continue to stir for 1.5h, then add 5g of magnetic fly ash, disperse evenly, add 0.0006mol of azobisisobutyronitrile, add 1.3mL of epoxy Chloropropane, stirred for 50 minutes, and then reacted with 80w microwave heating for 5 minutes to obtain molecularly imprinted material microspheres.

(4) Elution of template molecules:

The obtained product was repeatedly eluted with 1:9 acetic acid:methanol solution until no PNP molecules were detected in the filtrate, and then dried in a vacuum oven at 50°C to obtain microwave-assisted magnetic fly ash loaded p-nitrogen Phenol Molecularly Imprinted Solid Phase Extraction Material.

Example 5

A method for preparing a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction material, comprising the following steps:

(1) Pretreatment and activation of fly ash:

Pass the fly ash through a 200-mesh sieve, wash it three times with deionized water, stir it with a mixer at a speed of 120r/min for 30 minutes, then settle to remove the upper layer of turbid liquid, put it in an oven to dry for 36 hours, and stir several times during this period to prevent agglomeration. Put 30g of dried fly ash into 200mL of 6mol/L HCL, stir at 70°C for 5h, filter, wash repeatedly with distilled water until neutral, and then dry at 50°C.

(2) Preparation of magnetic fly ash:

Take 0.3g of activated fly ash and ultrasonically disperse in distilled water within 40min, add 3mmol FeCl ₃ 6H ₂ O and continue stirring for 1.5h, then add 2mmol FeSO ₄ 7H ₂ O under nitrogen protection and stir at 70°C for 0.5h , and then add ammonia water to make the pH of the solution ≥ 10, continue to stir for 2h, collect the product with a magnet and wash it with deionized water until neutral.

(3) Synthesis of microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted materials:

Dissolve 0.0042mol of PNP in 20mL of methanol and transfer it into a three-necked flask, heat and stir in a water bath at 70°C for 20min, dissolve 0.0014mol of γ-ureidopropyltrimethoxysilane in 15mL of methanol, and 0.0007mol of γ-ureido Propyltriethoxysilane was dissolved in 14mL of methanol, respectively added to the three-necked flask and continued to stir for 0.5h, then 5g of magnetic fly ash was added, after the dispersion was uniform, 0.0004mol of azobisisobutyronitrile, 0.0002mol of azobisisobutyronitrile Acrylic acid dimethyl ester, 3.2mL ethylene glycol dimethacrylate, stirred for 40min, and then heated with 240w microwave for a total of 15min to obtain molecularly imprinted material microspheres.

(4) Elution of template molecules:

The obtained product was repeatedly eluted with 1.5mol/L HCL solution until no PNP molecules were detected in the filtrate, and then dried in a vacuum oven at 50°C to obtain microwave-assisted magnetic fly ash-loaded p-nitrophenol molecules Blot solid-phase extraction material.

Example 6

In Example 6 of the present invention, the aforementioned microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column was used to study the influence of the eluent on the extraction efficiency.

100mg of the MIP materials prepared in Examples 1-5 were filled into 1mL small columns, and absorbent cotton was placed at both ends of the columns to prepare microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction columns.

Before loading the sample, activate the solid-phase extraction column with methanol and distilled water in sequence;

After adjusting the pH of the PNP sample solution to 7, take 50mL of the sample and load it into the small column;

Select 5 mL of methanol with a volume ratio of 9:1: acetic acid, 7:1 methanol: acetic acid, 5:1 methanol: acetic acid, 3:1 methanol: acetic acid and 1:1 methanol: acetic acid solution for example 1 The solid phase extraction column made of ~5 materials is used for elution and elution;

The eluent was collected, and the content of p-nitrophenol in the eluent was measured by high performance liquid chromatography (HPLC), and the elution efficiency of different eluents was calculated. The results are shown in Table 1. It can be seen from Table 1 that in Example 5, when the ratio of methanol:acetic acid is 1:1, the highest elution efficiency reaches 99.2%.

Table 1 The influence of different eluents on the efficiency of solid phase extraction

eluent Example 1 Example 2 Example 3 Example 4 Example 5 Extraction rate 36.1% 39.5% 43.1% 46.4% 99.2%

Example 7

Example 7 of the present invention adopts the aforementioned method of using a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column to study the influence of the pH value of the sample solution on the extraction efficiency.

100 mg of the MIP material prepared in Example 1 was filled into a 1 mL small column, and absorbent cotton was placed at both ends of the column to prepare a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column.

Before loading the sample, activate the solid-phase extraction column with methanol and distilled water in sequence;

Adjust the pH of the PNP sample solution to 2-10 respectively, and load 50 mL of the sample into each small column;

Use 1 mL of methanol: acetic acid solution with a volume ratio of 1:1 to elute the column;

The eluent was collected, and the content of p-nitrophenol in the eluent was measured by high performance liquid chromatography (HPLC), and the elution efficiency of different eluents was calculated. The results are shown in Table 2. As can be seen from Table 2, when the pH value of the solution is 2 and 10, the extraction efficiency is 75.5% and 82.2% respectively, and when the pH value of the solution is 6-8, the extraction efficiency is 96.8% and 98.6% respectively and 96.0%, so the efficiency of solid phase extraction is the best under neutral conditions.

The influence of table 2 solution pH value on solid phase extraction efficiency

pH value 2 3 4 5 6 7 8 9 10 Extraction rate 75.5% 84.8% 92.1% 94.8% 96.9% 98.6% 96.0% 88.7% 82.3%

Example 8

Example 8 of the present invention adopts the aforementioned method of using a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column to study the selectivity of the solid-phase extraction column.

100 mg of the MIP material prepared in Example 1 was filled into a 1 mL small column, and absorbent cotton was placed at both ends of the column to prepare a microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column.

Before loading the sample, activate the solid-phase extraction column with methanol and distilled water in sequence;

Adjust the sample solution of PNP, 2,4-dinitrophenol, catechol and phenol at the same concentration to pH=7, and take 50mL of the sample solution to the small column;

Use 3 mL of methanol: acetic acid solution with a volume ratio of 1:1 to elute the column;

The eluate was collected, and the content of p-nitrophenol in the eluate was measured by high performance liquid chromatography (HPLC), and the elution efficiency of different eluents was calculated. The results are shown in Table 3. As can be seen from Table 3, when the four compounds coexist, the extraction rate of PNP by the solid-phase extraction column is 98.7%, which is significantly higher than the extraction efficiency of 2,4-dinitrophenol, catechol and phenol, which are 60.7%, 42.3% and 59.0%, which indicated that the microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column had good selectivity to PNP.

Table 3 Selectivity of p-nitrophenol molecularly imprinted solid-phase extraction column

sample PNP 2,4-Dinitrophenol Catechol phenol SPE rate 98.7% 60.7% 42.3% 59.0%

Example 9

Example 9 of the present invention adopts the aforementioned microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column, and the microwave-assisted magnetic fly ash loaded p-nitrophenol molecularly imprinted solid-phase extraction column is loaded with the materials prepared in Examples 1 to 5 under optimal conditions. The solid-phase extraction performance of the magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column was tested.

Before loading the sample, activate the solid-phase extraction column with methanol and distilled water in sequence;

Adjust the pH of the PNP sample solution to 7, and load 50 mL of the sample into the small column;

Use 3 mL of methanol: acetic acid solution with a volume ratio of 1:1 to elute the column;

The eluent was collected, and the p-nitrophenol content in the eluent was measured by high performance liquid chromatography (HPLC), and the elution efficiency of different eluents was calculated. The results are shown in Table 4. As can be seen from Table 4, the extraction performance of the microwave-assisted magnetic fly ash-loaded p-nitrophenol molecularly imprinted solid-phase extraction column of the present invention is stable, and the solid-phase extraction efficiency of p-nitrophenol is all above 96%.

Table 4 Performance of the p-nitrophenol molecularly imprinted solid-phase extraction column made of materials in Examples 1 to 5

Example Example 1 Example 2 Example 3 Example 4 Example 5 SPE rate 96.6% 99.0% 99.3% 98.2% 97.1%

The above descriptions are preferred embodiments of the present invention, and are not intended to limit the present invention. It should be pointed out that on the premise of not departing from the principle of the present invention, any equivalent replacement of any raw material, improvement and modification of specific methods of the present invention all fall within the protection scope of the present invention.

Claims (10)

1. the preparation method of microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material, its feature exist In comprising the following steps：

（1）The preparation of magnetic flyash：

Take 10 ~ 40min of flyash ultrasound to be dispersed in distilled water, add FeCl₃•6H₂O simultaneously continues 0.5 ~ 1.5h of stirring, then FeSO is added under nitrogen protection₄•7H₂O simultaneously stirs 10 ~ 40min in 30 ~ 80 DEG C, and then adding ammonium hydroxide makes pH >=10 of solution, Continue 2 ~ 4h of stirring, obtain black precipitate, collected the product with permanent magnet and be washed with deionized to neutrality, obtained magnetic Flyash；

（2）The synthesis of microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram material：

Weigh p-nitrophenol to be dissolved in organic solvent, 20 ~ 60min of heating stirring in 40 ~ 80 DEG C of water-bath, in p-nitrophenyl The monomer that can dissolve in organic solvent is added in phenol solution and continues 0.5 ~ 1.5h of stirring, then adds magnetic flyash, point Initiator and crosslinking agent are added after dissipating uniformly, heated by microwave reaction 5-15min obtains molecular engram material microballoon after stirring；

（3）The elution of template molecule：

Elution repeatedly is carried out to product with acid solution until being not detected by PNP molecules in filtrate, after 40 ~ 60 DEG C of vacuum drying To microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material.

2. the microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material according to claim 1 The preparation method of material, it is characterised in that the flyash is in step（1）By pretreatment and activation, pre- place before ultrasonic disperse Manage and be the step of activation：Flyash crosses 100 ~ 200 mesh sieves, is eluriated 3 ~ 4 times with deionized water, with the speed of 80 ~ 120r/min Precipitation removes upper strata turbid solution after being stirred with mixer, is put into 24 ~ 36h of oven drying, during which stirring for several times prevents from luming；Will be dry Flyash after dry is put into the HCL of 1 ~ 6mol/L to be filtered after 40 ~ 70 DEG C of 6 ~ 10h of stirring, is washed repeatedly into distilled water Property after with 30 ~ 60 DEG C drying.

3. the microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material according to claim 1 The preparation method of material, it is characterised in that the FeCl₃•6H₂O and FeSO₄•7H₂The molar ratio of O is（1.5~2）：1.

4. microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material according to claim 1 Preparation method, it is characterised in that the monomer is γ-ureido-propyl trimethoxy silane and γ-ureido-propyl triethoxy One kind in silane or the mixture with arbitrary proportion mixing；The initiator for azodiisobutyronitrile, azobisisoheptonitrile, One or more in azo-bis-iso-dimethyl.

5. microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material according to claim 1 Preparation method, it is characterised in that the crosslinking agent for ethylene glycol dimethacrylate, epoxychloropropane, N, N- methylene One or more in bisacrylamide.

6. microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material according to claim 1 Preparation method, it is characterised in that the PNP, monomer, crosslinking agent, initiator molar ratio be 1：（3-5）：（2-4）： （0.15-0.3）, crosslinking agent, the volume ratio of organic solvent are 1：（15-35）.

7. microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction material according to claim 1 Preparation method, it is characterised in that the hydrochloric acid or volume ratio that acid solution is 0.5-1.5mol/L are 9:1 methanol and acetic acid.

8. the microwave radiation technology magnetism fly ash loading p-nitrophenol molecule according to claim 1 to 7 any claim The microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram that the preparation method of trace Solid Phase Extraction material is prepared Application of the Solid Phase Extraction material in p-nitrophenol pollutant is selectively adsorbing and separating.

9. a kind of microwave radiation technology magnetism fly ash loading p-nitrophenol molecularly imprinted solid phase extraction column, it is characterised in that described Solid-phase extraction column is with the microwave radiation technology magnetism fly ash loading p-nitrophenyl described in any claim claim 1 to 7 described The microwave radiation technology magnetism fly ash loading p-nitrophenol point that the preparation method of phenol molecular engram solid phase extraction material is prepared Sub- trace Solid Phase Extraction material is filler.

A kind of 10. microwave radiation technology magnetism fly ash loading p-nitrophenol molecular engram solid phase extraction according to claim 9 Take column, it is characterised in that the step of its application method includes is as follows：

（1）After loading solid-phase extraction column, solid-phase extraction column is activated with methanol and distilled water successively；

（2）Sample solution tune pH is added in column for 2 ~ 10；

（3）Elution elution is carried out to the solid-phase extraction column after loading with eluent, with high effective liquid chromatography for measuring eluent Content of p-nitrophenol, the eluent for methanol,（1-9）：1 methanol：One kind in acetic acid, acetic acid, distilled water, volume are 1~5mL。