Preparation method of solid-phase extraction membrane and product thereof

Abstract

The invention relates to a preparation method of a solid-phase extraction membrane and a product thereof, and the preparation method comprises the following steps: immersing a quartz fiber membrane into a polymer solution with a solid-phase extraction function, taking out the membrane, and naturally drying, heating and drying, drying at low temperature or immersing the membrane into a non-solvent of the polymer to obtain the solid-phase extraction membrane taking the polymer as an extraction function material; or immersing the quartz fiber membrane in an acid solution or an ethylene-vinyl alcohol copolymer or a polyvinyl alcohol solution for a certain time, then taking out the quartz fiber membrane, washing and drying the quartz fiber membrane, then bonding octadecyl trichlorosilane or octadecyl trichlorosilane in dry toluene by using triethylamine as a catalyst, and then carrying out tail sealing by using trimethylchlorosilane, so as to obtain the quartz fiber membrane. The solid-phase extraction membrane bonded with octadecyl or octaalkyl is obtained. The used quartz fiber base membrane is high in purity, solid-phase extraction membranes of various materials and specifications can be obtained by adopting the method, and the requirements of analysis and test pretreatment can be met.

Description

Technical Field

[0001] The invention relates to the technical field of membrane materials, and in particular to a method for preparing a solid phase extraction membrane, and a product prepared by the method. Background Art

[0002] Solid phase extraction (SPE) refers to the use of solid adsorbents to adsorb trace or minute amounts of target compounds in liquids, followed by elution with an eluent or desorption by heating, thereby achieving the purpose of enriching and separating target compounds [1]. The solvent required for SPE is only about 1 / 10 of that required for liquid-liquid extraction. It is low-cost, environmentally friendly, can avoid problems such as emulsification, and has good method reproducibility. It is currently mainly used in sample analysis pretreatment, such as enrichment of trace pollutants in water, veterinary drug residues and other harmful substances in animal food, pesticide residues in fruits and vegetables, drugs and their metabolites in blood, etc. It is widely used in environmental science and engineering, food science, biomedicine, pharmaceutical engineering, fine chemicals, organic synthesis and other fields. Solid phase extraction can be divided into technologies such as solid phase extraction columns, solid phase microextraction and solid phase extraction membranes.

[0003] Solid phase extraction membrane is a special solid phase extraction material designed for various large volume water samples. Its basic extraction principle is the same as that of solid phase extraction column. The thickness of solid phase extraction membrane is generally less than 1mm. Compared with solid phase extraction column, the main features of solid phase extraction membrane are:

[0004] (1) Large diameter and large area, mainly used for rapid extraction of large volume water samples. In trace analysis, in order to obtain a high enough analyte concentration to meet the detection sensitivity, it is often necessary to extract a large volume of sample. For example, in the analysis of pesticide residues in water, 250 to 1000 mL or even larger samples are often required. Large volume samples often bring disadvantages to solid phase extraction. First, it is very time-consuming for large volume samples to pass through the SPE column; second, large volume samples passing through the SPE column will often change the kinetic bonding environment of the SPE column, so that trace analytes cannot be completely adsorbed by the SPE column. The best way to solve this problem is to use SPE membranes. Solid phase extraction membranes are particularly suitable for the treatment of water quality environmental samples.

[0005] (2) Suitable for the extraction of sewage samples. Since sewage contains many particles that are visible or invisible to the naked eye, it is easy for the extraction column to be blocked when using solid phase extraction columns to treat sewage. However, due to the large area of ​​solid phase extraction membranes, the probability of blockage is much smaller than that of solid phase extraction columns.

[0006] (3) High detection sensitivity. The volume of eluent in solid phase extraction membrane is small, making the actual concentration higher than that of classic SPE column.

[0007] However, the preparation process of solid phase extraction membrane is complicated and the price is high. 3M Company in the United States first launched Empore solid phase extraction membrane, which uses polytetrafluoroethylene (PTFE) fiber as the skeleton, and reversed silica gel or polystyrene-divinylbenzene (PS-DVB) adsorbent particles between the fibers. 90% of the extraction membrane is SPE adsorbent and 10% is PTFE. Its preparation adopts a material composite process of repeatedly rolling PTFE and bonded silica gel to make PTFE fiber. There are also mixed matrix membranes prepared by dispersing adsorbent particles in polymer membrane liquid for solid phase extraction, but the adsorbent is easy to suspend and aggregate in the polymer membrane liquid, making it difficult to disperse evenly. The amount of adsorbent that can be added is also very limited, and the adsorbent is also easy to fall off. Summary of the invention

[0008] In order to overcome the defects of the prior art, the present invention proposes a new method for preparing solid phase extraction membrane: solid phase extraction functional materials are introduced into the quartz fiber membrane by dip coating, in-situ polymerization, bonding or grafting methods, and then the membrane pore size and porosity are adjusted by special treatments such as immersion precipitation and thermally induced phase separation to obtain a new solid phase extraction membrane based on quartz fiber.

[0009] The technical solution of the present invention is: a method for preparing a solid phase extraction membrane, characterized in that:

[0010] (1) immersing a quartz fiber membrane in a polymer solution having a solid phase extraction function, taking out the membrane and drying it naturally, heating it, drying it at low temperature, or immersing it in a non-solvent for the polymer to obtain a solid phase extraction membrane with the polymer as an extraction functional material;

[0011] (2) Alternatively, immersing the quartz fiber membrane in a monomer solution having a solid phase extraction function, adding an initiator to initiate in-situ polymerization, and taking out the membrane and drying it naturally, heating it, drying it at low temperature, or immersing it in a non-solvent for the polymer to obtain a solid phase extraction membrane with the polymer as the extraction function material;

[0012] (3) Alternatively, immerse the quartz fiber membrane in an acid solution or ethylene vinyl alcohol copolymer (EVOH)

[0013] Alternatively, the membrane is taken out after a certain period of time in the polyvinyl alcohol solution, washed and dried, a large number of hydroxyl groups are introduced on the membrane, and then octadecyltrichlorosilane or octadecyltrichlorosilane is bonded in dry toluene with triethylamine as a catalyst, and then tail-capped with trimethylchlorosilane to obtain a solid phase extraction membrane bonded with octadecyl or octadecyl;

[0014] The polymer with solid phase extraction function is one or more of styrene-divinylbenzene prepolymer, vinylpyrrolidone-divinylbenzene prepolymer, sulfonated polystyrene-divinylbenzene, and quaternized polystyrene-divinylbenzene. The non-solvent of the polymer cannot dissolve the polymer, but is miscible with the solvent in the polymer solution. The acid solution is one or more of sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, phosphoric acid or organic acid.

[0015] The present invention has the following advantages: (1) The quartz fiber membrane is made of high-purity quartz fiber (SiO2) and does not contain any adhesive. It has excellent total amount and structural stability, low background value, is suitable for enrichment and quantitative analysis, and can meet the requirements of analytical testing. (2) The solid phase extraction functional material is introduced into the quartz fiber membrane by dip coating, in-situ polymerization, bonding or grafting. The pore size and porosity of the material are adjusted by changing the conditions of wet papermaking, immersion precipitation and thermal phase separation of the quartz fiber to obtain a multi-level gradient pore structure, and a solid phase extraction membrane of various materials (such as PV-DVB, PVP-DVB, C18, C8) and specifications can be obtained, which can meet the technical index requirements of the solid phase extraction membrane.

[0016] The invention also provides a product using the solid phase extraction membrane preparation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The effect of polymerization time on membrane flux of the PS-DVB solid phase extraction membrane obtained according to Example 1 of the present invention

[0018] Figure 2 The effect of polymerization time on the recovery rate of the PS-DVB solid phase extraction membrane obtained in Example 1 of the present invention

[0019] Figure 3 Graph showing the relationship between the filtration rate and recovery rate of the sulfonated PS-DVB solid phase extraction membrane obtained according to Example 2 of the present invention.

[0020] Figure 4 It is the recovery rate of the octadecyl (C18) solid phase extraction membrane obtained according to Example 3 of the present invention for phenol solutions of different volumes. DETAILED DESCRIPTION

[0021] Several specific embodiments of the present invention are described in detail below. The described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1

[0023] Cyclohexane was used as solvent, 2 ml of styrene was added (the inhibitor was removed first), 0.3 ml of divinylbenzene was added, stirred and dissolved, and 0.03 g of dibenzoyl peroxide initiator was added, and stirred under heating conditions of 60 ° C. The quartz fiber membrane was immersed in the polymer at different polymerization times, taken out after 5 minutes, and then immersed in ethanol to precipitate, and then taken out and dried naturally. The results show that as the polymerization time increases, the polymer on the surface of the solid phase extraction membrane gradually increases, and the water flux decreases ( Figure 1 ), membrane phenol (50ml0.02mg L -1 The recovery rate of solution was significantly improved (such as Figure 2 As shown in the figure, the recovery rate was 0.83 after 9 hours of copolymerization, and reached 1.0 after 12 hours, which means that complete recovery was achieved.

[0024] Example 2

[0025] The quartz fiber membrane was immersed in a polystyrene-divinylbenzene prepolymer solution, taken out and dried naturally after 2 minutes, then immersed in concentrated sulfuric acid for sulfonation for 1 hour, washed and dried, and used for solid phase extraction of copper ions in propanol (50ml, 5ppm). As the filtration rate increases, the recovery rate of copper ions by the membrane decreases (e.g. Figure 3 As shown), filtration speed 10ml min -1 When , the recovery rate of copper ions by solid phase extraction membrane reaches 1.

[0026] Example 3

[0027] The quartz fiber membrane was soaked in 30% sulfuric acid solution, and then taken out and dried naturally after 10 minutes. A large number of hydroxyl groups were introduced on the membrane, and then octadecyl trichlorosilane was bonded in dry toluene (triethylamine as catalyst, stirring at low speed at 25°C for 2h), and then the membrane was tail-capped with trimethylchlorosilane after washing to obtain octadecyl (C18) solid phase extraction membrane. Figure 4 As shown, phenol solution (50 ml 0.02 mg L -1 When the filtration volume of the solution was 25 ml, the recovery rate reached 1.0.

[0028] Example 4

[0029] The quartz fiber membrane was immersed in a 10% ethylene vinyl alcohol copolymer (EVOH) cyclohexane solution, and then taken out and dried naturally after 5 minutes. A large number of hydroxyl groups were introduced on the membrane, and then octaalkyl trichlorosilane was bonded in dry toluene (triethylamine as catalyst, stirring at 30°C for 2h), and the tail was sealed with trimethyl chlorosilane to obtain an octaalkyl (C18) solid phase extraction membrane. When the phenol solution (50ml 0.02mg L -1 When the filtration volume of the solution is 25 ml, the recovery rate is close to 1.0.

[0030] Example 5

[0031] Cyclohexane was used as solvent, 2 ml of styrene was added (the inhibitor was removed first), 0.3 ml of divinylbenzene was added, stirred and dissolved, and then a quartz fiber membrane and 0.03 g of dibenzoyl peroxide initiator were added for in-situ polymerization, heated and stirred at 60 °C, and the membrane was taken out after 10 hours and immersed in ethanol for precipitation, and then naturally dried. The results showed that the membrane was very effective for phenol (50 ml 0.02 mg L -1 The recovery rate of the solution was 0.985.

[0032] The above description of the disclosed embodiments enables professionals and technicians in the field to implement or use the present invention. Various modifications to these embodiments will be obvious to professionals and technicians in the field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. The above description is only an individual embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a solid phase extraction membrane, characterized in that: (1) immersing a quartz fiber membrane in a polymer solution having a solid phase extraction function, taking out the membrane and drying it naturally, heating it, drying it at low temperature, or immersing it in a non-solvent for the polymer to obtain a solid phase extraction membrane with the polymer as an extraction functional material; (2) Alternatively, the quartz fiber membrane is immersed in a monomer solution having a solid phase extraction function, an initiator is added to initiate in-situ polymerization for a certain period of time, and the membrane is taken out and dried naturally, heated, low-temperature dried, or immersed in a non-solvent for the polymer to obtain a solid phase extraction membrane with the polymer as the extraction function material; (3) Alternatively, the quartz fiber membrane is immersed in an acid solution, ethylene vinyl alcohol copolymer or polyvinyl alcohol solution for a certain period of time, then taken out, washed and dried, a large number of hydroxyl groups are introduced into the membrane, and then octadecyltrichlorosilane or octadecyltrichlorosilane is bonded in dry toluene using triethylamine as a catalyst, and then tail-capped with trimethylchlorosilane to obtain a solid phase extraction membrane bonded with octadecyl or octadecyl.

2. The method for preparing a solid phase extraction membrane according to claim 1, characterized in that: The polymer with solid phase extraction function is one or more of styrene-divinylbenzene prepolymer, vinylpyrrolidone-divinylbenzene prepolymer, sulfonated polystyrene-divinylbenzene, and quaternized polystyrene-divinylbenzene.

3. The method for preparing a solid phase extraction membrane according to claim 1, characterized in that: The non-solvent for the polymer cannot dissolve the polymer but is miscible with the solvent in the polymer solution.

4. The method for preparing a solid phase extraction membrane according to claim 1, characterized in that: The acid solution is a solution of one or more of sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, phosphoric acid or an organic acid.

5. The product of the solid phase extraction membrane preparation method according to claims 1-4.

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