CN110961132A

CN110961132A - C3N4Preparation method and application of modified organic membrane

Info

Publication number: CN110961132A
Application number: CN201911112869.4A
Authority: CN
Inventors: 庄涛; 赵玉强; 张利钧; 张建琳; 王永新; 刘善军
Original assignee: Jinan Environmental Research Institute
Current assignee: Jinan Environmental Research Institute
Priority date: 2019-11-14
Filing date: 2019-11-14
Publication date: 2020-04-07
Also published as: WO2021093832A1

Abstract

The invention provides a compound C₃N₄The preparation method and the application of the modified organic film comprise the following steps: step 1) adding Carbon Nitride (CN) and a pore-forming agent into an organic solvent, wherein the mass ratio of the CN to the pore-forming agent is 0.4:1-2.5:1, and the mass ratio of the pore-forming agent to the organic solvent is 1:81-1: 87; carrying out ultrasonic treatment to obtain a mixed solution, then adding a polymeric polymer membrane material PFM into the mixed solution, wherein the PFM accounts for 12-15% of the total mass of the PFM and the mixed solution, stirring at constant temperature, standing and defoaming to form a membrane casting solution; step 2) pouring the prepared casting solution into clean and dry glassScraping liquid film on one side of the plate by using a square coater, immersing the glass plate with the scraped liquid film into deionized water for phase exchange, taking out the film after the film casting liquid is solidified into a film, placing the film into the deionized water for immersion, and removing residual organic solvent to obtain C₃N₄And (3) modifying the organic film. The method ensures that the organic film has the capability of catalyzing and degrading organic matters, and the anti-pollution performance of the film is improved.

Description

C3N4Preparation method and application of modified organic membrane

Technical Field

The invention relates to the technical field of preparation of environment functional materials, in particular to a C₃N₄A preparation method and application of the modified organic membrane.

Background

The photocatalytic oxidation technology has wide adaptability to the degradation of organic pollutants, the degradation reaction can be carried out at normal temperature and normal pressure, and the organic pollutants can be degraded by using cheap sunlight as required energy, so that the photocatalytic oxidation technology is one of the environmental technologies with the most application prospect. However, in the process of photocatalytic research, the powdered photocatalyst generally has the problems of difficult catalyst recovery and regeneration and easy secondary pollution, and the problems can be effectively avoided through the immobilization of the photocatalyst.

Graphite phase carbon nitride (g-C)₃N₄) The photocatalyst is an excellent photocatalyst, and has the performances of good visible light response, low cost and simple preparation process. In g-C₃N₄On the basis, a series of C with larger specific surface area and better photocatalytic performance can be obtained by modification₃N₄E.g. mesoporous g-C₃N₄(MCN), nitrogen-rich g-C₃N₄(NCN) and defect g-C₃N₄(DCN). Mesoporous g-C₃N₄The mesoporous silica gel has higher specific surface area and abundant mesoporous channels, can expose more surface active sites, and improves the performance of the mesoporous silica gel in the application aspects of catalytic reaction and the like. Rich in nitrogen g-C₃N₄The visible light absorption capacity is obvious, and the separation of photo-generated electrons and holes is promoted. Defect g-C₃N₄Has high specific surface area, greatly improved visible light absorption capacity and greatly improved photocatalytic performance.

Polyvinylidene fluoride (PVDF), Polysulfone (PSF), polyethersulfoneOrganic membranes such as (PES), Polyacrylonitrile (PAN) and Polytetrafluoroethylene (PTFE) membranes are widely used in industrial microfiltration and ultrafiltration processes due to their excellent mechanical properties, thermal stability and chemical resistance and simple preparation process. However, the organic film is easily contaminated by adsorption of organic impurities due to its high hydrophobicity, and thus its application is limited. There are currently known about C₃N₄The related research results loaded on the organic membrane mostly adopt methods such as vacuum filtration, grafting, surface coating and the like, the methods are relatively complex to operate, the bonding layer is easy to fall off in the operation process, and the catalytic efficiency is relatively low.

Therefore, a method for modifying a membrane is needed to fix the photocatalyst and improve the anti-pollution performance of the membrane.

Disclosure of Invention

The invention provides a compound C₃N₄A preparation method and application of a modified organic film, which aims to overcome the defects in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme.

One aspect of the present invention provides C₃N₄A method of preparing a modified organic film comprising:

step 1) adding Carbon Nitride (CN) and a pore-forming agent into an organic solvent, wherein the mass ratio of the CN to the pore-forming agent is 0.4:1-2.5:1, and the mass ratio of the pore-forming agent to the organic solvent is 1:81-1: 87; carrying out ultrasonic treatment to obtain a mixed solution, then adding a polymeric polymer membrane material PFM into the mixed solution, wherein the PFM accounts for 12-15% of the total mass of the PFM and the mixed solution, stirring at constant temperature, standing and defoaming to form a membrane casting solution;

step 2) pouring the prepared casting solution to one side of a clean and dry glass plate, scraping the liquid film by using a square coater, immersing the glass plate with the scraped liquid film into deionized water for phase exchange, taking out the film after the casting solution is solidified into a film, immersing the film in the deionized water, and removing residual organic solvent to obtain C₃N₄And (3) modifying the organic film.

Preferably, CN is graphite phase carbon nitride g-C₃N₄And mesoporous g-C₃N₄Nitrogen-rich g-C₃N₄Or defect g-C₃N₄One kind of (1).

Preferably, the PFM is one of polyvinylidene fluoride, polysulfone, polyethersulfone, polyacrylonitrile or polytetrafluoroethylene.

Preferably, the mass ratio of CN and PFM in step 1) is from 1:6.25 to 1: 25.

Preferably, in the step 1), the power of the ultrasound is 500W, and the ultrasound time is 1 h; stirring at a constant temperature of 50 ℃, at a rotation speed of 200rpm, for 12 h; standing for defoaming for 12 h.

Preferably, the pore-forming agent is one of polyvinylpyrrolidone PVP and polyethylene glycol PEG, and the organic solvent is one of 1-methyl-2-pyrrolidone NMP, dimethylformamide DMF and dimethylacetamide DMAc.

Preferably, the glass plate with the scraped liquid film is still left to stand in the air for 15 seconds before the glass plate with the scraped liquid film is immersed in deionized water for phase exchange in the step 2).

Preferably, the thickness of the liquid film in the step 2) is 250 μm, and the soaking time in the deionized water is 24 h.

Preferably, the PFM is polyvinylidene fluoride PVDF, and the mass ratio of CN to PVDF is 1: 6.25.

In another aspect of the invention, C prepared by the method is provided₃N₄Modified organic film, C prepared₃N₄The modified organic membrane is used for catalyzing and degrading sewage containing organic dye and antibiotic.

From one of the above-mentioned inventions C₃N₄The preparation method and the application of the modified organic membrane provide the technical scheme that the method enables CN particles to be tightly wrapped by organic macromolecules, the repeated utilization rate of the membrane is greatly improved, and the catalytic efficiency is improved by more than 6 times; the CN modified organic film can fully exert the catalytic performance of the photocatalyst under the condition of visible light irradiation, and the organic film can immobilize the CN to provide attachment sites for the CN, so that the CN is easy to recycle and solve the problems that the photocatalyst is difficult to separate and recycle and is easy to generate secondary pollution; simultaneously, the organic film has the capability of catalyzing and degrading organic matters, and the anti-pollution performance of the film is obtainedTo lift; the degradation efficiency of the photocatalytic film is directly examined under the sun illumination, and is C₃N₄The modified organic film is put into practical production to provide data support.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 shows CN in this example₈₀SEM images of PVDF hybrid membranes and PVDF membranes;

FIG. 2 shows CN in this example₈₀-x-ray diffraction spectra of PVDF hybrid membranes and PVDF membranes;

FIG. 3 is a graph showing the result of photocatalytic degradation of antibiotic by the hybrid membrane of this example

FIG. 4 is a graph showing the results of the photocatalytic degradation of antibiotics by sunlight by the hybrid membrane of the present example;

fig. 5 is a graph showing the experimental results of the solar photocatalytic degradation cycle of the hybrid membrane of the present embodiment on dyes.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, and/or operations, but do not preclude the presence or addition of one or more other features, integers, steps, and/or operations. It should be understood that the term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

To facilitate understanding of the embodiments of the present invention, the following description will be further explained by taking specific embodiments as examples with reference to the accompanying drawings.

Examples

This example provides a C₃N₄A preparation method of a modified organic membrane, in particular to a preparation method of a CN-PVDF (mesoporous graphite phase carbon nitride-polyvinylidene fluoride) hybrid membrane, which comprises the following steps:

step 1) 80mg of carbon nitride CN (mesoporous g-C)₃N₄) Adding 35.7mg of polyvinylpyrrolidone PVP into 3ml of 1-methyl-2-pyrrolidone NMP, carrying out ultrasonic treatment for 1h in a 500W ultrasonic cleaner to obtain a mixed solution, then adding 500mg of PVDF (namely a polymeric polymer membrane material PFM) into the mixed solution, wherein the mass ratio of CN to PFM is 1:6.25, stirring at the constant temperature of 50 ℃ for 12h, standing and defoaming for 12h to form a membrane casting solution;

step 2) pouring the prepared casting solution to one side of a clean and dry glass plate, scraping a liquid film with the thickness of 250 microns by using a square coater, standing the glass plate with the scraped liquid film in air for 15s, quickly immersing the glass plate into deionized water to complete the intersection and exchange process, solidifying the casting solution to form a film, taking out the film after solidifying the film, placing the film in the deionized water for soaking for 24h, removing the residual NMP solvent to obtain CN₈₀PVDF hybridizationAnd (3) a membrane.

FIG. 1 is an SEM image of the CN-PVDF hybrid membrane of the present example: wherein, FIG. 1(a) is a film surface diagram of PVDF, and it can be seen that the film surface is smoother; fig. 1(b) is a cross-sectional view of the PVDF membrane, and the channel structure of the membrane sub-layer can be clearly seen. FIG. 1(c) shows CN obtained in this example₈₀A PVDF hybrid membrane surface diagram, through which it is obvious that CN particles are loaded relatively uniformly in the PVDF membrane, and the particle size of the CN particles is about 1-5 μm; FIG. 1(d) is CN₈₀Cross-sectional view of PVDF hybrid membrane, it can be seen by comparing that the channel structure in FIG. 1(b) is changed, part of the macropores are replaced by finger-shaped pores, and the structure is more preferable, because adding CN particles in the polymer solution can increase the phase conversion rate by increasing the thermodynamic instability, so that the structure of the membrane is changed.

FIG. 2 shows CN in this example₈₀X-ray diffraction patterns of PVDF hybrid film and PVDF film, referring to FIG. 2, it can be seen that the 27.2 ° diffraction peak corresponds to the stacking (002) crystal plane between conjugated CN layers, in the PVDF pattern, 18.2 ° and 26.5 ° correspond to α phase PVDF, 20.2 ° corresponds to β phase PVDF, in CN₈₀In the PVDF curve, a higher peak is observed at 27.2 ℃ indicating that CN and PVDF are successfully complexed together, while the peak originally at 20.2 ℃ disappears, indicating that PVDF undergoes a change in the crystal structure during the complexation with CN, phase α is reduced, and therefore the stronger hydrophobicity caused by phase α is also reduced.

According to the above steps, CN/PVDF hybrid membranes were prepared in the following mass ratio, CN: PVDF 1:25 (CN)₂₀-PVDF)、CN:PVDF＝1:12.5(CN₄₀-PVDF)、CN:PVDF＝1:8.3(CN₆₀-PVDF)、CN:PVDF＝1:6.25(CN₈₀PVDF), wherein the specific CN addition amounts are 20mg, 40mg, 60mg and 80mg, respectively, and the PVDF amount and other amounts are as described above, and the application experiments were performed by the CN/PVDF hybrid membranes obtained by the different ratios. The specific contents are as follows:

application example 1

The performance of the samples was evaluated by the visible light degradation performance of cefotaxime sodium in water at room temperature. Respectively putting the 4 pre-prepared hybrid membranes with different proportions into 2 mg/L100 mL cephalosporinsIn a sodium tioxime antibiotic aqueous solution, under the magnetic stirring, the solution is placed in the dark for adsorption for 30min, then the solution is placed in a 300W xenon lamp visible light with the wavelength below 420nm and is filtered, and 1mL of the solution is taken every 20min and is filtered for concentration analysis. Each group of experiments are repeated for three times, so that the accuracy of the experiments is guaranteed. FIG. 3 is a graph showing the result of photocatalytic degradation of antibiotics by the hybrid membrane. Referring to FIG. 3, it can be seen that after 180min of visible light irradiation, when CN: PVDF is 1:6.25, namely CN₈₀The removal rate of cefotaxime sodium of the PVDF hybrid membrane reaches 98.5%, which shows that the hybrid membrane has good removal effect on antibiotics.

By using CN₈₀-PVDF membrane after the completion of the photocatalytic experiment, the membrane is taken out, the surface of the membrane is cleaned and soaked in deionized water for 12h for standby.

Application example 2

The prepared CN₈₀-PVDF (CN: PVDF ═ 1:6.25) hybrid membrane was placed in 2 mg/L100 mL aqueous solution of cefotaxime sodium, then placed under the sun, and 1mL of solution was filtered every 30min for concentration analysis. FIG. 4 is a graph of the experimental results of the cycle of the solar photocatalytic degradation of the hybrid membrane to antibiotics. Referring to fig. 4, after 5h of solar irradiation, when CN: PVDF is 1:6.25, the removal rate of cefotaxime sodium reaches 97.5%, indicating that the hybrid membrane has a good removal effect on dyes.

And taking out the membrane after the sunlight catalysis experiment is finished, cleaning the surface of the membrane, and soaking the membrane in deionized water for 12 hours for later use. The above photocatalytic experiment is circulated, and CN is repeatedly used₈₀PVDF membrane tests the stability of the samples. Referring to fig. 4, it can be seen that after the hybrid membrane of the present invention is recycled for five times under the condition of solar photocatalysis, the removal effect of cefotaxime sodium still reaches 97.4%, so that the sample has good stability and practical applicability.

Application example 3

The prepared CN₈₀The hybrid membrane of PVDF (CN: PVDF ═ 1:6.25) was placed in 100mL of an aqueous rhodamine B solution at 2mg/L, and then placed under sunlight, and 3mL of the solution was filtered every 30min to analyze the concentration. FIG. 5 is a solar photocatalytic degradation cycle of a hybrid membrane to a dyeAnd (4) a ring experiment result graph. Referring to FIG. 5, CN after 5h of solar irradiation₈₀The removal rate of PVDF (CN: PVDF ═ 1:6.25) to rhodamine B reaches 98.1%, which shows that the hybrid membrane has good removal effect to dye.

And taking out the membrane after the sunlight catalysis experiment is finished, cleaning the surface of the membrane, and soaking the membrane in deionized water for 12 hours for later use. The above photocatalytic experiment is circulated, and CN is repeatedly used₈₀PVDF membrane tests the stability of the samples. Referring to fig. 5, it can be seen that after the hybrid membrane of the present invention is used in a solar photocatalytic condition for five times, the removal effect of rhodamine B reaches 99.6%, and the photocatalytic performance of the rhodamine B is not affected, so that the sample has good stability and practical applicability.

To CN₈₀And comparing the surfaces of the PVDF membrane and the 100ml rhodamine B membrane which is degraded in a sunlight catalytic way and absorbed in a dark way by 2mg/L to obtain that the surface color of the membrane under the sunlight catalytic degradation is obviously lighter than that of the membrane after the dark absorption, which indicates that the sample has good self-cleaning performance.

Application example 4

Adding 100 mu L of bacterial liquid required by the experiment into a sterile conical flask containing 100mL of liquid culture medium, and culturing at constant temperature of 180rpm for 10h for later use. Taking 1mL of the above bacterial liquid, adding 99mL of phosphoric acid buffer solution (PBS), adding a CN/PVDF membrane, stirring for 30min, then placing under a xenon lamp (300W) equipped with a 420nm optical filter for irradiation, sampling 1mL every 30min, and placing the sample at 4 ℃ for dark storage. The obtained water samples were subjected to gradient dilution with sterile PBS, 100. mu.L each, diluted on a solid medium plate, uniformly coated with a glass coating rod, in parallel in 3 parts, cultured at 37 ℃ for 24 hours, and then subjected to colony counting (CFU/mL). Initial E.coli concentration was about 10⁷CFU/mL, 4 hours later, the E.coli concentration decreased to 10⁴CFU/mL, which indicates a certain reduction in the large intestine rods, demonstrates that the membrane has a certain antimicrobial property.

It will be appreciated by those skilled in the art that the foregoing types of applications are merely exemplary, and that other types of applications, whether presently existing or later to be developed, that may be suitable for use with the embodiments of the present invention, are also intended to be encompassed within the scope of the present invention and are hereby incorporated by reference.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. C₃N₄A method for producing a modified organic film, comprising:

2. The method of claim 1, wherein CN is graphite phase carbon nitride g-C₃N₄And mesoporous g-C₃N₄Nitrogen-rich g-C₃N₄Or defect g-C₃N₄One kind of (1).

3. The method of claim 1, wherein the PFM is one of polyvinylidene fluoride, polysulfone, polyethersulfone, polyacrylonitrile, or polytetrafluoroethylene.

4. The method according to claim 1, wherein the mass ratio of CN and PFM in step 1) is 1:6.25-1: 25.

5. The method according to claim 1, wherein in the step 1), the power of the ultrasound is 500W, and the ultrasound time is 1 h; stirring at a constant temperature of 50 ℃, at a rotation speed of 200rpm, for 12 h; standing for defoaming for 12 h.

6. The method according to claim 1, wherein the pore-forming agent is one of polyvinylpyrrolidone PVP and polyethylene glycol PEG, and the organic solvent is one of 1-methyl-2-pyrrolidone NMP, dimethylformamide DMF and dimethylacetamide DMAc.

7. The method according to claim 1, wherein the scraped glass sheet is left to stand in air for 15 seconds before the scraped glass sheet is subjected to the phase exchange in step 2) by immersing the scraped glass sheet in deionized water.

8. The method as claimed in claim 1, wherein the liquid film in step 2) has a thickness of 250 μm, and is soaked in deionized water for 24 h.

9. The method of claim 1, wherein the PFM is polyvinylidene fluoride, PVDF, and the mass ratio of CN to PVDF is 1: 6.25.

10. C prepared by the method of any one of claims 1 to 9₃N₄Modified organic film, characterized in that C is prepared₃N₄The modified organic membrane is used for catalyzing and degrading sewage containing organic dye and antibiotic.