An anti-biofouling catalytic photothermal membrane for organic industrial wastewater treatment and its preparation method

Abstract

The present invention discloses an anti-biofouling catalytic photothermal membrane for treating organic industrial wastewater and a preparation method thereof, which solves the problem that the photothermal membrane material is easily subject to biofouling during the treatment of organic industrial wastewater, resulting in performance degradation, and the presence of organic pollutants further worsens the performance degradation. The present invention utilizes electrospinning technology to prepare an electrospun base membrane; constructs an iron-based electrospun base membrane loaded with an iron-based catalyst by a hydrothermal method; loads graphite phase carbon nitride and silver nitrate solution on the iron-based electrospun base membrane by vacuum filtration to form a graphite phase carbon nitride-silver ion / iron-based electrospun base membrane; and finally obtains an anti-biofouling catalytic photothermal membrane after irradiation with a xenon lamp light source. The present invention can effectively achieve the purpose of simultaneous organic pollutant removal and microbial inhibition during the treatment of organic industrial wastewater, and maintain long-term efficient evaporation and degradation performance. The present invention is scalable, suitable for mass production, conducive to industrialization, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to an anti-biofouling catalytic photothermal membrane for treating organic industrial wastewater and a preparation method thereof. Background Art

[0002] Solar interfacial evaporation technology is considered to be a pollution-free and convenient method for supplying clean water. Among them, solar thermal membranes convert sunlight into thermal energy through the photothermal materials loaded on the surface, raising the surface temperature to evaporate wastewater and condense it into fresh water. However, the surface temperature of existing photothermal membranes is generally 35-40°C. In the process of treating industrial wastewater generated by industries such as pharmaceuticals, food, and medicine, the suitable growth environment on the surface of the photothermal membrane may promote the attachment and accumulation of microorganisms. At the same time, a large amount of organic pollutants in industrial wastewater will continuously provide carbon source nutrition for these microorganisms, resulting in the accumulation and fouling of microorganisms on the photothermal membrane. These biofoulings will block the pore structure of the photothermal membrane, thereby affecting the evaporation performance and water purification performance of the photothermal membrane, and at the same time reduce the durability of the photothermal membrane. Therefore, it is necessary to develop anti-biofouling catalytic photothermal membranes that take into account both the removal of organic pollutants and the inhibition of microorganisms. Summary of the Invention

[0003] The present invention aims to address the problems of microorganisms clogging the photothermal interface during the treatment of organic industrial wastewater, which leads to reduced evaporation performance and water purification performance, and the problem that organic pollutants in organic industrial wastewater will aggravate the fouling of the photothermal membrane. The present invention provides an anti-biofouling catalytic photothermal membrane for the treatment of organic industrial wastewater and a preparation method thereof. The present invention loads anti-biofouling materials and iron-based catalysts onto an electrospun base membrane to develop an anti-biofouling catalytic photothermal membrane that simultaneously removes organic pollutants and inhibits microorganisms, thereby achieving efficient treatment of organic industrial wastewater. The anti-biofouling catalytic photothermal membrane prepared by the present invention has excellent anti-biological properties for organic industrial wastewater, and at the same time has a good catalytic degradation effect on organic pollutants, which can effectively achieve the purpose of simultaneously removing organic pollutants and inhibiting microorganisms.

[0004] In order to achieve the above object, the present invention provides a method for preparing an anti-biofouling catalytic photothermal membrane for treating organic industrial wastewater. The specific preparation method comprises the following steps:

[0005] (1) dissolving polyacrylonitrile powder in N,N-dimethylformamide to obtain a spinning solution A; and preparing an electrospun base membrane from the spinning solution A by electrospinning technology;

[0006] (2) soaking the electrospun base membrane prepared in step (1) in a hydrochloric acid-water mixture containing ferric chloride hexahydrate, and subjecting the mixture to a hydrothermal process at 55-75° C. for 8.0-15.0 h to in situ loading of the iron-based catalyst on the electrospun base membrane, thereby obtaining an iron-based electrospun base membrane; wherein the concentration of the ferric chloride hexahydrate is 0.04-0.10 M, and the pH of the hydrochloric acid-water mixture is 2-4;

[0007] (3) placing the melamine powder in a muffle furnace for calcining at a temperature of 500-600° C., a heating rate of 2-5° C. / min, and a calcining time of 1.0-3.0 h, and cooling to obtain carbon nitride powder; grinding the obtained carbon nitride powder for 0.5-1.0 h and then placing it in a muffle furnace for secondary calcination at a temperature of 450-550° C., a heating rate of 2-10° C. / min, and a calcining time of 1.0-3.0 h, and cooling to obtain graphite phase carbon nitride powder;

[0008] (4) uniformly dispersing the graphite phase carbon nitride powder prepared in step (3) into a silver nitrate solution to obtain a mixed solution B; loading the mixed solution B onto an iron-based electrospun membrane by vacuum filtration to obtain a graphite phase carbon nitride-silver ion / iron-based electrospun membrane; wherein the ratio of the graphite phase carbon nitride powder to the silver nitrate solution is 0.2-2 g:1 L, preferably 1.2 g:1 L; and the concentration of the silver nitrate solution is 0.1-0.3 M;

[0009] (5) The graphite phase carbon nitride-silver ion / iron-based electrospun membrane prepared in step (4) is irradiated with a xenon lamp light source to obtain an anti-biofouling catalytic photothermal membrane.

[0010] In the step (1), the mass fraction of the polyacrylonitrile powder in the spinning solution A is 8.0wt%-15.0wt%; the molecular weight of the polyacrylonitrile powder is 80,000-200,000; and the electrospinning conditions are: voltage 12.0-18.0kV, spinning speed 0.8-1.5mL / h, and time 10.0-20.0h.

[0011] In the step (3), the grinding time of the carbon nitride powder is 0.5-1.0h.

[0012] In the step (4), the vacuum filtration time is 1.0-3.0 h, and the operating pressure is 0.02-0.1 MPa.

[0013] In the step (5), the xenon lamp light source has a power of 300W and an irradiation time of 1.0-3.0h.

[0014] The second aspect of the present invention provides an anti-biofouling catalytic photothermal membrane for treating organic industrial wastewater obtained by the above-mentioned preparation method.

[0015] A third aspect of the present invention provides the use of the above-mentioned anti-biofouling catalytic photothermal membrane in the treatment of organic industrial wastewater. The application method comprises the following steps:

[0016] The anti-biofouling catalytic photothermal membrane prepared by the preparation method of the present invention is placed on the surface of organic industrial wastewater, and is treated by solar irradiation for 6.0-15.0 hours to achieve the purpose of simultaneous removal of organic pollutants and inhibition of microorganisms.

[0017] The anti-biofouling catalytic photothermal membrane prepared by this invention, based on an electrospun membrane, possesses an excellent pore structure and numerous attachment sites for anti-biofouling materials, which facilitates improved evaporation and anti-fouling performance. Furthermore, the advanced oxidation technology induced by photocatalytic in-situ generation of hydrogen peroxide continuously produces highly oxidizing free radicals, achieving simultaneous degradation of organic pollutants.

[0018] The pH of the organic industrial wastewater is 2.0-10.0, preferably 5.0-7.2, more preferably 6.0;

[0019] The sunlight intensity is 100-1000kW / m 2 , preferably 1000kW / m 2 ;

[0020] The organic pollutants are one or more of phenol, aniline, dyes, and antibiotics;

[0021] The microorganisms are one or more of Escherichia coli and Staphylococcus aureus.

[0022] The present invention solves the problem that the photothermal membrane material is susceptible to biofouling during the treatment of organic industrial wastewater, resulting in performance degradation, and the presence of organic pollutants further worsens the performance degradation. The present invention first prepares a base membrane through electrospinning technology; then, an iron-based catalyst is loaded onto the electrospun base membrane through a hydrothermal reaction to obtain an iron-based electrospun base membrane with the ability to catalyze hydrogen peroxide; then, graphite phase carbon nitride and silver nanoparticles with the ability to generate hydrogen peroxide in situ are loaded on the iron-based electrospun base membrane by vacuum filtration and light irradiation to form an anti-biofouling catalytic photothermal membrane. Based on the electrospun membrane with an excellent pore structure and a large number of attachment sites for anti-biofouling material silver nanoparticles as a substrate, the present invention has a good inhibitory ability against microorganisms in organic industrial wastewater. At the same time, based on the photocatalytic graphite phase carbon nitride that can self-generate hydrogen peroxide and induce advanced oxidation technology that occurs in situ with the iron-based catalyst, it can continuously generate free radicals with strong oxidizing properties, thereby achieving the synchronous degradation of organic pollutants in organic industrial wastewater. This invention imparts new functionality to solar interface photothermal films. When used in organic industrial wastewater treatment, it can simultaneously remove organic pollutants and inhibit microorganisms, maintaining long-term, efficient evaporation and degradation performance, thereby sustaining the long-term, efficient application of the photothermal film. This invention is scalable, suitable for mass production, and conducive to industrialization, with broad application prospects.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The anti-biofouling catalytic photothermal membrane prepared in the present invention can be used in the process of treating organic industrial wastewater to simultaneously achieve efficient in-situ catalytic degradation of organic pollutants in the wastewater by self-generated hydrogen peroxide, and inhibit the growth and enrichment of wastewater microorganisms on the surface, ultimately obtaining high-quality pure water.

[0025] (2) The anti-biofouling catalytic photothermal film prepared in the present invention has excellent catalytic effect and anti-biofouling effect. Compared with other structural photothermal films, it has excellent evaporation performance, more internal attachment sites, better degradation effect on organic pollutants, and better inhibition of microorganisms.

[0026] (3) The graphite-phase carbon nitride loaded in the anti-biofouling catalytic photothermal membrane prepared in the present invention can self-generate hydrogen peroxide and induce in-situ advanced oxidation technology with iron-based catalysts, which makes up for the defect that the advanced oxidation technology based on catalytic hydrogen peroxide always needs to add exogenous hydrogen peroxide.

[0027] (4) The iron-based catalyst loaded in the anti-biofouling catalytic photothermal membrane prepared in the present invention is safer, more stable, regenerable and does not produce additional pollution in the process of catalyzing hydrogen peroxide compared with other metal catalysts.

[0028] (5) The catalytic photothermal membrane prepared in the present invention has excellent anti-biofouling properties, effectively preventing microbial clogging of the pores, and can be recycled multiple times while maintaining efficient evaporation performance. It is also scalable, suitable for mass production, conducive to industrialization, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described with reference to the accompanying drawings and embodiments.

[0030] Figure 1 This is a photo of the prepared anti-biofouling catalytic photothermal film.

[0031] Figure 2 This is a scanning electron microscope image of the prepared anti-biofouling catalytic photothermal film.

[0032] Figure 3 These are pictures of the inhibition zones of Escherichia coli in organic industrial wastewater in Example 1 and Example 6 without adding anti-biofouling materials.

[0033] Figure 4 These are the effect diagrams of the long-term evaporation rate performance of Examples 1, 3, 4, 5, 6, and 7 in organic industrial wastewater.

[0034] Figure 5 The figures are the degradation effects of phenol, an organic pollutant in organic industrial wastewater, in Examples 1, 3, 4, 5, 6 and 7.

[0035] Figure 6 This is a rendering of the long-term evaporation rate performance of Examples 1 and 2 in organic industrial wastewater.

[0036] Figure 7 The figures are the degradation effects of Examples 1 and 2 on the organic pollutant aniline in organic industrial wastewater. DETAILED DESCRIPTION

[0037] The embodiments described below are merely typical embodiments of the present invention and do not constitute an improper limitation of the present invention. Therefore, all obvious modifications described in the scope of the patent application of the present invention, as well as other modifications that do not depart from the essence of the present invention, should be included in the scope of protection of the present invention.

[0038] The following is a further description of the specific embodiments of the present invention in combination with the technical solutions, but the present invention is not limited to the following embodiments.

[0039] Example 1

[0040] A method for preparing an anti-biofouling catalytic photothermal membrane for treating organic industrial wastewater, the specific preparation method comprising the following steps:

[0041] (1) 1.35 g of polyacrylonitrile powder with a molecular weight of 100,000 was dissolved in 13.65 g of N,N-dimethylformamide to obtain a spinning solution A; the spinning solution A was used to prepare an electrospun substrate membrane under electrospinning conditions of a voltage of 14.5 kV, a spinning speed of 0.9 mL / h, and a spinning time of 12 h;

[0042] (2) immersing the electrospun base membrane prepared in step (1) in a hydrochloric acid-water mixture containing 0.08 M ferric chloride hexahydrate at a pH of 3, and subjecting the mixture to a hydrothermal process at 65° C. for 12.0 h to in-situ load the iron-based catalyst on the electrospun base membrane, thereby obtaining an iron-based electrospun base membrane;

[0043] (3) calcining the melamine powder in a muffle furnace at a calcination temperature of 560°C, a heating rate of 4°C / min, and a calcination time of 1.5 h, and obtaining carbon nitride powder after cooling; grinding the obtained carbon nitride powder in an agate mortar for 0.5 h and then calcining it in a muffle furnace for a second time at a calcination temperature of 500°C, a heating rate of 5°C / min, and a calcination time of 2.0 h, and obtaining graphite phase carbon nitride powder after cooling;

[0044] (4) Weighing 0.06 g of the graphite phase carbon nitride powder prepared in step (3) and uniformly dispersing it into 50 mL of 0.2 M silver nitrate solution to obtain a mixed solution B; loading the mixed solution B onto an iron-based electrospun membrane by vacuum filtration at an operating pressure of 0.1 MPa for 1.0 h to obtain a graphite phase carbon nitride-silver ion / iron-based electrospun membrane;

[0045] (5) The graphite phase carbon nitride-silver ion / iron-based electrospun membrane prepared in step (4) was irradiated with a xenon lamp light source with a bulb power of 300 W for 1.5 hours to obtain an anti-biofouling catalytic photothermal membrane.

[0046] Figure 1 This is a photo of the prepared anti-biofouling catalytic photothermal film.

[0047] Figure 2 This is a scanning electron microscope image of the prepared anti-biofouling catalytic photothermal film. Figure 2 It can be seen that Example 1 is in the form of nanofibers and has abundant pores, which helps the iron-based catalyst and the anti-biofouling material to be evenly loaded on the base membrane.

[0048] Example 2

[0049] The difference between this embodiment and Example 1 in the preparation process is that the base membrane in step (1) is replaced with a commercial polyacrylonitrile membrane with a pore size of 0.2 μm purchased from Beijing SafeLab Co., Ltd., without the need for electrospinning technology. Other aspects are the same as Example 1.

[0050] Example 3

[0051] The difference between this embodiment and Example 1 in the preparation process is that there is no need to add ferric chloride hexahydrate in step (2), and the rest is the same as Example 1.

[0052] Example 4

[0053] The difference between this embodiment and Example 1 in the preparation process is that the melamine powder in step (3) does not need to be subjected to secondary calcination, and the rest is the same as Example 1.

[0054] Example 5

[0055] The difference between this embodiment and Example 1 in the preparation process is that no graphite phase carbon nitride powder is added in step (4), and the rest is the same as Example 1.

[0056] Example 6

[0057] The difference between this embodiment and Example 1 in the preparation process is that the silver nitrate solution in step (4) is replaced by water, and the rest is the same as Example 1.

[0058] Example 7

[0059] The difference between this embodiment and Example 1 in the preparation process is that the concentration of the silver nitrate solution in step (4) is 0.1 M, and the rest is the same as Example 1.

[0060] Example 8

[0061] Application of different anti-biofouling catalytic photothermal membranes to organic industrial wastewater. The photothermal membranes obtained in Examples 1, 3, 4, 5, 6, and 7 were placed on the surface of 100 mL of organic industrial wastewater (pH not adjusted, solution pH is 5.0) and irradiated with sunlight for 8.0 hours to treat the organic industrial wastewater. The sunlight intensity was 1000 kW / m 2 The main organic pollutant in organic industrial wastewater is phenol, and the main microorganism is Escherichia coli. The phenol concentration is about 25 mg / L, and the number of Escherichia coli is about 10,000 / L. The inhibition zone and long-term evaporation rate performance were used to test the photothermal film's ability to inhibit microorganisms and resist biofouling. The results are as follows: Figure 3 and Figure 4 As shown; at the same time, the concentration of organic pollutant phenol in the original industrial wastewater and condensate was determined by liquid chromatography, and the degradation efficiency of the photothermal film on the organic pollutant phenol was calculated. The results are shown in Figure 5 shown.

[0062] Figure 3 These are pictures of the inhibition zones of Escherichia coli in organic industrial wastewater in Example 1 and Example 6 without adding anti-biofouling materials.

[0063] Figure 4 These are the effect diagrams of the long-term evaporation rate performance of Examples 1, 3, 4, 5, 6, and 7 in organic industrial wastewater.

[0064] Figure 5 The figures are the degradation effects of phenol, an organic pollutant in organic industrial wastewater, in Examples 1, 3, 4, 5, 6 and 7.

[0065] Depend on Figure 3 It can be seen that when the culture medium coated with organic industrial wastewater is cultured at 37°C for 48 hours, Example 1 of the present invention shows a clear inhibition zone in the Escherichia coli in the organic industrial wastewater, while Example 6 without adding anti-biofouling material does not show an inhibition zone under the same conditions, indicating that the present invention has an excellent effect of inhibiting microorganisms. Figure 4 It can be seen that the anti-biofouling catalytic photothermal membrane of the present invention can maintain an evaporation performance of 1.60-1.65 kg m in organic industrial wastewater within five days. -2 h -1 There will be no phenomenon of microorganisms blocking the pores and reducing the evaporation rate, and it has good anti-biological fouling ability.

[0066] Depend on Figure 5 As can be seen, Example 1 achieved a 98.9% degradation efficiency for the phenol organic pollutant in organic industrial wastewater on the first day, while Example 3 achieved a degradation efficiency of only 57.2% on the first day. Using potassium titanium oxalate spectrophotometry to determine the hydrogen peroxide concentration, no hydrogen peroxide was detected in the organic industrial wastewater treated on the first day in Example 1, while hydrogen peroxide was detected in the organic industrial wastewater treated on the first day in Example 3. This demonstrates that the iron-based catalyst is effectively and efficiently catalyzed by hydrogen peroxide, degrading the phenol organic pollutant in organic industrial wastewater. Meanwhile, no hydrogen peroxide was detected in the organic industrial wastewater treated on the first day in Example 4. However, Example 4 achieved a only 53.4% ​​degradation efficiency for the phenol organic pollutant on the first day, demonstrating that Example 1 of the present invention achieves degradation of organic pollutants in organic industrial wastewater by self-generating hydrogen peroxide and inducing in-situ advanced oxidation technology with the iron-based catalyst. The anti-biofouling catalytic photothermal membrane of the present invention maintained a degradation efficiency of 98.2-98.9% over five days, with no decrease in degradation efficiency due to microbial enrichment and subsequent coverage of catalytic sites, further demonstrating its excellent anti-biofouling capabilities.

[0067] Example 9

[0068] The photothermal film obtained in Examples 1 and 2 was placed on the surface of 100 mL of organic industrial wastewater (pH not adjusted, solution pH is 7.2), and was irradiated with sunlight for 8.0 hours to treat the organic industrial wastewater. The sunlight intensity was 1000 kW / m 2The main organic pollutant in organic industrial wastewater is aniline, and the main microorganism is Staphylococcus aureus. The aniline concentration is about 30 mg / L, and the number of Staphylococcus aureus is about 5000 / L. The long-term evaporation rate performance is used to test the anti-biofouling ability of the photothermal membrane. The results are as follows Figure 6 As shown; at the same time, the concentration of organic pollutant aniline in the original industrial wastewater and condensate was determined by liquid chromatography, and the degradation efficiency of the photothermal film on the organic pollutant aniline was calculated. The results are shown in Figure 7 shown.

[0069] Figure 6 This is a rendering of the long-term evaporation rate performance of Examples 1 and 2 in organic industrial wastewater.

[0070] Figure 7 The figures are the degradation effects of Examples 1 and 2 on the organic pollutant aniline in organic industrial wastewater.

[0071] Depend on Figure 6 It can be seen that the evaporation rate of the anti-biofouling catalytic photothermal membrane in Example 1 of the present invention in organic industrial wastewater on the first day is 1.61 kg m -2 h -1 And the evaporation performance can be maintained at 1.57-1.61 kg m within five days. -2 h -1 The evaporation rate on the first day of Example 2 was 1.42 kg m -2 h -1 The evaporation performance showed a downward trend within five days, indicating that compared with other structured photothermal films, the present invention has excellent evaporation performance and good anti-biofouling ability. Figure 7 As can be seen, the present invention has a good degradation rate for aniline, an organic pollutant in organic industrial wastewater, reaching 91.2% on the first day and maintaining a degradation rate above 89.3% over five days. This shows that compared to other structured photothermal films, the present invention has more internal attachment sites, better degradation of organic pollutants, and wider applicability.

Claims

1. A method for preparing an anti-biofouling catalytic photothermal membrane for treating organic industrial wastewater, characterized in that: The preparation method comprises the following steps: (1) dissolving polyacrylonitrile powder in N,N-dimethylformamide to obtain a spinning solution A; and preparing an electrospun base membrane from the spinning solution A by electrospinning technology; (2) soaking the electrospun base membrane prepared in step (1) in a hydrochloric acid-water mixture containing ferric chloride hexahydrate, and subjecting the mixture to a hydrothermal process at 55-75° C. for 8.0-15.0 h to in situ loading of the iron-based catalyst on the electrospun base membrane, thereby obtaining an iron-based electrospun base membrane; wherein the concentration of the ferric chloride hexahydrate is 0.04-0.10 M, and the pH of the hydrochloric acid-water mixture is 2-4; (3) placing the melamine powder in a muffle furnace for calcining at a temperature of 500-600° C., a heating rate of 2-5° C. / min, and a calcining time of 1.0-3.0 h, and cooling to obtain carbon nitride powder; grinding the obtained carbon nitride powder and placing it in a muffle furnace for secondary calcination at a temperature of 450-550° C., a heating rate of 2-10° C. / min, and a calcining time of 1.0-3.0 h, and cooling to obtain graphite phase carbon nitride powder; (4) dispersing the graphite phase carbon nitride powder prepared in step (3) into a silver nitrate solution to obtain a mixed solution B; loading the mixed solution B onto an iron-based electrospun membrane by vacuum filtration to obtain a graphite phase carbon nitride-silver ion / iron-based electrospun membrane; wherein the ratio of the graphite phase carbon nitride powder to the silver nitrate solution is 0.2-2 g:1 L, and the concentration of the silver nitrate solution is 0.1-0.3 M; (5) The graphite phase carbon nitride-silver ion / iron-based electrospun membrane prepared in step (4) is irradiated with a xenon lamp light source to obtain an anti-biofouling catalytic photothermal membrane.

2. The preparation method according to claim 1, characterized in that In step (1), the mass fraction of polyacrylonitrile powder in the spinning solution A is 8.0 wt%-15.0 wt%.

3. The preparation method according to claim 1, characterized in that In step (1), the molecular weight of the polyacrylonitrile powder is 80,000-200,000.

4. The preparation method according to claim 1, characterized in that In step (1), the electrospinning conditions are: voltage 12.0-18.0 kV, spinning speed 0.8-1.5 mL / h, and time 10.0-20.0 h.

5. The preparation method according to claim 1, characterized in that In step (3), the grinding time of the carbon nitride powder is 0.5-1.0h; In step (4), the vacuum filtration time is 1.0-3.0 h, and the operating pressure is 0.02-0.1 MPa.

6. The preparation method according to claim 1, characterized in that In step (5), the xenon lamp light source has a bulb power of 300W and an irradiation time of 1.0-3.0h.

7. An anti-biofouling catalytic photothermal membrane for treating organic industrial wastewater obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the anti-biofouling catalytic photothermal membrane according to claim 7 in organic industrial wastewater.

9. The use according to claim 8, characterized in that The application method comprises the following steps: The anti-biofouling catalytic photothermal membrane is placed on the surface of organic industrial wastewater, and the organic industrial wastewater is treated by irradiating it with sunlight for 6.0-15.0 hours.

10. The use according to claim 9, characterized in that The pH of the organic industrial wastewater is 2.0-10.0; The sunlight intensity is 100-1000kW / m 2 ; The organic pollutants are one or more of phenol, aniline, dyes, and antibiotics; The microorganisms are one or more of Escherichia coli and Staphylococcus aureus.

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