CN111672335A - Preparation method and application of a CuO@CuS/PVDF composite membrane for water treatment - Google Patents

Abstract

The invention discloses a preparation method and application of a CuO @ CuS/PVDF water treatment composite membrane, wherein the preparation method comprises the following steps: (1) by chemical co-reactionPrecipitation of Na₂CO₃Mixing the solution with CuSO₄Calcining the precipitate generated by the solution reaction to obtain nano CuO powder; (2) adding CuO powder into CuSO₄After the solution is evenly stirred, Na is added into the mixed solution₂S₂O₃Stirring the solution to obtain fluorescent green precipitate, and transferring the fluorescent green precipitate into a microwave reactor to prepare CuO @ CuS nano composite powder by a microwave method; (3) adding PVDF particles into DMAC solvent, reacting in 80 ℃ constant temperature water bath to form homogeneous solution, and adding (NaPO) at room temperature₃)₆PVP and CuO @ CuS nano composite powder are uniformly stirred, kept stand for defoaming, poured onto a plane glass plate, uniformly scraped into a film, and finally soaked in an ethanol solution for demoulding to obtain the CuO @ CuS/PVDF composite film. The CuO @ CuS/PVDF composite membrane prepared by the invention can be used for degrading organic pollutants in water, and has the advantages of strong stability, good oxidation resistance, low cost, simple and convenient operation, environmental protection and no secondary pollution.

Description

Preparation method and application of a CuO@CuS/PVDF composite membrane for water treatment

technical field

The invention belongs to the technical field of water treatment, and in particular relates to a preparation method and application of a CuO@CuS/PVDF composite membrane for water treatment.

Background technique

Water resources are a necessary guarantee for sustainable development. However, with the acceleration of urban development and the increase of population, industrial production wastewater, domestic sewage, and agricultural and breeding sewage are discharged in large quantities, and the water environment deteriorates sharply, which affects the utilization of water resources. Pollutants in water are mainly divided into organic pollutants, inorganic pollutants and microorganisms. Among them, organic pollutants are difficult to degrade, there are many types of pollutants, and their toxicity has a bad impact on the biological environment, which will cause various environmental problems, such as clogging sewage. Treatment plants have adverse effects on aquatic biological communities, increase biochemical oxygen demand, destroy aquatic ecosystems and aquatic organisms, and cause serious harm to human health.

In recent years, sulfate (SO4·-)-based advanced oxidation process (SR-AOPs), as a new type of oxidation process, has the advantages of high catalytic efficiency, good stability, Due to the advantages of low cost, it has received more and more attention, and it is often used to effectively degrade organic pollutants in water and soil. With the in-depth study of SR-AOPs, there are various activation methods for persulfate (PS), among which transition metal activation is divided into heterogeneous catalysts and homogeneous catalysts. In addition, water treatment membrane technology is one of the most advanced sewage treatment technologies, which can not only solve the conversion of sewage and reclaimed water, but also solve the problems of water pollution and water shortage, which is of strategic significance for the utilization and protection of water resources in my country. Compared with traditional water treatment methods, membrane water treatment has many advantages such as low energy consumption, simple process, wide application range of water quality and greatly improved effluent quality. It has been used in sewage treatment (including municipal sewage treatment and industrial sewage treatment), water supply purification. (including municipal water supply purification and industrial water supply purification), seawater desalination (brackish water desalination) and pure water preparation and many other fields. According to different manufacturing materials, water treatment membranes can be divided into inorganic membranes and organic membranes. Organic membrane technology has the advantages of strong stability, good oxidation resistance, low cost, easy operation, environmental protection and no secondary pollution, and is widely used in the field of water resources and industrial special separation.

At present, the degradation of organic pollutants in water is relatively difficult. If only heterogeneous catalysts are used for degradation, there are still problems such as poor stability, easy agglomeration, and difficulty in recycling. Based on the outstanding advantages of heterogeneous catalysts and water treatment membrane technology, if the Combining heterogeneous catalysts with water treatment membrane technology will become an effective means of degrading organic pollutants in water.

SUMMARY OF THE INVENTION

In view of the deficiencies pointed out in the above background technology, the present invention provides a preparation method and application of a CuO@CuS/PVDF composite membrane for water treatment, aiming to solve the problems existing in the prior art in the above background technology.

For achieving the above object, the technical scheme adopted in the present invention is:

A preparation method of CuO@CuS/PVDF composite membrane for water treatment, comprising the following steps:

(1) Preparation of nano-CuO powder

The Na ₂ CO ₃ solution was reacted with the CuSO ₄ solution to form basic copper carbonate by chemical co-precipitation method. After standing at room temperature for 3 hours, centrifuged and washed with deionized water and absolute ethanol, and the washed precipitate was placed in 80 ℃ oven drying for 12 hours, then placed in a muffle furnace, calcined at 400 ℃ for 2 hours, to obtain nano CuO powder;

(2) Preparation of CuO@CuS nanocomposite powder

The CuO@CuS nanocomposite powder was prepared by microwave method. First, CuSO ₄ ·5H ₂ O and Na ₂ S ₂ O ₃ were dissolved in deionized water to form CuSO ₄ solution and Na ₂ S ₂ O ₃ solution, respectively. The CuO powder was added to the CuSO ₄ solution, and stirred until the mixture was uniform. The Na ₂ S ₂ O ₃ solution was added to the mixed solution, stirred for 10 minutes to obtain a fluorescent green precipitate, and then transferred to a microwave reactor to react for 20 minutes, The blue-black precipitated product was obtained, washed with absolute ethanol and deionized water, and dried in an oven at 60 °C for 12 hours to finally obtain CuO@CuS nanocomposite powder;

(3) Preparation of CuO@CuS/PVDF composite membrane

Add quantitative dry polyvinylidene fluoride PVDF particles to dimethylacetamide DMAC solvent, place it in a constant temperature water bath stirrer at 80°C and stir until a homogeneous solution is formed, then add quantitative (NaPO ₃ ) ₆ , PVP at dry room temperature and the CuO@CuS nanocomposite powder, slowly stir until the mixture is uniform, and let stand for 48 hours for defoaming, and then pour it on a flat glass plate, uniformly scrape the film with a fixed thickness of 200 μm, and finally soak it in Et-OH:H ₂ The CuO@CuS/PVDF composite film was obtained by stripping the film in ethanol solution with O=1:2.

Preferably, the molar ratio of CuO to CuS in the CuO@CuS nanocomposite powder is 2:1.

Preferably, in step (3), the mass percentages of the DMAC, PVDF, (NaPO ₃ ) ₆ , PVP and CuO@CuS nanocomposite powder are 73.5wt.%, 20wt.%, 1.5wt.%, 4 wt.% and 1 wt.%.

The present invention further provides a CuO@CuS/PVDF composite membrane for water treatment.

The invention also provides the application of a CuO@CuS/PVDF water treatment composite membrane in degrading organic pollutants in water.

Preferably, the CuO@CuS/PVDF water treatment composite membrane is applied to the degradation treatment of medical wastewater.

Preferably, the CuO@CuS/PVDF water treatment composite membrane is added with 0.4 g/L persulfate when degrading organic pollutants in water, and the initial pH value of the degradation is 3-9.

Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects:

(1) The present invention creates a heterogeneous catalyst by preparing CuO@CuS nanocomposite materials, so that the product has better reaction selectivity and wider pH tolerance, and the pH range is about 3-9.

(2) The transition metal element in the heterogeneous catalyst of the present invention selects copper element. According to the study of element abundance, copper element resources are relatively abundant. In addition, CuO and CuS nanoparticles are used as effective catalysts for PS activation systems, which have the advantages of high efficiency, non-toxicity, and low cost.

(3) The heterogeneous catalyst of the present invention is combined with the organic membrane PVDF to obtain the CuO@CuS/PVDF organic composite membrane, which has the advantages of strong stability, good oxidation resistance, low cost, simple operation, environmental protection and no secondary pollution.

Description of drawings

FIG. 1 is a flow chart of the preparation of the CuO@CuS/PVDF water treatment composite membrane provided by the embodiment of the present invention.

FIG. 2 is a comparison diagram of the water flux of the CuO@CuS/PVDF water treatment composite membrane provided by the embodiment of the present invention.

FIG. 3 is a result diagram of the optimization result of the compound ratio of CuO and CuS provided by the embodiment of the present invention.

4 is a graph showing the results of activating PS to degrade rhodamine B by the CuO@CuS/PVDF water treatment composite membrane provided in the embodiment of the present invention.

Figure 5 is a graph showing the results of the CuO@CuS/PVDF water treatment composite membrane provided in the embodiment of the present invention activating PS to degrade and degrade different antibiotics.

FIG. 6 is a graph showing the results of the pH tolerance of the PS system activated by the CuO@CuS/PVDF water treatment composite membrane provided in the embodiment of the present invention.

FIG. 7 is a graph showing the repeatability of the activated PS system of the CuO@CuS/PVDF water treatment composite membrane provided in the embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Example 1

The preparation of CuO@CuS/PVDF composite membrane for water treatment, the preparation process is shown in Figure 1, and the specific method is as follows:

(1) Preparation of nano-CuO powder

Using chemical co-precipitation method, 25 mL of 3 mol/L Na ₂ CO ₃ solution was reacted with 40 mL of 3 mol/L CuSO ₄ solution to form basic copper carbonate (peacock blue precipitate), and the precursor of nano-CuO was obtained. Then, after standing at room temperature for 3 hours, centrifuged and washed with deionized water and absolute ethanol, and the washed precipitate was placed in an oven at 80 °C for 12 hours, and then placed in a muffle furnace and calcined at 400 °C for 2 hours. , to obtain nano-CuO powder.

(2) Preparation of CuO@CuS nanocomposite powder

The CuO@CuS nanocomposite powders were prepared by microwave method. First, 0.1 mol CuSO ₄ 5H ₂ O and 0.1 mol Na ₂ S ₂ O ₃ were dissolved in 50 mL of deionized water to form CuSO ₄ solution and Na ₂ S ₂ O ₃ solution, respectively, and then The nano CuO powder prepared above was added to the CuSO ₄ solution, and stirred until the mixture was uniform, then Na ₂ S ₂ O ₃ solution was added to the mixed solution, stirred for 10 minutes to obtain a fluorescent green precipitate, which was transferred to a microwave reactor to react for 20 minutes , the reaction conditions are as follows: 2450MHz, 650W, every microwave reaction for 9s, stop standing for 21s to obtain a blue-black precipitated product, washed with absolute ethanol and deionized water, and dried in a 60 °C oven for 12 hours to finally obtain CuO@ CuS nanocomposite powder.

(3) Preparation of CuO@CuS/PVDF composite membrane

20 wt.% of dry polyvinylidene fluoride (PVDF) particles were added to 73.5 wt.% of dimethylacetamide (DMAC) solvent, placed in a constant temperature water bath stirrer at 80 °C and stirred until a homogeneous solution was formed, and then dried 1.5 wt.% (NaPO ₃ ) ₆ , 4 wt.% PVP, and 1 wt.% CuO@CuS nanocomposite powder prepared above were added at room temperature, stirred slowly until uniformly mixed, and left to stand for 48 hours for defoaming, followed by It was poured onto a flat glass plate, and the film was uniformly scraped with a fixed thickness of 200 μm. Finally, it was immersed in an ethanol solution with Et-OH:H ₂ O=1:2 to remove the film to obtain a CuO@CuS/PVDF composite film.

The CuO@CuS/PVDF water treatment composite membrane prepared by the present invention and the pure PVDF membrane, CuO/PVDF membrane and CuS/PVDF membrane were tested for membrane flux respectively. The results are shown in Figure 2. It can be seen that CuO@CuS/ Compared with the pure PVDF membrane, the PVDF water treatment composite membrane has a significantly lower membrane flux, and is significantly higher than that of the CuO/PVDF membrane and CuS/PVDF membrane. The above membrane properties can effectively prolong the residence of the organic pollutant solution on the composite membrane. time, so as to achieve the effect of fully catalytic degradation of organic pollutants.

Example 2

When the CuO@CuS/PVDF composite membrane for water treatment degrades organic pollutants in water, the CuO@CuS/PVDF composite membrane for water treatment was first added to the water to be treated containing organic pollutants, and 0.4g/L persulfate (PS) was added. , the initial pH value of degradation is controlled at 3-9. Then, it is fully contacted under the action of physical external force (ie, water pressure, stirring, etc.), so as to finally realize the catalytic degradation of pollutants.

(1) Based on the catalytic degradation efficiency, the composite ratio of CuO to CuS in the CuO@CuS nanocomposite powder was optimized, and the molar ratio of CuO to CuS was set as 1:100, 1:50, 1:1, 2:1, 3, respectively :1 The CuO@CuS nanocomposite powder was prepared, and then the organic matter degradation reaction was carried out. During the degradation process, a certain amount of samples were taken from the pollutant solution within a certain time interval, and the absorbance of the filtrate at a specific wavelength was detected by an ultraviolet spectrophotometer. The degradation efficiency of pollutants was determined by the measurement of absorbance. The results are shown in Figure 3. Finally, the optimal composite ratio of CuO and CuS was determined to be 2:1, and the degradation efficiency was the best, and the degradation could reach 63.2% in about 100 minutes. In the process of degrading organic pollutants in water by the CuO@CuS/PVDF water treatment composite membrane prepared with a composite ratio of CuO and CuS of 2:1, the change of its degradation efficiency within 40min is shown in Figure 4. It can be seen that within 40min Its catalytic degradation efficiency is as high as 86.5%.

(2) The degradation of tetracycline, enrofloxacin, ciprofloxacin and lomefloxacin by the CuO@CuS/PVDF composite membrane for water treatment prepared with a composite ratio of CuO to CuS of 2:1 is shown in Figure 5. It can be seen that the activated PS of the CuO@CuS/PVDF water treatment composite membrane of the present invention has a relatively obvious degradation effect on a variety of new antibiotics (tetracycline, enrofloxacin, ciprofloxacin and lomefloxacin), so it can be applied to medical wastewater. The advanced treatment in other fields shows that the CuO@CuS/PVDF water treatment composite membrane of the present invention has a wide range of applications in the field of water treatment.

(3) When the CuO@CuS/PVDF composite membrane for water treatment prepared with a composite ratio of CuO and CuS of 2:1 degrades organic pollutants in water, the pollutant solutions with different initial pH values were set to analyze the CuO@CuS/PVDF The pH tolerance of the composite membrane for water treatment, the results are shown in Figure 6, indicating that the CuO@CuS/PVDF composite membrane for water treatment has excellent pH tolerance, and its degradation efficiency is excellent in the pH range of 3 to 9. Therefore, , the CuO@CuS/PVDF water treatment composite membrane prepared by the invention is suitable for organic wastewater with pH value of 3-9.

(4) In order to further test the reusability of the CuO@CuS/PVDF composite membrane for water treatment prepared with a composite ratio of CuO to CuS of 2:1, the repeated use of the CuO@CuS/PVDF composite membrane for water treatment to degrade organic pollutants was carried out. , the results are shown in Fig. 7, indicating that the CuO@CuS/PVDF water treatment composite membrane still has excellent degradation efficiency after being reused 8 times. Therefore, the CuO@CuS/PVDF water treatment composite membrane prepared by the present invention can degrade water It has good stability in the process of organic pollutants.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (7)

1. A preparation method of a CuO @ CuS/PVDF water treatment composite membrane is characterized by comprising the following steps:

(1) preparation of nano CuO powder

Chemical coprecipitation method is adopted to mix Na₂CO₃Mixing the solution with CuSO₄The solution reacts to generate basic copper carbonate, the basic copper carbonate is kept stand for 3 hours at room temperature, then is centrifugally washed by deionized water and absolute ethyl alcohol, and the washed precipitate is placed in an oven at 80 ℃ for drying for 12 hours, then is placed in a muffle furnace and is calcined for 2 hours at 400 ℃ to obtain nano CuO powder;

(2) preparation of CuO @ CuS nano composite powder

Preparing CuO @ CuS nano composite powder by adopting a microwave method, namely firstly, preparing CuSO₄·5H₂O and Na₂S₂O₃Respectively dissolved in deionized water to form CuSO₄Solution and Na₂S₂O₃Solution, then adding the nano CuO powder to the CuSO₄Adding Na into the solution, stirring until the mixture is uniformly mixed, and adding the Na into the mixed solution₂S₂O₃Stirring the solution for 10 minutes to obtain fluorescent green precipitate, transferring the fluorescent green precipitate into a microwave reactor to react for 20 minutes to obtain a blue-black precipitate product, washing the blue-black precipitate product with absolute ethyl alcohol and deionized water, and drying the washed blue-black precipitate product in a drying oven at 60 ℃ for 12 hours to finally obtain CuO @ CuS nano composite powder;

(3) preparation of CuO @ CuS/PVDF composite membrane

Adding quantitative dry polyvinylidene fluoride (PVDF) particles into a Dimethylacetamide (DMAC) solvent, placing the mixture in a constant-temperature water bath stirrer at the temperature of 80 ℃ for stirring until a homogeneous solution is formed, and then adding quantitative (NaPO) into the mixture at the dry room temperature₃)₆PVP and the CuO @ CuS nano composite powder are slowly stirred to be uniformly mixed, kept stand for 48 hours for defoaming, poured on a plane glass plate, uniformly scraped into a film with the thickness of 200 mu m, and finally soaked in Et-OH₂And (3) stripping in an ethanol solution with the ratio of O to 1:2 to obtain the CuO @ CuS/PVDF composite membrane.

2. The method of claim 1 for preparing a CuO @ CuS/PVDF composite membrane in a water treatment system, wherein the molar ratio of CuO to CuS in the CuO @ CuS nanocomposite powder is 2: 1.

3. The method for preparing the CuO @ CuS/PVDF composite membrane as claimed in claim 1, wherein in step (3), the DMAC, PVDF and (NaPO) are used₃)₆PVP, and CuO @ CuS nanocomposite powder were 73.5 wt.%, 20 wt.%, 1.5 wt.%, 4 wt.%, and 1 wt.%, respectively.

4. A CuO @ CuS/PVDF water treatment composite membrane prepared by the preparation method as set forth in any one of claims 1 to 3.

5. The use of the CuO @ CuS/PVDF composite membrane as defined in claim 4 for water treatment to degrade organic contaminants in water.

6. The use of claim 5, wherein said CuO @ CuS/PVDF composite water treatment membrane is used in the degradation treatment of medical wastewater.

7. The application of claim 5 or 6, wherein 0.4g/L of persulfate is added when the CuO @ CuS/PVDF composite membrane for water treatment is used for degrading organic pollutants in water, and the initial pH value of degradation is 3-9.

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