CN105749981B - A kind of CNT/zinc oxide PTFE film and preparation method thereof - Google Patents

Abstract

The invention discloses a method for preparing a carbon nanotube/zinc oxide PTFE photocatalytic film. Firstly, fully mix acidified carbon nanotubes and Zn(CH ₃ COO) ₂ , adjust the pH to be alkaline, and then undergo high-temperature reaction, filtration, Washing and drying to obtain the carbon nanotube/zinc oxide composite material, then put the carbon nanotube/zinc oxide composite material and PTFE into the mold, cold press forming, high temperature sintering, and obtain the carbon nanotube/zinc oxide PTFE photocatalytic film . The carbon nanotube/zinc oxide PTFE photocatalytic membrane prepared by the invention not only prolongs the service life of the PTFE membrane, but also enhances the performance of ZnO photocatalytic degradation of organic pollutants. The process equipment of the invention is simple, easy for large-scale production, and has great market prospect.

Description

A kind of carbon nanotube/zinc oxide PTFE film and preparation method thereof

technical field

The invention relates to a carbon nanotube/zinc oxide PTFE photocatalytic film and a preparation method thereof, belonging to the technical field of composite materials.

Background technique

In today's increasingly scarce water resources, the treatment of sewage has aroused widespread attention. Membrane separation technology appeared in the early 20th century, and developed rapidly into a new water treatment technology after the 1960s. Due to its functions of separation, concentration and purification, as well as high efficiency, energy saving, environmental protection and filtration, and the filtration process is simple and easy to control, membrane separation technology has been widely used in the fields of biology and environmental protection, and has become an important part of separation science. One of the most important means. PTFE membrane is made of polytetrafluoroethylene, which is breathable, impermeable, large air flow, high temperature resistance, strong acid resistance, non-toxic, and plays an important role in membrane separation technology. However, the application of PTFE membrane alone in the process of pesticide wastewater treatment can only physically separate the pesticide wastewater, and does not effectively remove the pollutants in the wastewater, and the PTFE membrane will be polluted during long-term operation, thereby reducing the separation efficiency. Effect. Therefore, it is particularly important to find a method to make organic wastewater harmless.

Nanophotocatalytic technology is an advanced oxidation technology, which is widely used in wastewater treatment process. The nano-photocatalyst generates hydroxyl radicals with strong oxidation effect under the irradiation of light, degrades harmful substances in wastewater, generates water and harmless gases, and does not produce secondary pollution. The most mature nano-photocatalyst studied at present is TiO ₂ , but TiO ₂ can only be catalyzed by ultraviolet light, which limits its wide application in wastewater treatment. As a photocatalyst, ZnO has the characteristics of low price, non-toxicity, and high photocatalytic performance, and has become a research hotspot. In order to further improve the photodegradation activity of ZnO, nanoscale ZnO came into being. However, during the use of nano-ZnO, serious photocorrosion phenomenon will occur, which limits the application of ZnO. In recent years, carbon nanotube wall functional groups have developed rapidly, and carbon nanotubes have excellent electronic conductivity, adsorption and desorption properties for reactants and reaction products, strong metal-support interaction between carbon and metal catalysts, and quantum The effect and energy characteristics make it more and more used as a catalyst carrier. The composite material of carbon nanotubes and nano-ZnO can reduce the photocorrosion of ZnO and improve the photocatalytic degradation effect of ZnO on organic wastewater.

Contents of the invention

The object of the present invention provides a kind of carbon nanotube/zinc oxide PTFE photocatalyst membrane and preparation method thereof, according to the respective advantages and disadvantages of PTFE membrane and carbon nanotube/zinc oxide, add carbon nanotube/zinc oxide composite material in PTFE membrane , not only solves the problem of PTFE membrane being easily polluted, but also makes PTFE membrane have the photocatalytic performance of zinc oxide, which can purify polluted water.

Technical scheme of the present invention is as follows:

A kind of preparation method of carbon nanotube/zinc oxide PTFE photocatalytic film of the present invention, comprises the following steps:

1) Take carbon nanotubes, add mixed acid, and continue to stir in a water bath at 80-90°C, then filter, wash, and dry the mixture of carbon nanotubes and mixed acid to obtain acidified carbon nanotubes;

2) Mix the acidified carbon nanotubes and Zn(CH ₂ COOH) ₂ in a certain proportion in step 1), add ammonia water to make the pH become weakly alkaline, continue to stir, and then react at a high temperature of 100~150°C, Filtrating, washing and drying to obtain the carbon nanotube/zinc oxide composite material;

3) Add the carbon nanotube/zinc oxide composite material and polytetrafluoroethylene powder obtained in step 2) into the organic solvent according to a certain mass ratio, and stir with ultrasonic waves and high-speed machinery for 2 to 3 hours until it becomes a viscous mixture ;

4) After heating the mixed solution in step 3), place it in a mold for cold pressing, and sinter at high temperature to obtain a carbon nanotube/zinc oxide PTFE film.

The mixed acid added in the above step 1) is a mixture of concentrated sulfuric acid and concentrated nitric acid at a volume ratio of 1-3:1.

The proportion relationship between carbon nanotubes and Zn(CH ₂ COOH) ₂ in the above step 2) is determined by the mass ratio of carbon nanotubes and zinc oxide in the finally obtained carbon nanotube/zinc oxide composite material. Generally, carbon nanotubes and zinc oxide The mass ratio of zinc is 1:25~50.

The mass ratio of the carbon nanotube/zinc oxide composite material to the polytetrafluoroethylene powder in the above step 3) is 1:6~20; the organic solvent is N-methylpyrrolidone; the speed of high-speed mechanical stirring is 300~400r/min.

The medium-high temperature sintering temperature in the above step 4) is 300-400°C.

The carbon nanotube/zinc oxide PTFE photocatalytic film prepared by the method not only prolongs the service life of the PTFE film, but also enhances the performance of ZnO photocatalytic degradation of organic pollutants, and has a better effect in sewage treatment. Both the removal rate of phenol and COD can reach more than 95%. After the membrane is ultrasonically cleaned with distilled water for 5-6 hours, the flux of the membrane can be restored to more than 90%, which is easy to clean.

Beneficial effect:

According to the advantages and disadvantages of PTFE film and carbon nanotube/zinc oxide, add carbon nanotube/zinc oxide composite material to PTFE film to prepare carbon nanotube/zinc oxide PTFE photocatalytic film, carbon nanotube/zinc oxide PTFE photocatalytic film The catalytic membrane not only prolongs the service life of the PTFE membrane, but also enhances the photocatalytic degradation of organic pollutants of ZnO. The process equipment of the invention is simple, easy for large-scale production, and has great market prospect. It solves the problem that the PTFE membrane is easily polluted, has a purifying effect on polluted water, can effectively degrade organic wastewater, and has a broad market prospect.

Description of drawings

Fig. 1 schematic diagram of carbon nanotube/zinc oxide-PTFE photocatalytic membrane wastewater treatment device;

Among them: 1-Wastewater pool, 2-Inlet pump, 3-Heater, 4-Membrane distiller, 5-Carbon nanotube/zinc oxide PTFE photocatalytic membrane, 6-Quartz cold trap, 7-Light source, 8-Circulating water pump , 9-circulating pool, 10-collecting pool.

Detailed ways

The following are several specific embodiments of the present invention to further illustrate the present invention, but the present invention is not limited thereto.

Example 1

Take 500mg of carbon nanotubes and put them into a 100mL single-neck flat-bottomed flask with magnetic stirring, add 40mL of mixed acid (concentrated sulfuric acid:concentrated nitric acid=3:1, volume ratio), first use a 60HZ ultrasonic water bath for 1h, then stir in a 90°C water bath for 2h, After the mixture was diluted 10 times with deionized water, it was suction-filtered with a 0.22 μm mixed membrane, washed with deionized water repeatedly and then dried in a vacuum oven at 60°C for 24 hours.

Ultrasonic disperse 20 mg of the above-mentioned carbon nanotubes into 150 mL of a mixture of absolute ethanol and water (volume ratio 1:1), add 30 mL of zinc acetate solution with a concentration of 0.2 mol/L, stir well, and add ammonia water to adjust the pH to Alkaline (pH 8~9), stir well and filter, disperse the solid phase in deionized water, and adjust the pH to be neutral. The above reactants were placed in a reaction kettle and reacted at 120°C for 5 hours, then rapidly cooled to room temperature, and the product was filtered, washed, and dried at 60-80°C to obtain a 4% carbon nanotube/zinc oxide composite material.

Add the above-mentioned carbon nanotube/zinc oxide composite material to polytetrafluoroethylene at a mass fraction of 10%, add N-methylpyrrolidone, and fully mix with ultrasonic waves and a high-speed mechanical stirrer. The high-speed mechanical stirring speed is 300~400r/ min, heat the mixture to completely volatilize N-methylpyrrolidone, then put the mixture of carbon nanotubes/zinc oxide and polytetrafluoroethylene into a mold (6mm×20mm×20mm) for cold pressing, and then heat it at 300~400℃ Sintering to obtain a 10% carbon nanotube/zinc oxide-PTFE photocatalytic film.

Example 2

The 10% carbon nanotube/zinc oxide-PTFE photocatalyst membrane that prepares with embodiment 1 carries out waste water treatment, is the phenol waste water of 40mg/L with concentration as waste water to be treated, by the waste water treatment device as shown in Figure 1, will The phenol waste water is added to the waste water tank 1, and the waste water is drawn into the hot side of the membrane still 4 through the suction pump 2. The temperature of the hot side is set at 65°C, the temperature of the cold side is at room temperature, and the hydraulic retention time is set at 3h. The thermal measurement temperature is determined by The heater 3 controls the carbon nanotube/zinc oxide PTFE photocatalytic membrane 5 to treat the wastewater under the condition of 500W visible light irradiation. Liquefied into water, the vapor pressure difference on both sides of the membrane is used as the driving force; the water inlet pump 2 and the circulating water pump 8 with a liquid level controller are turned on to circulate the hot and cold side water of the membrane distiller, and the water in the circulating pool 9 passes through the circulation The pump 8 enters the cold side of the photocatalytic membrane and brings the liquefied water into the circulating pool 9 , and finally the produced water from the membrane distillation enters the sump 10 . Take a sample every 0.5h, and measure the concentration of phenol and the COD value in the sump 10, and find that the removal rate of phenol and COD can reach 95%. After the membrane used up in the experiment is ultrasonically cleaned with distilled water for 5-6 hours, the flux of the membrane can be restored to more than 90%.

Claims (7)

1. a preparation method of carbon nanotube/zinc oxide PTFE photocatalytic film, is characterized in that, comprises the following steps: 1) Take carbon nanotubes, add mixed acid, stir in a water bath at 80-90°C, then filter, wash, and dry the mixture of carbon nanotubes and mixed acid to obtain acidified carbon nanotubes; the mixed acid is concentrated sulfuric acid It is mixed with concentrated nitric acid at a volume ratio of 1~3:1; 2) Take the acidified carbon nanotubes in step 1) and mix them with Zn(CH ₂ COOH) ₂ , add ammonia water to make the pH become weakly alkaline, continue to stir, and then undergo high temperature reaction at 100~150°C, filter, wash, drying to obtain carbon nanotube/zinc oxide composite material; the mass ratio of carbon nanotube and zinc oxide in the carbon nanotube/zinc oxide composite material is 1:25～50; 3) Add the carbon nanotube/zinc oxide composite material and polytetrafluoroethylene powder obtained in step 2) into an organic solvent, and stir with ultrasonic waves and high-speed machinery for 2 to 3 hours until it becomes a viscous mixture; 4) After heating the mixed solution in step 3), place it in a mold for cold pressing, and sinter at high temperature to obtain a carbon nanotube/zinc oxide PTFE film. 2. The preparation method of a carbon nanotube/zinc oxide PTFE photocatalytic film according to claim 1, characterized in that the weak alkalinity described in step 2) has a pH of 8-9. 3. The preparation method of a kind of carbon nanotube/zinc oxide PTFE photocatalytic membrane according to claim 1, is characterized in that, the mass ratio of carbon nanotube/zinc oxide composite material and polytetrafluoroethylene powder in step 3) It is 1:6~20. 4 . The method for preparing a carbon nanotube/zinc oxide PTFE photocatalytic film according to claim 1 , wherein the organic solvent in step 3) is N-methylpyrrolidone. 5. The method for preparing a carbon nanotube/zinc oxide PTFE photocatalytic film according to claim 1, characterized in that, step 3) the high-speed mechanical stirring speed is 300~400r/min. 6 . The method for preparing a carbon nanotube/zinc oxide PTFE photocatalytic film according to claim 1 , wherein the high-temperature sintering temperature in step 4) is 300-400° C. 7. The carbon nanotube/zinc oxide PTFE photocatalyst film prepared by any method in claim 1-6.