A carbon nanomaterial modified polytetrafluoroethylene membrane and its preparation method and application

Abstract

The invention discloses a method for preparing a carbon nano material modified polytetrafluoroethylene membrane, comprising the following steps: adding carbon nano material to organic fluoride, adding fluorosilane coupling agent to the above dispersion system, dispersing carbon nano material in organic fluoride emulsion by mechanical stirring and ultrasound, utilizing the dispersing effect of fluorosilane coupling agent; selecting polytetrafluoroethylene membrane as support membrane and performing vacuum filtration; taking out the filtration membrane and placing it in a blast drying oven for heating and curing, and obtaining carbon nano material modified polytetrafluoroethylene membrane material after curing. The invention selects polytetrafluoroethylene or polyvinylidene fluoride emulsion, which are both organic fluoride and polytetrafluoroethylene membrane, and because of their identical or similar structures, they have strong bonding ability to polytetrafluoroethylene membrane after heating and curing, so that carbon nano material can be tightly fixed on the porous structure of polytetrafluoroethylene membrane, and can effectively prevent the carbon nano material from falling off.

Description

Technical Field

[0001] The invention relates to the field of polymer technology, and in particular to a carbon nanomaterial modified polytetrafluoroethylene membrane, a preparation method thereof, and an application thereof in adsorbing metal ions. Background Art

[0002] At present, the vacuum filtration method is commonly used for modifying polytetrafluoroethylene membranes with carbon nanomaterials, that is, using polytetrafluoroethylene membrane as a support membrane, dispersing carbon nanomaterials in a solution, and filtering the dispersion onto the polytetrafluoroethylene membrane under vacuum. The porous structure of the polytetrafluoroethylene membrane can block the passage of some carbon nanomaterials, so that some carbon nanomaterials remain on its surface, thereby achieving the purpose of modifying the polytetrafluoroethylene membrane with carbon nanomaterials. For example, application number CN202011388708.0 disperses carbon nanotubes containing Fe2O3 in ethanol, and uses a vacuum filtration method to attach carbon nanotubes containing Fe2O3 to the surface of the polytetrafluoroethylene membrane, thereby preparing a carbon nanotube membrane. Application number CN202011643339.5 disperses carbon nanomaterial graphene in an aqueous solution, and attaches graphene to the surface of the polytetrafluoroethylene membrane by vacuum filtration, thereby achieving graphene-modified polytetrafluoroethylene membrane. The use of vacuum filtration to prepare carbon nanomaterial-modified polytetrafluoroethylene membranes has the advantages of simple preparation method, short cycle and mild conditions.

[0003] In the method of preparing carbon nanomaterial modified polytetrafluoroethylene membrane by vacuum filtration, the carbon nanomaterial stays on the surface of the membrane due to the blocking effect of the porous structure of the polytetrafluoroethylene membrane. There is no chemical bonding and physical effect between the carbon nanomaterial and the porous structure of the polytetrafluoroethylene membrane. In actual use, the carbon nanomaterial is easy to fall off. For example, when the carbon nanomaterial modified polytetrafluoroethylene membrane is used as a conductive and thermal conductive membrane, when the surface is scratched, the carbon nanomaterial falls off, resulting in a decrease in the conductive and thermal conductivity of the composite membrane; when the carbon nanomaterial modified polytetrafluoroethylene membrane is used as a filter membrane, when the pressure of the solution to be filtered is too high, the carbon nanomaterial is easy to fall off, which not only affects the filtration effect of the composite membrane, but also the fallen carbon nanomaterial enters the filtered solution, thereby affecting the quality of the filtered solution. Summary of the invention

[0004] The object of the present invention is to provide a carbon nanomaterial-modified polytetrafluoroethylene membrane which has good adsorption and can effectively prevent the carbon nanomaterial from falling off, and a preparation method thereof.

[0005] In order to solve the above technical problems, the present invention provides a preparation method of a carbon nano material modified polytetrafluoroethylene membrane, comprising the following steps: adding a carbon nano material to an organic fluoride, adding a fluorosilane coupling agent to the above dispersion system, dispersing the carbon nano material in the organic fluoride emulsion by means of mechanical stirring and ultrasound and utilizing the dispersing effect of the fluorosilane coupling agent; selecting a polytetrafluoroethylene membrane as a support membrane and performing vacuum filtration; taking out the filtration membrane and placing it in a blast drying oven for heating and curing, and obtaining a carbon nano material modified polytetrafluoroethylene membrane material after curing.

[0006] Preferably, the carbon nanomaterial is any one or more of carbon nanotubes, graphene, MXene, or carbon nitride.

[0007] Preferably, the fluorosilane coupling agent is any one of 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane, tridecafluorooctyltrimethoxysilane or trichloropropyltrichlorosilane.

[0008] Preferably, the molecular weight of the polytetrafluoroethylene emulsion is 0.5-2W, and the molecular weight of the polyvinylidene fluoride emulsion is 15-30W.

[0009] Preferably, the weight ratio of the organic fluoride to the carbon nanomaterial is (10-15):1.

[0010] Preferably, the weight ratio of the carbon nanomaterial to the fluorosilane coupling agent is 1:(0.005-0.03).

[0011] Preferably, the mechanical stirring time is 1 to 3 hours, and the ultrasonic dispersion time is 0.5 to 1 hour.

[0012] Preferably, the heating curing temperature is 90-110° C., and the curing time is 1-4 hours.

[0013] A carbon nanomaterial modified polytetrafluoroethylene membrane is prepared by the above method.

[0014] The present invention also provides the use of any of the above-mentioned carbon nanomaterial-modified polytetrafluoroethylene membrane materials in the adsorption of metal ions. Taking the metal ion Fe(III) as the research object, the above-mentioned carbon nanomaterial-modified polytetrafluoroethylene membrane material is used as a suction filtration membrane, and the aqueous solution containing Fe(III) is passed through the suction filtration membrane by vacuum filtration, and the negatively charged hydroxyl, carboxyl and other groups on the surface of the carbon nanomaterial are utilized to achieve the adsorption of the metal ion Fe(III) through electrostatic attraction.

[0015] The present invention disperses the carbon nano material in an organic fluoride emulsion through a fluorosilane coupling agent, performs vacuum filtration and then heat curing, and uses the organic fluoride to tightly fix the carbon nano material on the porous structure of the polytetrafluoroethylene membrane, thereby making the carbon nano material not easy to fall off. In addition, since the surface of the carbon nano material carries negatively charged groups such as hydroxyl and carboxyl, the carbon nano material modified polytetrafluoroethylene membrane prepared by the method of the present invention can be used to adsorb metal ions such as Fe (III).

[0016] In summary, the technical solution of the present invention has the following beneficial effects:

[0017] 1. The present invention uses polytetrafluoroethylene or polyvinylidene fluoride emulsion, which are both organic fluorides and polytetrafluoroethylene membranes. Because of their identical or similar structures, they have strong bonding ability to polytetrafluoroethylene membranes after heating and curing, so that the carbon nanomaterials can be tightly fixed on the porous structure of the polytetrafluoroethylene membrane, which can effectively prevent the carbon nanomaterials from falling off;

[0018] 2. The present invention uses perfluorosilane as a dispersant, which can evenly disperse the carbon nanomaterial in the organic fluoride emulsion, thereby preventing the carbon nanomaterial from agglomerating during the filtration process;

[0019] 3. The carbon nanomaterial described in the present invention is any one or more of carbon nanotubes, graphene, MXene or carbon nitride, all of which have abundant negatively charged groups such as hydroxyl and carboxyl groups on their surfaces, and can achieve the adsorption of metal ions such as Fe(III) through electrostatic attraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a graph showing the change in resistance value of the carbon nanomaterial-modified polytetrafluoroethylene membrane before and after vacuum filtration. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with specific embodiments.

[0022] The invention provides a carbon nano material modified polytetrafluoroethylene membrane and a preparation method thereof, as well as application of the carbon nano material in adsorbing metal ions. The carbon nano material is uniformly dispersed in an organic fluoride emulsion through the dispersing effect of a fluorosilane coupling agent, thereby avoiding agglomeration of the carbon nano material under vacuum filtration. After heating and curing, the structure of the organic fluoride is the same as or similar to that of polytetrafluoroethylene, and the carbon nano material can be firmly fixed on the surface of the polytetrafluoroethylene membrane, thereby solving the problem that the carbon nano material is easy to fall off in actual use. The surface of the carbon nano material carries many negatively charged groups such as hydroxyl groups and carboxyl groups, and can be used to adsorb metal ions through electrostatic adsorption. The carbon nano material modified polytetrafluoroethylene membrane prepared by the invention can realize the adsorption of metal ions such as Fe(III).

[0023] Example 1

[0024] S1: Dispersion of carbon nanotubes: Carbon nanotubes are selected as carbon nanomaterials, polytetrafluoroethylene emulsion with a molecular weight of 1W is selected as organic fluoride emulsion, and 1H,1H,2H,2H-perfluorodecyltrichlorosilane is selected as fluorosilane coupling agent. Carbon nanotubes, polytetrafluoroethylene emulsion and 1H,1H,2H,2H-perfluorodecyltrichlorosilane are mixed in a weight ratio of 1:10:0.03. After mixing, the mixture is mechanically stirred for 1 hour and ultrasonically dispersed for 0.5 hour.

[0025] S2: Preparation of carbon nanotube modified polytetrafluoroethylene membrane: Using polytetrafluoroethylene membrane as support membrane, vacuum filter the carbon nanotube dispersion, take it out after filtration, place the composite membrane in a forced air drying oven and heat cure at 100°C for 1h, and obtain carbon nanotube modified polytetrafluoroethylene membrane after curing.

[0026] Example 2

[0027] S1: Dispersion of graphene: Graphene is selected as the carbon nanomaterial, polytetrafluoroethylene emulsion with a molecular weight of 1W is selected as the organic fluoride emulsion, and tridecafluorooctyltrimethoxysilane is selected as the fluorosilane coupling agent. Graphene, polytetrafluoroethylene emulsion and tridecafluorooctyltrimethoxysilane are mixed in a weight ratio of 1:10:0.01. After mixing, the mixture is mechanically stirred for 1.5 hours and ultrasonically dispersed for 1 hour.

[0028] S2: Preparation of graphene-modified polytetrafluoroethylene membrane: Using polytetrafluoroethylene membrane as support membrane, vacuum filter the graphene dispersion, take it out after filtration, place the composite membrane in a forced air drying oven and heat cure at 100°C for 1h, and obtain the graphene-modified polytetrafluoroethylene membrane after curing.

[0029] Example 3

[0030] S1: Dispersion of MXene: MXene was selected as the carbon nanomaterial, polyvinylidene fluoride emulsion with a molecular weight of 18W was selected as the organic fluoride emulsion, and trichloropropyltrichlorosilane was selected as the fluorosilane coupling agent. MXene, polyvinylidene fluoride emulsion and trichloropropyltrichlorosilane were mixed in a weight ratio of 1:15:0.01. After mixing, the mixture was mechanically stirred for 2 hours and ultrasonically dispersed for 0.5 hours.

[0031] S2: Preparation of MXene-modified polytetrafluoroethylene membrane: Using polytetrafluoroethylene membrane as the support membrane, vacuum filter the above MXene dispersion, take it out after filtration, place the composite membrane in a forced air drying oven and heat cure at 110°C for 2h, and after curing, a MXene-modified polytetrafluoroethylene membrane can be obtained.

[0032] Embodiment 4:

[0033] S1: Dispersion of carbon nitride: Carbon nitride is selected as the carbon nanomaterial, polyvinylidene fluoride emulsion with a molecular weight of 30W is selected as the organic fluoride emulsion, and 1H,1H,2H,2H-perfluorodecyltrichlorosilane is selected as the fluorosilane coupling agent. Carbon nitride, polyvinylidene fluoride emulsion and 1H,1H,2H,2H-perfluorodecyltrichlorosilane are mixed in a weight ratio of 1:15:0.03. After mixing, the mixture is mechanically stirred for 3 hours and ultrasonically dispersed for 1 hour.

[0034] S2: Preparation of carbon nitride modified polytetrafluoroethylene membrane: Using polytetrafluoroethylene membrane as support membrane, vacuum filter the carbon nitride dispersion, take it out after filtration, place the composite membrane in a forced air drying oven and heat cure at 110°C for 2h, and obtain carbon nitride modified polytetrafluoroethylene membrane after curing.

[0035] Comparative Example:

[0036] S1: Dispersion of carbon nanotubes: Carbon nanotubes are selected as carbon nanomaterials, and deionized water is selected as a dispersion medium. The carbon nanotubes and deionized water are mixed at a weight ratio of 1:10. After mixing, the mixture is mechanically stirred for 1 hour and ultrasonically dispersed for 0.5 hour.

[0037] S2: Preparation of carbon nanotube-modified polytetrafluoroethylene membrane: Using polytetrafluoroethylene membrane as support membrane, vacuum filtration is performed on the carbon nanotube dispersion liquid, and after the filtration, the carbon nanotube-modified polytetrafluoroethylene membrane is obtained.

[0038] Table 1 Proportions of carbon nanomaterials, organic fluoride emulsions and fluorosilane coupling agents in Examples 1-4 and Comparative Examples

[0039]

[0040]

[0041] The present invention uses a potassium thiocyanate method to determine the content of Fe(III) in an aqueous solution, uses an ultraviolet spectrophotometer to determine the absorbance of an iron standard solution and draws a standard curve of Fe(III), determines the absorbance of Fe(III) after adsorption by the carbon nanomaterial modified polytetrafluoroethylene membrane prepared by the present invention, and calculates the adsorption rate of Fe(III) in Examples 1 to 4 according to the drawn standard curve. The calculation results are shown in Table 2.

[0042] Table 2 Adsorption rate of Fe(III) in aqueous solution of Examples 1-4

[0043] Adsorption rate of Fe(III) Example 1 40.98％ Example 2 52.35％ Example 3 58.19％ Example 4 38.91％

[0044] In order to prove that the carbon nanomaterial of the present invention is not easy to fall off, deionized water is used as the filtration medium, and the carbon nanomaterial modified polytetrafluoroethylene membrane of the present invention is vacuum filtered for multiple times to test the changes in the resistance value before and after multiple vacuum filtration of Example 1 and the comparative example. The test results are as follows: Figure 1 shown.

[0045] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon nanomaterial-modified polytetrafluoroethylene membrane, It is characterized in that The method comprises the following steps: adding carbon nanomaterials to organic fluoride, adding fluorosilane coupling agent to the dispersion system, dispersing the carbon nanomaterials in the organic fluoride emulsion by mechanical stirring and ultrasound and utilizing the dispersing effect of the fluorosilane coupling agent; selecting a polytetrafluoroethylene membrane as a support membrane and performing vacuum filtration; taking out the filtration membrane and placing it in a blast drying oven for heating and curing, and obtaining a carbon nanomaterial-modified polytetrafluoroethylene membrane material after curing; The carbon nanomaterial is any one or more of carbon nanotubes, graphene, MXene, or carbon nitride; The fluorosilane coupling agent is any one of 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane or tridecafluorooctyltrimethoxysilane; The organic fluoride is polytetrafluoroethylene emulsion or polyvinylidene fluoride emulsion, the molecular weight of the polytetrafluoroethylene emulsion is 0.5-2 W, and the molecular weight of the polyvinylidene fluoride emulsion is 15-30 W.

2. The method for preparing a carbon nanomaterial modified polytetrafluoroethylene membrane according to claim 1, Features: The weight ratio of the organic fluoride to the carbon nanomaterial is (10-15):

1.

3. The method for preparing a carbon nanomaterial-modified polytetrafluoroethylene membrane according to claim 1, Features: The weight ratio of the carbon nanomaterial to the fluorosilane coupling agent is 1:(0.005-0.03).

4. The method for preparing a carbon nanomaterial modified polytetrafluoroethylene membrane according to claim 1, Features: The mechanical stirring time is 1 to 3 h, and the ultrasonic dispersion time is 0.5 to 1 h.

5. The method for preparing a carbon nanomaterial-modified polytetrafluoroethylene membrane according to claim 1, Features: The heating curing temperature is 90-110° C., and the curing time is 1-4 h.

6. A carbon nanomaterial modified polytetrafluoroethylene membrane, It is characterized in that Prepared according to the method according to any one of claims 1 to 5.

7. Use of the carbon nanomaterial modified polytetrafluoroethylene membrane as claimed in claim 6 in adsorbing metal ions.

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