CN111514856A - Graphene oxide adsorption film, preparation method thereof and water treatment method - Google Patents

Abstract

The invention discloses a graphene oxide adsorption film, a preparation method thereof and a water treatment method. The graphene oxide adsorption film includes: a porous polymer-based membrane; the carbon nanotube layer is arranged on the surface of the polymer-based film; and the graphene oxide layer is arranged on the surface of the carbon nano tube layer.

Description

Graphene oxide adsorption film, its preparation method and water treatment method

technical field

The invention belongs to the technical field of adsorption film materials, and in particular relates to a graphene oxide adsorption film, a preparation method thereof and a water treatment method.

Background technique

People will produce a large amount of waste water in production and life. Purifying the waste water can reduce pollution, and even achieve the recycling of waste water and make full use of water resources.

Membrane technology can realize the separation of impurities in wastewater by the interception effect of membrane. For example, microfiltration membranes can retain particles between 0.1 μm and 1 μm, such as suspended solids, bacteria and large molecular weight colloids. The use of membrane technology to treat wastewater has the advantages of high degree of automation and good treatment effect, and the separation of membrane is a physical process without the addition of chemical reagents, so it is widely used in the field of wastewater treatment.

With the increasing emphasis on environmental protection and water resource recycling, higher requirements have been placed on wastewater treatment. In order to further improve the level of membrane wastewater treatment, it is necessary to provide a membrane material with better performance.

SUMMARY OF THE INVENTION

A first aspect of the present invention provides a graphene oxide adsorption film, which includes: a porous polymer base film; a carbon nanotube layer disposed on the surface of the polymer base film; a graphene oxide layer disposed on the carbon nanotubes surface of the tube layer.

In any of the foregoing embodiments of the first aspect of the present invention, the carbon nanotube layer may contain carbon nanotubes in an amount of 0.3 g/m ² to 1.6 g/m ² .

In any of the foregoing embodiments of the first aspect of the present invention, the carbon nanotubes may be selected from one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes.

In any of the foregoing embodiments of the first aspect of the present invention, the carbon nanotube layer may further comprise chitosan.

In any of the foregoing embodiments of the first aspect of the present invention, the graphene oxide layer may contain graphene oxide in an amount of 0.05 g/m ² to 1.0 g/m ² .

In any of the foregoing embodiments of the first aspect of the present invention, the pore size of the polymer-based membrane may be 10 nm to 0.8 μm, such as 0.1 μm to 0.5 μm.

A second aspect of the present invention provides a method for preparing a graphite oxide adsorption film, which comprises the following steps:

a) providing an aqueous solution of graphene oxide;

b) providing carbon nanotube suspension;

c) using a filtration method to form a carbon nanotube layer of carbon nanotubes on the surface of the porous polymer base film by the carbon nanotube suspension;

d) using a filtration method to form a graphene oxide layer on the surface of the carbon nanotube layer with the aqueous solution of graphene oxide to obtain a graphene oxide adsorption film.

In any of the preceding embodiments of the second aspect of the present invention, the method may also satisfy one or more of the following:

(1) the concentration of the graphene oxide aqueous solution is 0.01mg/mL～0.5mg/mL;

(2) In the carbon nanotube suspension, the concentration of carbon nanotubes is 0.01 mg/mL to 0.1 mg/mL;

(3) The carbon nanotube suspension further comprises chitosan, wherein the mass ratio of chitosan and carbon nanotubes is 1:0.1-1:1.

In any of the foregoing embodiments of the second aspect of the present invention, in steps c) and d), the filtration method may be a vacuum filtration method.

A third aspect of the present invention provides a water treatment method, which comprises using the graphene oxide adsorption film according to the first aspect of the present invention or the graphene oxide adsorption film prepared by the method according to the second aspect of the present invention to purify water A step of.

In any of the foregoing embodiments of the third aspect of the present invention, the water contains one or more of ionic metals, colloidal metals and organics with a molecular weight of 100-1000.

In any of the aforementioned embodiments of the third aspect of the present invention, in the water purification treatment step, the membrane flux of the graphene oxide adsorption membrane is 100L/m ² /h/bar˜1500L/m ² /h/bar.

Compared with the prior art, the present invention has at least the following advantages:

In the present invention, a carbon nanotube layer and a graphene oxide layer are sequentially formed on the surface of the porous polymer base film, and the obtained graphene oxide adsorption film not only has a larger membrane flux, but also obtains a higher adsorption performance, which includes It has a high rejection rate for metal ions and small organic molecules. Using the graphene oxide adsorption membrane of the present invention for wastewater treatment can obtain higher wastewater treatment efficiency.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings that need to be used in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the drawings without any creative effort.

1 is a statistical diagram of the membrane flux and the rejection rate of metal ions of the graphene oxide adsorption membranes of Example 1 and Comparative Examples 1-1, 1-2, and 1-3.

Fig. 2 is the statistic diagram of membrane flux of the graphene oxide adsorption membranes of Example 2 and Comparative Example 2 and the rejection rate of metal ions.

Detailed ways

In order to make the invention purpose, technical solution and beneficial technical effect of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present invention, not for limiting the present invention.

For the sake of brevity, only some numerical ranges are expressly disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with any other lower limit to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, every point or single value between the endpoints of a range is included within the range, even if not expressly recited. Thus, each point or single value may serve as its own lower or upper limit in combination with any other point or single value or with other lower or upper limits to form a range not expressly recited.

In the description herein, it should be noted that, unless otherwise specified, "above" and "below" are inclusive of the number, "one or more" and "one or more" in "multiple (one)" The meaning is two (a) or more.

The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The following description illustrates exemplary embodiments in more detail. In various places throughout this application, guidance is provided through a series of examples, which examples can be used in various combinations. In various instances, the enumeration is merely a representative group and should not be construed as exhaustive.

Membrane technology is currently the most advanced wastewater treatment technology. Commonly used low-pressure membrane filtration such as ultrafiltration and microfiltration has high interception efficiency for colloids and particulates in wastewater, and has large membrane flux and low energy consumption, but it is not effective for metal ions and small molecular organic compounds (molecular weight 100 ~ 1000). ) has a poor retention effect.

The surface of graphene oxide is rich in oxygen-containing functional groups such as carboxyl and hydroxyl groups, which makes it have very excellent adsorption performance, and can efficiently adsorb and remove various ions, small molecular organic compounds, etc., so it is considered to be the most potential new adsorption material. However, due to the instability of graphene oxide in water and the difficulty of material recovery, its application and development in the field of wastewater treatment are hindered.

The inventor's research has found that if graphene oxide is combined with a membrane to prepare an adsorption membrane material with an adsorption/retention coupling function, it is expected to solve the above-mentioned technical difficulties in the application of graphene oxide in wastewater treatment, and obtain higher metal ions. and retention of small organics.

However, the inventors found that when graphene oxide is compounded on the surface of the microfiltration membrane, the membrane flux of the obtained graphene oxide membrane is too low, usually at the nanofiltration level.

The inventors have further done a lot of research, and unexpectedly found that when a middle interlayer containing carbon nanotubes is arranged between the graphene oxide layer and the base film layer, the membrane flux of the graphene oxide film can be greatly improved At the same time, the advantages of graphene oxide and membrane are coupled, so that high adsorption performance can be achieved while low-pressure, high-flux membrane filtration, including high rejection of metal ions and small organic molecules.

Therefore, an embodiment of the present invention provides a graphene oxide adsorption film, which includes: a porous polymer base film; a carbon nanotube layer disposed on the surface of the polymer base film; a graphene oxide layer disposed on the The surface of the carbon nanotube layer.

Porous polymer-based films are films with porous structures prepared from polymers. There is no particular limitation on the porous polymer-based membrane, which can be a nanofiltration membrane, an ultrafiltration membrane, a microfiltration membrane, etc. known in the art, and those skilled in the art can choose according to actual needs.

In some embodiments, the pore size of the polymer-based membrane may be 10 nm to 0.8 μm. Further, the pore size of the polymer-based membrane may be 10 nm˜100 nm, 0.1 μm˜0.5 μm, or 0.2 μm˜0.5 μm. For example, the pore size of the polymer-based membrane is 0.22 μm, 0.3 μm or 0.45 μm.

In some embodiments, the thickness of the polymer base film may be 50 μm to 500 μm, such as 100 μm to 200 μm.

In some embodiments, the polymer-based membrane can be selected from one or more of cellulose acetate membrane, polyvinylidene fluoride membrane, polytetrafluoroethylene membrane, polypropylene membrane, nylon membrane, and polyethersulfone, or a composite of two or more. membrane.

The carbon nanotube layer can be bound to the surface of the polymer-based film through the interaction between the carbon nanotubes and the polymer-based film (eg, electrostatic force, hydrogen bonding, covalent bonding, etc.).

In some embodiments, the carbon nanotube layer may contain carbon nanotubes in an amount of 0.3 g/m ² to 1.6 g/m ² . Further, the carbon nanotube layer may contain carbon nanotubes in an amount of 0.35g/m ² -1.4g/m ² , 0.4g/m ² -1.2g/m ² , 0.4g/m ² -0.8g/m ² , or 0.5g/m ² to 1g/m ² . The carbon nanotube layer contains an appropriate amount of carbon nanotubes, which not only helps to improve the membrane flux of the graphene oxide adsorption membrane, but also improves the retention rate of metal ions and small organic molecules.

Carbon nanotubes known in the art can be used in the graphene oxide adsorption film of the present invention. In some embodiments, the carbon nanotubes may be selected from one or more of single-wall carbon nanotubes and multi-wall carbon nanotubes, eg, including or multi-wall carbon nanotubes.

In some optional embodiments, the diameter of the carbon nanotubes may be 10 nm˜50 nm, such as 20 nm˜40 nm or 30 nm˜50 nm.

In some optional embodiments, the length of the carbon nanotubes may be 5 μm˜25 μm, such as 10 μm˜20 μm or 8 μm˜15 μm.

In some optional embodiments, the carbon nanotubes are > 95% pure.

In some embodiments, the carbon nanotube layer further comprises chitosan. Chitosan helps to disperse carbon nanotubes and form a carbon nanotube layer with uniform distribution of carbon nanotubes, thereby improving the overall performance of the graphene oxide adsorption film. In addition, chitosan can form strong interactions (such as electrostatic forces, hydrogen bonds, covalent bonds, etc.) with the polymer base film, carbon nanotubes and graphene oxide, which can strengthen the carbon nanotube layer and the polymer base film. The bonding fastness between the carbon nanotube layer and the graphene oxide layer can improve the service life of the graphene oxide adsorption film.

Optionally, in the carbon nanotube layer, the mass ratio M of chitosan and carbon nanotubes may satisfy 0<M≤10:1. For example, M≤5:1, M≤2:1, or M≤1:1.

The graphene oxide layer may be bonded to the surface of the carbon nanotube layer through the interaction between the graphene oxide and the carbon nanotubes (eg, electrostatic force, hydrogen bond, covalent bond, etc.).

In some optional embodiments, the thickness of the graphene oxide layer may be 20 μm˜300 μm, further 50 μm˜200 μm. For example, the thickness of the graphene oxide layer is 60 μm, 80 μm, 100 μm, 120 μm, 150 μm, or the like.

In some embodiments, the graphene oxide layer includes graphene oxide in an amount of 0.05 g/m ² to 1.0 g/m ² . Further, the amount of graphene oxide contained in the graphene oxide layer may be 0.07g/m ² -1.0g/m ² , 0.08g/m ² -0.8g/m ² , or 0.2g/m ² -0.6g/ m ² . The adsorption membrane per unit area contains an appropriate amount of graphene oxide, so that the graphene oxide adsorption membrane can have a larger membrane flux, and at the same time, the adsorption performance of the membrane can be improved, and a higher retention rate of metal ions and small organic molecules can be obtained.

Next, the present invention also provides a preparation method of a graphene oxide adsorption film, and any one of the above graphene oxide adsorption films can be prepared by using the preparation method.

The preparation method of the graphene oxide adsorption film provided by the present invention comprises the following steps:

S10, an aqueous solution of graphene oxide is provided.

In some embodiments, at S10, the concentration of the aqueous solution of graphene oxide may be 0.01 mg/mL to 0.5 mg/mL. For example, the concentration of the aqueous solution of graphene oxide is 0.02 mg/mL, 0.05 mg/mL, 0.08 mg/mL, 0.1 mg/mL, 0.15 mg/mL, 0.2 mg/mL, 0.3 mg/mL or 0.4 mg/mL.

At S10, an aqueous solution of graphene oxide can be prepared by a method known in the art. For example, graphene oxide can be dispersed in water to obtain an aqueous solution of graphene oxide. The aforementioned water may be deionized water. The aforementioned dispersion may be mechanical stirring dispersion (eg, using a high-speed disperser) or ultrasonic dispersion. Preferably, the aforementioned dispersion is ultrasonic dispersion. Wherein, the frequency of the ultrasonic dispersion can be 15kHz˜25kHz, such as 20kHz. The time of ultrasonic dispersion can be 10min-45min. It is preferably 0.2h to 0.5h.

At S10, graphene oxide can be obtained commercially or prepared by methods known in the art, such as Hummers method.

S20, providing a carbon nanotube suspension.

In some embodiments, the concentration of carbon nanotubes in the carbon nanotube suspension may be 0.01 mg/mL to 0.1 mg/mL, such as 0.02 mg/mL, 0.05 mg/mL or 0.08 mg/mL.

In order to form a uniform and stable carbon nanotube suspension, in some embodiments, the carbon nanotube suspension further comprises chitosan. Wherein, the mass ratio of chitosan and carbon nanotubes may be 1:0.1-1:1, such as 1:0.2-1:1.

In some embodiments, the concentration of chitosan in the carbon nanotube suspension may be 0.05 mg/mL to 0.1 mg/mL, such as 0.1 mg/mL.

At S20, the carbon nanotube suspension can be prepared by a method known in the art. For example, carbon nanotubes can be prepared by dispersing in chitosan solution.

As an example, at S20 may include:

S21, dissolving chitosan in an organic acid aqueous solution to obtain a chitosan solution.

The organic acid can be formic acid, acetic acid, benzoic acid, etc., such as acetic acid. The organic acid aqueous solution facilitates the dissolution of the chitosan, which is beneficial to the subsequent uniform and stable dispersion of the carbon nanotubes, and finally obtains a graphene oxide adsorption film in which the carbon nanotubes in the carbon nanotube layer are uniformly distributed.

The concentration of the organic acid aqueous solution may be 0.01 mol/L to 0.05 mol/L, such as 0.02 mol/L to 0.03 mol/L.

In S21, mechanical stirring (eg, using a high-speed disperser) or ultrasonic dispersion can be used to promote the dissolution of chitosan. For example ultrasonic dispersion. Wherein, the frequency of the ultrasonic dispersion can be 15kHz˜25kHz, such as 20kHz.

As an example, chitosan can be added to a 0.02 mol/L acetic acid aqueous solution and dispersed by ultrasonic to obtain a chitosan solution with a concentration of 0.1 mg/mL.

Optionally, the relative molecular mass of chitosan can be 10k˜500k.

S22, dispersing the carbon nanotubes in the chitosan solution to obtain a carbon nanotube suspension.

In some embodiments, mechanical stirring (eg, using a high-speed disperser) or ultrasonic dispersion can be used to promote uniform and stable dispersion of carbon nanotubes. For example ultrasonic dispersion. Wherein, the frequency of the ultrasonic dispersion can be 15kHz˜25kHz, such as 20kHz. The time of ultrasonic dispersion can be 2h-8h, such as 4h-6h.

S30 , a filtration method is used to form a carbon nanotube layer on the surface of the porous polymer base film from the mixed solution containing chitosan and carbon nanotubes.

At S30, specifically, the carbon nanotube suspension is passed through the porous polymer-based membrane, and solids are trapped and deposited on the surface of the polymer-based membrane to form a carbon nanotube layer.

At S30, the carbon nanotube layer may be deposited using a vacuum filtration method. That is, a vacuum is formed on the liquid outflow side of the polymer-based membrane, so that the polymer-based membrane forms a transmembrane pressure difference, and the driving force of the suspension through the polymer-based membrane is increased. In this way, the carbon nanotube layer with the required thickness can be obtained, and the uniformity of distribution of the carbon nanotubes in the carbon nanotube layer can be improved.

The transmembrane pressure difference of the polymer-based membrane may be 0.05 MPa to 0.1 MPa, such as 0.08 MPa to 0.1 MPa.

Optionally, at S30, the carbon nanotube layer may also be dried. The drying temperature may be 25°C to 40°C, such as 30°C to 40°C. The drying time can be more than 2h, such as 2h～5h.

S40 , a filtration method is used to form a graphene oxide layer on the surface of the carbon nanotube layer with an aqueous solution of graphene oxide to obtain a graphene oxide adsorption film.

In S40, specifically, the aqueous solution of graphene oxide is passed through the polymer base film having the carbon nanotube layer, the graphene oxide is trapped and deposited on the surface of the carbon nanotube layer, and after drying, the graphene oxide layer is formed.

At S40, a graphene oxide layer may be deposited using a vacuum filtration method. That is, a vacuum is formed on the liquid outflow side of the polymer-based membrane, so that the polymer-based membrane forms a transmembrane pressure difference, and the driving force of the graphene oxide aqueous solution to pass through the polymer-based membrane is improved. In this way, a graphene oxide layer with a desired thickness can be obtained, and the uniformity of the distribution of the graphene oxide can be improved.

The formed transmembrane pressure difference of the polymer-based membrane may be 0.05 MPa to 0.1 MPa, such as 0.08 MPa to 0.1 MPa.

Optionally, at S40, the graphene oxide layer may also be dried. The drying temperature may be 20°C to 35°C, such as 25°C to 30°C. The drying time can be 0.5h to 5h, such as 1h to 2h.

In S30 and S40, the process of filtration and film formation may be performed by a vacuum filtration device, and the drying may be performed by a drying oven.

It can be understood that the preferred technical features of the graphene oxide adsorption film of the present invention can also be applied to the preparation method of the graphene oxide film of the present invention.

The graphene oxide adsorption membrane of the present invention has the advantages of simple and easy preparation method, green environmental protection, low cost and excellent product performance, and can achieve a relatively high performance in the fields of radioactive waste liquid treatment, industrial waste water treatment, deep purification of drinking water and the like. The processing efficiency has great application potential.

Next, the present invention also provides a water treatment method, which includes the steps of using any one of the graphene oxide adsorption membranes described in the present invention to purify water.

Since the water treatment method of the present invention adopts the graphene oxide adsorption film of the present invention, it has at least corresponding beneficial effects. The water treatment method of the invention can obtain a higher retention rate of metal ions and small molecular organic substances under a larger membrane flux.

In the water treatment method of the present invention, the treated water contains one or more of ionic metals, colloidal metals and small molecular organics.

The ionic metal may be of any kind, and specific examples may include cobalt ion, cesium ion, strontium ion, and the like. Due to the adoption of the adsorption membrane of the present invention, a higher retention rate of metal ions can be achieved. Therefore, the adsorption membrane of the present invention can be used for the treatment of radioactive waste water and obtains better treatment efficiency.

The colloidal metal may be of any kind, and a specific example may include colloidal silver. The adsorption membrane of the present invention can achieve good purification efficiency for the waste liquid containing colloidal nuclides.

The small molecular organic matter is, for example, a small molecular dye, such as methyl orange, rhodamine B, and the like. Due to the adoption of the adsorption membrane of the present invention, a higher retention rate can also be achieved for small molecular organic compounds.

In some embodiments, during water treatment, the membrane flux of the graphene oxide adsorption membrane (the amount of liquid passing through the graphene oxide adsorption membrane at a membrane area of 1 m, within ¹ h, at a pressure differential across the membrane of 1 bar) can be It is 100L/m ² /h/bar～1500L/m ² /h/bar. Further, the membrane flux of the graphene oxide adsorption membrane can be 200L/m ² /h/bar～300L/m ² /h/bar, 400L/m ² /h/bar～600L/m ² /h/bar, 500L/m ² /h/bar～800L/m ² /h/bar, 700L/m ² /h/bar～1000L/m ² /h/bar or 1200L/m ² /h/bar～1500L/m ² / h/bar, etc. The water treatment method of the invention can obtain a higher retention rate of metal ions and small molecular organic substances under a larger membrane flux.

Example

The present disclosure is more specifically described by the following examples, which are for illustrative purposes only, since various modifications and changes within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are on a weight basis, and all reagents used in the examples are either commercially available or synthesized according to conventional methods, and can be directly Used without further processing, and the instruments used in the examples are commercially available.

In the following examples and comparative examples, the Hummers method was used to prepare graphene oxide, and the graphene oxide was vacuum-dried for subsequent use. The preparation of graphene oxide by Hummers method specifically includes the following steps:

Pre-oxidation: 48 mL of concentrated sulfuric acid was added to a round-bottomed flask, followed by 8.0 g of potassium persulfate and 8.0 g of phosphorus pentoxide, and vigorous stirring to obtain a clear solution. The water bath was heated to 80 °C, 4 g of natural graphite powder was added, and the reaction was carried out for 5 h to obtain a black mixture, which was cooled at room temperature overnight. The cellulose acetate filter membrane with a pore size of 0.22 μm was used for suction filtration, washed with deionized water until the filtrate was neutral, and the filter cake was transferred to a glass petri dish and baked at 60 °C for 12 h to obtain a graphite pre-oxidized product.

Reoxidation: place the round-bottomed flask in an ice bath, add 135 mL of concentrated sulfuric acid, and slowly add 3 g of the pre-oxidized product under stirring. Weigh 18.225 g of potassium permanganate, slowly add a small amount of it to the above mixture with stirring, and stir for 40 min. Then add 3 g of sodium nitrate, stir for 25 min, the solution turns black green. The ice bath was removed and the reaction was stirred at 35°C for 2 hours, turning from dark green to brown. 300 mL of deionized water was added, and the reaction was stirred at 5°C for 2 hours. Then add 500 mL of deionized water to dilute, and slowly add H ₂ O ₂ , a large amount of bubbles are generated, the mixed solution turns bright yellow, and it is still cooled.

Dialysis to remove impurity ions: remove the surface water after static, and wash the yellow precipitate to remove ions by dialysis. The final product is freeze-dried to obtain graphene oxide.

Example 1

A certain amount of graphene oxide powder was dissolved in pure water, and ultrasonically dispersed for 0.5 h to prepare a graphene oxide aqueous solution with a concentration of 0.02 mg/mL.

Chitosan was added to the acetic acid aqueous solution with a concentration of 0.02 mol/L, and after ultrasonic dissolution, a chitosan solution with a concentration of 0.1 mg/mL was obtained; a certain amount of multi-walled carbon nanotubes (diameter: 30nm～50nm, length: 10μm～20μm, purity: >95%, purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.), ultrasonically dispersed for 4h～6h to obtain carbon nanotube suspension with a concentration of 0.1mg/mL of carbon nanotubes turbid liquid.

A cellulose acetate microporous membrane with a pore size of 0.45 μm (Beijing Beihua Liming Membrane Separation Technology Co., Ltd., membrane diameter 50 mm, effective diameter 38 mm) was used as the base membrane, and a vacuum filtration device was used under the transmembrane pressure difference of 0.1 MPa. 10 mL of carbon nanotube suspension was passed through the base film, and the carbon nanotubes were uniformly deposited on the surface of the base film, and the corresponding amount of carbon nanotubes was 0.88g/m ² ; after drying at 40°C for 2 hours in a constant temperature drying box, carbon nanotubes were obtained. tube layer. Then, using a vacuum filtration device, 30 mL of the graphene oxide aqueous solution was passed through the base film with the carbon nanotube layer under the transmembrane pressure difference of 0.1 MPa, and the graphene oxide was uniformly deposited on the surface of the carbon nanotube layer, corresponding to the amount of graphene oxide. was 0.53 g/m ² ; after drying at room temperature for 12 h, a graphene oxide layer was obtained, and a graphene oxide adsorption film was made, which was recorded as a CG film.

Comparative Example 1-1

The difference from Example 1 is that the graphene oxide aqueous solution is directly filtered into a film on the cellulose acetate microporous membrane, and the double-layer graphene oxide adsorption film that the graphene oxide layer and the base film are directly compounded is prepared, which is denoted as G. membrane.

Comparative Example 1-2

Different from Example 1, a chitosan interlayer was formed on the cellulose acetate microporous filter membrane, and then the graphene oxide aqueous solution was filtered to form a film to prepare a composite of the graphene oxide layer, the chitosan interlayer and the base film. layer graphene oxide adsorption film, denoted as NG film.

Comparative Examples 1-3

The difference from Example 1 is that after the graphene oxide aqueous solution and the carbon nanotube suspension are mixed, the cellulose acetate microporous membrane is filtered to form a film to obtain graphene oxide/carbon nanotubes/chitosan carbon nanometers. The double-layer graphene oxide adsorption film composited with the tube layer and the base film is denoted as CNG film.

The pure water fluxes of the two graphene oxide adsorption membranes of Example 1 and Comparative Examples 1-1, 1-2, and 1-3 were tested respectively, and their interception effects on ions Cs ⁺ , Co ²⁺ and Sr ²⁺ , The results are shown in Figure 1. The pure water flux of the CG membrane is 230L/m ² /h/bar, while the pure water flux of the G membrane is only 30L/m ² /h/bar, and the pure water flux of the NG membrane is only 35L/m ² / The pure water flux of h/bar and CNG membrane is only 32L/m ² /h/bar. The pure water flux of the CG membrane was 6.7 times higher than that of the G membrane. The initial concentrations of the three nuclide ions in the aqueous solution were all 0.1 mol/L, and the flux of the CG membrane was 150 L/m ² /h/bar. The rejection rates of the adsorption membrane for the three kinds of nuclide ions can be seen. The rejection rates of the CG membrane for the three kinds of nuclide ions of Co, Sr and Cs are 72%, 63% and 58%, respectively, which are higher than those of the G membrane, NG membrane and CNG membrane. The retention rate of the membrane for three kinds of nuclide ions, and the membrane flux of the CG membrane increased significantly.

Example 2

The difference from Example 1 is that the concentration of the graphene oxide aqueous solution is 0.01 mg/mL; the carbon nanotube concentration of the carbon nanotube suspension is 0.02 mg/mL; the carbon nanotube suspension used for preparing the carbon nanotube layer is The amount of carbon nanotubes is 30 mL, and the corresponding amount of carbon nanotubes is 0.53 g/m ² ; the amount of graphene oxide solution used for preparing the graphene oxide layer is 10 mL, and the corresponding amount of graphene oxide is 0.09 g/m ² . The corresponding graphene oxide adsorption film was obtained, denoted as CG film.

Comparative Example 2

The difference from Example 2 is that the graphene oxide aqueous solution is directly filtered to form a film on the cellulose acetate microporous membrane to prepare a graphene oxide adsorption film in which the graphene oxide layer and the base film are directly compounded, which is denoted as G film.

Test the pure water flux of two kinds of graphene oxide adsorption membranes of Example 2 and Comparative Example 2 respectively, and their adsorption and retention effects on two kinds of small molecule dyes (methyl orange and rhodamine B), the results are shown in Figure 2 . The pure water flux of the CG membrane is 1200-1500 L/m ² /h/bar, while the pure water flux of the G membrane is 400-600 L/m ² /h/bar. The pure water flux of the former is 2 to 3 times that of the latter. The initial concentrations of methyl orange and rhodamine B in the aqueous solution were 5.2 mg/L and 5.4 mg/L, respectively, and the CG membrane fluxes were 1300 L/m ² /h/bar and 1400 L/m ² /h/bar, respectively. The rejection rates of CG membrane for rhodamine B and methyl orange were 94% and 96%, respectively, and the rejection rates for G membrane for rhodamine B and methyl orange were 80% and 90%, respectively. This shows that the flux of CG membrane is significantly higher than that of G membrane, and at the same time, it also has a higher rejection rate for small molecular organics.

Example 3

Different from Example 1, the concentration of the graphene oxide aqueous solution is 0.01 mg/mL; the carbon nanotube concentration of the carbon nanotube suspension is 0.05 mg/mL; the carbon nanotube suspension used for preparing the carbon nanotube layer is The amount of carbon nanotubes is 20 mL, and the corresponding amount of carbon nanotubes is 0.88 g/m ² ; the amount of graphene oxide solution used for preparing the graphene oxide layer is 30 mL, and the corresponding amount of graphene oxide is 0.26 g/m ² . The corresponding graphene oxide adsorption film was obtained, denoted as CG film.

Comparative Example 3

The difference from Example 3 is that the graphene oxide aqueous solution is directly filtered to form a film on the cellulose acetate microporous membrane to prepare a graphene oxide adsorption film in which the graphene oxide layer and the base film are directly compounded, which is denoted as G film.

The pure water flux of the two graphene oxide adsorption membranes in Example 3 and Comparative Example 3 and their adsorption and retention effects on the colloidal nuclide Ag were tested respectively. The pure water flux of the CG membrane is 480-530 L/m ² /h/bar, and the pure water flux of the G membrane is 55-70 L/m ² /h/bar. The pure water flux of the former is about 8 times that of the latter. The initial concentration of colloidal nuclide Ag in the aqueous solution was 5 mg/L, and the CG membrane flux was 400 L/m ² /h/bar. The rejection rates of colloidal silver by CG membrane and G membrane were both above 90%, while the membrane flux of CG membrane was significantly increased.

As can be seen from the above test results, the present invention forms a carbon nanotube layer and a graphene oxide layer successively on the surface of the porous polymer base film, and the obtained graphene oxide adsorption film not only has a larger membrane flux, but also has a strong effect on metal ions and Small molecule organics have a higher retention rate.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited to this. Any person skilled in the art can easily think of various equivalents within the technical scope disclosed by the present invention. Modifications or substitutions should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (12)

1. A graphene oxide adsorption film comprising:

a porous polymer-based membrane;

the carbon nanotube layer is arranged on the surface of the polymer-based film;

and the graphene oxide layer is arranged on the surface of the carbon nano tube layer.

2. The graphene oxide adsorption film according to claim 1, wherein the carbon nanotube layer comprises carbon nanotubes in an amount of 0.3g/m²～1.6g/m²。

3. The graphene oxide adsorption film of claim 1, wherein the carbon nanotubes are selected from one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes.

4. The graphene oxide adsorption film according to claim 1, wherein the carbon nanotube layer further comprises chitosan.

5. The graphene oxide adsorption film according to claim 1, wherein the graphene oxide layer contains graphene oxide in an amount of 0.05g/m²～1.0g/m²。

6. The graphene oxide adsorption film according to claim 1, wherein the pore size of the polymer-based film is 10nm to 0.8 μm.

7. A preparation method of a graphite oxide adsorption film comprises the following steps:

a) providing an aqueous solution of graphene oxide;

b) providing a carbon nanotube suspension;

c) forming a carbon nanotube layer on the surface of the porous polymer base membrane by using the carbon nanotube suspension by adopting a filtration method;

d) and forming a graphene oxide layer on the surface of the carbon nanotube layer by using the water solution of the graphene oxide by using a filtration method to obtain the graphene oxide adsorption film.

8. The method of claim 7, wherein the method further satisfies one or more of the following:

(1) the concentration of the aqueous solution of the graphene oxide is 0.01 mg/mL-0.5 mg/mL;

(2) in the carbon nano tube suspension, the concentration of the carbon nano tube is 0.01 mg/mL-0.1 mg/mL;

(3) the carbon nanotube suspension also comprises chitosan, wherein the mass ratio of the chitosan to the carbon nanotube is 1: 0.1-1: 1.

9. The method of claim 7, wherein in steps c) and d), the filtration process is a vacuum filtration process.

10. A water treatment method comprising a step of purifying water by using the graphene oxide adsorption membrane according to any one of claims 1 to 6 or the graphene oxide adsorption membrane prepared by the method according to any one of claims 7 to 9.

11. The method according to claim 10, wherein the water contains one or more of an ionic metal, a colloidal metal and an organic substance having a molecular weight of 100 to 1000.

12. The method according to claim 10 or 11, wherein in the water purification treatment step, the membrane flux of the graphene oxide adsorption membrane is 100L/m²/h/bar～1500L/m²/h/bar。

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