Preparation method and application method of graphene oxide/carbon nanotube asymmetric separation membrane

A technology of carbon nanotubes and application methods, which is applied in the field of membrane separation water treatment, can solve the problems of membrane water permeability limitation, reduction of graphene oxide oxygen-containing functional groups, reduction of interception performance, etc., to achieve enhanced ion interception performance and enhanced ion partitioning effect , The effect of ion retention improvement

Active Publication Date: 2021-03-16

DALIAN UNIV OF TECH

15 Cites 0 Cited by

AI-Extracted Technical Summary

Problems solved by technology

However, due to the reduction of the distance between the membrane layers, the water permeability of the membrane will be greatly limited.

In addition, reduction and crosslinkin...

Abstract

The invention belongs to the technical field of membrane separation water treatment, and provides a preparation method and an application method of a graphene oxide/carbon nanotube asymmetric separation membrane. The preparation method comprises the following steps: subjecting acidified carbon nanotubes to vacuum filtration onto a support membrane substrate to form a carbon nanotube layer of the separation membrane; and then preparing a mixed solution of graphene oxide, diamine and polyelectrolyte, and subjecting the mixed solution to vacuum filtration on to the carbon nanotube layer so as toform the graphene oxide/carbon nanotube asymmetric separation membrane. The application method comprises the following steps: taking the carbon nanotube layer of the graphene oxide/carbon nanotube asymmetric separation membrane as a working electrode, applying a voltage, enabling a graphene oxide layer to be positioned between the working electrode and a counter electrode, and performing electricfield assisted membrane filtration by adopting a cross-flow filtration mode. The preparation method provided by the invention is simple and easy to operate, and expensive raw materials and equipment are not needed; and water flux and ion interception performance can be improved at the same time under the auxiliary effect of an electric field.

Application Domain

Semi-permeable membranes

Technology Topic

DiamineChemistry +7

Image

Examples

Experimental program(3)

Example Embodiment

[0039] Example 1:

[0040] The invention provides a preparation method of a graphene oxide/carbon nanotube asymmetric separation membrane, which is specifically implemented according to the following steps:

[0041] (1) Use a mixed acid solution of 70wt.% concentrated nitric acid and concentrated sulfuric acid with v/v of 1:3 to acidify carbon nanotubes with an outer diameter of 10-20 nm, and oxidize at 80°C for 1 h to obtain acidified carbon nanotubes Tube. The acidified carbon nanotubes were then placed in high-purity water, dispersed uniformly by ultrasonic, and prepared to a concentration of 0.2 mg mL. -1 of carbon nanotube dispersions. Subsequently, 40 mL of the carbon nanotube dispersion liquid was suction filtered onto the polyvinylidene fluoride microfiltration membrane substrate through a vacuum filtration device, and dried at 60 °C for 2 h to form a carbon nanotube layer;

[0042] (2) Using 8000 mesh graphite powder to prepare graphene oxide by Hummers method, and uniformly dispersing graphene oxide into high-purity water by ultrasonic wave to form 0.05 mg mL -1 Graphene oxide dispersion liquid, then, get a certain amount of ethylenediamine and dissolve in high-purity water, prepare ethylenediamine solution, the concentration of described ethylenediamine solution is 20mg L -1 , and then add a certain amount of polystyrene sulfonic acid to it, so that the content of polystyrene sulfonic acid in the mixed solution is 0.2wt.%;

[0043] (3) the graphene oxide dispersion liquid prepared in the step (2) of 10mL is evenly mixed with the mixed solution of ethylenediamine and polystyrene sulfonic acid of 10mL, and the mixed solution is filtered to the step by vacuum filtration device The carbon nanotube layer prepared in (1) was dried at 60° C. for 2 h to obtain a graphene oxide/carbon nanotube asymmetric separation membrane. The surface of the graphene oxide layer of the graphene oxide/carbon nanotube asymmetric separation membrane prepared by this implementation step is negatively charged, and its thickness is 0.4 μm, and the thickness of the carbon nanotube layer is 1.5 μm.

[0044] The present invention also provides an application method of a graphene oxide/carbon nanotube asymmetric separation membrane, which is specifically implemented according to the following steps:

[0045] (1) The graphene oxide/carbon nanotube asymmetric separation membrane is sealed in the membrane module, the carbon nanotube layer of the separation membrane is used as the working cathode, and a titanium mesh is placed parallel to the membrane on the stock solution side as the counter electrode. The electrode spacing is 0.8mm, the graphene oxide layer of the separation membrane is between the working electrode and the counter electrode, and the working electrode and the counter electrode are connected to the DC voltage stabilized power supply through a titanium wire;

[0046] (2) Place the membrane module in the membrane filtration device, apply a voltage through the power supply, adopt a cross-flow filtration method, use a 2mM NaCl solution as the stock solution to be treated, and pass through the graphene oxide/carbon under the action of a transmembrane pressure difference of 1bar. Nanotube asymmetric separation membrane to realize electric field-assisted membrane filtration process. When the applied voltage is 0V, the bias voltage on the working electrode is 0V vs. SCE, and the water flux is 9.1L m -2 h -1 , the NaCl rejection was 52.4%; when the applied voltage was 3.0V, the bias voltage on the working electrode was -1.32V vs. SCE, and the water flux increased to 17.4L m -2 h -1 , while the NaCl rejection increased to 78.3%.

Example Embodiment

[0047] Embodiment 2:

[0048] The invention provides a preparation method of a graphene oxide/carbon nanotube asymmetric separation membrane, which is specifically implemented according to the following steps:

[0049] (1) Use a mixed acid solution of 70wt.% concentrated nitric acid and concentrated sulfuric acid with a v/v of 1:3 to acidify carbon nanotubes with an outer diameter of 8-15nm, and oxidize at 60°C for 2h to obtain acidified carbon nanotubes Tube. The acidified carbon nanotubes were then placed in high-purity water, dispersed uniformly by ultrasonic, and prepared to a concentration of 0.2 mg mL. -1 of carbon nanotube dispersions. Subsequently, 50 mL of the carbon nanotube dispersion liquid was suction filtered onto the polyethersulfone ultrafiltration membrane substrate through a vacuum filtration device, and dried at 80 °C for 2 h to form a carbon nanotube layer;

[0050] (2) Using 2000 mesh graphite powder to prepare graphene oxide by Hummers method, and uniformly dispersing graphene oxide into high-purity water by ultrasonic wave to form 0.05 mg mL -1 Graphene oxide dispersion liquid, subsequently, get a certain amount of m-phenylenediamine and dissolve in high-purity water, prepare m-phenylenediamine solution, the concentration of described m-phenylenediamine solution is 10mg L -1 , and then add a certain amount of polyacrylic acid to it, so that the content of polyacrylic acid in the mixed solution is 0.1wt.%;

[0051] (3) the graphene oxide dispersion liquid prepared in the step (2) of 15mL is uniformly mixed with the mixed solution of m-phenylenediamine and polyacrylic acid of 15mL, and the mixed solution is filtered to step (1) by vacuum filtration device ) on the carbon nanotube layer prepared in ), and dried at 50 °C for 4 h to obtain a graphene oxide/carbon nanotube asymmetric separation membrane. The surface of the graphene oxide layer of the graphene oxide/carbon nanotube asymmetric separation membrane prepared by this implementation step is negatively charged, and its thickness is 0.6 μm, and the thickness of the carbon nanotube layer is 1.8 μm.

[0052] The present invention also provides an application method of a graphene oxide/carbon nanotube asymmetric separation membrane, which is specifically implemented according to the following steps:

[0053] (1) The graphene oxide/carbon nanotube asymmetric separation membrane is sealed in the membrane module, the carbon nanotube layer of the separation membrane is used as the working cathode, and a titanium sheet is placed parallel to the membrane on the stock solution side as the counter electrode. The electrode spacing is 1.5mm, the graphene oxide layer of the separation membrane is between the working electrode and the counter electrode, and the working electrode and the counter electrode are connected to the DC voltage stabilized power supply through copper wires;

[0054] (2) place the membrane module in the membrane filtration device, apply a voltage through the power supply, adopt a cross-flow filtration method, use a 5mM NaCl solution as the stock solution to be treated, and pass through the graphene oxide/ The carbon nanotube asymmetric separation membrane realizes the electric field-assisted membrane filtration process. When the applied voltage is 0V, the bias voltage on the working electrode is 0V vs. SCE, and the water flux is 7.2L m -2 h -1 , the NaCl rejection rate is 44.7%; when the applied voltage is 2.5V, the bias voltage on the working electrode is -1.18V vs. SCE, and the water flux increases to 13.8L m -2 h -1 , while the NaCl rejection increased to 68.1%.

Example Embodiment

[0055] Embodiment three:

[0056] The invention provides a preparation method of a graphene oxide/carbon nanotube asymmetric separation membrane, which is specifically implemented according to the following steps:

[0057] (1) Using a mixed acid solution of 70wt.% concentrated nitric acid and concentrated sulfuric acid with a v/v of 1:3 to acidify carbon nanotubes with an outer diameter of 20-40nm, and oxidize at 100°C for 0.5h to obtain acidified carbon nanotube. The acidified carbon nanotubes were then placed in high-purity water, dispersed uniformly by ultrasonic, and prepared to a concentration of 0.2 mg mL. -1 of carbon nanotube dispersions. Subsequently, 60 mL of the carbon nanotube dispersion liquid was suction filtered onto the cellulose acetate microfiltration membrane substrate through a vacuum filtration device, and dried at 80 °C for 2 h to form a carbon nanotube layer;

[0058] (2) Using 325 mesh graphite powder to prepare graphene oxide by Hummers method, and uniformly dispersing graphene oxide into high-purity water by ultrasonic wave to form 0.05 mg mL -1 Graphene oxide dispersion liquid, subsequently, get a certain amount of p-phenylenediamine and dissolve in high-purity water, prepare p-phenylenediamine solution, the concentration of described p-phenylenediamine solution is 50mg L -1 , and then add a certain amount of poly(acrylamine hydrochloride) to it, so that the content of poly(acrylamine hydrochloride) in the mixed solution is 0.5wt.%;

[0059] (3) the graphene oxide dispersion liquid prepared in the step (2) of 15mL is uniformly mixed with the mixed solution of p-phenylenediamine and poly(acrylamine hydrochloride) of 15mL, and the mixed solution is passed through the vacuum filtration device Suction filtration onto the carbon nanotube layer prepared in step (1), and drying at 60° C. for 4 hours to obtain a graphene oxide/carbon nanotube asymmetric separation membrane. The surface of the graphene oxide layer of the graphene oxide/carbon nanotube asymmetric separation membrane prepared by this implementation step is positively charged, and its thickness is 0.5 μm, and the thickness of the carbon nanotube layer is 2.3 μm.

[0060] The present invention also provides an application method of a graphene oxide/carbon nanotube asymmetric separation membrane, which is specifically implemented according to the following steps:

[0061] (1) The graphene oxide/carbon nanotube asymmetric separation membrane is sealed in the membrane module, the carbon nanotube layer of the separation membrane is used as the working cathode, and a stainless steel sheet is placed parallel to the membrane on the stock solution side as the counter electrode. The electrode spacing is 0.5mm, the graphene oxide layer of the separation membrane is between the working electrode and the counter electrode, and the working electrode and the counter electrode are connected to the DC voltage stabilized power supply through a stainless steel wire;

[0062] (2) Place the membrane module in the membrane filtration device, apply a voltage through the power supply, adopt a cross-flow filtration method, use a 2mM NaCl solution as the stock solution to be treated, and pass through the graphene oxide/ The carbon nanotube asymmetric separation membrane realizes the electric field-assisted membrane filtration process. When the applied voltage is 0V, the bias voltage on the working electrode is 0V vs. SCE, and the water flux is 6.8L m -2 h -1 , the NaCl rejection rate is 48.8%; when the applied voltage is 2.0V, the bias voltage on the working electrode is +1.04Vvs.SCE, and the water flux increases to 12.8L m -2 h -1 , while the NaCl rejection rate increased to 75.6%.

PUM

Property	Measurement	Unit
Thickness	0.1 ~ 1.0	µm
Thickness	0.5 ~ 5.0	µm
Thickness	0.4	µm

Description & Claims & Application Information

We can also present the details of the Description, Claims and Application information to help users get a comprehensive understanding of the technical details of the patent, such as background art, summary of invention, brief description of drawings, description of embodiments, and other original content. On the other hand, users can also determine the specific scope of protection of the technology through the list of claims; as well as understand the changes in the life cycle of the technology with the presentation of the patent timeline. Login to view more.

Classification and recommendation of technical efficacy words

Increase water flux

Method for performing fast in-situ conversion on microfiltration or ultrafiltration membrane into nanofiltration membrane

ActiveCN106621831Alow operating pressureIncrease water flux

Owner:RES CENT FOR ECO ENVIRONMENTAL SCI THE CHINESE ACAD OF SCI

Preparation method and application method of graphene oxide/carbon nanotube asymmetric separation membrane

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

Similar technology patents

Black talc nano particle modified polyamide composite nano-filtration membrane

Regenerated cellulose ultrafiltration membrane and preparation method thereof

High-performance tantalum disulfide two-dimensional layered film as well as preparation method and application thereof

Application of graphene oxide nanofiltration membrane under high operation pressure

Preparation method of arginine modified composite nanofiltration membrane

Classification and recommendation of technical efficacy words

Method for preparing hydrophilic anti-pollution reverse osmosis membrane

Graft-modified macromolecular filter membrane for water treatment and method for preparing same

High-throughput polyamide reverse osmosis composite membrane

Modifying method for polyamide film composite film, polyamide film composite film and application thereof

Method for performing fast in-situ conversion on microfiltration or ultrafiltration membrane into nanofiltration membrane