KR20190094919A - Highly electrically conductive flat-type membrane using carbon-based nanomaterials, preparation method of thereof and operating methods of electro-oxidation reactor using the same - Google Patents

Abstract

The present invention relates to a membrane structure in a form of a pouch having an open top and a space therein, comprising a metal support and a carbon material. The metal support is formed of a metal plate of a mesh structure, has an open top, and has a pouch shape having a space therein. The carbon material is entangled to from a three-dimensional network structure. A part of the network structure is entangled with the mesh structure of the metal support.

Description

Highly conductive conductive flat-type membrane using carbon-based nanomaterials, preparation method of honey and operating methods of electro-oxidation reactor using the same}

The present invention relates to a membrane structure, a method for manufacturing the same, and a method of using the same for water treatment, and more particularly, a conductive plate designed to simultaneously perform a role of an electrode of an electrochemical oxidation process and a membrane of a membrane filtration process in a water treatment process. The present invention relates to a membrane structure using a carbon-based nanomaterial, a method for preparing the same, and a method of operating an electrooxidation reactor using the same.

Due to the recent inflow of hardly degradable pollutants into the water system, it is very difficult to decompose by conventional treatment. Therefore, various advanced oxidation processes have been developed to solve this problem. The electrochemical advanced oxidation treatment process consists of an anode and a cathode, and has attracted attention as a treatment method for micro-pollutants in water due to the advantages of simple operation and high removal efficiency.

In the electrochemical advanced oxidation process, the characteristics of the electrode are the most important because pollutants are oxidized on the surface of the anode by an external voltage difference. Until now, research has focused on oxides of precious metals as electrode materials. However, considering the electrochemical stability, durability, and environmental aspects, there is a need for a substitute material, and the treatment efficiency decreases with time because of the slow diffusion rate of water contaminants to be treated with the electrode material onto the electrode surface. In addition, the fundamental limitation of the need for additional separation of influent and treated water remains a challenge to be solved.

Membrane-based water treatment technology (membrane filtration technology) has advantages such as high treatment water quality and low energy consumption, leading the current water treatment technology together with the electrochemical advanced oxidation treatment process. Membrane filtration refers to a physical removal process in which specific contaminants are removed by adsorption or filtration using a membrane having selective permeability.

 However, membranes applied to the membrane filtration process up to now have limitations in terms of application range and membrane fouling cleaning method due to the characteristics of the polymer, and performance and energy in that the energy efficiency of the polymer-based membrane process has reached a critical point. The importance of developing new water treatment membranes to innovatively improve efficiency has recently been highlighted.

Recently, to solve this problem, studies on composite membranes incorporating carbon-based materials to improve the water permeation / salt removal performance as well as durability and functionality have been actively conducted. Carbon-based nanomaterials, such as graphene and carbon nanotubes, have proven their potential as a new concept membrane material as well as electrode materials due to their excellent specific surface area, high strength and electrical conductivity, and their versatility showing their structural and physical properties. It became. In particular, the high water permeability due to the movement of frictionless water through the pores in the graphene and carbon nanotube structure has shown the advantages of high contamination removal and anti-fouling.

The problem to be solved by the present invention is to provide a highly conductive membrane structure that can be used simultaneously as the anode of the electrochemical oxidation process and the membrane of the membrane filtration process.

Another object of the present invention is to provide a method for producing the membrane structure.

Another object of the present invention is to provide a water treatment method using a new electrooxidation reactor including the membrane structure.

In order to solve the above problems, the present invention is a pouch-type film structure having a top and open space therein, comprising a metal support and a carbon material,

The metal support is composed of a metal plate of a mesh structure, the top is open, is in the form of a pouch having a space therein,

The carbon material is entangled with each other to form a three-dimensional network structure, and part of the network structure provides a membrane structure, which is intertwined with the mesh structure of the metal support.

According to the present invention, the conductive carbon membrane structure for water treatment may simultaneously perform the role of the anode of the electrochemical oxidation process and the membrane of the membrane filtration process in the water treatment process.

According to the present invention, the pore size of the mesh structure of the metal support may be 0.01 to 1.5 mm.

According to the present invention, the membrane structure may have a specific surface area of 30 to 500 m ² / g.

According to the present invention, the membrane structure may have a plurality of pores having a size of 1 to 100 nm.

According to the present invention, the membrane structure includes a plurality of micropores and mesopores, and the volume of the micropores is 1.00 × 10 ⁻³ to 50.00 × 10 ⁻³ cm ³ / g, and the volume of the meso pores is 0.01 to 0.50. cm ³ / g.

According to the present invention, the metal plate of the mesh structure may be composed of one or more selected from the group consisting of stainless steel, copper, nickel, zinc, chromium, zirconium and iron.

According to the present invention, the carbon material may be selected from the group consisting of graphene, carbon nanotubes, carbon nanowires, and carbon fibers.

In addition, the present invention comprises the steps of: a) processing the metal plate of the mesh structure to form a pouch-shaped metal support having an open top and an inner space;

b) inserting a combustible material in the form of a film into the interior space of the metal support;

c) treating the solution in which the carbon material is dispersed in the metal support into which the combustible material is inserted, so that the carbon material is entangled with each other to form a three-dimensional network structure, wherein a part of the formed network structure is entangled with the mesh structure of the metal support, Adhering the carbon material to the metal support; And

and d) removing the combustible material by heat treatment.

According to the present invention, the adhesion of step c) may be performed by one or more methods selected from spin coating, dip coating and spray coating.

According to the present invention, the step c) may be to adhere the carbon material to the metal support by immersing the metal support in which the combustible material is inserted in a solution in which the carbon material is dispersed.

According to the present invention, the steps a) to d) may be sequentially performed 1 to 20 times in order to increase the thickness of the carbon material adhered to the metal support.

According to the present invention, the pore size of the mesh structure of the metal support may be 0.01 to 1.5 mm.

According to the present invention, the combustible material may be at least one member selected from the group consisting of polyvinyl chloride, polystyrene, polyethylene, and polymethyl methacrylate.

According to the present invention, the carbon material may be selected from the group consisting of graphene, carbon nanotubes, carbon nanowires, and carbon fibers.

In addition, the carbon material may be attached to the metal nanoparticles to achieve a specific purpose (for example, increased reactivity). The metal nanoparticles are not particularly limited and may be, for example, titanium dioxide.

According to the present invention, the carbon structure and the metal support may be bonded by the heat treatment.

In addition, the present invention provides a novel electrooxidation tank using the membrane structure as an anode of an electrochemical oxidation process and a separation membrane of a membrane filtration process, and a water treatment method using the same.

The membrane structure according to the present invention has a high specific surface area, a metal support of a mesh structure serves as a current collector, and a three-dimensional network structure in which carbon materials are entangled with each other exhibits conductivity. And at the same time as the membrane of the membrane filtration process. In addition, the membrane structure of the present invention can minimize the resistance between the current collector and the electroactive material due to the above-described structural characteristics. Therefore, the problem of reduction of oxidation efficiency due to diffusion is improved compared to the water treatment membrane according to the prior art, the speed at which the organic material in the contaminated water moves to the membrane structure of the present invention is improved, and the water permeation performance and salt removal performance are excellent. There is no need for separation process, and it is industrially advantageous because of its excellent mechanical strength and electrical properties.

1 is a schematic view showing a method of manufacturing a membrane structure according to an embodiment of the present invention.
2 is a block diagram of a film structure according to an embodiment of the present invention and an image taken by a scanning electron microscope.
Figure 3a is an image of the metal support prepared in one embodiment of the present invention, Figure 3b is a membrane structure prepared in accordance with an embodiment of the present invention, Figure 3c is a planar carbon nanotube electrode according to the prior art.
Figure 4 shows a schematic view of the water treatment process using a comparative example (electrochemical oxidation process) and one embodiment of the present invention.
5 is a result of confirming the treatment efficiency of water contaminants using a comparative example (electrochemical oxidation process) and one embodiment of the present invention.
6 is a schematic diagram showing an electrooxidation reactor for water treatment according to another embodiment of the present invention.

The present invention provides a membrane structure designed to maximize the characteristics such as high specific surface area, porosity, and electrical conductivity of carbon-based nanomaterials to simultaneously serve as the anode of the electrochemical oxidation process and the membrane of the membrane filtration process. It was developed to complete the present invention.

The membrane structure according to the present invention solves the problem of reduction of oxidation efficiency by diffusion, which is a problem of the conventional electrooxidation process. In addition, it can perform the role of the anode of the electrochemical oxidation process and the membrane of the membrane filtration process at the same time, it is possible to perform the filtration process without a separate separation process, and improved water permeation performance and salt removal performance compared to the prior art The efficiency of the membrane filtration process is excellent.

Hereinafter, the present invention will be described in more detail.

The present invention is a pouch-type membrane structure having a top and an interior therein, comprising a metal support and a carbon material,

The metal support is composed of a metal plate of a mesh structure, the top is open, is in the form of a pouch having a space therein,

The carbon material is entangled with each other to form a three-dimensional network structure, and part of the network structure provides a membrane structure, which is intertwined with the mesh structure of the metal support.

According to the present invention, the membrane structure may simultaneously serve as an anode of the electrochemical oxidation process and a separator of the membrane filtration process in the water treatment process.

According to the present invention, the pore size of the mesh structure of the metal support may be 0.01 to 1.5 mm. If the pore size is less than the above range, the membrane filtration efficiency may be low. If the pore size exceeds the above range, the current collecting rate may be lowered.

According to the present invention, the film structure may have a specific surface area of 30 to 500 m ² / g, but is not limited thereto, and may preferably be 50 to 100 m ² / g. If the specific surface area is less than 50 m ² / g, the permeation performance may be lowered, and if it exceeds 500 m ² / g, the removal performance of the contaminants may be lowered.

According to the present invention, the membrane structure may have a plurality of pores having a size of 1 to 100 nm. If the pore size is less than the above range, the movement speed of the treated water may be low, and the efficiency of water treatment may be lowered.

According to the present invention, the membrane structure includes a plurality of micropores and mesopores, and the volume of the micropores is 1.00 × 10 ⁻³ to 50.00 × 10 ⁻³ cm ³ / g, and the volume of the meso pores is 0.01 to 0.50. cm ³ / g.

In the present invention, since the organic material in the contaminated water can be improved to move to the membrane structure, the water treatment efficiency and performance can be improved through the micropores and mesopores smaller than the membrane structure according to the prior art.

According to the present invention, the metal support may serve as a current collector.

According to the present invention, the metal plate of the mesh structure may be composed of one or more selected from the group consisting of stainless steel, copper, nickel, zinc, chromium, zirconium and iron, but is not limited thereto. You can use whatever you can.

In the present invention, the carbon material may be a carbon-based nanomaterial, for example, may be selected from the group consisting of graphene, carbon nanotubes, carbon nanowires and carbon fibers, but is not limited thereto. In general, any carbon material used in water treatment can be used. In addition, the carbon material may be nanoparticles attached to the carbon for a specific purpose or to increase the reactivity. The nanoparticles may be, for example, titanium dioxide, but are not limited thereto, and any nanoparticles may be used as long as they meet the desired purpose.

The form of the carbon material is not particularly limited, and may be, for example, tubular, branched, plate-shaped, or a combination thereof. The carbon material is entangled with each other to form a porous three-dimensional network structure, and the mesh structure of the metal support is also entangled with each other to form an integrated pouch form.

The membrane structure is a structure in which a metal support serves as a current collector and a resistance value of a carbon material, which is an electroactive material, can be minimized. Such a structure can oxidize the contaminants on the surface and filter the water through the pores, so that the contaminants can quickly move to the membrane structure, thereby improving the treatment efficiency and processing speed of the contaminants.

On the other hand, the present invention

a) processing a metal plate of a mesh structure to produce a pouch-shaped metal support having an open top and having an inner space;

b) inserting a combustible material in the form of a film into the interior space of the metal support;

c) treating the solution in which the carbon material is dispersed in the metal support into which the combustible material is inserted, so that the carbon material is entangled with each other to form a three-dimensional network structure, wherein a part of the formed network structure is entangled with the mesh structure of the metal support, Adhering the carbon material to the metal support; And

and d) removing the combustible material by heat treatment.

According to the present invention, the pouch-shaped metal support of step a) may be a form into which a structure can be inserted, such as, for example, an envelope, and preferably a form designed to insert a structure into a film form. Can be.

The combustible material in the form of a film to be inserted into the metal support may be easily inserted into the inside of the metal support, preferably less than the volume of the internal space of the metal support or 1/3 or more of the internal space volume, The thickness of the combustible material may be adjusted according to the thickness of the membrane structure. If the thickness of the combustible material exceeds the above range, it cannot be inserted into the metal support, and it is difficult to bond the carbon material to the mesh structure of the metal support, resulting in a film structure in which the 'metal support-carbon material' is integrated. it's difficult.

According to the present invention, the combustible material of step b) may be of a property that is easily removed through heat treatment, preferably a combustible polymer, and more preferably polyvinyl chloride, polystyrene, polyethylene and polymethylmethacrylate. It may be one or more selected from the group consisting of.

According to the present invention, the carbon material in step c) may be dispersed in an organic solvent or an aqueous solvent. The organic solvent is not particularly limited as long as it is used to disperse the carbon material in the technical field to which the present invention belongs, and preferably isopropyl acetate or N-methyl-2-pyrrolidone may be used.

According to the present invention, a binder may be further added in step c) to improve the dispersibility of the carbon material and to easily adhere to the metal support. The binder may be preferably polyvinyl alcohol or polyvinyl butyral, but is not limited thereto.

According to the present invention, the adhesion of step c) may be performed by one or more methods selected from spin coating, dip coating, and spray coating, and preferably, may be dip coating, and specifically, a flammable material may be inserted. The metal support may be immersed in a solution in which the carbon material is dispersed, thereby adhering the carbon material to the metal support.

According to the present invention, for the purpose of increasing the thickness of the carbon material adhered to the metal support, the steps a) to d) may be sequentially performed 1 to 20 times. It may further comprise the step of drying in the repeating process.

Next, heat treatment is performed to selectively remove the combustible material.

Through the above process, the upper part is opened and a pouch-shaped film structure having an inner space of uniform thickness is formed.

The membrane structure has the structure and properties as described above.

The present invention also provides a method for operating an electrooxidation reactor for water treatment using the membrane structure as an anode of an electrochemical oxidation process and a separator of a membrane filtration process.

Electrochemical reaction tank for water treatment according to the present invention is a container; It consists of an anode and a cathode.

The anode may be in a position facing the cathode, or the cathode may be shaped to surround the anode. At this time, the cathode and the anode should not be in contact, and there is no particular limitation between the cathode and the anode. When the separator according to the present invention is used as an anode, the distance to the cathode can be reduced to within 2 mm, and may be more than that for convenience.

Hereinafter, the present invention will be described in more detail. However, the following examples are provided to illustrate the present invention more easily, and the content of the present invention is not limited to the examples.

Preparation Example 1 Fabrication of Anode

A metal support was manufactured by processing a stainless steel mesh plate (Woven Wire Mesh SUS, 200 mesh, pore size 0.077 mm) in the form of an open pouch. After inserting the flammable polymer film into the metal support, the carbon material was adhered to the metal support by supporting the carbon nanotube dispersed solution (MWCNTs: PVB: NMP = 2: 1: 17 (wt%)). The conductive carbon film structure was completed by heat treatment to selectively remove the combustible polymer.

The prepared carbon membrane structure has a specific surface area of 77.81 m ² / g, a volume of mesopores of 0.22 cm ³ / g, a volume of fine pores of 14.03 × 10 ^-3 cm ³ / g, and a pore size of 13.76 nm. Was measured.

Preparation Example 2 Preparation of Electrooxidation Reactor for Water Treatment

Using the prepared carbon film structure as an anode, an electrooxidation tank for water treatment based on the anode and the cathode was prepared, as shown in FIG. 4.

Specifically, a cylindrical electrode made of cylindrical perforated stainless steel having a length of 10 cm was disposed in a cylindrical container made of acrylic material, and an anode (4.75 cm ² ) of Preparation Example 1 was mounted in a cylindrical inner space of the reduction electrode. At this time, the distance between the anode and the cathode is 3 mm.

Preparation Example 3 Preparation of Electrooxidation Reactor for Water Treatment 2

The prepared conductive carbon film structure was used as an anode, and an electrooxidation tank for water treatment was prepared together with a cathode, which is shown in FIG. 5.

Example 1.

Bisphenol A, a contaminant, was prepared in a 10 mM NaNO ₃ electrolyte solution (pH = 7) at a concentration of 1 mg / L, and then flowed at a rate of 12.4 mL / h outside the electrochemical reactor for water treatment using a syringe pump. The internal pressure is generated by continuously flowing the electrolyte into the reaction tank, whereby water moves to the carbon membrane structure prepared according to Preparation Example 1 and collected from the outside. The experiment was performed for 30 minutes under a current density of 4 mA / cm ² using a power supply by connecting the anode and the cathode.

Comparative example

The anode used in Comparative Example was prepared by dispersing the carbon nanotube solution prepared in the present invention to a thickness of 15 μm using a casting machine, followed by heat treatment in the same manner as in Preparation Example 1. Except for using the anode of the comparative example, the experiment in the form of batch was carried out in the same operation except for the use of a syringe pump using the same device and the same device as used in Example 1.

Test Example 1 Efficiency Comparison

Water treatment efficiency using the electrooxidation reactor for water treatment according to Example 1 and Comparative Example was compared, shown in Figure 6 below.

After operation, both Example 1 and Comparative Example were sampled at reaction times of 0, 1, 2, 5, 10, 20, 30 minutes, and the samples were mass spectrophotometer and Shim-pack GISH HP C18 (2.1 ×). 100, 3 μm) column and liquid chromatography-mass spectrometer using water and methanol (solvent A: water, solvent B: methanol, solvent C: 50% water + 50% methanol) as the mobile phase solvent Analyzes (LCMS-2020, Shimadzu, Japan).

In Example 1, most of the contaminants were treated within about 2 minutes because the contaminants were rapidly moved to the separator, but in the comparative example, less than half of the contaminants were treated even after 30 minutes of treatment.

As a result of 30 minutes of treatment, about 35.4% was treated in the comparative example, while in Example 1, 100% of the contaminants were treated.

Claims (15)

A pouch-shaped film structure comprising a metal support and a carbon material, the top of which is open and has a space therein,
The metal support is composed of a metal plate of a mesh structure, the top is open, is in the form of a pouch having a space therein,
Wherein the carbon material is entangled with each other to form a three-dimensional network structure, and a portion of the network structure is entangled with the mesh structure of the metal support. The method of claim 1,
The pore size of the mesh structure of the metal support is 0.01 to 1.5 mm The method of claim 1,
The membrane structure has a specific surface area of 30 to 500 m ² / g. The method of claim 1,
The membrane structure is a membrane structure having a plurality of pores of 1 to 100 nm size. The method of claim 1,
The membrane structure includes a plurality of micropores and mesopores,
The volume of the micropores is from 1.00 × 10 ⁻³ to 50.00 × 10 ⁻³ cm ³ / g,
A membrane structure in which the volume of mesopores is 0.01 to 0.50 cm ³ / g. The method of claim 1,
The metal plate of the mesh structure is composed of one or more selected from the group consisting of stainless, copper, nickel, zinc, chromium, zirconium and iron. The method of claim 1,
The carbon material is selected from the group consisting of graphene, carbon nanotubes, carbon nanowires and carbon fibers. a) processing a metal plate of a mesh structure to produce a pouch-shaped metal support having an open top and having an inner space;
b) inserting a combustible material in the form of a film into the interior space of the metal support;
c) treating the solution in which the carbon material is dispersed in the metal support into which the combustible material is inserted, so that the carbon material is entangled with each other to form a three-dimensional network structure, wherein a part of the formed network structure is entangled with the mesh structure of the metal support, Adhering the carbon material to the metal support; And
and d) heat treating to remove the combustible material. The method of claim 8,
Wherein the c) step of adhesion is performed by one or more methods selected from spin coating, dip coating and spray coating. The method of claim 8,
The step c) is to immerse the metal support into which the combustible material is inserted in a solution in which the carbon material is dispersed. The method of claim 8,
And repeating steps a) to d) one to twenty times in order to increase the thickness of the carbon material adhered to the metal support. The method of claim 8,
The pore size of the mesh structure of the metal support is 0.01 to 1.5 mm. The method of claim 8,
The combustible material is at least one selected from the group consisting of polyvinyl chloride, polystyrene, polyethylene, and polymethylmethacrylate. The method of claim 8,
The carbon material is selected from the group consisting of graphene, carbon nanotubes, carbon nanowires and carbon fibers. The water treatment method using the membrane structure of any one of Claims 1-7 as an electrode of an electrochemical oxidation process, and a separator of a membrane filtration process.

Images