Application of high-salt organic dyeing and printing wastewater treatment

Abstract

The invention belongs to the technical field of environment-friendly materials and water treatment, and particularly relates to application of high-salt organic dyeing and printing wastewater treatment. The porous graphene film is provided with nano-pore mass transfer channels which are arranged in a staggered and stacked manner and have proper sizes in a vertical plane, and is provided with narrow interlayer mass transfer channels in a transverse plane, so that a two-dimensional nano-channel through which small-size water molecules and salt ions can rapidly permeate but large-size organic dye cannot permeate is formed. According to the porous graphene membrane prepared by the method disclosed by the invention, under the conditions of no operation pressure and 0.1 MPa operation pressure, the rejection rate of organic dye molecules is greater than 99%, the permeation flux of the porous graphene membrane is 2-4 orders of magnitude higher than that of the existing separation membrane, and the porous graphene membrane has good dye salt separation performance. The method has the advantages of green and environment-friendly preparation process, low energy loss, no need of pressure in the application process, extremely high economic cost performance and high synergy degree with other processes, and has a huge application prospect in the field of dyeing and printing wastewater treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of environmentally friendly materials and water treatment, and specifically relates to an application of high-salt organic dyeing and printing wastewater treatment. Background Art

[0002] The scarcity of water resources has become a severe challenge to the long-term survival of mankind. With the acceleration of the global industrialization process, various pollutants discharged by industrial production activities, especially in the textile industry, the dyes, auxiliaries and chemicals used in the printing and dyeing process will discharge high-salt organic dyeing and printing wastewater, which continuously invades the water environment. This trend has further aggravated the scarcity of water resources and has posed a significant constraint on the sustainable and healthy development of the social economy. In view of this, it is particularly urgent and critical to develop a green, environmentally friendly, efficient and reliable organic dyeing and printing wastewater treatment technology to efficiently separate salt components and salt ions.

[0003] As a traditional water treatment method, membrane technology has attracted more and more attention in recent years due to its low energy consumption, simple operation and environmentally friendly characteristics. Graphene membrane, due to its unique physical and chemical structure, can achieve accurate screening of ions and molecules in water treatment, showing great application potential. However, it is still a huge challenge to improve permeability while ensuring high selectivity, that is, to overcome the "seesaw" effect between permeability and selectivity, and to prepare a graphene membrane with both high flux and selective permeability of salt ions. Introducing nanopores of appropriate size in the two-dimensional plane of graphene can not only utilize the steric hindrance effect of nanopores to achieve the removal of organic dyes in water, but also significantly shorten the mass transfer path of water molecules, allowing small-sized salt ions to pass through and increase the water flux of the membrane. It is an ideal solution. However, this solution has extremely high requirements on the prepared pore size and its arrangement. Therefore, it is urgent to develop a method that can accurately introduce nanopores on the graphene membrane and realize the reasonable arrangement of nanopores to prepare a porous graphene membrane with both high selectivity and high permeability. Summary of the invention

[0004] As a traditional water treatment method, membrane technology has the characteristics of low energy consumption, simple operation and environmental friendliness. As a hot new generation of membrane separation materials, graphene membrane has received widespread attention in the treatment of dyeing and printing wastewater. However, how to break through the "seesaw" effect between the permeability and selectivity inherent in the membrane separation process and prepare graphene membranes with both high flux and high selectivity is still a great challenge. Introducing nanopores with precisely controlled sizes on the graphene membrane and distributing the pores reasonably to effectively shorten the mass transfer path of water molecules and effectively intercept organic dyes is a potential method. The present invention aims to provide a method for preparing a porous graphene membrane with a staggered stacked pore structure prepared using carbon black as a raw material. The prepared porous graphene membrane has both high water flux and high separation efficiency, can efficiently separate high-salt organic dyes in water, and the preparation process is green and environmentally friendly with low energy consumption.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] An application of high-salt organic dyeing and printing wastewater treatment, comprising the following steps:

[0007] Step 1: Using carbon black as raw material, a porous carbon material is synthesized by reduction with high temperature gas (O2, CO, O3), and then subjected to high temperature graphitization treatment to prepare a porous graphite material with a special nanoporous structure;

[0008] Step 2: further oxidizing the porous graphite material with a special nanopore structure to obtain an oxidized porous graphene dispersion, and then performing ultrasound treatment;

[0009] Step 3: The oxidized porous graphene dispersion is filtered under pressure and deposited on a porous substrate to obtain an oxidized porous graphene membrane with adjustable thickness and staggered nanopore structures between graphene sheets. Small water molecules and salt ions can quickly penetrate the membrane through the ultrashort nanochannels between the graphene membrane layers. The staggered nanopores and narrow interlayer lateral channels on the membrane can effectively block the transport of large molecular organic dyes in the membrane, thereby separating salt ions and organic components in water.

[0010] Preferably, the defect degree of the porous carbon material is evaluated by the ID / IG value of Raman spectroscopy, and the value is between 0.7 and 1.2.

[0011] Preferably, in the porous graphene material having a special nanopore structure, the shape of the special nanopore structure includes circle, triangle, diamond, dot, rectangle, square and irregular ellipse.

[0012] Preferably, in the porous graphene material having a special nanopore structure, the size of the nanopores is between 0.5 and 3.0 nanometers.

[0013] Preferably, the oxidation treatment in step 2 includes traditional Hummers method, improved Hummers method, Brodie method and Staudenmaier method.

[0014] Preferably, in the oxidized porous graphene membrane in which the nanopore structures between the graphene sheets are arranged in a staggered manner, the shapes of the nanopore structures after oxidation include circle, triangle, diamond, dot, rectangle, square and irregular ellipse.

[0015] Preferably, in the oxidized porous graphene membrane in which the nanopore structures between the graphene sheets are staggered, the size of the nanopores is between 0.5 and 2 nanometers, and the lateral size of the sheets is between 20 and 60 nanometers.

[0016] Preferably, the graphene has a thickness between 200 nanometers and 500 micrometers.

[0017] Preferably, the interlayer channels include laterally narrow interlayer channels with a spatial dimension of less than 0.7 nanometers, and longitudinally interlayer nanopore-based channels are staggered.

[0018] Preferably, for the high-salt organic dyeing and printing wastewater pollutants in the water body, the salt concentration is between 500 and 2000 mg / L, and the organic dye concentration is between 0.1 and 10 mg / L, and the applied pressure during the purification process is 0 MPa or 0.02-5 MPa.

[0019] Compared with the prior art, the present invention has the following obvious outstanding substantive features and significant advantages:

[0020] 1. The preparation process of the method of the present invention is green and environmentally friendly, easy to operate, has low energy loss, and has high synergy with other processes;

[0021] 2. The porous graphene membrane prepared by the method of the present invention has a special nanopore structure and narrow interlayer channels. The prepared separation membrane has an extremely high permeation flux, which is 2-4 orders of magnitude higher than that of the existing separation membrane, and has low separation energy consumption. It has good application prospects in the field of dyeing and printing wastewater treatment;

[0022] 3. The porous graphene membrane prepared by the method of the present invention can purify water without pressure driving, which significantly reduces the cost of dyeing and printing wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is an AFM image of a porous graphene membrane with a staggered pore structure according to Example 1 of the present invention;

[0024] Figure 2 This is a pore size distribution diagram of a porous graphene membrane with a staggered pore structure according to Example 1 of the present invention;

[0025] Figure 3 This is a graph showing the separation performance of a porous graphene membrane with a staggered pore structure in removing organic dyes from water at an operating pressure of 0.1 MPa according to Example 2 of the present invention;

[0026] Figure 4 This is a graph showing the separation performance of a porous graphene membrane with a staggered pore structure in removing salt ions from water at an operating pressure of 0.1 MPa according to Example 2 of the present invention;

[0027] Figure 5 This is a graph showing the separation performance of a porous graphene membrane with a staggered pore structure for separating organic dyes and salt ions in water at an operating pressure of 0.1 MPa according to Example 2 of the present invention;

[0028] Figure 6 This is a graph showing the separation performance of a porous graphene membrane with a staggered pore structure in Example 3 of the present invention for separating organic dyes and salt ions in water without operating pressure. DETAILED DESCRIPTION

[0029] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0030] In the following examples, inductively coupled plasma emission spectroscopy and ultraviolet spectrophotometer were used to test the concentrations of ions and dyes in water.

[0031] The above scheme is further described below in conjunction with specific implementation examples. The preferred embodiments of the present invention are described in detail as follows:

[0032] Example 1

[0033] In this embodiment, see Figure 1 and Figure 2 , an application of high-salt organic dyeing and printing wastewater treatment, the steps are as follows:

[0034] A water-based microporous filter membrane with a pore size of 0.22 μm was used as a supporting base membrane. A certain amount of porous graphene oxide solution was filtered using a membrane filtration method, and the porous graphene oxide was deposited and retained on the water-based microporous filter membrane as a supporting base, thereby preparing a porous graphene oxide membrane with a thickness of 120 μm and a composite lamellar structure. The morphology of the membrane was observed using a scanning electron microscope, and the pore size was analyzed.

[0035] Experimental test analysis:

[0036] Depend on Figure 1 and Figure 2It can be seen that a large number of nanopores are distributed between the layers of the prepared porous graphene oxide membrane, which lays a structural foundation for the rapid mass transfer of water molecules. Photo analysis of the membrane surface found that the membrane surface is distributed with wrinkled nanopores of different sizes and shapes, as well as stacked two-dimensional graphene sheets, providing a large number of dislocated pore structures, which can effectively block organic pollutants in the water body without hindering the penetration of water molecules and salt ions. This is also the main reason why the porous graphene membrane has both high selectivity and high permeability. In addition, through testing and analysis, it was found that the average pore size of the prepared porous graphene membrane is about 2.8 nanometers.

[0037] Example 2

[0038] In this embodiment, see Figure 3 , Figure 4 and Figure 5 , an application of high-salt organic dyeing and printing wastewater treatment, the steps are as follows:

[0039] In this embodiment, a porous graphene membrane was prepared based on the method in Example 1, and a membrane separation experiment was performed at 0.1 MPa for a solution of alkali metal salt ions (NaCl, MgCl2, Na2SO4 and MgSO4) with a concentration of 2000 mg / L and a solution of dyes (methyl orange, methyl red, rhodamine B and methylene blue) with a concentration of 10 mg / L, respectively, to test the change of pollutant concentration before and after the membrane, record the interception rate and water flux, and evaluate the separation performance of the porous graphene membrane. And a membrane separation experiment was performed at 0.1 MPa for a mixed solution of alkali metal salt ions (NaCl, MgCl2, Na2SO4 and MgSO4) with a concentration of 2000 mg / L and rhodamine B with a concentration of 10 mg / L, to test the change of pollutant concentration before and after the membrane, record the interception rate and water flux, and evaluate the dye-salt separation performance of the porous graphene membrane.

[0040] Experimental test analysis:

[0041] Depend on Figure 3 It can be seen that the retention rate of the porous graphene membrane for the four organic dyes in this embodiment is greater than 99%, and the water flux in the membrane separation process can be maintained at about 2000-4000Lm -2 h -1 bar -1 The permeation flux of the membrane is 2-3 orders of magnitude higher than that of ordinary commercial separation membranes. Figure 4 It can be seen that the interception rate of the porous graphene membrane for salt ions in this embodiment is less than 10%, and the water flux in the membrane separation process can be maintained at about 5500-8100 L m -2 h -1 bar -1 Within the range of Figure 5It can be seen that the porous graphene membrane in this embodiment has a retention rate of more than 99% for the mixed solution of four salts and rhodamine B dye, and a removal efficiency of less than 10% for salt ions. The water flux in the membrane separation process can be maintained at about 3000-5800 L m -2 h -1 bar -1 The permeation flux of the membrane is 2-3 orders of magnitude higher than that of ordinary commercial separation membranes, and it has excellent dye-salt separation performance. In summary, a porous graphene membrane with a staggered pore structure has extremely broad application prospects in water treatment, especially in the treatment of high-salt dyeing and printing wastewater.

[0042] Example 3

[0043] In this embodiment, see Figure 6 , an application of high-salt organic dyeing and printing wastewater treatment, the steps are as follows:

[0044] In this example, a porous graphene membrane was prepared based on the method in Example 1. A membrane separation experiment was carried out under pressure-free conditions on a mixed solution of 2000 mg / L alkali metal salt ions (NaCl, MgCl2, Na2SO4 and MgSO4) and 10 mg / L rhodamine B. The changes in pollutant concentrations before and after the membrane were tested, the retention rate and water flux were recorded, and the separation performance of the porous graphene membrane was evaluated.

[0045] Experimental test analysis:

[0046] Depend on Figure 6 It can be seen that the porous graphene membrane in this embodiment has a retention rate of more than 99% for the mixed solution of four salts and rhodamine B dye, and a removal efficiency of less than 10% for salt ions, and the water flux in the membrane separation process can be maintained at about 18000-21000 L m -2 h -1 bar -1 The permeation flux of the prepared porous graphene membrane is 6-8 orders of magnitude higher than that of ordinary commercial separation membranes, and it has excellent salt separation performance. In summary, it can be shown that the prepared porous graphene membrane has both high selectivity and high permeability, and can achieve water purification by gravity without operating pressure. It is an extremely green and environmentally friendly membrane separation material.

[0047] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention of the present invention. Any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention should be equivalent replacement methods. As long as they meet the purpose of the invention of the present invention and do not deviate from the technical principles and inventive concepts of the present invention, they belong to the protection scope of the present invention.

Claims

1. An application for treating high-salt organic dyeing and printing wastewater, comprising the following steps: Step 1: Synthesize porous carbon materials using carbon black as raw material, and prepare porous graphene materials with special nanopore structure through high-temperature graphitization treatment; Step 2: further oxidizing the porous graphene material with a special nanopore structure to obtain an oxidized porous graphene dispersion, and performing ultrasound treatment; Step 3: The oxidized porous graphene dispersion is filtered under pressure and deposited on a porous substrate to obtain an oxidized porous graphene membrane with adjustable thickness and staggered nanopore structures between graphene sheets. Small water molecules and salt ions can quickly penetrate the membrane through the ultrashort nanochannels between the graphene membrane layers. The staggered nanopores and narrow interlayer lateral channels on the membrane can effectively block the transport of large molecular organic dyes in the membrane, thereby separating salt ions and organic components in water.

2. The application of high-salt organic dyeing and printing wastewater treatment according to claim 1, characterized in that: The defect degree of the porous carbon material is determined by Raman spectroscopy. D / I G The value is between 0.7 and 1.

2.

3. The application of high-salt organic dyeing and printing wastewater treatment according to claim 1 is characterized by: In the porous graphene material with a special nanopore structure, the shape of the special nanopore structure includes circle, triangle, diamond, dot, rectangle, square and irregular ellipse.

4. The application of high-salt organic dyeing and printing wastewater treatment according to claim 3 is characterized by: In the porous graphene material with a special nanopore structure, the size of the nanopores is between 0.5 and 3.0 nanometers.

5. The application of high-salt organic dyeing and printing wastewater treatment according to claim 1 is characterized by: The oxidation treatment in step 2 includes the traditional Hummers method, the improved Hummers method, the Brodie method and the Staudenmaier method.

6. The application of high-salt organic dyeing and printing wastewater treatment according to claim 1 is characterized by: In the oxidized porous graphene membrane in which the nanopore structures between the graphene sheets are arranged in a staggered manner, the shapes of the nanopore structures after oxidation include circle, triangle, diamond, dot, rectangle, square and irregular ellipse.

7. The application of high-salt organic dyeing and printing wastewater treatment according to claim 6, characterized in that: In the oxidized porous graphene membrane in which the nanopore structures are staggered between the graphene sheets, the size of the nanopores is between 0.5 and 3.5 nanometers, and the lateral size of the sheets is between 20 and 60 nanometers.

8. The application of high-salt organic dyeing and printing wastewater treatment according to claim 1, characterized in that: The thickness of the graphene is between 200 nanometers and 500 micrometers.

9. The application of high-salt organic dyeing and printing wastewater treatment according to claim 1, characterized in that: The interlayer channels include transversely narrow interlayer channels with a spatial dimension of less than 0.7 nanometers, and longitudinally interlayer nanopore-based channels are arranged in a staggered manner.

10. The application of high-salt organic dyeing and printing wastewater treatment according to claim 1, characterized in that: The pressure applied in the purification process for high-salt organic dyeing and printing wastewater pollutants in the water body is 0 MPa or 0.02-5 MPa, with a salt concentration between 500 and 2000 mg / L and an organic dye concentration between 0.1 and 10 mg / L.

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