Membrane treatment process for wastewater treatment

Abstract

The application belongs to the technical field of printing wastewater treatment, and discloses a membrane treatment process for wastewater treatment, wherein firstly, an anionic metal organic framework and a polyethylene imine solution with positive charges are used to treat a base film to obtain an organic-inorganic hybrid composite film; after the whole composite film is electrically neutral, the whole composite film is further immersed in the polyethylene imine solution or the metal organic framework material to control the electric charges of the whole wastewater treatment film, so that selective adsorption of cationic dyes or anionic dyes is realized; and since the loaded metal organic framework is a porous material, the dyes can be further selectively adsorbed through size effect and charge effect.

Description

Technical Field

[0001] This invention relates to the field of printing wastewater treatment technology, and more specifically to a membrane treatment process for wastewater treatment. Background Technology

[0002] Currently, the dyes in printing dye wastewater mainly originate from processes such as desizing, dyeing, and printing in the printing industry. The water quality varies depending on the raw materials, product types, production processes, and management level. However, generally speaking, printing dye wastewater is characterized by large volume, deep color, complex water quality, and significant variations in both quantity and quality.

[0003] This invention provides a membrane treatment process that allows the base membrane to be positively or negatively charged to achieve the adsorption of anionic or cationic dyes. The metal-organic framework material used in this process is a porous material with a large porosity, thus enabling size-controlled dye adsorption. Membranes treated using this process can selectively adsorb dyes from dye wastewater. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a membrane treatment process for wastewater treatment.

[0005] This invention is achieved through the following technical solution:

[0006] A membrane treatment process for wastewater treatment includes the following steps:

[0007] (1) Prepare a polyethyleneimine solution by dissolving 10 ml of 5 wt% polyethyleneimine in 100 ml of methanol, and then ultrasonically heating and stirring for 30 ml at a temperature of 40-50℃ to disperse it evenly.

[0008] (2) Cut the base film into a circle with a circumference area of ​​15 cm². 2 Place it in the polyethyleneimine solution from step 1 and retain it for 1-2 days to give the surface of the base film a positive charge. After removing it, place it in a vacuum drying oven at 40°C to dry.

[0009] (3) Synthesize negatively charged metal-organic framework materials;

[0010] (4) Disperse 50g of the negatively charged metal-organic framework powder from step 3 in batches into 200ml of methanol solution while adding it and stirring ultrasonically to prevent the metal-organic framework powder from agglomerating. Then immerse the base film from step 2 in the methanol solution of the metal-organic framework powder for 1-2 days. After taking it out, place it in a vacuum drying oven at 40°C to dry it, and obtain the metal-organic framework material powder and the base film loaded with polyethyleneimine.

[0011] (5) Immerse the base film obtained in step 4 in the polyethyleneimine solution in step 1 for 1-2 days, take it out and place it in a vacuum drying oven at 40°C to dry, and then place it in the methanol solution of Zn-metal-organic framework material powder in step 4 for 1-2 days, take it out and place it in a vacuum drying oven at 40°C to dry.

[0012] (6) Repeat step 5 to obtain a multilayer uniformly dispersed Zn-metal-organic framework material and polyethyleneimine base film, and make the base film electrically neutral in the final state;

[0013] (7) Place the base film from step 6 in a polyethyleneimine solution, or disperse the negatively charged metal-organic framework material from step 4 in 200 ml of methanol solution, so that the entire base film is positively or negatively charged.

[0014] Furthermore, the preparation method of the negatively charged metal-organic framework material in step 3 includes the following steps: 0.1 mol of zinc nitrate hexahydrate, 0.11 mol of the organic ligand 4,8-disulfonic-2,6-naphthalenedicarboxylic acid, and 0.05 mol of 2,2'-bipyridine are placed in 15 ml of DMF solution, heated and sonicated, and then 10 drops of formic acid solution are added to the mixed solution. The above mixed solution is placed in a high-pressure reactor, and the high-pressure reactor is placed in a heating furnace, with the temperature inside the furnace controlled at 80°C. After two days, the reactor is removed, the obtained product is centrifuged and filtered, the supernatant is poured off, and the precipitate is placed in methanol. The methanol solution is replaced every other day to obtain the Zn-metal-organic framework material powder synthesized by the composite ligand.

[0015] Furthermore, the base membrane is an ultrafiltration membrane or a nanofiltration membrane.

[0016] The beneficial effects of this invention are as follows: In this invention, the Zn-metal-organic framework material coordinated with 4,8-disulfonic acid-2,6-naphthalenedicarboxylic acid and 2,2'-bipyridine dual ligands has a columnar bilayer three-dimensional structure. The three-dimensional structure is an anionic framework. Since polyethyleneimine carries a positive charge, it can attract the anionic metal-organic framework to obtain an organic-inorganic hybrid composite membrane. After the composite membrane is electrically neutral, it is further impregnated in a polyethyleneimine solution or a metal-organic framework material to control the charge of the entire composite membrane. By combining the composite membranes together, the adsorption of cationic or anionic dyes can be achieved. Since the supported metal-organic framework is a porous material, the dyes can be further selectively adsorbed through size effect and charge effect.

[0017] The wastewater treatment membrane can selectively adsorb and separate organic dyes by controlling both charge and size effects. First, dyes with opposite charges to the membrane are adsorbed through the charge effect. Then, selective adsorption is achieved by selecting the pore size in the metal-organic framework material. In other words, the wastewater treatment membrane can selectively adsorb smaller cationic or anionic dyes in the wastewater. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0019] Figure 1 This is a schematic diagram of the metal-organic framework of the present invention;

[0020] Figure 2 This is an experimental diagram showing the adsorption effect of methyl orange according to the present invention;

[0021] Figure 3 This is an experimental diagram showing the adsorption effect of methylene blue according to the present invention; Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0024] For ease of explanation, spatial relative terms such as “up,” “down,” “left,” and “right” may be used herein to describe the relationship of one element or feature shown in the figure relative to another element or feature. It should be understood that, in addition to the orientation shown in the figure, spatial terms are intended to include different orientations of the device in use or operation. For example, if the device in the figure is inverted, an element described as being “down” of other elements or features would be positioned “up” of those other elements or features. Therefore, the exemplary term “down” can encompass both up and down orientations.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] Example 1

[0027] A membrane treatment process for wastewater treatment includes the following steps:

[0028] (1) Prepare a polyethyleneimine solution by dissolving 10 ml of 5 wt% polyethyleneimine in 100 ml of methanol, and then ultrasonically heating and stirring for 30 ml at a temperature of 40-50℃ to disperse it evenly.

[0029] (2) Cut the base film into a circle with a circumference area of ​​15 cm². 2 Place it in the polyethyleneimine solution from step 1 and retain it for 1-2 days to give the surface of the base film a positive charge. After removing it, place it in a vacuum drying oven at 40°C to dry.

[0030] (3) Synthesize negatively charged metal-organic framework materials;

[0031] (4) Disperse 50g of the negatively charged metal-organic framework powder from step 3 in batches into 200ml of methanol solution while adding it and stirring ultrasonically to prevent the metal-organic framework powder from agglomerating. Then immerse the base film from step 2 in the methanol solution of the organic framework material powder for 1-2 days. After taking it out, place it in a vacuum drying oven at 40°C to dry it, and obtain the metal-organic framework material powder and the base film loaded with polyethyleneimine.

[0032] (5) Immerse the base film obtained in step 4 in the polyethyleneimine solution in step 1 for 1-2 days, take it out and place it in a vacuum drying oven at 40°C to dry, and then place it in the methanol solution of Zn-metal-organic framework material powder in step 4 for 1-2 days, take it out and place it in a vacuum drying oven at 40°C to dry.

[0033] (6) Repeat step 5 to obtain a multilayer uniformly dispersed Zn-metal-organic framework material and polyethyleneimine base film, and make the base film electrically neutral in the final state;

[0034] (7) Place the base film from step 6 in a polyethyleneimine solution, and the entire base film will be positively charged.

[0035] (8) Combine the positively charged base membrane from step 7 to obtain a membrane for wastewater treatment.

[0036] The preparation method of the negatively charged metal-organic framework material in step 3 includes the following steps: 0.1 mol zinc nitrate hexahydrate, 0.11 mol organic ligand 4,8-disulfonic-2,6-naphthalenedicarboxylic acid, and 0.05 mol 2,2'-bipyridine are placed in 15 ml of DMF solution and subjected to heating and ultrasonic treatment. Then, 10 drops of formic acid solution are added to the mixed solution. The above mixed solution is placed in a high-pressure reactor, and the high-pressure reactor is placed in a heating furnace. The temperature inside the furnace is controlled at 80°C. After two days, the reactor is removed, the obtained product is centrifuged and filtered, the supernatant is poured off, and the precipitate is immersed in methanol. The methanol solution is replaced every other day to obtain Zn-metal-organic framework material powder synthesized by composite ligand.

[0037] The base membrane is an ultrafiltration membrane or a nanofiltration membrane.

[0038] Example 2

[0039] A membrane treatment process for wastewater treatment includes the following steps:

[0040] (1) Prepare a polyethyleneimine solution by dissolving 10 ml of 5 wt% polyethyleneimine in 100 ml of methanol, and then ultrasonically heating and stirring for 30 ml at a temperature of 40-50℃ to disperse it evenly.

[0041] (2) Cut the base film into a circle with a circumference area of ​​15 cm². 2 Place it in the polyethyleneimine solution from step 1 and retain it for 1-2 days to give the surface of the base film a positive charge. After removing it, place it in a vacuum drying oven at 40°C to dry.

[0042] (3) Synthesize negatively charged metal-organic framework materials;

[0043] (4) Disperse 50g of the negatively charged metal-organic framework powder from step 3 in batches into 200ml of methanol solution while adding it and stirring ultrasonically to prevent the metal-organic framework powder from agglomerating. Then immerse the base film from step 2 in the methanol solution of the organic framework material powder for 1-2 days. After taking it out, place it in a vacuum drying oven at 40°C to dry it, and obtain the metal-organic framework material powder and the base film loaded with polyethyleneimine.

[0044] (5) Immerse the base film obtained in step 4 in the polyethyleneimine solution in step 1 for 1-2 days, take it out and place it in a vacuum drying oven at 40°C to dry, and then place it in the methanol solution of Zn-metal-organic framework material powder in step 4 for 1-2 days, take it out and place it in a vacuum drying oven at 40°C to dry.

[0045] (6) Repeat step 5 to obtain a multilayer uniformly dispersed Zn-metal-organic framework material and polyethyleneimine base film, and make the base film electrically neutral in the final state;

[0046] (7) Place the base film from step 6 into a 200 ml methanol solution containing the negatively charged metal-organic framework material from step 4, so that the entire base film is negatively charged.

[0047] (8) Combine the negatively charged base membrane from step 7 to obtain a membrane for wastewater treatment.

[0048] The preparation method of the negatively charged metal-organic framework material in step 3 includes the following steps: 0.1 mol zinc nitrate hexahydrate, 0.11 mol organic ligand 4,8-disulfonic-2,6-naphthalenedicarboxylic acid, and 0.05 mol 2,2'-bipyridine are placed in 15 ml of DMF solution and subjected to heating and ultrasonic treatment. Then, 10 drops of formic acid solution are added to the mixed solution. The above mixed solution is placed in a high-pressure reactor, and the high-pressure reactor is placed in a heating furnace. The temperature inside the furnace is controlled at 80°C. After two days, the reactor is removed, the obtained product is centrifuged and filtered, the supernatant is poured off, and the precipitate is immersed in methanol. The methanol solution is replaced every other day to obtain Zn-metal-organic framework material powder synthesized by composite ligand.

[0049] The base membrane can be an ultrafiltration membrane or a nanofiltration membrane.

[0050] Experimental effect test

[0051] A dye solution with a concentration of 200 mg / L was prepared and placed in a transparent vial. Then, the wastewater treatment membranes prepared in Examples 1 and 2 were added to the dye solution. The color change of the dye was observed at room temperature, and its adsorption capacity was determined by UV-Vis absorption spectroscopy. The results showed that the wastewater treatment membrane in Example 1 exhibited good removal efficiency for the anionic dye methyl orange. (See [link to relevant documentation]). Figure 2 The wastewater treatment membrane in Example 2 showed good removal efficiency for the cationic dye methylene blue. (See [link to example]). Figure 3 Then, the concentrations of methylene blue and methyl orange dyes before and after adsorption were determined by UV-Vis absorption spectroscopy, and the amount of dye adsorbed was calculated according to formula (1):

[0052] (1)

[0053] In formula (1), q is the amount of dye adsorbed per unit mass of adsorbent, c0 is the dye concentration before adsorption, c is the dye concentration after adsorption, the experiment was repeated five times and the average value was taken, V is the volume of the dye solution, and m is the mass of the adsorbent. The calculation results show that: the wastewater treatment membrane prepared in Example 1 can achieve an adsorption capacity of 147.89 mg / g for the anionic dye methyl orange; the wastewater treatment membrane prepared in Example 2 can achieve an adsorption capacity of 210.99 mg / g for the cationic dye methylene blue.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A membrane treatment process for wastewater treatment, characterized by: Includes the following steps: (1) Prepare a polyethyleneimine solution by dissolving 10 ml of 5 wt% polyethyleneimine in 100 ml of methanol, and then ultrasonically heating and stirring for 30 ml at a temperature of 40-50℃ to disperse it evenly. (2) Cut the base film into a circle with a circumference area of ​​15 cm². 2 Place it in the polyethyleneimine solution in step (1) and retain it for 1-2 days to make the surface of the base film positively charged. After taking it out, place it in a vacuum drying oven at 40°C to dry. (3) Synthesize negatively charged metal-organic framework materials; (4) Disperse 50g of the negatively charged metal-organic framework powder from step (3) in batches into 200ml of methanol solution while adding it and stirring ultrasonically to prevent the metal-organic framework powder from agglomerating. Then immerse the base film from step (2) in the methanol solution of the metal-organic framework powder for 1-2 days. After taking it out, place it in a vacuum drying oven at 40°C to dry it, and obtain the metal-organic framework material powder and the base film loaded with polyethyleneimine. (5) Immerse the base film obtained in step (4) in the polyethyleneimine solution in step (1) for 1-2 days, take it out and place it in a vacuum drying oven at 40°C to dry, and then place it in the methanol solution of Zn-metal-organic framework material powder in step (4) for 1-2 days, take it out and place it in a vacuum drying oven at 40°C to dry. (6) Repeat step (5) to obtain a multilayer uniformly dispersed Zn-metal-organic framework material and polyethyleneimine base film, and make the base film electrically neutral in the final state. (7) Place the base film from step (6) in a polyethyleneimine solution, or disperse the negatively charged metal-organic framework material from step (4) in 200 ml of methanol solution, so that the entire base film is positively or negatively charged. (8) Combine the positively or negatively charged base membranes from step (7) to obtain a membrane for wastewater treatment; The preparation method of the negatively charged metal-organic framework material in step (3) includes the following steps: 0.1 mol zinc nitrate hexahydrate, 0.11 mol organic ligand 4,8-disulfonic-2,6-naphthalenedicarboxylic acid and 0.05 mol 2,2'-bipyridine are placed in 15 ml of DMF solution, heated and sonicated for 10 minutes, and then 10 drops of formic acid solution are added to the mixed solution. The above mixed solution is placed in a high-pressure reactor, and the high-pressure reactor is placed in a heating furnace. The temperature inside the furnace is controlled at 80°C. After two days, the reactor is removed, the product is centrifuged and filtered, the supernatant is poured out, the precipitate is placed in methanol, and the methanol solution is replaced every other day to obtain Zn-metal-organic framework material powder synthesized by composite ligand.

2. A membrane treatment process for wastewater treatment according to claim 1, characterized by: The base membrane in step (2) is an ultrafiltration membrane or a nanofiltration membrane.

3. The application of the wastewater treatment membrane obtained by the wastewater treatment membrane process according to any one of claims 1-2 in dye adsorption.

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