Preparation method and application of a composite two-dimensional montmorillonite paint mist coagulant

Abstract

The present invention relates to the technical field of water treatment, and specifically relates to a preparation method and application of a composite two-dimensional montmorillonite paint mist coagulant. A two-dimensional montmorillonite nanosheet suspension is mixed and reacted with a reinforcing agent containing a hydrogen bond donor or acceptor functional group to obtain a composite two-dimensional montmorillonite nanosheet suspension; the obtained composite two-dimensional montmorillonite nanosheet suspension is uniformly mixed with an aqueous binder solution to obtain a composite two-dimensional montmorillonite paint mist coagulant. The preparation method of the invention uses two-dimensional montmorillonite as the main raw material. On the one hand, more potential sites will be exposed on the two-dimensional montmorillonite nanosheets, and its electrostatic attraction is beneficial to the capture of paint mist particles. On the other hand, the interaction ability of two-dimensional montmorillonite with the agent is stronger than that of montmorillonite, and the effect is good. The introduction of a reinforcing agent strengthens the hydrogen bond interaction between the composite two-dimensional montmorillonite nanosheets and different types of waterborne paints, enhancing the capture ability of the paint mist coagulant for different types of waterborne paints, and having a wide adaptability.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a preparation method and application of a composite two-dimensional montmorillonite paint mist coagulant. Background Art

[0002] In the spraying process of modern automobiles, home appliances, furniture, engineering machinery, electronic products, some plastic products and other industries, only 40% to 60% of the paint can be effectively attached to the device, and the rest splashes into the surrounding environment and air in the form of paint mist, which is extremely harmful to human health. Therefore, a wet spray paint circulating water system is needed to capture this part of the paint mist. However, when a large amount of paint mist enters the circulating water, it is difficult to separate it from the water due to its complete miscibility with water. It is easy to adhere to the water tank, pipe wall, water pump and other equipment, and produce a large amount of foam, affecting the operation of the circulating water system. In order to ensure the normal operation of the wet spray paint circulating water system, it is necessary to add a paint mist coagulant to the circulating water to eliminate the viscosity of the paint mist, so that it can be condensed into large pieces and float up, and the paint pieces can be salvaged through the salvage system. This not only effectively extends the life of the equipment, but also promotes the recycling of water, greatly saving costs.

[0003] The Chinese patent "Preparation and Application of Environmentally Friendly Biodegradable Paint Mist Coagulants" (Publication No. CN101767853A) uses modified bentonite, chitosan, etc. as main raw materials and mixes and stirs at room temperature to prepare paint mist coagulants. The production process is simple and environmentally friendly, but the paint mist removal rate is not high. The Chinese patent "A New Environmentally Friendly Water-Based Paint Mist Coagulant and Preparation Method thereof" (Publication No. CN112500734A) discloses a paint mist coagulant prepared by high-speed stirring in a stirring kettle with bentonite, carboxymethyl cellulose, etc. as main raw materials. It can effectively degrade organic solvents in water-based paints and effectively eliminate the viscosity of paint mist. However, the patent does not pay attention to the size and strength of the paint residue after treatment. At the same time, there are many types of water-based paints on the market, and most paint mist coagulants can hardly meet the treatment of different types of water-based paint wastewater.

[0004] Therefore, there is an urgent need to develop a new type of paint mist coagulant that has a simple production process, strong paint mist capture ability, large and high-strength paint residue flocs after treatment, and is suitable for the treatment of various types of water-based paint wastewater. Summary of the invention

[0005] One of the purposes of the present invention is to provide a method for preparing a composite two-dimensional montmorillonite paint mist coagulant. The preparation method is simple and easy to adjust. The prepared paint mist coagulant can achieve large paint residue flocs with high strength after treatment, which is easy to salvage and has wide adaptability to meet the application needs of the market.

[0006] The second purpose of the present invention is to provide an application of a composite two-dimensional montmorillonite paint mist coagulant.

[0007] One of the solutions adopted by the present invention to achieve the objective is: a preparation method of a composite two-dimensional montmorillonite paint mist coagulant, comprising the following steps:

[0008] (1) Mix and react a two-dimensional montmorillonite nanosheet suspension with a reinforcing agent containing a hydrogen bond donor or acceptor functional group to obtain a composite two-dimensional montmorillonite nanosheet suspension;

[0009] (2) Mix the composite two-dimensional montmorillonite nanosheet suspension obtained in step (1) with an aqueous binder solution evenly to obtain a composite two-dimensional montmorillonite paint mist coagulant.

[0010] Preferably, in step (1), the aspect ratio of the two-dimensional montmorillonite nanosheets is 50 - 800, and the mass percentage of the two-dimensional montmorillonite nanosheet suspension is 0.1% - 8%.

[0011] Preferably, in step (1), the functional group in the reinforcing agent containing a hydrogen bond donor or acceptor functional group is at least one of amino group, ether group, carboxyl group or sulfonic acid group, and the mass ratio of the two-dimensional montmorillonite nanosheets to the reinforcing agent is 100:0.01 - 50.

[0012] Preferably, the reinforcing agent containing an amino functional group is at least one of triethanolamine, acrylamide, isobutylamine, cyclohexylamine, hexamethylenediamine; the reinforcing agent containing an ether functional group is at least one of vinyl ethyl ether, 18-crown-6, methyl sulfide, diethyl ether, tetrahydrofuran; the reinforcing agent containing a carboxyl functional group is at least one of aluminate, citric acid, benzoic acid, maleic acid, phthalic acid; the reinforcing agent containing a sulfonic acid group is at least one of sodium dodecylsulfonate, sodium dodecylbenzenesulfonate, sodium hydroxymethylsulfonate, methanesulfonic acid, sodium petroleum sulfonate.

[0013] Preferably, in step (2), the binder is at least one of polyvinyl alcohol, polyethylene glycol, hydroxyethyl cellulose, polyethylene oxide, poly(ethylene oxide), poly(maleic anhydride), and the mass percentage of the aqueous binder solution is 0.01% - 30%.

[0014] Preferably, in step (2), the volume ratio of the composite two-dimensional montmorillonite nanosheet suspension to the aqueous binder solution is 0.1 - 300:1.

[0015] One of the solutions adopted by the present invention to achieve the second objective is: an application of a composite two-dimensional montmorillonite paint mist coagulant prepared by the above-mentioned preparation method. The application method is to add the composite two-dimensional montmorillonite paint mist coagulant into industrial wastewater containing water-based paint. After the paint mist coagulant is fully mixed with the water-based paint wastewater, add an aqueous solution of cationic polyacrylamide, stir, stand, and salvage the paint sludge after it floats up.

[0016] Preferably, the water-based paint is any one of acrylic type, alkyd type, polyurethane type, epoxy resin type, vinyl resin type, silicone resin type, fluorocarbon resin type.

[0017] Preferably, the mass percentage of the cationic polyacrylamide aqueous solution is 0.01%-1%, and the concentration of the industrial wastewater containing the water-based paint is 1000-50000 mg / L.

[0018] Preferably, the volume ratio of the paint mist coagulant, the cationic polyacrylamide aqueous solution, and the industrial wastewater containing the water-based paint is 1:0.1-10:100-800.

[0019] The preparation principle of the present invention is as follows: Due to the opening of the lamellar structure of the two-dimensional montmorillonite nanosheets, more potential sites are exposed, which is beneficial to electrostatic attraction for capturing paint mist particles. Since various types of water-based paints such as acrylic type, alkyd type, and polyurethane type on the market all contain hydroxyl functional groups, and the hydroxyl functional group can act as both a hydrogen bond acceptor and a hydrogen bond donor, therefore, by introducing an enhancer containing a hydrogen bond donor or acceptor functional group to compound and strengthen with the montmorillonite nanosheets, the hydrogen bond interaction between the montmorillonite nanosheets and the paint mist particles after compounding can further enhance the capturing ability of the paint mist coagulant for different types of water-based paints. The addition of the binder can further bond the paint mist particles captured by the montmorillonite nanosheets into high-strength large paint agglomerates. Finally, adding cationic polyacrylamide can achieve the rapid aggregation and floating of the bonded paint agglomerates.

[0020] In the prior art, ordinary montmorillonite or bentonite is generally used. Montmorillonite is the main component of bentonite, so montmorillonite plays a major role in the prior art. Montmorillonite is a layered structure composed of countless lamellae stacked longitudinally. Both the surface and the end face of its lamellae carry charges, while two-dimensional montmorillonite is to peel the longitudinally stacked lamellae of montmorillonite into single lamellae or a few lamellae with a longitudinal thickness of only a few nanometers. The structure diagrams of montmorillonite and two-dimensional montmorillonite nanosheets are as Figure 1 shown. Compared with the montmorillonite technology used in the prior art, the two-dimensional montmorillonite nanosheets used in the present technology have the following advantages: On the one hand, the lamellar structure of the two-dimensional montmorillonite nanosheets is opened, and more potential sites are exposed on the surface, which is beneficial to electrostatic attraction for capturing paint mist particles and enhances the direct capturing ability for water-based paint mist; on the other hand, more active sites are exposed on the surface of the two-dimensional montmorillonite nanosheets, strengthening the interaction ability with subsequent medicaments, with better reaction effects and being more conducive to enhancing the action effect of the paint mist coagulant.

[0021] The present invention has the following advantages and beneficial effects:

[0022] 1. The preparation method of the invention uses two-dimensional montmorillonite as the main raw material. On the one hand, more potential sites will be exposed on the two-dimensional montmorillonite nanosheets, and its electrostatic attraction is beneficial to the capture of paint mist particles. On the other hand, the interaction ability of two-dimensional montmorillonite with agents is stronger than that of montmorillonite, and the effect is good. The enhanced two-dimensional montmorillonite nanosheets after introducing the enhancer can form hydrogen bond interactions with different types of waterborne paints, enhancing the capture ability of the paint mist coagulant for different types of waterborne paints, and having a wide adaptability.

[0023] 2. In the preparation method of the invention, by introducing a binder, the paint mist particles captured by the two-dimensional montmorillonite nanosheets can be further bonded into large paint clusters, and the strength of the paint clusters is high, which is beneficial to salvage.

[0024] 3. The two-dimensional montmorillonite nanosheets used in the preparation method of the invention have excellent dispersion stability, which is beneficial to the better dispersion of the paint mist coagulant in the waterborne paint wastewater to quickly capture paint mist particles, and at the same time ensures that the paint mist coagulant can be stored for a long time without sedimentation.

[0025] 4. The preparation method of the invention selects montmorillonite nanosheets as raw materials, which are low in price, wide in source, simple in production process, and free of secondary pollution, and can be directly used for the treatment of waterborne paint wastewater in various industries such as automobiles, home appliances, furniture, construction machinery, and electronic products. Brief Description of the Drawings

[0026] Figure 1 a and Figure 1 b are respectively the structure schematic diagrams of montmorillonite and two-dimensional montmorillonite and the diagram showing the structural advantages of two-dimensional montmorillonite;

[0027] Figure 2 a and Figure 2 b are respectively the pictures of the water quality and flocs after treatment with the paint mist coagulant in Example 1;

[0028] Figure 3 is the picture of the flocs after the paint mist coagulant treats acrylic waterborne paint in Example 3;

[0029] Figure 4 is the picture of the flocs after the paint mist coagulant treats polyurethane waterborne paint in Example 4;

[0030] Figure 5 is the picture of the water quality after treatment with the paint mist coagulant in the comparative example. Detailed Embodiments

[0031] For a better understanding of the present invention, the following examples are further descriptions of the present invention, but the content of the present invention is not limited to the following examples only.

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will further describe the present invention with reference to examples, but it is not a limitation to the present invention. The preparation steps of two-dimensional montmorillonite nanosheets in the present invention refer to the patent with the publication number CN114890433A.

[0033] Example 1

[0034] 1) Mix and stir a suspension of montmorillonite nanosheets with a diameter-to-thickness ratio of 50 - 120 and a mass fraction of 0.1% with triethanolamine as the enhancer in a mass ratio of montmorillonite nanosheets to the enhancer of 100:0.01 to obtain a composite two-dimensional montmorillonite nanosheet suspension.

[0035] 2) Mix and stir the composite two-dimensional montmorillonite nanosheet suspension with a binder (an aqueous polyethylene glycol solution with a mass fraction of 30%) in a volume ratio of 300:1 to obtain a composite two-dimensional montmorillonite paint mist coagulant.

[0036] 3) Add the above-prepared paint mist coagulant to industrial wastewater containing acrylic-based waterborne paint (the concentration of the waterborne paint wastewater is 8000 mg / L), and stir; after the paint mist coagulant is fully mixed with the waterborne paint wastewater, add an aqueous solution of cationic polyacrylamide with a mass fraction of 0.01%, stir, and let it stand. After the paint sludge floats to the surface, fish it out. The volume ratio of the paint mist coagulant, the aqueous solution of cationic polyacrylamide, and the industrial wastewater containing waterborne paint is 1:0.1:100. After testing, the paint mist removal rate is 98%, and the turbidity removal rate reaches 99%.

[0037] Figure 1 a and Figure 1 b are respectively the pictures of the water quality and flocs after treatment with the paint mist coagulant in Example 1. It can be seen from the pictures that: after treating the waterborne paint wastewater with the paint mist coagulant prepared by this technology, the water quality is clear, there is less foam, and the formed paint agglomerates are large and easy to fish out.

[0038] Example 2

[0039] 1) Mix and stir a suspension of montmorillonite nanosheets with a diameter-to-thickness ratio of 500 - 600 and a mass fraction of 5% with crown ether as the enhancer in a mass ratio of montmorillonite nanosheets to the enhancer of 100:20 to obtain a composite two-dimensional montmorillonite nanosheet suspension.

[0040] 2) Mix and stir the composite two-dimensional montmorillonite nanosheet suspension with a binder (an aqueous polyvinyl alcohol solution with a mass fraction of 0.01%) in a volume ratio of 0.1:1 to obtain a composite two-dimensional montmorillonite paint mist coagulant.

[0041] 3) Add the above-prepared paint mist coagulant into the industrial wastewater containing acid-alcohol type waterborne paint (the concentration of the waterborne paint wastewater is 1000 mg / L), and stir. After the paint mist coagulant and the waterborne paint wastewater are fully mixed, add an aqueous solution of cationic polyacrylamide with a mass fraction of 0.1%, stir, and let it stand. After the paint sludge floats to the surface, fish it out. The volume ratio of the paint mist coagulant, the aqueous solution of cationic polyacrylamide, and the industrial wastewater containing waterborne paint is 1:10:800. After testing, the paint mist removal rate is 97%, and the turbidity removal rate reaches 98%.

[0042] Example 3

[0043] 1) Mix and stir the montmorillonite nanosheet suspension with an aspect ratio of 700 - 800 and a mass fraction of 1% and the coupling agent aluminate ester according to the mass ratio of montmorillonite nanosheets to the coupling agent of 100:30 to obtain a composite two-dimensional montmorillonite nanosheet suspension.

[0044] 2) Mix and stir the composite two-dimensional montmorillonite nanosheet suspension and the binder (an aqueous solution of hydroxyethyl cellulose with a mass fraction of 3%) according to a volume ratio of 100:1 to obtain a composite two-dimensional montmorillonite paint mist coagulant.

[0045] 3) Add the above-prepared paint mist coagulant into the industrial wastewater containing acrylic acid type waterborne paint (the concentration of the waterborne paint wastewater is 1000 mg / L), and stir. After the paint mist coagulant and the waterborne paint wastewater are fully mixed, add an aqueous solution of cationic polyacrylamide with a mass fraction of 0.5%, stir, and let it stand. After the paint sludge floats to the surface, fish it out. The volume ratio of the paint mist coagulant, the aqueous solution of cationic polyacrylamide, and the industrial wastewater containing waterborne paint is 1:5:700. After testing, the paint mist removal rate is 98%, and the turbidity removal rate reaches 98%.

[0046] Figure 2 It is a picture of the flocs formed by the paint mist coagulant in Example 3 for treating acrylic acid type waterborne paint. It can be seen from the figure that the paint flocs formed after treating the waterborne paint wastewater with the paint mist coagulant prepared by this technology are large, have a compact structure, and are easy to fish out.

[0047] Example 4

[0048] 1) Mix and stir the montmorillonite nanosheet suspension with an aspect ratio of 200 - 300 and a mass fraction of 6% and the coupling agent sodium dodecyl sulfonate according to the mass ratio of montmorillonite nanosheets to the coupling agent of 100:50 to obtain a composite two-dimensional montmorillonite nanosheet suspension.

[0049] 2) Mix and stir the composite two-dimensional montmorillonite nanosheet suspension and the binder (an aqueous solution of polyethylene oxide with a mass fraction of 1%) according to a volume ratio of 200:1 to obtain a two-dimensional montmorillonite paint mist coagulant.

[0050] 3) Add the above-prepared paint mist coagulant to the industrial wastewater containing polyurethane-based waterborne paint (the concentration of the waterborne paint wastewater is 50,000 mg / L), and stir. After the paint mist coagulant and the waterborne paint wastewater are fully mixed, add an aqueous solution of cationic polyacrylamide with a mass fraction of 1%, stir, and let stand. After the paint sludge floats to the surface, fish it out. The volume ratio of the paint mist coagulant, the aqueous solution of cationic polyacrylamide, and the industrial wastewater containing waterborne paint is 1:2.5:400. After testing, the paint mist removal rate is 97%, and the turbidity removal rate reaches 95%.

[0051] Figure 3 It is a picture of the flocs formed by the paint mist coagulant in Example 4 for treating polyurethane-based waterborne paint. It can be seen from the picture that when the paint mist coagulant prepared by this technology is used to treat different types of waterborne paint wastewater, the treated paint flocs are large and have a compact structure, which is easy to fish out, indicating that the paint mist coagulant prepared by this technology has a wide adaptability.

[0052] Comparative Example

[0053] 1) Mix and stir the unpeeled montmorillonite suspension with a diameter-to-thickness ratio of 10 - 30 and a mass fraction of 0.1% and the reinforcing agent triethanolamine according to the mass ratio of montmorillonite to the reinforcing agent of 100:0.01 to obtain a composite montmorillonite suspension.

[0054] 2) Mix and stir the composite montmorillonite suspension and the binder (an aqueous solution of polyethylene glycol with a mass fraction of 30%) according to a volume ratio of 300:1 to obtain a montmorillonite paint mist coagulant.

[0055] 3) Add the above-prepared paint mist coagulant to the industrial wastewater containing acrylic-based waterborne paint (the concentration of the waterborne paint wastewater is 8,000 mg / L), and stir. After the paint mist coagulant and the waterborne paint wastewater are fully mixed, add an aqueous solution of cationic polyacrylamide with a mass fraction of 0.01%, stir, and let stand. After the paint sludge floats to the surface, fish it out. The volume ratio of the paint mist coagulant, the aqueous solution of cationic polyacrylamide, and the industrial wastewater containing waterborne paint is 1:0.1:100. After testing, the paint mist removal rate is 78%, and the turbidity removal rate is 70%.

[0056] Figure 5 It is a picture of the paint mist coagulant prepared with montmorillonite in the comparative example for treating acrylic-based waterborne paint wastewater. It can be seen from the picture that after treating the waterborne paint wastewater with the paint mist coagulant prepared with montmorillonite as the raw material, the water quality is relatively turbid, and the formed paint flocs are small, which is not conducive to fishing out. The treatment effect is far worse than that of the paint mist coagulant prepared with two-dimensional montmorillonite as the raw material.

[0057] The above is the preferred embodiment of the present invention, and of course, it cannot be used to limit the scope of the rights of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A preparation method of a composite two-dimensional montmorillonite paint mist coagulant, characterized in that, It includes the following steps: (1) Mix and react a two-dimensional montmorillonite nanosheet suspension with a reinforcing agent containing a hydrogen bond donor or acceptor functional group to obtain a composite two-dimensional montmorillonite nanosheet suspension; (2) Mix the composite two-dimensional montmorillonite nanosheet suspension obtained in step (1) with an aqueous binder solution evenly to obtain a composite two-dimensional montmorillonite paint mist coagulant; In the said step (1), the aspect ratio of the two-dimensional montmorillonite nanosheets is 50 - 800, and the mass percentage of the two-dimensional montmorillonite nanosheet suspension is 0.1% - 8%; the functional groups in the reinforcing agent containing a hydrogen bond donor or acceptor functional group are at least one of amino group, ether group, carboxyl group or sulfonic acid group, and the mass ratio of the two-dimensional montmorillonite nanosheets to the reinforcing agent is 100:0.01 - 50; In the said step (2), the binder is at least one of polyvinyl alcohol, polyethylene glycol, hydroxyethyl cellulose, polyethylene oxide, and poly maleic anhydride, and the mass percentage of the aqueous binder solution is 0.01% - 30%; the volume ratio of the composite two-dimensional montmorillonite nanosheet suspension to the aqueous binder solution is 0.1 - 300:1; The reinforcing agent containing an amino functional group is at least one of triethanolamine, acrylamide, isobutylamine, cyclohexylamine, and hexamethylenediamine; the reinforcing agent containing an ether functional group is at least one of vinyl ethyl ether, 18-crown-6, methyl sulfide, diethyl ether, and tetrahydrofuran; the reinforcing agent containing a carboxyl functional group is at least one of citric acid, benzoic acid, maleic acid, and phthalic acid; the reinforcing agent containing a sulfonic acid functional group is at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium hydroxymethyl sulfonate, methanesulfonic acid, and sodium petroleum sulfonate.

2. Application of a composite two-dimensional montmorillonite paint mist coagulant prepared by the preparation method as described in claim 1, characterized in that: The application method is to add the said composite two-dimensional montmorillonite paint mist coagulant into the industrial wastewater containing water-based paint. After the paint mist coagulant is fully mixed with the water-based paint wastewater, add an aqueous solution of cationic polyacrylamide, stir, stand, and fish out the paint sludge after it floats up.

3. Use of the composite two-dimensional montmorillonite paint mist coagulant according to claim 2, characterized in that: The said water-based paint is any one of acrylic type, alkyd type, polyurethane type, epoxy resin type, vinyl resin type, silicone resin type, and fluorocarbon resin type.

4. Use of the composite two-dimensional montmorillonite paint mist coagulant according to claim 2, characterized in that: The mass percentage of the said aqueous solution of cationic polyacrylamide is 0.01% - 1%, and the concentration of the industrial wastewater containing water-based paint is 1000 - 50000 mg / L.

5. Use of the composite two-dimensional montmorillonite paint mist coagulant according to claim 2, characterized in that: The volume ratio of the paint mist coagulant, the aqueous solution of cationic polyacrylamide, and the industrial wastewater containing water-based paint is 1:0.1 - 10:100 - 800.

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