Preparation method and application of a lignin-based zero-swelling hydrogel adsorbent

Abstract

The application belongs to the technical field of adsorbent preparation, and more particularly relates to a preparation method and application of a lignin-based zero-swelling hydrogel adsorbent. The lignin-based zero-swelling hydrogel adsorbent is prepared by using sodium lignosulfonate, acrylic acid, acrylamide and polyethylene glycol as reactants, using a metal salt as a chelating agent, using potassium persulfate as an initiator, and using water as a reaction medium through a cross-linking polymerization reaction. In the use process, the lignin-based zero-swelling hydrogel adsorbent does not swell, improves the adsorption effect and service life, has good adsorption performance, and can effectively remove pollutants in water, especially the adsorption rate of Ni + can reach 400 mg / L.

Description

Technical Field

[0001] The present invention belongs to the technical field of adsorbent preparation, and more particularly relates to a preparation method and application of a lignin-based zero-swelling hydrogel adsorbent. Background Art

[0002] Many adsorbents currently on the market suffer from severe swelling issues in practical applications. When placed in water or a specific solution environment, the adsorbent absorbs a large amount of liquid due to its structural characteristics and material properties, causing a rapid expansion in volume. This swelling phenomenon can lead to a variety of adverse effects, such as:

[0003] The internal structure of the adsorbent changes after swelling, and the originally ordered adsorption sites may be destroyed or become disordered, significantly reducing the adsorption capacity of the target pollutants. For example, when treating wastewater containing heavy metal ions, the adsorption capacity of the swollen adsorbent for heavy metal ions may decrease by 20% to 30%. Swelling may also weaken the binding force between the adsorbent and the pollutants, making it easy for the adsorbed pollutants to be released back into the environment, failing to achieve effective pollution control results.

[0004] Frequent swelling and shrinkage gradually damage the adsorbent's structure and reduce the material's mechanical strength. In practical applications, this means the adsorbent needs to be replaced more frequently, increasing treatment costs and operational difficulties. For example, in industrial wastewater treatment, traditional adsorbents may lose most of their adsorption performance after just 36 hours of use due to swelling, necessitating replacement.

[0005] The swollen adsorbent undergoes significant volume changes, potentially causing blockage and damage to treatment equipment. In continuously operating water treatment systems, this can increase downtime for maintenance and reduce production efficiency. Furthermore, the unstable volume changes make the adsorbent difficult to control and manage during actual operation.

[0006] It can be seen that the problems caused by the swelling phenomenon, such as decreased adsorption performance, shortened service life and poor operational stability, have plagued the application of adsorbents in industrial production processes. Summary of the Invention

[0007] The purpose of the present invention is to provide a preparation method and application of a lignin-based zero-swelling hydrogel adsorbent to solve the problems existing in the above-mentioned prior art.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] One of the technical solutions of the present invention is to provide a method for preparing a lignin-based zero-swelling hydrogel adsorbent, comprising the following steps:

[0010] The lignin-based zero-swelling hydrogel adsorbent is obtained by cross-linking polymerization reaction using sodium lignin sulfonate, acrylic acid, acrylamide and polyethylene glycol as reactants, metal salt as a chelating agent, potassium persulfate as an initiator and water as a reaction medium.

[0011] Furthermore, the metal salt includes zinc chloride, manganese chloride or nickel chloride.

[0012] Optionally, the metal salt is zinc chloride.

[0013] In the present invention, the swelling problem of the hydrogel adsorbent during use is solved by the synergistic combination of sodium lignin sulfonate, acrylic acid, acrylamide and polyethylene glycol. Among them, sodium lignin sulfonate has a good adsorption effect, and the sulfonic acid group has good water absorption. The metal chelating agent enables the gel to be stably formed and the forming method is different from traditional cross-linking. It has higher bond energy and is not easy to break, thereby reducing the swelling characteristics of the gel. Polyethylene glycol further reduces its swelling characteristics.

[0014] Furthermore, the mass ratio of the sodium lignin sulfonate to water is 1:50.

[0015] Furthermore, the mass ratio of the sodium lignin sulfonate, acrylic acid, acrylamide and polyethylene glycol is 10:5:5:2.

[0016] Furthermore, the mass ratio of the metal salt to sodium lignin sulfonate is 1:2.

[0017] Furthermore, the mass ratio of the potassium persulfate to the sodium lignin sulfonate is 1:4.

[0018] According to the ratio of the components, too little sodium lignin sulfonate will make the gel unable to form, while too much will make the gel have better hydrophilicity; too little metal salt will make the gel difficult to form (thin packing); too much polyethylene glycol will make the gel amorphous, while too little will make the gel swell.

[0019] Furthermore, the cross-linking polymerization reaction is carried out at a temperature of 60° C. and for 3 hours.

[0020] A more preferred preparation method comprises the following steps:

[0021] Mixing sodium lignin sulfonate with water and stirring to fully dissolve the mixture to obtain a sodium lignin sulfonate solution;

[0022] Adding acrylic acid, acrylamide and polyethylene glycol to the sodium lignin sulfonate solution, stirring for 30 minutes to fully mix, to obtain a mixed solution;

[0023] adding a metal salt to the mixed solution and stirring to fully dissolve the metal salt to obtain a reaction solution;

[0024] adding potassium persulfate to the reaction solution and stirring to fully dissolve it to obtain an initiating solution;

[0025] The initiating solution was reacted in a water bath at 60° C. for 3 hours to obtain the lignin-based zero-swelling hydrogel adsorbent.

[0026] The second technical solution of the present invention is to provide a lignin-based zero-swelling hydrogel adsorbent prepared by the above preparation method.

[0027] The third technical solution of the present invention is to provide an application of the above-mentioned lignin-based zero-swelling hydrogel adsorbent in water pollution treatment.

[0028] Furthermore, the application is the treatment of water bodies polluted by heavy metals and / or water bodies containing organic pollutants.

[0029] The present invention discloses the following technical effects:

[0030] The lignin-based zero-swelling hydrogel adsorbent prepared by the present invention has good adsorption performance and can effectively remove pollutants in water. + The adsorption capacity can reach 400 mg / L.

[0031] The lignin-based zero-swelling hydrogel adsorbent prepared by the present invention does not swell during use, thereby improving the adsorption effect and service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0033] Figure 1 The Ni 2+ The adsorption results.

[0034] Figure 2 This is a comparison chart of the adsorption amount of the hydrogel prepared in Example 1 after 10 cycles of adsorption. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0037] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0038] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0040] The raw materials and reagents used in the specific embodiment of the present invention are all commercially available products, among which sodium lignin sulfonate is industrial grade with a purity of ≥90%; acrylic acid is analytical grade with a purity of ≥99%; acrylamide is analytical grade with a purity of ≥99%; polyethylene glycol has a molecular weight of 2000 and is analytical grade; zinc chloride is analytical grade with a purity of ≥98%; and potassium persulfate is analytical grade with a purity of ≥99%.

[0041] The zero swelling referred to in the present invention means that the original volume and mass are substantially maintained after absorbing the solvent, and no change can be observed with the naked eye.

[0042] Example 1

[0043] The preparation steps of the lignin-based zero-swelling hydrogel adsorbent are as follows:

[0044] S1. Add 2 g of sodium lignin sulfonate to 100 mL of deionized water and stir on a magnetic stirrer for 30 min to fully dissolve it to obtain a sodium lignin sulfonate solution;

[0045] S2, adding 5 g of acrylic acid, 5 g of acrylamide and 2 g of polyethylene glycol to the sodium lignin sulfonate solution of step S1, stirring on a magnetic stirrer for 30 min to fully mix, to obtain a mixed solution;

[0046] S3, adding 1 g of zinc chloride to the mixed solution of step S2, stirring on a magnetic stirrer for 30 min to fully dissolve it, to obtain a reaction solution;

[0047] S4, adding 0.5 g of potassium persulfate to the reaction solution of step S3, stirring on a magnetic stirrer for 10 min to fully dissolve it, to obtain an initiating solution;

[0048] S5. Pour the initiating solution of step S4 into a mold (size: 10 mm×10 mm×10 mm), place the mold in a constant temperature water bath, and react at 60° C. for 4 h to obtain a lignin-based zero-swelling hydrogel adsorbent.

[0049] Example 2

[0050] Same as Example 1, except that the added amount of sodium lignin sulfonate is 10 g.

[0051] Example 3

[0052] The difference from Example 1 is that the mass of zinc chloride is replaced by manganese chloride.

[0053] Comparative Example 1

[0054] Same as Example 1, except that the chelating agent zinc chloride is replaced by the cross-linking agent N,N-methylenebisacrylamide.

[0055] Comparative Example 2

[0056] Compared with Example 1, the difference is that sodium lignin sulfonate is replaced by alkali lignin.

[0057] When sodium lignin sulfonate was replaced with alkali lignin, the results showed that the gel did not form.

[0058] Comparative Example 3

[0059] Compared with Example 1, the difference is that polyethylene glycol is not added.

[0060] Test Example 1

[0061] The hydrogels prepared in Examples 1 to 3, Comparative Example 1 and Comparative Example 3 were immersed in deionized water, and the mass of the hydrogels at different times was counted. The results are shown in Table 1.

[0062] Table 1

[0063]

[0064] As can be seen from the data in Table 1, the mass of the hydrogel in Example 1 increased by only 0.034 g after immersion in water for 48 h, and no swelling occurred. When zinc chloride was replaced with manganese chloride (Example 3), the mass increase in 48 h was only 0.673 g. In Example 2, the swelling phenomenon was also maintained within 12 h without significant change.

[0065] Test Example 2

[0066] Adsorption effect experiment

[0067] The hydrogels prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to Ni 2+ Adsorption was performed, wherein the adsorption conditions were Ni 2+ The initial concentration was 500 mg / L, the temperature was 25°C, and the adsorption time was 20 min. The results were as follows: Figure 1 shown.

[0068] Figure 1 The Ni 2+ As can be seen from the figure, the hydrogels of Examples 1 and 2 of the present application have an adsorption effect on Ni 2+ Has excellent adsorption effect.

[0069] Test Example 3

[0070] Adsorption stability experiment

[0071] The adsorption was repeated 10 times according to the method of Experimental Example 2 to determine the adsorption stability of the hydrogel prepared in Example 1. The results are as follows: Figure 2 shown.

[0072] Figure 2 This is a comparison chart of the adsorption capacity of the hydrogel prepared in Example 1 after 10 cycles of adsorption. As can be seen from the figure, after 10 cycles, the initial adsorption capacity of 763.21 mg / g decreased to 718.34 mg / g, which is still 94.13% of the initial adsorption capacity.

[0073] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0074] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a lignin-based zero-swelling hydrogel adsorbent, characterized in that the steps include: Sodium lignin sulfonate, acrylic acid, acrylamide and polyethylene glycol are used as reactants, metal salt is used as a chelating agent, potassium persulfate is used as an initiator, and water is used as a reaction medium. Through a cross-linking polymerization reaction, the lignin-based zero-swelling hydrogel adsorbent is obtained; The metal salt includes zinc chloride, manganese chloride or nickel chloride; The mass ratio of the sodium lignin sulfonate to water is 1:50; The mass ratio of the sodium lignin sulfonate, acrylic acid, acrylamide and polyethylene glycol is 10:5:5:2; The mass ratio of the chelating agent to sodium lignin sulfonate is 1:2; The mass ratio of the potassium persulfate to the sodium lignin sulfonate is 1:

4.

2. The preparation method according to claim 1, wherein The cross-linking polymerization reaction was carried out at a temperature of 60° C. and for 3 hours.

3. The lignin-based zero-swelling hydrogel adsorbent prepared by the preparation method according to claim 1 or 2.

4. Use of the lignin-based zero-swelling hydrogel adsorbent as claimed in claim 3 in water pollution treatment.

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