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

Abstract

The invention belongs to the technical field of adsorbent preparation, and particularly relates to a preparation method and application of a lignin-based zero-swelling hydrogel adsorbent. Sodium lignin sulfonate, acrylic acid, acrylamide and polyethylene glycol are used as reactants, metal salt is used as a chelating agent, potassium peroxodisulfate is used as an initiator, water is used as a reaction medium, and the lignin-based zero-swelling hydrogel adsorbent is prepared through a cross-linking polymerization reaction, does not have a swelling phenomenon in the use process, and is high in adsorption capacity. According to the present invention, the adsorption effect is improved, the service life is prolonged, the good adsorption performance is provided, the pollutants in the water can be effectively removed, and the adsorption rate on the Ni < + > can achieve 400 mg / L.

Description

Technical Field

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

[0002] Many adsorbents currently on the market have serious swelling problems in practical applications. When the adsorbent is placed in water or a specific solution environment, due to its structural characteristics and material properties, it will absorb a large amount of liquid, resulting in a sharp expansion of volume. This swelling phenomenon will bring about many 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, which greatly reduces the adsorption capacity of the target pollutants. For example, when treating wastewater containing heavy metal ions, the adsorption amount of heavy metal ions by the swollen adsorbent may be reduced 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, and failing to achieve effective pollution control effects;

[0004] Frequent swelling and shrinking processes will gradually damage the structure of the adsorbent and reduce the mechanical strength of the material. In practical applications, this means that the adsorbent needs to be replaced more frequently, increasing treatment costs and operating difficulties. Taking industrial wastewater treatment as an example, traditional adsorbents may lose most of their adsorption properties due to swelling problems after 36 hours of use and have to be replaced.

[0005] The volume change of the swelled adsorbent is large, which may cause blockage and damage to the treatment equipment. In a continuously running water treatment system, this will increase the system downtime for maintenance and reduce production efficiency. At the same time, the unstable volume change also makes 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, plague 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, the steps comprising:

[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, wherein 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 the traditional cross-linking, has a higher bond energy and is not easy to break, and reduces the swelling characteristics of the gel; the 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 potassium persulfate to 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 sodium lignin sulfonate 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 polyethylene glycol will make the gel swell.

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

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

[0021] Mixing sodium lignin sulfonate with water, stirring to fully dissolve, and obtaining 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 them, and obtaining 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 400mg / L.

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

[0032] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0033] Figure 1 Examples 1-3 and Comparative Examples 1-3 were subjected to the same conditions for 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 should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

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

[0037] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation 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 a conflict with any incorporated document, the content 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 of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary 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 implementation scheme 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 by naked eyes.

[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 hours 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 weight of the hydrogels at different times was counted. The results are shown in Table 1.

[0062] Table 1

[0063]

[0064] It can be seen from the data in Table 1 that the mass of the hydrogel in Example 1 only increased by 0.034 g after being immersed in water for 48 hours, and no swelling occurred. When zinc chloride was replaced with manganese chloride (Example 3), the mass increase in 48 hours was only 0.673 g, and in Example 2, the swelling phenomenon was also not significant within 12 hours.

[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 Examples 1-3 and Comparative Examples 1-3 were subjected to the same conditions for Ni 2+ As can be seen from the figure, the hydrogels of Examples 1 and 2 of the present application have an adsorption capacity of 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 amount 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 amount of 763.21 mg / g decreased to 718.34 mg / g, which is still 94.13% of the initial amount.

[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 enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather 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, and a cross-linking polymerization reaction is performed to obtain the lignin-based zero-swelling hydrogel adsorbent; The metal salt includes zinc chloride, manganese chloride or nickel chloride.

2. The preparation method according to claim 1, characterized in that The mass ratio of the sodium lignin sulfonate to water is 1:

50.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the sodium lignin sulfonate, acrylic acid, acrylamide and polyethylene glycol is 10:5:5:

2.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the chelating agent to sodium lignin sulfonate is 1:

2.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the potassium persulfate to the sodium lignin sulfonate is 1:

4.

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

7. The lignin-based zero-swelling hydrogel adsorbent prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the lignin-based zero-swelling hydrogel adsorbent as claimed in claim 7 in water pollution treatment.

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