Cyclodextrin-based adsorption hydrogel as well as preparation method and application thereof

Abstract

The invention provides cyclodextrin-based adsorption hydrogel as well as a preparation method and application thereof, and belongs to the technical field of adsorption materials. The preparation method of the cyclodextrin-based adsorption hydrogel comprises the following steps: mixing acrylic acid with a neutralizer, carrying out a neutralization reaction, adding alpha-cyclodextrin, carboxymethyl chitosan, sodium 4-styrene sulfonate, a cross-linking agent and an initiator into a reaction system, and carrying out a free radical polymerization reaction to obtain the cyclodextrin-based adsorption hydrogel. The maximum adsorption capacity of the prepared cyclodextrin-based adsorption hydrogel adsorbent for norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions under low concentration can reach 800 mg / g or above, and the removal rate of norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions within 3 hours can reach 85% or above. Compared with a common multifunctional adsorption material in the market, the adsorbent has extremely high adsorption performance and removal efficiency, and also has a relatively high adsorption rate.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorption materials, and particularly relates to a cyclodextrin-based adsorbent hydrogel, a preparation method thereof, and an application thereof. Background Art

[0002] Environmental pollution has now become a major challenge to the ecosystem. The main reason is the large amount of domestic sewage and industrial wastewater discharged, resulting in the continuous accumulation of pollutants in the soil and rivers. Common pollutants in these environments include heavy metals, dyes, and organic pollutants. They not only accumulate in plants but also enter the human body directly or indirectly through the food chain cycle, posing a potential threat to human health. To address this problem, various pollutant treatment technologies have been studied, including advanced oxidation processes, membrane technologies, coagulation precipitation methods, and adsorption methods. However, most of these methods have limitations such as high cost, difficult operation, and poor biodegradability. In contrast, the adsorption method has received extensive attention due to its simple operation, high efficiency, and excellent economy. However, the current adsorption materials generally have the problem of small adsorption capacity and are difficult to effectively remove pollutants. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a cyclodextrin-based adsorbent hydrogel, a preparation method thereof, and an application thereof.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] One of the technical solutions of the present invention is a preparation method of a cyclodextrin-based adsorbent hydrogel, comprising the following steps:

[0006] Mix acrylic acid with a neutralizing agent and then carry out a neutralization reaction. After that, add α-cyclodextrin, carboxymethyl chitosan, 4-styrenesulfonic acid sodium, a crosslinking agent, and an initiator to the reaction system and carry out a free radical polymerization reaction to obtain the cyclodextrin-based adsorbent hydrogel.

[0007] Another technical solution of the present invention is a cyclodextrin-based adsorbent hydrogel prepared by the above preparation method.

[0008] Another technical solution of the present invention is an application of the above cyclodextrin-based adsorbent hydrogel in adsorbing wastewater pollutants; the pollutants are antibiotics, dyes, or heavy metals.

[0009] The present invention discloses the following technical effects:

[0010] The maximum adsorption capacities of the cyclodextrin-based adsorbent hydrogel prepared by the present invention for norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions at low concentrations can reach over 800 mg / g. The removal rates of norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions are high within 3 h. Compared with common multifunctional adsorption materials on the market, it not only has extremely high adsorption performance and removal efficiency, but also has a fast adsorption rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0012] Figure 1 It is a schematic diagram for the preparation of the cyclodextrin adsorbent hydrogel;

[0013] Figure 2 It is the infrared spectrum diagram of the cyclodextrin-based adsorbent hydrogel obtained in Example 1;

[0014] Figure 3 It is the XRD diagram of the cyclodextrin-based adsorbent hydrogel obtained in Example 1;

[0015] Figure 4 It is the scanning electron microscope diagram of the cyclodextrin-based adsorbent hydrogel obtained in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0016] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and implementation manners of the present invention.

[0017] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0018] Unless otherwise specified, 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. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0019] Without departing from the scope or spirit of this invention, various modifications and variations can be made to the specific embodiments of the specification of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of this invention are obvious to those skilled in the art. The specification and examples of this invention are merely exemplary.

[0020] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0021] Cyclodextrin (CD) is a cyclic oligosaccharide obtained by the degradation of amylase. The hydrophobic cavity structure of cyclodextrin enables it to match with molecules of appropriate size and polarity and form host-guest interactions. In particular, it shows significant adsorption capacity for aromatic organic pollutants. The abundant hydroxyl groups on its surface can also form coordination complexes and electrostatic attractions with heavy metal ions. These two characteristics can both illustrate the potential of cyclodextrin-based adsorbents in achieving efficient adsorption of organic pollutants and heavy metals.

[0022] Carboxymethyl chitosan (CMS) is a chemically modified derivative of chitosan. Its active functional groups (amino group, hydroxyl group, carboxyl group) can interact with heavy metal ions and organic pollutants through chelation, electrostatic force, and hydrogen bonding, thereby improving the adsorption efficiency.

[0023] This invention introduces α-CD into CMS, making up for the deficiency of CMS in the adsorption of organic pollutants. This cyclodextrin-based composite hydrogel has application potential in the field of simultaneously adsorbing multiple pollutants.

[0024] The first aspect of this invention provides a preparation method of a cyclodextrin-based adsorbent hydrogel, comprising the following steps:

[0025] Mix acrylic acid (AA) with a neutralizing agent and carry out a neutralization reaction. Then, add α-cyclodextrin (α-CD), carboxymethyl chitosan (CMS), sodium 4-styrenesulfonate (SS), a cross-linking agent, and an initiator into the reaction system, and carry out a radical polymerization reaction to obtain the cyclodextrin-based adsorbent hydrogel.

[0026] In a preferred embodiment of the present invention, the neutralizing agent is sodium hydroxide; the dosage of the neutralizing agent is added according to the neutralization degree of acrylic acid being 5-30%.

[0027] In a preferred embodiment of the present invention, the dosage of the neutralizing agent is added according to the neutralization degree of acrylic acid being 5-20%.

[0028] In a preferred embodiment of the present invention, the dosage of the neutralizing agent is added according to the neutralization degree of acrylic acid being 10%.

[0029] In the present invention, if the neutralization degree of acrylic acid exceeds the above parameter range, the adsorption performance of the obtained cyclodextrin-based adsorbent hydrogel will be significantly reduced.

[0030] In a preferred embodiment of the present invention, the molar ratio of acrylic acid to sodium 4-styrenesulfonate is 1:1-13:1.

[0031] In a preferred embodiment of the present invention, the molar ratio of acrylic acid to sodium 4-styrenesulfonate is 7:1-10:1.

[0032] In a preferred embodiment of the present invention, the molar ratio of acrylic acid to sodium 4-styrenesulfonate is 8:1.

[0033] In the present invention, if the molar ratio of acrylic acid to sodium 4-styrenesulfonate exceeds the above range, the adsorption performance of the obtained cyclodextrin-based adsorbent hydrogel for norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions will be significantly decreased.

[0034] In a preferred embodiment of the present invention, the dosage of α-cyclodextrin is 0.1%-1.2% of the total molar amount of acrylic acid and sodium 4-styrenesulfonate.

[0035] In a preferred embodiment of the present invention, the dosage of α-cyclodextrin is 0.6%-0.8% of the total molar amount of acrylic acid and sodium 4-styrenesulfonate.

[0036] In a preferred embodiment of the present invention, the molar ratio of α-cyclodextrin to carboxymethyl chitosan is 3:1-4:1. In the present invention, the prepared cyclodextrin-based adsorbent hydrogel mainly selectively adsorbs small molecule organic pollutants, and the cavity of α-cyclodextrin is more compatible with small molecule aromatic groups. Therefore, α-cyclodextrin is selected in the present invention; carboxymethyl chitosan is soluble in water, and compared with chitosan, carboxymethyl chitosan has more adsorption sites. Therefore, carboxymethyl chitosan is selected in the present invention.

[0037] In a preferred embodiment of the present invention, the crosslinking agent is N,N'-methylenebisacrylamide; the initiator is potassium persulfate; the crosslinking agent is 0.05% - 0.5% of the total molar amount of acrylic acid and sodium 4-styrenesulfonate; the initiator is 0.1 - 0.8% of the total molar amount of acrylic acid and sodium 4-styrenesulfonate.

[0038] In a preferred embodiment of the present invention, the crosslinking agent is 0.2% - 0.3% of the total molar amount of acrylic acid and sodium 4-styrenesulfonate; the initiator is 0.6 - 0.7% of the total molar amount of acrylic acid and sodium 4-styrenesulfonate.

[0039] In the present invention, if the dosage of the crosslinking agent exceeds the above parameter range, the adsorption performance of the resulting cyclodextrin-based adsorbent hydrogel for pollutants will be reduced.

[0040] If the dosage of the initiator is higher than the above parameters, it will cause the polymerization reaction to be too fast, thereby reducing the adsorption capacity of the resulting cyclodextrin-based adsorbent hydrogel for norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions.

[0041] In a preferred embodiment of the present invention, the temperature of the free radical polymerization reaction is 70 - 80 °C and the time is 30 - 40 min.

[0042] The second aspect of the present invention provides a cyclodextrin-based adsorbent hydrogel prepared by the above preparation method.

[0043] The adsorbent prepared by the present invention contains a large number of hydroxyl groups, carboxyl groups and sulfonic acid groups, which have hydrogen bond interactions and electrostatic interactions with pollutant molecules, while α-cyclodextrin can form host-guest inclusion interactions with antibiotic and dye molecules.

[0044] The third aspect of the present invention provides an application of the above cyclodextrin-based adsorbent hydrogel in adsorbing wastewater pollutants; the pollutants are antibiotics, dyes or heavy metals.

[0045] In a preferred embodiment of the present invention, the antibiotic is at least one of norfloxacin, tetracycline hydrochloride and procaine; the dye is methylene blue; the heavy metal is manganese ions and / or copper ions.

[0046] In a preferred embodiment of the present invention, the dosage of the cyclodextrin-based adsorbent hydrogel is: 20 - 25 mg of the cyclodextrin-based adsorbent hydrogel is added to every 20 ml of wastewater.

[0047] The technical solutions of the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are all purchased from commercial channels or have been made public.

[0048] In the examples, the removal rate Removal (%) and the adsorption capacity Qe (mg / g) were calculated by the following formulas:

[0049]

[0050] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with examples. However, the content of the present invention is not limited to the following examples only.

[0051] Example 1

[0052] Dissolve 0.3501 g of sodium hydroxide in 3 mL of deionized water, mix it evenly with 6 mL of AA for a neutralization reaction (neutralization degree 10%), then add 2.2552 g of sodium 4-styrenesulfonate (the molar ratio of AA to sodium 4-styrenesulfonate is 8:1), 0.01 g of carboxymethyl chitosan and 0.1158 g of α-cyclodextrin to the reaction system, and place the mixed solution in a three-necked flask and stir; introduce nitrogen into the system. When the temperature reaches 75 °C, first add 0.044 g of N,N'-methylenebisacrylamide and stir for 10 min, and finally add 0.1597 g of potassium persulfate. The polymerization reaction time is 20 min. After the reaction is completed, the obtained product is washed with absolute ethanol, dried at 60 °C and pulverized to obtain adsorbent particles (i.e., cyclodextrin-based adsorbent hydrogel).

[0053] As Figure 2 、 3 shown in the infrared spectrum, XRD spectrum, and scanning electron microscope image of 4, the characteristic peaks of α-cyclodextrin are obvious, proving the successful synthesis of this material.

[0054] Adsorption performance test: Under the condition that the pH is equal to 5, 20 mg of adsorbent was added to 20 ml of norfloxacin (concentration 10 mg / ml), tetracycline hydrochloride (concentration 2.5 mg / ml), procaine (concentration 10 mg / ml), methylene blue (concentration 500 mg / ml), manganese ions (concentration 10 mg / ml) and copper ions (concentration 25 mg / ml) solutions respectively for the adsorption performance test. At 3 h, the adsorption of the adsorbent to each pollutant had reached basic stability, and the pollutant removal rate at this time was measured. The results showed that within 3 h, the removal rates of 10 mg / L norfloxacin, 2.5 mg / L tetracycline hydrochloride, 10 mg / L procaine, 500 mg / L methylene blue, 10 mg / L manganese ions and 25 mg / L copper ions solutions were 99.6%, 84.8%, 97.1%, 99.6%, 97.6% and 99.2% respectively. For pollutants with an initial concentration of 2000 mg / L, the maximum adsorption capacities of this adsorption hydrogel for norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions could reach 861.48, 924.94, 829.84, 1667.52, 1054.87 and 1226.00 mg / g;

[0055] Example 2

[0056] The difference from Example 1 was only that the molar ratio of AA and sodium 4-styrenesulfonate was adjusted from "8:1" to "10:1", and other steps and parameters were the same as those in Example 1.

[0057] The adsorption hydrogel obtained in this example was subjected to the same adsorption performance test as in Example 1. The results showed that for the adsorption experiment of the obtained adsorption hydrogel on each pollutant, within 3 h, the removal rates of norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions solutions were 92.4%, 33.9%, 38.4%, 94.7%, 89.5% and 95.8% respectively.

[0058] Example 3

[0059] The difference from Example 1 was only that the mass of N,N'-methylenebisacrylamide was adjusted from "0.044 g" to "0.0379 g", and other steps and parameters were the same as those in Example 1.

[0060] The adsorption hydrogel obtained in this example was subjected to the same adsorption performance test as in Example 1. The results showed that for the adsorption experiment of the obtained adsorption hydrogel on norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions, within 3 h, the removal rates of norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions solutions were 95.9%, 76.6%, 78.1%, 99.6%, 93.0% and 96.3% respectively.

[0061] Example 4

[0062] The difference from Example 1 is only that the mass of potassium persulfate is adjusted from "0.1597 g" to "0.1331 g".

[0063] The adsorption hydrogel obtained in this example was subjected to the same adsorption performance test as in Example 1. The results showed that the obtained adsorption hydrogel was used for the adsorption experiments of norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ions. The removal rates of norfloxacin, tetracycline hydrochloride, procaine, methylene blue, manganese ions and copper ion solutions within 3 h were 96.9%, 72.7%, 75.8%, 96.5%, 92.4% and 93.5% respectively.

[0064] It can be seen from the above examples that the adsorption hydrogel prepared by the present invention has high adsorption performance and fast adsorption rate, and has broad application prospects.

[0065] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a cyclodextrin-based adsorbent hydrogel, characterized in that, It includes the following steps: Mix acrylic acid with a neutralizing agent and conduct a neutralization reaction. Then, add α-cyclodextrin, carboxymethyl chitosan, sodium 4-styrenesulfonate, a crosslinking agent, and an initiator to the reaction system to conduct a free radical polymerization reaction to obtain the cyclodextrin-based adsorbent hydrogel.

2. The preparation method according to claim 1, characterized in that, The neutralizing agent is sodium hydroxide; the dosage of the neutralizing agent is added according to the neutralization degree of acrylic acid being 5-30%.

3. The preparation method according to claim 1, characterized in that, The molar ratio of acrylic acid to sodium 4-styrenesulfonate is 1:1-13:1; the dosage of α-cyclodextrin is 0.1%-1.2% of the total molar amount of acrylic acid and sodium 4-styrenesulfonate; the molar ratio of α-cyclodextrin to carboxymethyl chitosan is 3:1-4:

1.

4. The preparation method according to claim 1, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide; the initiator is potassium persulfate; the crosslinking agent is 0.05%-0.5% of the total molar amount of acrylic acid and sodium 4-styrenesulfonate; the initiator is 0.1%-0.8% of the total molar amount of acrylic acid and sodium 4-styrenesulfonate.

5. The preparation method according to claim 1, characterized in that, The temperature of the free radical polymerization reaction is 70-80°C, and the time is 30-40 min.

6. A cyclodextrin-based adsorbent hydrogel prepared by the preparation method according to any one of claims 1-5.

7. An application of the cyclodextrin-based adsorbent hydrogel according to claim 6 in adsorbing wastewater pollutants; the pollutants are antibiotics, dyes, or heavy metals.

8. The application according to claim 7, wherein The antibiotics are at least one of norfloxacin, tetracycline hydrochloride, and procaine; the dye is methylene blue; the heavy metals are manganese ions and / or copper ions.

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