Juncus roemerianus-based water absorbing material as well as preparation and application thereof

Abstract

The invention discloses a juncus roemerianus-based water absorbing material and preparation and application thereof, a chlorite solution with a certain concentration is prepared, the pH value of the solution is adjusted to 3-6 with glacial acetic acid, then a proper amount of juncus roemerianus is added, and the mixture is subjected to a delignification reaction at a set temperature. And taking out the reacted juncus roemerianus, washing and drying to obtain the juncus roemerianus-based water absorbing material. The juncus roemerianus-based water-absorbing material adopts renewable resources as raw materials, and is natural and environment-friendly; the preparation method is simple; the acidic sodium chlorite can completely retain the natural three-dimensional network structure of the juncus roemerianus while selectively removing lignin; the finally prepared water absorbing material is good in salt resistance and good in reusability; and even if the material is broken, fibrous chips cannot be generated.

Description

Technical Field

[0001] The invention belongs to the technical field of functionalization and high-value application of cellulose resources, and specifically discloses a rush-based water-absorbing material and a preparation method and application thereof. Background Art

[0002] Water-absorbing materials, hydrophilic materials with three-dimensional cross-linked structures, have been widely used in personal care products, agriculture, biomedical applications, heavy metal adsorption, and drug delivery. However, the vast majority of reported water-absorbing materials are synthetic polymers based on petrochemicals, particularly acrylic acid and its copolymer with acrylamide. These are not only expensive to prepare, difficult to biodegrade, but also potentially biotoxic.

[0003] Cellulose is the most abundant renewable resource in nature, with advantages such as wide availability, low price, and biodegradability. However, the preparation of cellulose-based water-absorbing materials reported so far usually requires dissolving or nano-processing the cellulose first, and then obtaining it through reactions such as cross-linking and grafting. The preparation process is cumbersome, consumes a lot of process chemicals, and is costly. Therefore, exploring cellulose-based water-absorbing materials with simple raw materials, simple preparation processes, and strong water-absorbing properties has broad application prospects. Rush is a perennial herb that mostly grows in swamps and wetlands. It has a three-dimensional network structure, high surface area and porosity, and is a very promising natural cellulose-based water-absorbing material. However, because rush fiber contains lignin, it has poor wettability and is hydrophobic, making it difficult to use it directly as a water-absorbing material.

[0004] Based on this, the present invention discloses a method and application for preparing a water-absorbing material using rush, effectively solving the technical problem of poor wettability. The material has a three-dimensional network structure, good salt tolerance and repeated water absorption performance, and the preparation method is simple and low-cost. Summary of the Invention

[0005] Based on the above analysis, the present invention utilizes acidic sodium chlorite to selectively remove lignin from rush, producing a rush-based water-absorbing material with a three-dimensional network structure. This method is simple, and the resulting water-absorbing material is readily biodegradable, exhibits excellent salt tolerance, and is reusable. Furthermore, even if the rush-based water-absorbing material breaks, it does not produce fibrous debris.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] The present invention first discloses a method for preparing a rush-based water-absorbing material, comprising the following steps:

[0008] (1) Prepare a chlorite solution of a certain concentration and adjust the pH value of the solution to 3-6 with glacial acetic acid;

[0009] (2) adding a certain amount of rush to the chlorite solution and setting the corresponding temperature to carry out the delignification reaction;

[0010] (3) After the reaction is completed, the rush is taken out, washed and dried to obtain the rush-based water-absorbing material.

[0011] Furthermore, the mass concentration of the chlorite solution in step (1) is 0.25%-4%.

[0012] Furthermore, the mass concentration of the chlorite solution is 1%.

[0013] Furthermore, in step (1), the pH value of the solution is adjusted to 4.5 with glacial acetic acid.

[0014] Furthermore, the amount of rush added in step (2) is 5g / L-50g / L.

[0015] Furthermore, the addition amount of the rush is 5 g / L.

[0016] Furthermore, the corresponding temperature in step (2) is 50-100° C., and the reaction time is 0.5-3 h.

[0017] Furthermore, the corresponding temperature is 80° C. and the reaction time is 2 h.

[0018] The present invention also discloses a rush-based water-absorbing material prepared according to any of the above preparation methods.

[0019] The present invention also discloses an application of the rush-based water-absorbing material in preparing personal care products, surgical absorbent materials, and heavy metal adsorbents.

[0020] The beneficial effects of the present invention are:

[0021] The rush-based water-absorbing material used in the present invention uses renewable resources as raw materials, is natural and environmentally friendly, and has a simple preparation method. Acidic sodium chlorite can fully retain the natural three-dimensional network structure of rush while selectively removing lignin. The resulting water-absorbing material has good salt resistance and good reusability. Even if the material is broken or fractured, it will not produce fibrous debris. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 a and Figure 1 b are actual photos of rush and the rush-based water-absorbing material prepared in Example 4, respectively.

[0023] Figure 2 SEM images of rush (a, b) and SEM images of the rush-based water-absorbing material prepared in Example 4 (c, d).

[0024] Figure 3 FTIR patterns of rush and the rush-based water-absorbing material prepared in Example 4.

[0025] Figure 4 XRD patterns of rush and the rush-based water-absorbing material prepared in Example 4.

[0026] Figure 5 Water absorption of the rush-based water-absorbing material prepared in Example 4 in NaCl solutions of different concentrations.

[0027] Figure 6 Repeated water absorption of the rush-based water-absorbing material prepared in Example 4 in 0.9% physiological saline.

[0028] Figure 7 A photograph of the rush-based water-absorbing material prepared in Example 4 after repeated water absorption 100 times in 0.9% saline. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0030] Example 1

[0031] (1) Prepare chlorite solutions with a mass concentration of 1%, and adjust the pH values of the solutions to pH = 3, 4, 4.5, 5, 6 and 7 respectively with glacial acetic acid.

[0032] (2) Add 0.5 g of rush to each 100 mL of the sodium chlorite solution with the pH adjusted in step (1).

[0033] (3) The mixture of step (2) was placed in a constant temperature water bath at 80°C for 2 h.

[0034] (4) washing and drying the rush after the reaction in step (3) to obtain the rush-based water-absorbing material.

[0035] Under the conditions of pH = 3, 4, 4.5, 5, 6 and 7, the water absorption capacity of the prepared rush-based water-absorbing material for deionized water was 45.56 g / g, 52.93 g / g, 53.73 g / g, 47.22 g / g and 39.60 g / g respectively.

[0036] Example 2

[0037] (1) Prepare chlorite solutions with mass concentrations of 0.25%, 0.5%, 0.75%, 1% and 2%, and adjust the pH of the solution to 4.5 with glacial acetic acid.

[0038] (2) Add 0.5 g of rush to each 100 mL of the sodium chlorite solution with the pH adjusted in step (1).

[0039] (3) The mixture of step (2) was placed in a constant temperature water bath at 80°C for 2 h.

[0040] (4) washing and drying the rush after the reaction in step (3) to obtain the rush-based water-absorbing material.

[0041] When the concentration of the chlorite solution is 0.25%, 0.5%, 1%, 2% and 4%, respectively, the water absorption capacity of the prepared rush-based water-absorbing material for deionized water is 50.63 g / g, 50.09 g / g, 54.06 g / g and 48.82 g / g, respectively.

[0042] Example 3

[0043] (1) Prepare a chlorite solution with a mass concentration of 1% and adjust the pH value of the solution to 4.5 with glacial acetic acid.

[0044] (2) To three portions of the sodium chlorite solution adjusted to the pH value in step (1), 100 mL each, 0.5 g of rush was added to each portion.

[0045] (3) The mixture of step (2) was placed in a constant temperature water bath at 50°C, 60°C, 80°C and 100°C for different reaction times.

[0046] (4) washing and drying the rush after the reaction in step (3) to obtain the rush-based water-absorbing material.

[0047] When the concentration of the chlorite solution is 1%, the amount of water absorbed by the rush-based water-absorbing materials prepared under different temperatures and reaction times is shown in Table 1.

[0048] Table 1 Water absorption of rush-based water-absorbing materials prepared under different temperature and reaction time conditions

[0049] Temperature / ℃ 50 60 80 80 80 100 100 Reaction time 3h 3h 1h 2h 3h 5min 10min Water absorption (g / g) 44.35 46.58 52.75 54.20 53.06 48.09 50.07

[0050] The results in Table 1 show that the maximum water absorption by the rush base was achieved when the rush dosage was 5 g / L, the chlorite solution concentration was 1%, the reaction temperature was 80°C, and the reaction time was 2 h. Based on these results, we further completed Example 4.

[0051] Example 4

[0052] A rush-based water-absorbing material was prepared under the conditions of a chlorite solution concentration of 1%, a solution pH of 4.5, a reaction temperature of 80° C., and a reaction time of 2 h.

[0053] Figure 1 a and Figure 1 Figures b and c show photos of rush and the rush-based absorbent material prepared in this example. As can be seen, the rush is light yellow and somewhat flexible. After delignification with 1% acidic sodium chlorite, the resulting rush-based absorbent material turns white and exhibits increased flexibility.

[0054] Figure 2 The SEM images of rush and rush-based water-absorbing material prepared in this embodiment are shown. It can be seen that rush has a natural three-dimensional network and interconnected pipeline structure, and the surface of rush fiber is relatively smooth (such as Figure 2 After delignification with 1% acidic sodium chlorite, the rush-based water-absorbing material retained the complete three-dimensional network structure of rush, but wrinkles appeared on the surface of rush fibers (such as Figure 2 c, as shown in 2d).

[0055] Figure 3 The FTIR images of rush and rush-based water-absorbing material prepared in this example are shown. It can be seen that after delignification with 1% acidic sodium chlorite, the absorption peak intensity representing different functional groups on the surface of the material shows obvious changes. Among them, the peak at 3332 cm -1 The strong absorption peak at 1506 cm-1, which is attributed to the stretching vibration of hydroxyl (-OH), is significantly enhanced after delignification, indicating that the hydrophilicity of the material is enhanced. -1 The characteristic peak representing the stretching vibration of the C=C bond in the benzene ring skeleton of lignin almost disappeared, confirming that the lignin in the rush was removed.

[0056] Figure 4 The XRD patterns of rush and the rush-based water-absorbing material prepared in this example are shown below. Compared to rush, the rush-based water-absorbing material exhibits a higher and sharper diffraction peak at a diffraction angle of 2θ = 22.5°, indicating an increase in the material's crystallinity. This is due to the removal of amorphous lignin, which increases the content of crystalline cellulose.

[0057] In summary, acidic sodium chlorite treatment not only selectively removes lignin from rush, improving the hydrophilicity of rush fibers, but also fully preserves the natural three-dimensional network structure of rush. All of these provide strong support for the preparation of rush-based water-absorbing materials.

[0058] Test Example 1

[0059] Using deionized water, tap water, 0.9% saline, and simulated plasma as experimental media, the water absorption capacity of the rush-based absorbent material prepared in Example 4, along with absorbent cotton, gauze, napkins, and rush, was measured three times in different media. The first cycle involved directly placing the dry material into the media. The second and third cycles involved squeezing and dehydrating the material after the previous absorption, before adding it to the media as the starting material. The experimental results are listed in Tables 2, 3, 4, and 5, respectively.

[0060] Table 2 Water absorption of different materials in deionized water

[0061]

[0062]

[0063] Table 3 Water absorption of different materials in tap water

[0064]

[0065] Table 4 Water absorption of different materials in normal saline (0.9%)

[0066]

[0067] Table 5 Water absorption of different materials in simulated plasma

[0068]

[0069] It can be seen that among the five materials in the experiment, the rush-based absorbent material prepared in this project not only has the highest water absorption capacity, but also has a small difference in water absorption between dry and wet states. In comparison, the three common absorbent materials (absorbent cotton, gauze and napkins) significantly reduced their water absorption in the second experiment, especially the absorbent cotton, which reduced its water absorption by more than 50%. The reason why the water absorption of rush becomes abnormal with the increase in the number of experiments is that rush fibers have a certain hydrophobicity. As the soaking time increases, its hydrophobic surface is gradually wetted, but its saturated water absorption capacity is only 28.39g / g. In addition, the rush-based absorbent material absorbs water very quickly. After contacting the above four liquids, it can instantly absorb them and reach saturation in <1s.

[0070] Test Example 2

[0071] The salt tolerance test of the rush-based water-absorbing material prepared in Example 4 was carried out. The specific operation was as follows: 0%, 0.9%, 5% and 10% NaCl solutions were prepared. After that, the rush-based water-absorbing material was placed in NaCl solutions of different concentrations and its water absorption was measured. The results are as follows: Figure 5As shown in the figure, the prepared rush-based water-absorbing material has good salt tolerance. When the NaCl concentration in the solution increases from 0% to 10%, the water absorption rate of the rush-based water-absorbing material decreases by less than 5%.

[0072] Test Example 3

[0073] The rush-based water-absorbing material prepared in Example 4 was subjected to repeated water absorption experiments. The specific operation was as follows: the rush-based water-absorbing material was placed in 0.9% saline, and after saturation, it was removed, squeezed to dehydrate, and then placed in 0.9% saline. This cycle was repeated 100 times, and the water absorption was measured at the same time. The results are as follows: Figure 6 .

[0074] It can be seen that after 100 cycles of water absorption, squeezing, dehydration, and water absorption in saline, the water absorption of the rush-based absorbent material only showed a significant decrease in the second cycle, and then showed only slight fluctuations, with the maximum reduction rate of water absorption being only 6.51%. At the same time, its structure remained stable. Although a small amount of it broke into segments, it did not lose fiber debris like ordinary fiber products (such as Figure 7 ).

[0075] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A method for preparing a rush-based water-absorbing material, comprising: (1) Prepare a chlorite solution of a certain concentration and adjust the pH value of the solution to 3-6 with glacial acetic acid; (2) adding an appropriate amount of rush to the chlorite solution and then performing delignification reaction at a set temperature; (3) After the reaction is completed, the rush is taken out, washed and dried to obtain the rush-based water-absorbing material.

2. The preparation method according to claim 1, wherein: The mass concentration of the chlorite solution in step (1) is 0.25%-4%.

3. The preparation method according to claim 2, wherein: The mass concentration of the chlorite solution is 1%.

4. The preparation method according to claim 1, wherein: In step (1), the pH value of the solution is adjusted to 4.5 with glacial acetic acid.

5. The preparation method according to claim 1, wherein: The amount of rush added in step (2) is 5g / L-50g / L.

6. The preparation method according to claim 5, wherein: The addition amount of the rush is 5 g / L.

7. The preparation method according to claim 1, wherein: The corresponding temperature in step (2) is 50-100° C., and the reaction time is 0.5-3 h.

8. The preparation method according to claim 7, wherein: The corresponding temperature is 80° C. and the reaction time is 2 h.

9. A rush-based water-absorbing material prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the rush-based water-absorbing material according to claim 9 in the preparation of personal care products, surgical absorbent materials, and heavy metal adsorbents.

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