Preparation method and application of heterostructure cellulose nanofluid film
By embedding negatively charged modified cellulose into the anodic aluminum layer to form a heterostructured cellulose nanofluid film, the problem of insufficient ion selectivity and stability in the permeability collection of the homogeneous membrane is solved, and efficient ion transport and permeability conversion are achieved.
Patent Information
- Application Number
- CN202510364618.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-06-27
AI Technical Summary
The existing homogeneous membranes have low ion selectivity and strong concentration polarization in permeability collection, which limits the efficiency and stability of permeability energy conversion.
Using the preparation method of heterostructured cellulose nanofluid film, a typical heterostructure is formed by embedding negative charge modified cellulose into an anodized aluminum layer with a vertical and highly ordered pore channel structure.
The rapid and selective transmission of ions in the solution system and excellent ion rectification characteristics are achieved, effectively converting marine salt difference energy into electrical energy, and improving the stability and permeability conversion performance of the membrane.
Smart Images
Figure CN120222847A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical fields of membrane materials, ion transport, and green energy, and more specifically relates to a preparation method and application of a heterostructured cellulose nanofluid membrane. Background Art
[0002] Energy security and environmental pollution have become worldwide problems. Developing green and sustainable clean energy to replace traditional fossil energy is of great significance. The osmotic energy released by mixing water with different salt concentrations is a green and sustainable but yet-to-be-developed energy source. Ion-selective nanofluid membranes show great potential in harvesting this kind of energy. For example, homogeneous membranes such as graphene oxide, bacterial cellulose, and polystyrene sulfonic acid have been successfully prepared for osmotic energy harvesting. However, the relatively low ion selectivity and strong concentration polarization phenomenon (ICP) of homogeneous membranes further limit the osmotic energy conversion. Therefore, developing novel heterostructured nanofluid membranes is an important means to improve ion selectivity and osmotic energy conversion.
[0003] Anodic aluminum oxide membrane (AAO) has become the preferred material for preparing asymmetric membrane structures due to its high pore density and ordered vertical pore channels. Unfortunately, the current methods for preparing AAO-based asymmetric membranes mainly involve assembling other materials on the surface of AAO. However, there is poor compatibility between the two materials, resulting in delamination and unstable structure, and further leading to low osmotic energy conversion and unsatisfactory stability. In addition, the high price, non-renewability of other materials, and the complex preparation process of asymmetric nanofluid membranes limit their wide application. Therefore, it is urgent to develop a heterostructured nanofluid membrane material with mild preparation conditions, low-cost raw materials, environmental friendliness, and stable interfacial structure, which is one of the promising development directions for osmotic energy conversion. Summary of the Invention
[0004] The purpose of the present invention is to provide a preparation method and application of a heterostructured cellulose nanofluid membrane to solve the problems existing in the above-mentioned prior art.
[0005] To achieve the above purpose, the present invention provides the following solutions:
[0006] One of the technical solutions of the present invention: Provide a heterostructured cellulose nanofluid membrane, which includes an anodic aluminum oxide layer with a vertical and highly ordered pore channel structure, and a cellulose layer formed by embedding a negatively charged cellulose part into the anodic aluminum oxide layer. The anodic aluminum oxide layer and the cellulose layer form a heterostructure.
[0007] Another technical solution of the present invention: Provide a preparation method of the above-mentioned heterostructured cellulose nanofluid membrane, and the steps include:
[0008] The cellulose solution is coated on the surface of anodic aluminum oxide, and after vacuum treatment, water immersion treatment, and drying, the heterogeneous structure cellulose nanofluid membrane is obtained.
[0009] The cellulose solution is prepared by dissolving negatively charged modified cellulose in a cellulose solvent.
[0010] Furthermore, the mass fraction of the modified cellulose in the cellulose solution is 0.5% - 5%.
[0011] Furthermore, the negatively charged modified cellulose includes at least one of sulfonated cellulose, carboxylated cellulose, and phosphorylated cellulose.
[0012] Furthermore, the cellulose solvent includes an ionic liquid and / or an N-methylmorpholine-N-oxide (NMMO) solvent.
[0013] Optionally, the ionic liquid is 1-allyl-3-methylimidazolium chloride.
[0014] Furthermore, the pore diameter of the anodic aluminum oxide is 60 - 300 nm.
[0015] Furthermore, the coating amount of the cellulose solution coated on the surface of the anodic aluminum oxide is 15 - 20 μL / mm 2 .
[0016] Furthermore, the time of the water immersion treatment is 12 - 24 h.
[0017] Furthermore, the time of the vacuum treatment is 1 - 30 min, and the vacuum degree is -0.05 kPa to -1 MPa.
[0018] Furthermore, the drying temperature is 10 - 40 °C, and the time is 12 - 24 h.
[0019] The third technical solution of the present invention: Provide an application of the above heterogeneous structure cellulose nanofluid membrane in osmotic energy conversion.
[0020] The heterogeneous structure cellulose nanofluid membrane prepared by the present invention can be used as an ion exchange membrane to convert salinity gradient energy into electrical energy.
[0021] The present invention discloses the following technical effects:
[0022] The nanofluidic membrane of the present invention is composed of negatively charged cellulose embedded in anodic aluminum oxide, presenting a typical heterogeneous structure (the cellulose layer has small pore diameters and negative charges as the cation-selective layer, and the anodic aluminum oxide layer has large pore diameters and positive charges as the ion storage layer). The heterogeneous structure cellulose nanofluidic membrane has a vertical and highly ordered pore channel structure, which can achieve rapid and selective ion transport in the solution system and excellent ion rectification characteristics, and can effectively convert ocean salinity energy into electrical energy.
[0023] The preparation method of the present invention is simple and efficient, and the obtained heterogeneous structure cellulose nanofluidic membrane has the characteristics of rapid and selective transport of solution ions and excellent ion rectification.
[0024] In the present invention, the anodic aluminum oxide has a highly ordered vertical pore structure, which helps the nanofluidic membrane to efficiently transport ions. The modified cellulose layer has small pore diameters and negative charges, and the anodic aluminum oxide layer has large pore diameters and positive charges. Therefore, the cellulose nanofluidic membrane presents a typical heterogeneous structure, and the modified cellulose is embedded in the pore channels of the anodic aluminum oxide to achieve an effective combination of the two, ensuring the stability of the material operation. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:
[0026] Figure 1 It is a cross-sectional SEM image of the AAO membrane used in Example 3.
[0027] Figure 2 It is a cross-sectional SEM image of the heterogeneous structure cellulose nanofluidic membrane prepared in Example 3.
[0028] Figure 3 It is a Zeta potential distribution curve of the homogeneous cellulose nanofluidic membrane prepared in Comparative Example 1.
[0029] Figure 4 It is a Zeta potential distribution curve of the AAO membrane used in Example 3. DETAILED DESCRIPTION OF THE INVENTION
[0030] 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.
[0031] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, 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.
[0032] 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 the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can 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 related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.
[0033] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.
[0034] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.
[0035] It should be noted that the aspects not detailed in the present invention are all conventional operating means in the art and are not the focus of the present invention.
[0036] The raw materials and reagents used in the specific embodiments of the present invention are all commercially available products.
[0037] Unless otherwise specified, the normal temperature and room temperature involved in the specific embodiments of the present invention are both 20 - 30 °C.
[0038] The ionic liquid used in the specific embodiments of the present invention is 1 - allyl - 3 - methylimidazolium chloride, provided by Lanzhou Yulu Fine Chemical Co., Ltd.; the phosphorylated cellulose used is provided by Tianjin Musing Biological Technology Co., Ltd.
[0039] Example 1
[0040] The preparation steps of the heterostructure cellulose nanofluid membrane include:
[0041] Carboxylated cellulose was added to 5 g of ionic liquid, and heated to prepare a cellulose solution with a mass fraction of 0.5%. Subsequently, 2 mL of the cellulose solution was dropped onto an AAO membrane with a pore size of 60 nm (113 mm 2 ), evacuated at a vacuum degree of -0.05 MPa for 1 min, and then immersed in deionized water for 12 h to form an asymmetric wet gel membrane. The asymmetric wet gel membrane was dried at 10 °C for 12 h to prepare a heterostructured cellulose nanofluid membrane.
[0042] Example 2
[0043] The preparation steps of the heterostructured cellulose nanofluid membrane include:
[0044] Phosphorylated cellulose was added to 5 g of NMMO, and heated to prepare a cellulose solution with a mass fraction of 1%. Subsequently, 2 mL of the cellulose solution was dropped onto an AAO membrane with a pore size of 80 nm (113 mm 2 ), evacuated at a vacuum degree of -0.1 MPa for 5 min, and then immersed in deionized water for 18 h to form an asymmetric wet gel membrane. The asymmetric wet gel membrane was dried at 20 °C for 15 h to prepare a heterostructured cellulose nanofluid membrane.
[0045] Example 3
[0046] The preparation steps of the heterostructured cellulose nanofluid membrane include:
[0047] Sulfonated cellulose was added to 5 g of ionic liquid, and heated to prepare a cellulose solution with a mass fraction of 2%. Subsequently, 2 mL of the cellulose solution was dropped onto an AAO membrane with a pore size of 100 nm (113 mm 2 ), evacuated at a vacuum degree of -0.3 MPa for 10 min, and then immersed in deionized water for 18 h to form an asymmetric wet gel membrane. The asymmetric wet gel membrane was dried at 25 °C for 20 h to prepare a heterostructured cellulose nanofluid membrane.
[0048] Example 4
[0049] The preparation steps of the heterostructured cellulose nanofluid membrane include:
[0050] Sulfonated cellulose was added to 5 g of ionic liquid, and heated to prepare a cellulose solution with a mass fraction of 3%. Subsequently, 2 mL of the cellulose solution was dropped onto an AAO membrane with a pore size of 150 nm (113 mm 2 ), evacuated at a vacuum degree of -0.5 MPa for 20 min, and then immersed in deionized water for 22 h to form an asymmetric wet gel membrane. The asymmetric wet gel membrane was dried at 30 °C for 22 h to prepare a heterostructured cellulose nanofluid membrane.
[0051] Example 5
[0052] The preparation steps of the heterostructured cellulose nanofluid membrane include:
[0053] Add carboxylated cellulose to 5 g of NMMO, heat to prepare a cellulose solution with a mass fraction of 4%, and then drop 2 mL of the cellulose solution onto an AAO membrane with a pore size of 200 nm (113 mm 2 ). After evacuating for 25 min under a vacuum of -0.7 MPa, immerse it in deionized water for 24 h to form an asymmetric wet gel membrane, and dry the asymmetric wet gel membrane at 40 °C for 24 h to prepare the heterostructured cellulose nanofluid membrane.
[0054] Example 6
[0055] The preparation steps of the heterostructured cellulose nanofluid membrane include:
[0056] Add phosphorylated cellulose to 5 g of ionic liquid, heat to prepare a cellulose solution with a mass fraction of 5%, and then drop 2 mL of the cellulose solution onto an AAO membrane with a pore size of 300 nm (113 mm 2 ). After evacuating for 30 min under a vacuum of -1 MPa, immerse it in deionized water for 24 h to form an asymmetric wet gel membrane, and dry the asymmetric wet gel membrane at 40 °C for 24 h to prepare the heterostructured cellulose nanofluid membrane.
[0057] Comparative Example 1
[0058] Add sulfonated cellulose fibers to 5 g of ionic liquid, stir at 90 °C for 1 h to prepare a mixed solution with a mass fraction of 8%, and then scrape 2 mL of the mixed solution onto a glass plate (113 mm 2 ). After immersing in deionized water for 24 h to form a wet gel membrane, dry the wet gel membrane at 30 °C for 24 h to prepare the homogeneous cellulose nanofluid membrane.
[0059] Test Example
[0060] Select sodium chloride electrolytes with concentrations of 0.5 M and 10 mM, and perform performance tests on the cellulose nanofluid membranes prepared in Examples 1-6 and Comparative Example 1. Use the AAO membrane used in Example 3 as a control example, and the results are shown in Table 1.
[0061] The specific detection method is as follows: Install the nanofluid membrane in the middle of an H-type electrolytic cell, and use a pair of Ag / AgCl electrodes to collect the salinity gradient energy.
[0062] Table 1
[0063]
[0064] As can be seen from the data in Table 1, the cellulose heterogeneous membranes prepared in the embodiments of the present invention all exhibit excellent salinity gradient energy conversion performance, and the cellulose heterogeneous membrane prepared in Example 3 exhibits the most excellent salinity gradient energy conversion performance.
[0065] The stability of the cellulose nanofluid membranes prepared in Examples 1-6 and Comparative Example 1 was detected by the following method: the output current of the nanofluid membrane was tested by an electrochemical workstation, and the output power density was calculated by P = I 2 R, and the electrolyte was replaced before each test.
[0066] Detected by the above method, the stability of the heterogeneous cellulose nanofluid membranes prepared in Examples 1-6 of the present invention is all above 30 days.
[0067] Figure 1 It is the cross-sectional SEM image of the AAO membrane used in Example 3.
[0068] Figure 2 It is the cross-sectional SEM image of the heterogeneous cellulose nanofluid membrane prepared in Example 3.
[0069] Figure 3 It is the Zeta potential distribution curve of the homogeneous cellulose nanofluid membrane prepared in Comparative Example 1.
[0070] Figure 4 It is the Zeta potential distribution curve of the AAO membrane used in Example 3.
[0071] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.
[0072] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can 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 these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A heterogeneous structure cellulose nanofluid membrane, characterized in that: The heterostructured cellulose nanofluid membrane comprises an anodized aluminum layer having a vertical and highly ordered pore channel structure, and a cellulose layer in which negatively charged cellulose is partially embedded in the anodized aluminum layer, and the anodized aluminum layer and the cellulose layer form a heterostructure.
2. A method for preparing the heterogeneous structure cellulose nanofluid membrane according to claim 1, characterized in that the steps include: The cellulose solution is coated on the surface of anodized aluminum, and subjected to vacuum treatment, water immersion treatment, and drying to obtain the heterogeneous structure cellulose nanofluid membrane; The cellulose solution is prepared by dissolving negatively charged modified cellulose in a cellulose solvent.
3. The preparation method according to claim 2, characterized in that: The mass fraction of the modified cellulose in the cellulose solution is 0.5%-5%.
4. The preparation method according to claim 2, characterized in that: The negatively charged modified cellulose includes at least one of sulfonated cellulose, carboxylated cellulose and phosphorylated cellulose.
5. The preparation method according to claim 2, characterized in that: The cellulose solvent includes an ionic liquid and / or a NMMO solvent.
6. The preparation method according to claim 2, characterized in that: The pore size of the anodized aluminum is 60-300 nm.
7. The preparation method according to claim 2, characterized in that: The coating amount of the cellulose solution applied to the surface of the anodized aluminum is 15-20 μL / mm 2 .
8. The preparation method according to claim 2, characterized in that: The immersion treatment time is 12-24 hours; and / or the vacuum treatment time is 1-30 minutes, and the vacuum degree is -0.05 kPa to -1 MPa.
9. The preparation method according to claim 2, characterized in that: The drying temperature is 10-40°C and the drying time is 12-24h.
10. Use of the heterostructured cellulose nanofluid membrane according to claim 1 in osmotic energy conversion.