A floatable hydrogel film, its preparation method and application in adsorbing and removing pollutants in water
Patent Information
- Application Number
- CN202610744982.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-27
- Publication Date
- 2026-08-21
AI Technical Summary
[0006]本发明的目的在于提供一种可漂浮复合水凝胶膜及其制备方法和应用，以解决粉末光催化材料难以回收、常规水凝胶复合材料易浸没且界面光利用效率不足的问题
[0013] (1) Good interfacial buoyancy. By freeze-drying to construct a connected porous structure, the density of the composite membrane is less than that of water, which can stably float at the air/water interface, thereby improving light utilization and interfacial mass transfer efficiency.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmental functional materials technology, specifically relating to a floatable hydrogel membrane and its preparation method, as well as the application of the hydrogel membrane in the adsorption and photocatalytic synergistic degradation of organic pollutants in water. Background Technology
[0002] With the acceleration of industrialization and urbanization, organic pollutants such as dyes and phenolic compounds easily cause persistent pollution after entering water bodies. Therefore, developing efficient, low-energy-consumption, and recyclable water treatment materials is of great significance. Photocatalysis technology, which can promote the transformation of organic pollutants using photogenerated carriers and reactive oxygen species under mild conditions, is one of the important directions for water pollution control.
[0003] Most existing photocatalytic materials are used in powder form. Although powder materials have a high specific surface area, they are prone to aggregation, sedimentation, and loss during actual water treatment processes, making subsequent separation and recovery difficult and posing a risk of secondary pollution. Immobilizing photocatalytic or adsorption components in membrane or gel-like supports is an effective way to improve the recyclability and engineering applicability of materials.
[0004] Hydrogels possess characteristics such as a three-dimensional network structure, high water content, and ease of functionalization, enabling them to load adsorbed components, photocatalytic components, or oxidant-activated components. However, conventional hydrogel composites are typically immersed in water, where light absorption and scattering are affected, resulting in insufficient effective light exposure and limited contact with oxygen in the air, leading to decreased interfacial reaction efficiency.
[0005] Therefore, there is still a need to develop a composite membrane material that can float stably at the air / water interface and has the ability to adsorb and enrich, process light and light together, and be easily recycled, in order to improve the utilization of light energy and the applicability of materials engineering in water treatment processes driven by sunlight or simulated sunlight. Summary of the Invention
[0006] The purpose of this invention is to provide a floating composite hydrogel membrane, its preparation method and application, to solve the problems of difficult recycling of powder photocatalytic materials, easy immersion of conventional hydrogel composite materials and insufficient interfacial light utilization efficiency.
[0007] To achieve the above objectives, the present invention provides the following technical solution: a floatable composite hydrogel membrane, comprising a sodium alginate crosslinking network and a functional reinforcing material dispersed in the sodium alginate crosslinking network. The sodium alginate crosslinking network is formed by crosslinking sodium alginate with metal ions; the composite hydrogel membrane has an interconnected porous structure formed by freeze-drying and a density of less than 1 g / cm³. 3 It can float stably on the surface of water.
[0008] The functional enhancement material is selected from one or more of graphene, graphene oxide, carbon nanotubes, carbon nitride, and molecular sieves. Different functional enhancement materials can respectively provide adsorption and enrichment, photoresponse, electron transport, interfacial mass transfer, or pollutant capture functions. Preferably, the functional enhancement material is graphene, graphene oxide, or carbon nitride.
[0009] The metal ions are selected from Fe. 3+ Cu 2+ Mn 2+ Fe 2+ and Ca 2+ One or more of the following, preferably Fe 3+ Metal ions can coordinate and crosslink with the carboxyl groups in sodium alginate, enhancing the structural stability of the membrane material and helping to maintain a porous and lightweight structure.
[0010] The present invention also provides a method for preparing the above-mentioned floating composite hydrogel membrane, comprising: dispersing the functional enhancement material in deionized water; mixing sodium alginate solution with functional dispersion to obtain casting solution; spreading the casting solution, freezing and freeze-drying it to obtain a floating porous aerogel membrane; subsequently immersing it in a metal ion salt solution for crosslinking, and obtaining a floating composite hydrogel membrane after washing and drying.
[0011] This invention also provides the application of the above-mentioned floatable composite hydrogel membrane in the synergistic treatment of organic pollutants in water through adsorption-photocatalysis / oxidation. During treatment, the composite hydrogel membrane is placed on the surface of the polluted water, allowing it to float at the air / water interface, where it undergoes adsorption, enrichment, and synergistic degradation under light conditions. Depending on the type of pollutant and treatment requirements, persulfate oxidant can be added to further improve pollutant removal efficiency. After treatment, the composite hydrogel membrane can be directly retrieved and recycled. Beneficial effects
[0012] Compared with the prior art, the present invention has at least the following beneficial effects:
[0013] (1) Good interfacial buoyancy. By freeze-drying to construct a connected porous structure, the density of the composite membrane is less than that of water, which can stably float at the air / water interface, thereby improving light utilization and interfacial mass transfer efficiency.
[0014] (2) Strong synergistic effect of adsorption and light. The sodium alginate network provides a functionalized carrier, and the functional enhancement material provides adsorption enrichment, light response or oxidant activation functions, which is conducive to the enrichment of organic pollutants and subsequent synergistic removal.
[0015] (3) Simple recycling method. The membrane structure avoids the loss and difficulty in separation of powder materials in water. After treatment, it can be directly retrieved and recycled, which helps to reduce the risk of secondary pollution.
[0016] (4) The preparation process is mild. The sodium alginate used is widely available, and the preparation process mainly includes aqueous dispersion, freeze drying and metal ion crosslinking. The process is simple and easy to scale up. Attached Figure Description
[0017] Figure 1. Schematic diagram of the catalytic mechanism of photocatalyst; showing the reaction pathway of electron-hole separation, generation of hydroxyl radicals and superoxide radicals, and mineralization and degradation of organic pollutants during photocatalysis.
[0018] Figure 2. Front view of the graphene aerogel membrane; showing the surface morphology, uniform porous structure and overall appearance of the graphene-sodium alginate composite aerogel membrane.
[0019] Figure 3. Side view of the graphene aerogel membrane; showing the thickness, cross-sectional porous structure and three-dimensional network morphology of the graphene aerogel membrane.
[0020] Figure 4. Front view of carbon nanotube aerogel membrane; showing the surface smoothness, color and macroscopic membrane structure of carbon nanotube composite aerogel membrane.
[0021] Figure 5. Side view of carbon nanotube aerogel membrane; showing the cross-sectional thickness, internal loose porous structure and mechanical morphology of carbon nanotube aerogel membrane.
[0022] Figure 6. Front view of the molecular sieve aerogel membrane; showing the surface particle distribution, membrane integrity and macroscopic appearance of the molecular sieve composite aerogel membrane.
[0023] Figure 7. Side view of the molecular sieve aerogel membrane; showing the cross-sectional structure, thickness and internal pore distribution characteristics of the molecular sieve aerogel membrane.
[0024] Figure 8. Front view of carbon nitride aerogel membrane; showing the surface color, uniformity and intact morphology of carbon nitride composite aerogel membrane.
[0025] Figure 9. Side view of carbon nitride aerogel membrane; showing the cross-sectional thickness, porous structure and lightweight and fluffy characteristics of carbon nitride aerogel membrane.
[0026] Figure 10. Photocatalytic performance curves of carbon nitride hydrogel membranes after crosslinking with different metal ions without oxidant; the horizontal axis represents the reaction time (min), and the vertical axis represents the relative concentration of Rhodamine B solution C / C0; used to compare the differences in adsorption rate and adsorption equilibrium efficiency of carbon nitride hydrogel membranes for Rhodamine B under oxidant-free conditions after crosslinking modification with four metal ions: Fe³⁺, Fe²⁺, Ca²⁺, and Mn²⁺.
[0027] Figure 11. Photocatalytic reaction effect of Fe³⁺ loaded on hydrogel membranes with different carriers after the addition of oxidant; the horizontal axis is the reaction time (min), and the vertical axis is the relative concentration of Rhodamine B solution C / C0; used to compare the differences in the adsorption and photocatalytic synergistic degradation performance of Rhodamine B on four composite hydrogel membrane systems loaded with Fe³⁺ on graphene, carbon nanotubes, carbon nitride, and molecular sieves after the addition of potassium persulfate oxidant.
[0028] Figure 12 Comparison curves of photocatalysis of Fe³⁺ graphene hydrogel membrane and degradation by oxidant alone; the horizontal axis represents the reaction time (min), and the vertical axis represents the relative concentration of Rhodamine B solution C / C0; used to compare the degradation rate, reaction duration, and final removal rate of the Fe³⁺ graphene floating hydrogel membrane photocatalytic system of this invention with the system with only potassium persulfate oxidant added, demonstrating the long-term deep degradation advantage of the material.
[0029] Figure 13 Comparison curves of photocatalysis and degradation of Fe³⁺ graphene hydrogel film under light and dark conditions; the horizontal axis represents the reaction time (min), and the vertical axis represents the relative concentration of Rhodamine B solution C / C0; used to compare the adsorption and degradation behavior of the same Fe³⁺ graphene hydrogel film under light and dark conditions, demonstrating the significant improvement effect of light on photocatalytic reaction efficiency and the photoresponse characteristics of the material.
[0030] Figure 14 shows the actual floating state of the hydrogel membrane after the reaction; demonstrating the material's stable floating in water and its ability to automatically float to the surface after being pressed by external force. Detailed Implementation
[0031] The present invention will be further illustrated below with reference to embodiments. It should be understood that the embodiments are for illustrative purposes only and should not be construed as limiting the scope of protection of the present invention. Conventional substitutions or adjustments made by those skilled in the art to the types and proportions of raw materials, freezing conditions, crosslinking ions, and application targets without departing from the concept of the present invention should be included within the scope of protection of the present invention.
[0032] Example 1 Fe 3+ Preparation of Floating Graphene Oxide Composite Hydrogel Membranes
[0033] Graphene oxide dispersions were prepared using the Hummers method. Graphene oxide was dispersed in deionized water and then subjected to ultrasonic treatment to obtain a uniform functional dispersion.
[0034] Sodium alginate was weighed and added to deionized water to prepare a sodium alginate solution with a concentration of 20 mg / mL. The solution was magnetically stirred until completely dissolved and allowed to stand to remove bubbles. The graphene oxide functional dispersion was then added to the sodium alginate solution and stirred until homogeneous to obtain a mixed casting solution.
[0035] The mixed casting solution was poured into a petri dish and spread evenly. It was then frozen at -20°C for 2 h and subsequently freeze-dried for 24 h to obtain a floating porous aerogel membrane.
[0036] Prepare a 2 wt% ferric chloride solution, immerse the floatable porous aerogel membrane in the ferric chloride solution for crosslinking for 30 min; remove it, wash with deionized water, and dry to obtain Fe. 3+ - Graphene oxide can float composite hydrogel membranes. The resulting membranes can float stably on the surface of water.
[0037] Example 2: Rhodamine B Simulated Polluted Water Treatment Experiment
[0038] Using Rhodamine B as a model pollutant, simulated polluted water with a concentration of 10⁻³ wt% was prepared. The floatable composite hydrogel membrane prepared in Example 1 was placed on the liquid surface and treated under xenon lamp irradiation.
[0039] The treatment process included an adsorption phase of 30 minutes; followed by the addition of potassium persulfate and continued reaction under illumination for 90 minutes. The change in absorbance of the solution was detected at 554 nm using a UV-Vis spectrophotometer, and the removal rate of Rhodamine B was calculated.
[0040] The results showed that the adsorption rate was 55% after 30 minutes and the total removal rate reached 80% after 90 minutes. The composite hydrogel membrane remained floating throughout the treatment process and could be directly retrieved and recycled after treatment.
[0041] Example 3: Comparison of metal ion crosslinking effects
[0042] Using carbon nitride composite sodium alginate membrane as substrate, Fe was used respectively 3+ Fe 2+ Ca 2+ and Mn 2+ Cross-linking was performed, and the adsorption performance of the material was tested under the same conditions.
[0043] The results showed that different metal ions could achieve sodium alginate network cross-linking and form a floating composite film. Among them, Fe... 3+ The cross-linked membrane exhibits superior adsorption performance, achieving an adsorption rate of 45% within 30 minutes. Therefore, Fe... 3+ It can be used as a preferred crosslinking ion.
[0044] Example 4: Comparison of different functional enhancement materials
[0045] With Fe 3+ To identify crosslinking ions, composite hydrogel membranes of graphene, carbon nanotubes, carbon nitride, and molecular sieves were prepared, and adsorption-light synergistic treatment experiments were conducted under the same conditions.
[0046] The results showed that various functional enhancement materials could be combined with sodium alginate to form floating membrane materials. Among them, the graphene composite membrane exhibited better adsorption and removal performance, indicating that carbon-based functional enhancement materials are beneficial for improving pollutant enrichment and synergistic treatment effects.
Claims
1. A floatable composite hydrogel membrane, characterized in that: The composite hydrogel membrane includes a sodium alginate crosslinking network and a functional reinforcing material dispersed within the sodium alginate crosslinking network; the sodium alginate crosslinking network is formed by crosslinking sodium alginate with metal ions; the composite hydrogel membrane has an interconnected porous structure formed by freeze-drying and a density of less than 1 g / cm³. 3 It is capable of floating on the surface of water; the functional enhancement material is selected from one or more of graphene, graphene oxide, carbon nanotubes, carbon nitride, and molecular sieves; the metal ion is selected from Fe. 3+ Cu 2+ Mn 2 + Fe 2+ and Ca 2+ One or more of them.
2. The floatable composite hydrogel membrane according to claim 1, characterized in that: The metal ion is Fe. 3+ The Fe 3+ It is provided by one of ferric chloride, ferric nitrate or ferric sulfate.
3. The floatable composite hydrogel membrane according to claim 1 or 2, characterized in that: The functional enhancement material is graphene or graphene oxide, and the composite hydrogel membrane is used for the adsorption and enrichment of dye-based organic pollutants and their synergistic removal under light conditions.
4. The floatable composite hydrogel membrane according to claim 1 or 2, characterized in that: The functional enhancement material is carbon nitride, and the composite hydrogel membrane has photoresponsive activity, which is used for the adsorption-photocatalytic synergistic treatment of organic pollutants under light conditions.
5. A method for preparing the floatable composite hydrogel membrane according to any one of claims 1 to 4, characterized in that: Includes the following steps: (1) Disperse the functional enhancement material in deionized water to obtain a functional dispersion; (2) Dissolve sodium alginate in deionized water, degas it, and then mix it with the functional dispersion to obtain a casting solution; (3) Spread the casting solution into a film, freeze and freeze-dry it to obtain a floating porous aerogel film; (4) The floating porous aerogel membrane is immersed in a metal ion salt solution for cross-linking, and then washed and dried to obtain the floating composite hydrogel membrane.
6. The preparation method according to claim 5, characterized in that: The concentration of the sodium alginate solution in step (2) is 10-40 mg / mL, preferably 20 mg / mL.
7. The preparation method according to claim 5 or 6, characterized in that: In step (3), the freezing temperature is -10 to -80°C, the freezing time is 0.5 to 12 h, and the freeze-drying time is 12 to 48 h; preferably, the freezing temperature is -20°C, the freezing time is 2 h, and the freeze-drying time is 24 h.
8. The preparation method according to any one of claims 5 to 7, characterized in that: The concentration of the metal ion salt solution in step (4) is 0.5-10 wt%, and the cross-linking time is 5-120 min; preferably, the metal ion salt solution is a 2 wt% ferric chloride solution, and the cross-linking time is 30 min.
9. The application of the floatable composite hydrogel membrane according to any one of claims 1 to 4 in the synergistic treatment of organic pollutants in water by adsorption-photocatalysis / oxidation.
10. The application according to claim 9, characterized in that: The organic pollutants in the water include Rhodamine B, dye pollutants, or phenolic pollutants. During treatment, the floating composite hydrogel membrane is placed on the surface of the polluted water body and adsorbed and synergistically degraded under light conditions. Persulfate oxidant may be added optionally. After treatment, the composite hydrogel membrane is directly retrieved and recycled.