A biomass-based aerogel with high adsorption and excellent renewability and its preparation

Abstract

The present invention discloses a biomass-based aerogel with high-efficiency adsorption performance and excellent regeneration performance for dye wastewater treatment and its preparation. The key point is to chemically modify the photocatalytic nanoparticles, give them basic units participating in the polymerization reaction, make them participate in the polymerization reaction, and form a three-dimensional structure aerogel with the photocatalytic nanoparticles as "crosslinking points". The present invention uses natural, environmentally friendly, degradable biomass materials such as itaconic acid and chitosan as raw materials, and introduces photocatalytic nanoparticles as "crosslinking points" of the aerogel to achieve stable introduction of the photocatalytic nanoparticles. Through the above technology, the bottleneck problem of the limited practical application of aerogel adsorption materials in the prior art due to limited adsorption performance and poor regeneration performance is solved, and the practical value and application prospects of the material are improved.

Description

Technical Field

[0001] The present invention belongs to the field of environmental pollution control and energy, and specifically relates to a biomass-based aerogel with high-efficiency adsorption performance and excellent renewable performance and a preparation method thereof. Background Art

[0002] From the perspective of environmental pollution control, developing highly efficient adsorbents with excellent regeneration performance to remove non-degradable and highly toxic dye molecules in wastewater is of great significance for achieving the recycling of water resources.

[0003] In existing reports, adsorption separation technology based on functional materials is considered to be one of the most effective means of treating dye wastewater due to its low cost, convenient operation and wide range of applications.

[0004] However, most adsorption materials have limited adsorption capacity, and poor mechanical properties and anti-pollution properties lead to poor regeneration performance, limiting their widespread application.

[0005] Combining photocatalytic technology with dye adsorption materials is expected to degrade dyes through photocatalysis to break the original adsorption balance, which is an effective way to improve dye removal performance and anti-pollution performance.

[0006] However, most photocatalytic materials are in the form of nanoparticles, which are prone to agglomeration when used directly, thereby increasing the electron-hole recombination rate and reducing the photocatalytic performance. They are also difficult to recycle. Introducing them into adsorption materials can avoid agglomeration and give them excellent recycling performance.

[0007] Xiang Hengxue and others from Donghua University loaded TiO2 and g-C3N4 into lignin-derived carbon nanofibers (LCNFs) to establish TiO2 / g-C3N4@LCNFs photocatalytic materials, which achieved excellent RhB degradation performance under sunlight (Zhai GX, Zhou JL, Xie M. et al. International Journal of Biological Macromolecules, 2023, 233, 123588.).

[0008] Sheng Jiawei and others from Zhejiang University of Technology used an impregnation method to deposit N-TiO2 and g-C3N4 onto diatomite to prepare N-TiO2 / g-C3N4@diatomite composite materials, proving that N-TiO2 and g-C3N4-doped catalysts can synergistically enhance the response to the visible light region to achieve excellent reduction of Cr(VI) in wastewater (Sun Q, Hu XL, Zheng SL, et al. Environmental Pollution, 2019, 245, 53-62.).

[0009] The mechanical properties of aerogels directly affect the durability and regeneration performance during the recycling process. Studies have shown that the introduction of nanoparticles is an effective means to enhance the mechanical properties of aerogels.

[0010] Matthias M. Koebel and others from the Swiss Federal Institute of Materials Science and Technology dissolved chitosan in silica to prepare silica-reinforced chitosan aerogels with a compressive strength of 7 MPa (Zhao SY, Malfait WJ, Jeong E, et al. ACS Sustainable Chemistry Engineering, 2016, 10, 5674-5683.).

[0011] Recently, Li Zhongming and others from Sichuan University prepared TiO2 / cellulose nanocomposite carbon aerogels by freeze drying and carbonization. The in situ synthesized TiO2 (B) effectively strengthened the carbon skeleton and improved the aerogel's removal efficiency of dyes through photocatalytic degradation performance (Zhu JL, Chen SP, Ma GQ, et al. Journal of Colloid and Interface Science, 2023, 630, 772-782.).

[0012] Current research shows that introducing toughened nanoparticles with photocatalytic activity is a potential way to improve the dye removal and mechanical properties of aerogels. However, existing physical doping, embedding, loading and impregnation methods lack stable connections, and there is a risk of nanoparticles falling off and secondary contamination. There is no long-term guarantee for mechanical or photocatalytic properties, and the durability of the material is poor. It is still difficult to fundamentally and effectively solve the technical bottleneck that limits the practical application of aerogels due to limited dye removal performance and poor regeneration performance.

[0013] As a surface modifier, silane coupling agent can better impart functional groups to inorganic particles and is a reliable way to introduce inorganic nanoparticles into aerogel systems.

[0014] The present invention intends to modify photocatalytic nanoparticles through TMSPA and use it as the "cross-linking point" of the aerogel three-dimensional structure to achieve the stable introduction of toughened photocatalytic nanoparticles, ensure the durability of the material, and fundamentally solve the problems of limited dye removal performance and poor regeneration performance of aerogel. Summary of the invention

[0015] The purpose of the present invention is to fundamentally and effectively solve the technical bottleneck that limits the practical application of aerogels due to limited dye removal performance and poor regeneration performance, and to provide a biomass-based aerogel with high adsorption performance and excellent regeneration performance and a preparation method thereof.

[0016] The material is characterized in that the photocatalytic nanoparticles are used as "cross-linking points" of the aerogel three-dimensional structure.

[0017] To achieve the above purpose, the technical solution adopted by the present invention is: by modifying the photocatalytic nanoparticles, making them participate in the polymerization reaction, replacing the traditional cross-linking agent, and forming a three-dimensional network structure aerogel with the photocatalytic nanoparticles as the "cross-linking points".

[0018] The method for preparing the biomass-based aerogel specifically comprises the following steps:

[0019] A. Preparation of Ethylene-functionalized Photocatalytic Nanoparticles

[0020] The silane coupling agent TMSPA is added to a mixed solution of ethanol and water for hydrolysis, and then photocatalytic nanoparticles are added. After the reaction is completed, the excess unreacted TMSPA is washed away to obtain ethylene functionalized photocatalytic nanoparticles.

[0021] B. Preparation of biomass-based aerogels

[0022] The ethylene functionalized photocatalytic nanoparticles prepared in the above steps are dispersed in water, and a pre-prepared biomass raw material solution (mass ratio of 10-40%) and an initiator ammonium persulfate (APS) (mass ratio of 0.05-0.1%) are added. The reaction is stirred at a constant speed for 4 hours under a certain temperature condition to obtain a biomass-based hydrogel with ethylene functionalized photocatalytic nanoparticles as the "cross-linking points" of the three-dimensional structure, and the aerogel is obtained after freeze-drying for 48 hours.

[0023] Photocatalytic nanoparticles include silver / silver chloride (Ag / AgCl), MXene, chromium sulfide / cesium dioxide (CdS / CeO2), titanium dioxide (TiO2), iron oxide (Fe2O3), tungsten trioxide (WO3), zinc oxide (ZnO), bismuth oxide (Bi2O3), indium oxide (In2O3), tin oxide (SnO2), copper oxide (Cu2O), bismuth vanadate (BiVO4), bismuth tungstate (Bi2WO6), bismuth molybdate (Bi2MoO6), silver phosphate (Ag3PO4), silver chromate (Ag2CrO4), silver bromide (AgBr), graphitic carbon nitride (g-C3N4), TiO2 / g-C3N4, metal organic framework materials (MOFs), conjugated microporous polymers (CMPs), and covalent organic framework materials (COFs).

[0024] Biomass raw materials include chitosan, itaconic acid, alginate, phytic acid, cellulose, lignin, chitin, agarose, and gelatin.

[0025] The method for preparing biomass-based aerogel with high adsorption performance and excellent regeneration performance according to

[0016] is characterized in that the reaction temperature is 30-80°C.

[0026] According to the biomass-based aerogel with high adsorption performance and excellent regeneration performance described in

[0016] , the dye removal performance and regeneration performance (mechanical properties and anti-pollution performance) of the material are tested respectively using the aerogel prepared by using a common cross-linking agent under the same conditions as a reference sample. The obtained aerogel with photocatalytic nanoparticles as "cross-linking points" has better dye removal ability and regeneration performance. DETAILED DESCRIPTION

[0027] A method for preparing a biomass-based aerogel with high adsorption performance and excellent regeneration performance includes two steps: preparing ethylene-functionalized photocatalytic nanoparticles and preparing biomass-based aerogel. In order to better understand the present invention, the technical solution of the present invention is described in detail with specific examples below, but the present invention is not limited thereto.

[0028] Example 1

[0029] Ethylene-functionalized Ag / AgCl and initiator APS (0.05%) were added to a 30% chitosan and itaconic acid solution (mass ratio of 1:1), and the reaction was stirred at a constant speed at 40°C for 4 hours to obtain a biomass-based hydrogel with ethylene-functionalized photocatalytic nanoparticles as the "cross-linking points" of the three-dimensional structure. After freeze-drying for 48 hours, an aerogel was obtained.

[0030] Comparative Example 1

[0031] The ethylene-functionalized Ag / AgCl used in Example 1 was replaced by a common cross-linking agent with an equal molar ratio of cross-linking groups, and the same molar ratio of Ag / AgCl as in Example 1 was added. Initiator APS (0.05%) was added to a 30% chitosan and itaconic acid solution (mass ratio of 1:1), and the reaction was stirred at a uniform speed at 40°C for 4h to obtain Ag / AgCl blended biomass-based hydrogel, which was freeze-dried for 48h to obtain aerogel.

[0032] Example 2

[0033] Ethylene-functionalized TiO2 / g-C3N4 was added to a 40% sodium alginate and itaconic acid solution (mass ratio of 1:1), and initiator APS (0.1%) was added. The reaction was stirred at a constant speed at 50°C for 4 hours to obtain a biomass-based hydrogel with ethylene-functionalized photocatalytic nanoparticles as the "cross-linking points" of the three-dimensional structure. After freeze-drying for 48 hours, an aerogel was obtained.

[0034] Comparative Example 2

[0035] The ethylene-functionalized TiO2 / g-C3N4 used in Example 2 was replaced by a common cross-linking agent with an equal molar ratio of cross-linking groups, and the same molar ratio of TiO2 / g-C3N4 as in Example 2 was added. Initiator APS (0.1%) was added to 40% chitosan and itaconic acid solution (mass ratio of 1:1), and the reaction was stirred at a uniform speed at 50°C for 4h to obtain TiO2 / g-C3N4 blended biomass-based hydrogel, which was freeze-dried for 48h to obtain aerogel.

[0036] Example 3

[0037] Ethylene-functionalized CdS / CeO2 and initiator APS (0.1%) were added to a 25% gelatin and phytic acid solution (mass ratio of 1:1), and the reaction was stirred at a constant speed at 50°C for 4 hours to obtain a biomass-based hydrogel with ethylene-functionalized photocatalytic nanoparticles as the "cross-linking points" of the three-dimensional structure. After freeze-drying for 48 hours, an aerogel was obtained.

[0038] Comparative Example 3

[0039] The ethylene-functionalized CdS / CeO2 used in Example 3 was replaced by a common cross-linking agent with an equal molar ratio of cross-linking groups, and CdS / CeO2 with an equal molar ratio as in Example 3 was added, and initiator APS (0.1%) was added. The reaction was stirred at a uniform speed at 50°C for 4 hours to obtain CdS / CeO2 blended biomass-based hydrogel, and then freeze-dried for 48 hours to obtain aerogel.

[0040] Test Example 1: Removal performance test of methylene blue dye (maximum adsorption amount)

[0041] sample Maximum adsorption capacity Example 1 688.3mg / g Comparative Example 1 426.1mg / g Example 2 669.5mg / g Comparative Example 2 389.5mg / g Example 3 800.3mg / g Comparative Example 3 462.3mg / g

[0042] It can be seen from the results in the above table that Examples 1, 2, and 3 of the present invention all have excellent dye adsorption performance. Comparative Examples 1, 2, and 3 are added with the same molar ratio of photocatalyst by blending during the preparation process, but the physical introduction method cannot ensure that the photocatalyst is stably and uniformly present in the aerogel, thereby affecting the photocatalytic efficiency.

[0043] Test Example 2: Regeneration performance test (mechanical properties and anti-pollution performance test)

[0044]

[0045] It can be seen from the results in the above table that Examples 1, 2 and 3 of the present invention have high compressive strength and excellent anti-pollution performance. Comparative Examples 1, 2 and 3 have the same molar ratio of photocatalysts added by blending during the preparation process, but the toughening effect of the photocatalytic nanoparticles added by blending is weak, and the light-induced self-cleaning performance (anti-pollution performance) is not good.

Claims

1. A method for preparing a biomass-based aerogel with high-efficiency adsorption performance and excellent regeneration performance, characterized in that: The specific steps include: A. Preparation of Ethylene-functionalized Photocatalytic Nanoparticles The silane coupling agent 3-(trimethoxysilyl)propyl acrylate (TMSPA) is added to a mixed solution of ethanol and water for hydrolysis, and then photocatalytic nanoparticles are added. After the reaction is completed, the excess unreacted TMSPA is washed away to obtain ethylene functionalized photocatalytic nanoparticles. B. Preparation of biomass-based aerogels The ethylene functionalized photocatalytic nanoparticles prepared in step A are dispersed in water, and a biomass raw material solution prepared in advance is added, wherein the mass ratio of the biomass raw material solution is 10-40%, and an initiator ammonium persulfate (APS) is added, wherein the mass ratio of the initiator ammonium persulfate is 0.05-0.1%. The reaction is carried out under uniform stirring at a certain temperature for 4 hours to obtain a biomass-based hydrogel with ethylene functionalized photocatalytic nanoparticles as "cross-linking points" of a three-dimensional structure, and the aerogel is obtained after freeze-drying for 48 hours.

2. The method for preparing a biomass-based aerogel with high adsorption performance and excellent regeneration performance according to claim 1, characterized in that: The photocatalytic nanoparticles include silver / silver chloride (Ag / AgCl), MXene, chromium sulfide / cesium dioxide (CdS / CeO2), titanium dioxide (TiO2), ferric oxide (Fe2O3), tungsten trioxide (WO3), zinc oxide (ZnO), bismuth oxide (Bi2O3), indium oxide (In2O3), tin oxide (SnO2), copper oxide (Cu2O), bismuth vanadate (BiVO4), bismuth tungstate (Bi2WO6), bismuth molybdate (Bi2MoO6), silver phosphate (Ag3PO4), silver chromate (Ag2CrO4), silver bromide (AgBr), graphite phase carbon nitride (g-C3N4), TiO2 / g-C3N4, metal organic framework materials (MOFs), conjugated microporous polymers (CMPs), and covalent organic framework materials (COFs).

3. The method for preparing the biomass-based aerogel with high adsorption performance and excellent regeneration performance according to claim 1, characterized in that: The biomass raw materials include chitosan, itaconic acid, alginate, phytic acid, cellulose, lignin, chitin, agarose and gelatin.

4. The method for preparing a biomass-based aerogel with high adsorption performance and excellent regeneration performance according to claim 1, characterized in that: The reaction temperature is 30-80°C.

5. A biomass-based aerogel having high-efficiency adsorption performance and excellent regeneration performance prepared according to any one of claims 1 to 4.

Images