Plasma modified seaweed-based aerogel as well as preparation method and application thereof

Abstract

The invention provides plasma modified seaweed-based aerogel as well as a preparation method and application thereof, and relates to the field of adsorption materials. The preparation method of the plasma modified seaweed-based aerogel comprises the following steps: taking a seaweed biomass raw material, cleaning, drying and screening to obtain seaweed biomass powder; mixing the seaweed biomass powder with a gelatin solution and a calcium chloride solution, and stirring to form a precursor; then NTP modification is carried out through dielectric barrier discharge; then shaping through a mold and carrying out vacuum freeze drying; and finally calcining and carbonizing, washing and drying to obtain the plasma modified seaweed-based aerogel. According to the method, seaweed is used as a main raw material, gelatin is introduced to assist in forming, and calcium chloride is utilized to construct a porous structure in the carbonization process; then, NTP modification treatment is carried out under the nitrogen atmosphere, in the process, a nitrogen-containing functional group is introduced to the surface, an etching effect is carried out on the surface of the material, and the adsorption performance of the aerogel to VOCs is remarkably enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of adsorption materials, in particular to a plasma-modified seaweed-based aerogel and a preparation method and application thereof. BACKGROUND

[0002] Volatile organic compounds (VOCs) are one of the main pollutants in indoor air and industrial exhaust gas, which poses a serious threat to human health and the ecological environment. Therefore, it is crucial to develop efficient and economical VOCs treatment technologies. Among the many technologies, adsorption method occupies an important position due to its efficient purification, low cost, easy operation and strong adaptability. However, the core bottleneck of this technology lies in the performance of the adsorbent. Although adsorption technology, especially physical adsorption represented by activated carbon, plays an indispensable role in the field of VOCs treatment, the current mainstream adsorbents face severe challenges in terms of intrinsic material properties, regeneration process and system design.

[0003] Under this background, biomass aerogels emerged as the times require, which ingeniously combines the excellent performance of aerogel materials with the green and sustainable characteristics of biomass, providing a new solution for VOCs adsorption. Although biomass aerogels generally have high specific surface area, it is still difficult to precisely control the pore structure, especially mesopores for VOCs molecules. The aerogels prepared by many conventional methods are mainly macroporous, which is not conducive to the adsorption of VOCs molecules, resulting in that their actual adsorption capacity does not significantly exceed that of high-quality activated carbon, and they generally have poor selectivity for VOCs with different polarities and different molecular sizes. At the same time, their mechanical strength is usually poor, and their inherent brittleness makes them easily pulverized under the vibration and airflow impact of dynamic adsorption, leading to increased system pressure drop or even blockage, affecting the stability of long-term operation. In addition, in high humidity environment, most unmodified biomass aerogels (such as cellulose and chitosan-based) have rich hydrophilic groups on their surface, which can strongly adsorb water molecules, competing with VOCs for active sites, resulting in a sharp decline in their adsorption performance in real industrial exhaust gas.

[0004] Among various types of biomass raw materials, seaweed-based aerogels show unique value. In recent years, marine ecological problems such as "green tide" have occurred frequently worldwide. Using salvaged seaweed as raw material for aerogel is an excellent way to realize the resource utilization of marine waste, which not only greatly reduces the cost of raw materials, but also has the dual benefits of pollution control and environmental remediation. Moreover, seaweed can enrich a variety of natural metal salt ions from the marine environment during its growth. These inherent metal ions can act as precursors for activators, and in subsequent carbonization or activation treatment, they can induce the generation of more defects and microporous structures, thereby greatly increasing the specific surface area and porosity of the aerogel, providing more adsorption sites for VOCs molecules.

[0005] Non-thermal plasma (NTP, also known as non-thermal plasma) technology is a green method for modifying the surface of materials by generating high-activity particles (such as free radicals, ions, electrons, etc.) and light radiation through ionized gas at near room temperature. When applied to the modification of biomass aerogels, this technology exhibits significant advantages. It can precisely construct a rich microporous structure on the surface of the aerogel through physical etching and chemical cross-linking, and introduce hydrophobic groups, thereby greatly improving its specific surface area, porosity and hydrophobicity. Moreover, the entire process is efficient and environmentally friendly, without the need to use corrosive chemical reagents. This makes the technology an effective solution for developing high-performance, sustainable biomass adsorption materials and volatile organic compound pollution control. SUMMARY

[0006] In view of this, the present application provides a plasma-modified seaweed-based aerogel and its preparation method and application.

[0007] The present application provides a method for modifying seaweed-based aerogel using gelatin molding and combining low-temperature plasma technology under a nitrogen atmosphere. This method can effectively control the pore structure of the aerogel and introduce nitrogen-containing functional groups, thereby enhancing its adsorption performance for a variety of typical VOCs, including p-xylene, toluene, dimethyl disulfide, ethyl acetate and acetone.

[0008] The technical solution of the present application is as follows: A preparation method of a plasma-modified seaweed-based aerogel, comprising the following steps: taking seaweed biomass raw material, washing, drying and sieving to obtain seaweed biomass powder; then mixing the seaweed biomass powder with a gelatin solution and a calcium chloride solution, stirring to form a precursor; then performing NTP modification by dielectric barrier discharge; then shaping by a mold and vacuum freeze-drying; finally calcining and carbonizing, washing and drying to obtain the plasma-modified seaweed-based aerogel.

[0009] The preparation method of the plasma-modified seaweed-based aerogel of the present application specifically comprises the following steps: (1) Take seaweed biomass raw material, wash to remove sand and other impurities on the surface, dry and sieve to obtain seaweed biomass powder; (2) Take gelatin, add water and mix to obtain a gelatin solution; (3) Add the seaweed biomass powder of step (1) to the gelatin aqueous solution of step (2), and then add a calcium chloride solution and stir to obtain a precursor; (4) Place the precursor of step (3) in a dielectric barrier discharge NTP modification device and perform NTP modification under a nitrogen atmosphere; (5) Fill the NTP-modified material into a mold and perform vacuum freeze-drying treatment; (6) Finally, the obtained material is placed in a tube furnace for calcination and carbonization under a nitrogen atmosphere; after removal, it is subjected to acid washing, followed by water washing until neutral, drying, and obtaining a plasma-modified seaweed-based aerogel.

[0010] Further, in step (1), the seaweed biomass is at least one of Sargassum vachellianum, Sargassum horneri, Sargassum thunbergii, and Laminaria japonica.

[0011] Further, in step (1), the drying temperature is 90-110 ℃, and the drying time is 7-9 h; preferably, the drying temperature is 100 ℃, and the drying time is 8 h.

[0012] Further, in step (1), the mesh size of the sieving is 80-100 mesh, preferably 80 mesh.

[0013] Further, in step (2), the mass-to-volume ratio of the gelatin to water is 0.20-0.40 g:5-20 mL.

[0014] Further, in step (2), the mixing temperature is 50-55 ℃, preferably 50 ℃.

[0015] Further, in step (3), the concentration of the calcium chloride solution is 0.1-0.3 mol / L, preferably 0.2 mol / L.

[0016] Further, in step (3), the mass-to-volume ratio of the seaweed biomass powder to the calcium chloride solution is 1-3 g:3-6 mL.

[0017] Further, in step (3), after adding the calcium chloride solution, water is also added, and the mass-to-volume ratio of the seaweed biomass powder to water is 1-3 g:1-6 mL.

[0018] Further, in step (3), the stirring time is 10-20 min, preferably 15 min.

[0019] Further, in step (4), the weight of the precursor placed in the device is 8-12 g, preferably 10 g.

[0020] Further, in step (4), the modification voltage is 25-50 V, and the modification time is 5-20 min; preferably, the modification voltage is 40 V, the modification time is 10 min, and the discharge current is 1.95-2.05 A.

[0021] Further, in step (4), the NTP modification atmosphere is a nitrogen atmosphere.

[0022] Further, in step (5), the vacuum freeze-drying condition is 20-28 h at -50 ~ -70 ℃, preferably 24 h at -60 ℃.

[0023] Further, in step (6), the calcination temperature is 750-850 ℃, and the calcination time is 0.8-1.2 h; preferably, the calcination temperature is 800 ℃, and the calcination time is 1 h. Further, in step (6), the drying temperature is 100-105 ℃, and the drying time is 3-5 h; preferably, the drying temperature is 100 ℃, and the drying time is 4 h.

[0024] A plasma-modified seaweed-based aerogel prepared by any one of the preparation methods of the present application.

[0025] The plasma-modified seaweed-based aerogel of the present application is applied in adsorbing volatile organic compounds.

[0026] Mechanism of action of the present application: 1. The biomass aerogel prepared by the present application has a forming effect.

[0027] In deionized water at 50-55 ℃, the gelatin is fully dissolved and forms a uniform dispersion system. With the addition of kelp and the gradual reduction of the system temperature, the reorganization occurs between the gelatin molecular chains, and part of the original collagen protein structure is restored. These microscopic processes formed during cooling play a key role in "physical crosslinking points" in the macroscopic, connecting and fixing the surrounding gelatin molecular chains, thereby constructing a hydrogel with a stable three-dimensional network structure. The network can firmly bind water molecules and dispersed kelp in the grid through physical wrapping, achieving uniform fixation of water and solids. Subsequently, the freeze-drying technology is used to remove the internal water in the form of ice crystals. This process can maintain the original three-dimensional skeleton of the gel, and finally successfully prepare a biomass aerogel material with a forming structure, light weight and abundant pores.

[0028] 2. The biomass aerogel prepared by the present application has a uniform pore structure.

[0029] By introducing CaCl2 solution to regulate the gelation behavior of the hydrogel, the cross-linking structure of the hydrogel is improved, which lays a foundation for the subsequent preparation of high porosity materials. Subsequently, the vacuum freeze-drying technology is used to sublimate the internal moisture of the material in the form of ice crystals, which not only retains the three-dimensional skeleton of the original material, but also forms a rich pore system due to the removal of ice crystals, thereby improving the porosity and pore volume of the material, and providing more adsorption sites for VOCs. The NTP is used to modify the surface of the material, and the high-energy electrons and active particles generated by the NTP are used to physically etch the surface of the aerogel, which effectively increases the specific surface area and optimizes the pore distribution. In addition, the NTP treatment causes the water on the surface of the material to ionize, successfully grafting oxygen-containing functional groups such as hydroxyl and carboxyl groups, which enhances the surface polarity of the material. During the subsequent carbonization process, these oxygen-containing groups decompose and release gas products, further creating pores and expanding the pore structure, forming a multi-level pore structure including micropores and mesopores.

[0030] 3. The biomass aerogel of the present application increases the adsorption of VOCs by nitrogen doping.

[0031] During the NTP treatment process, under N2 atmosphere, nitrogen molecules are ionized and dissociated by high-energy discharge to generate high-reactivity nitrogen-containing particles including excited-state nitrogen atoms, nitrogen ions and active nitrogen radicals. These active particles interact with the surface of the material, effectively introducing and grafting nitrogen-containing functional groups, promoting the formation of specific nitrogen-containing heterocyclic structures such as pyridine nitrogen and pyrrole nitrogen, which can enhance the adsorption of p-xylene. On the other hand, gelatin itself contains nitrogen elements, which not only promotes the stable formation of biomass aerogel, but also enables the in-situ retention and transformation of nitrogen elements into nitrogen-containing functional groups during the subsequent carbonization process, achieving nitrogen doping of the carbon skeleton.

[0032] 4. The biomass aerogel prepared by the present application is green and environmentally friendly, realizing the resource utilization of biomass.

[0033] Currently, the overpopulation of some algae in the ocean has put pressure on the ecological balance. Kelp, as a large economic seaweed, has the advantages of strong environmental adaptability, short growth cycle, large biomass and renewable resources. Based on this, the present application uses kelp as a biomass raw material to develop a new type of seaweed-based aerogel, which not only effectively alleviates the environmental burden caused by seaweed accumulation, but also converts waste biomass into high-value functional materials, achieving the goal of resource recycling.

[0034] Compared with the prior art, the present application has the following advantages: The present application relates to a kind of preparation method of NTP modified seaweed-based biomass aerogel.The method uses seaweed as main raw material, by introducing gelatin auxiliary forming, and utilize CaCl2 In carbonization process, construct porous structure;Subsequently, non-thermal plasma (NTP) modification treatment is carried out under nitrogen atmosphere, this process not only introduces nitrogen-containing functional groups on the surface, but also etching is carried out on the surface of material, so as to significantly enhance the adsorption performance of aerogel to VOCs.

[0035] (1) The preparation process of the present application simplifies the synthesis path of biomass aerogel, uses water as solvent, combines vacuum freeze drying process, successfully avoids the dependence of traditional supercritical drying on high pressure equipment, greatly reduces equipment investment and energy consumption. This green drying method not only maintains the integrity of the three-dimensional porous structure of the material, but also avoids the residual of organic solvent, providing a feasible technical solution for large-scale production of low-cost and environmentally friendly aerogel.

[0036] (2) By introducing gelatin as a forming aid and natural nitrogen source, the present application realizes one-step completion of material forming and nitrogen doping. The nitrogen-containing functional groups in the gelatin molecular chain are uniformly distributed in the three-dimensional network skeleton during gelation, effectively enhancing the polarity and chemical adsorption active sites of the aerogel surface. This in-situ doping strategy not only simplifies the process, but also significantly improves the capture and adsorption capacity of the material for non-polar or weakly polar VOC molecules.

[0037] (3) The present application uses NTP technology to modify the surface of aerogel under N2 atmosphere, which is a high-efficiency, low-energy-consumption green modification method. This process realizes micro-etching and directional implantation of nitrogen-containing functional groups (such as amine group and pyridine nitrogen) on the surface of the material through high-energy particle bombardment, which optimizes the pore structure and thus synergistically improves the adsorption capacity of xylene.

[0038] (4) Under the conditions of temperature 30 ℃, initial concentration of p-xylene 19.671 mg / L, and adsorbent addition amount 0.10 g, the adsorption capacity of the aerogel to p-xylene reaches 149 mg / g within 120 min, which highlights the application potential of the material in the field of actual VOCs treatment.

[0039] (5) The present application uses renewable kelp as raw material, combined with NTP green modification technology, significantly reduces the amount of acid, alkali and other reagents used in traditional chemical activation method and subsequent pollution load. The whole preparation process is environmentally friendly, which is in line with the concept of green chemical industry and sustainable development. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 , Figure 1 (A): SW@G-NTP-Ca before carbonization; Figure 1(B): SW@G-NTP-Ca kelp-based biomass aerogel after carbonization; Figure 1 (C): SW@G-NTP-Ca standing on the flower; Figure 1 (D): SW@G-NTP-Ca bearing the weight of 100 g weight.

[0041] Figure 2 : P-xylene adsorption capacity of SW@G-NTP-Ca, SW@G, SW@G-Ca, SW@G-NTP; Adsorption capacity: adsorption capacity; Adsorption material: adsorption material.

[0042] Figure 3 : P-xylene adsorption capacity of SW@G-NTP-Ca on different VOCs.

[0043] Adsorption capacity: adsorption capacity; Types of VOCs: types of volatile organic compounds Figure 4 : P-xylene adsorption capacity of different seaweeds.

[0044] Adsorption capacity: adsorption capacity; Adsorption material: adsorption material.

[0045] Figure 5 : P-xylene adsorption capacity of SW@G-NTP-Ca after five adsorption-desorption cycles; Adsorption capacity: adsorption capacity; Cycle numbers: cycle numbers; Figure 6 : (a) SW@G, (b) SW@G-Ca, (c) SW@G-NTP, (d) SW@G-NTP-Ca 500 times magnification scanning electron microscope images; Figure 7 : (a) SW@G, (b) SW@G-Ca, (c) SW@G-NTP, (d) SW@G-NTP-Ca water contact angle test; Figure 8 : P-xylene adsorption capacity of SW@G-NTP-Ca, SW@G, SW@G-NTP-Cu, SW@G-NTP-Mg; Adsorption capacity: adsorption capacity; Adsorption material: adsorption material. DETAILED DESCRIPTION

[0046] The experimental methods used in the embodiments of the present application are conventional methods unless otherwise specified. The materials, reagents, etc. used in the embodiments of the present application can be obtained from commercial channels unless otherwise specified.

[0047] The room temperature range of the present application is 20-30℃.

[0048] The manufacturer of the dielectric barrier discharge NTP modification device used in the present application is Nanjing Sumen Plasma Technology Co., Ltd. in China, and the model is CTP-2000 K. The digital oscilloscope model is RIGOL DS1202Z-E.

[0049] The meanings of some abbreviations or Chinese corresponding to English used in the present application are as follows: DBD: Dielectric barrier discharge NTP: Non-thermal plasma VOCs: Volatile organic compounds PX: p-Xylene

[0050] Example 1 The NTP modification was used to prepare the kelp-based aerogel material (SW@G-NTP-Ca), and the steps included: (1) The kelp was washed, dried at 100℃ for 8 h, and sieved through an 80-mesh screen to obtain uniform kelp powder.

[0051] (2) 0.3 g of gelatin was weighed in a 100 mL beaker, 10 mL of deionized water was added, and the gelatin was dissolved in a 50℃ oven.

[0052] (3) After the gelatin was dissolved, 2.0 g of kelp powder was added, followed by the addition of 5 mL of 0.2 M CaCl2 solution and 5 mL of deionized water, and then magnetic stirring was performed for 15 min to obtain a precursor.

[0053] (4) About 10 g of the precursor was placed in a dielectric barrier discharge (DBD) NTP modification device, and NTP modification was performed under the following conditions: nitrogen atmosphere, modification voltage of 40 V, modification time of 10 min, and discharge current of 1.95-2.05 A.

[0054] (5) The NTP-modified material was subjected to mold filling and vacuum freeze-drying treatment at-60℃ for 24 h.

[0055] (6) Finally, the sample was placed in a tube furnace and heated at a rate of 5 °C / min under a nitrogen atmosphere, and calcined at 800 °C for 1 h. Then, it was cooled to room temperature at a rate of 5 °C / min. After removal, the sample was washed with HCl and then washed with deionized water until neutral. Finally, it was dried in an oven at 100 °C for 4 h to obtain biomass aerogel.

[0056] Example 2 The preparation of NTP-modified copper diatom-based biomass aerogel materials includes the following steps: (1) The copper algae was washed, dried at 100 ℃ for 8 h, and then passed through an 80-mesh sieve to obtain uniform copper algae powder.

[0057] (2) Weigh 0.3 g of gelatin into a 100 mL beaker, add 5 mL of deionized water, and dissolve the gelatin in an oven at 50 °C.

[0058] (3) After the gelatin is dissolved, add 2.5 g of copper algae powder, then add 5 mL of 0.2 M CaCl2 solution, and stir magnetically for 15 min to obtain the precursor.

[0059] (4) Weigh about 10 g of the precursor and place it in a dielectric barrier discharge (DBD) NTP modification device. Under nitrogen atmosphere, the modification voltage is 40 V, the modification time is 10 min, and the discharge current is 1.95-2.05 A to carry out NTP modification.

[0060] (5) The NTP-modified material was filled into a mold and subjected to vacuum freeze-drying at -60 ℃ for 24 h.

[0061] (6) Finally, the sample was placed in a tube furnace and heated at a rate of 5 °C / min under a nitrogen atmosphere, and calcined at 800 °C for 1 h. Then, it was cooled to room temperature at a rate of 5 °C / min. After removal, the sample was washed with HCl and then washed with deionized water until neutral. Finally, it was dried in an oven at 100 °C for 4 h to obtain biomass aerogel.

[0062] Example 3 The preparation of NTP-modified Sargassum fusiforme-based biomass aerogel materials includes the following steps: (1) Wash the green Sargassum, dry it at 100 ℃ for 8 hours, and obtain uniform green Sargassum powder by passing it through an 80-mesh sieve.

[0063] (2) Weigh 0.3 g of gelatin into a 100 mL beaker, add 5 mL of deionized water, and dissolve the gelatin in an oven at 50 °C.

[0064] (3) After the gelatin is dissolved, add 2.5 g of Sargassum fusiforme powder, then add 5 mL of 0.2 M CaCl2 solution, and stir magnetically for 15 min to obtain the precursor.

[0065] (4) Weigh about 10 g of the precursor and place it in a dielectric barrier discharge (DBD) NTP modification device. Under nitrogen atmosphere, the modification voltage is 40 V, the modification time is 10 min, and the discharge current is 1.95-2.05 A to carry out NTP modification.

[0066] (5) The NTP-modified material was filled into a mold and subjected to vacuum freeze-drying at -60 ℃ for 24 h.

[0067] (6) Finally, the sample was placed in a tube furnace and heated at a rate of 5 °C / min under a nitrogen atmosphere, and calcined at 800 °C for 1 h. Then, it was cooled to room temperature at a rate of 5 °C / min. After removal, the sample was washed with HCl and then washed with deionized water until neutral. Finally, it was dried in an oven at 100 °C for 4 h to obtain biomass aerogel.

[0068] Example 4 The preparation of NTP-modified Sargassum fusiforme-based biomass aerogel materials includes the following steps: (1) The Sargassum was washed, dried at 100 °C for 8 h, and then passed through an 80-mesh sieve to obtain uniform Sargassum powder.

[0069] (2) Weigh 0.3 g of gelatin into a 100 mL beaker, add 5 mL of deionized water, and dissolve the gelatin in an oven at 50 °C.

[0070] (3) After the gelatin is dissolved, add 2.5 g of Sargassum powder, then add 5 mL of 0.2 M CaCl2 solution, and stir magnetically for 15 min to obtain the precursor.

[0071] (4) Weigh about 10 g of the precursor and place it in a dielectric barrier discharge (DBD) NTP modification device. Under nitrogen atmosphere, the modification voltage is 40 V, the modification time is 10 min, and the discharge current is 1.95-2.05 A to carry out NTP modification.

[0072] (5) The NTP-modified material was filled into a mold and subjected to vacuum freeze-drying at -60 ℃ for 24 h.

[0073] (6) Finally, the sample was placed in a tube furnace and heated at a rate of 5 °C / min under a nitrogen atmosphere, and calcined at 800 °C for 1 h. Then, it was cooled to room temperature at a rate of 5 °C / min. After removal, the sample was washed with HCl and then washed with deionized water until neutral. Finally, it was dried in an oven at 100 °C for 4 h to obtain biomass aerogel.

[0074] Comparative Example 1 A method for preparing simple kelp-based biomass aerogels (SW@G) includes the following steps: (1) Wash the kelp, dry it at 100 ℃ for 8 h, and obtain uniform kelp powder by passing it through an 80-mesh sieve.

[0075] (2) Weigh 0.3 g of gelatin into a 100 mL beaker, add 10 mL of deionized water, and dissolve the gelatin in an oven at 50 °C to obtain a gelatin solution.

[0076] (3) After the gelatin is dissolved, add 2.0 g of kelp powder, then add 10 mL of deionized water, and stir magnetically for 15 min to obtain the precursor.

[0077] (4) The precursor is filled into a mold and then subjected to vacuum freeze drying at -60 ℃ for 24 h.

[0078] (5) Finally, the sample was placed in a tube furnace and heated at a rate of 5 °C / min under a nitrogen atmosphere, and calcined at 800 °C for 1 h. Then, it was cooled to room temperature at a rate of 5 °C / min. After removal, the sample was washed with HCl and then washed with deionized water until neutral. Finally, it was dried in an oven at 100 °C for 4 h to obtain biomass aerogel.

[0079] Comparative Example 2 The steps for preparing kelp-based biomass aerogel material (SW@G-Ca) by introducing calcium chloride include: (1) Wash the kelp, dry it at 100 ℃ for 8 h, and obtain uniform kelp powder by passing it through an 80-mesh sieve.

[0080] (2) Weigh 0.3 g of gelatin into a 100 mL beaker, add 10 mL of deionized water, and dissolve the gelatin in an oven at 50 °C.

[0081] (3) After the gelatin is dissolved, add 2.0 g of kelp powder, then add 5 mL of 0.2 M CaCl2 solution and 5 mL of deionized water, and then stir magnetically for 15 min to obtain the precursor.

[0082] (4) The precursor is filled into a mold and subjected to vacuum freeze drying at -60 ℃ for 24 h.

[0083] (5) Finally, the sample was placed in a tube furnace and heated at a rate of 5 °C / min under a nitrogen atmosphere, and calcined at 800 °C for 1 h. Then, it was cooled to room temperature at a rate of 5 °C / min. After removal, the sample was washed with HCl and then washed with deionized water until neutral. Finally, it was dried in an oven at 100 °C for 4 h to obtain biomass aerogel.

[0084] Comparative Example 3 The preparation of NTP-modified kelp-based biomass aerogel material (SW@G-NTP) involves the following steps: (1) Wash the kelp, dry it at 100 ℃ for 8 h, and obtain uniform kelp powder by passing it through an 80-mesh sieve.

[0085] (2) Weigh 0.3 g of gelatin into a 100 mL beaker, add 10 mL of deionized water, and dissolve the gelatin in an oven at 50 °C.

[0086] (3) After the gelatin is dissolved, add 2.0 g of kelp powder, then add 10 mL of deionized water, and then stir the precursor magnetically for 15 min.

[0087] (4) Weigh about 10 g of the precursor and place it in a dielectric barrier discharge (DBD) NTP modification device. Under nitrogen atmosphere, the modification voltage is 40 V, the modification time is 10 min, and the discharge current is 1.95-2.05 A to carry out NTP modification.

[0088] (5) The NTP-modified material was filled into a mold and subjected to vacuum freeze-drying at -60 ℃ for 24 h.

[0089] (6) Finally, the sample was placed in a tube furnace and heated at a rate of 5 °C / min under a nitrogen atmosphere, and calcined at 800 °C for 1 h. Then, it was cooled to room temperature at a rate of 5 °C / min. After removal, the sample was washed with HCl and then washed with deionized water until neutral. Finally, it was dried in an oven at 100 °C for 4 h to obtain biomass aerogel.

[0090] Experimental Example 1 To illustrate the improved adsorption performance of this invention, static headspace gas chromatography was used at an ambient temperature of 30°C in a 650 mL headspace vial. Gaseous p-xylene (PX 15 μL) at a concentration of 19.671 mg / L was used as the target pollutant. The adsorption performance of the kelp-based aerogel adsorbents SW@G-NTP-Ca, SW@G, SW@G-Ca, and SW@G-NTP prepared in Example 1 and Comparative Examples 1-3 was characterized. The amount of kelp-based aerogel used was 0.10 g / L in all cases. The results for adsorbing gaseous PX at a time of 120 min are as follows: Figure 2 As shown. From Figure 2It can be seen that the adsorption of kelp-based aerogels in Example 1 and Comparative Examples 1-3 tends to stabilize after 120 min. The adsorption amounts of PX at 120 min are 149.22 mg / g, 61.44 mg / g, 67.32 mg / g, and 77.16 mg / g, respectively. The adsorption amount of PX by the kelp-based biomass aerogel adsorbent SW@G-NTP-Ca prepared in Example 1 of this invention is significantly higher than that of the kelp-based biomass aerogels prepared in Comparative Examples 1-3, which are SW@G, SW@G-Ca, and SW@G-NTP. This indicates the effectiveness of the modification method of NTP modification, which involves etching and the interaction of grafted functional groups, and finally high-temperature activation to obtain the kelp-based biomass aerogel adsorbent.

[0091] Table 1. Adsorption capacity of different materials for PX

[0092] Experimental Example 2 To evaluate the adsorption performance of the kelp-based aerogel adsorbent prepared in this invention for various typical volatile organic compounds (VOCs), static headspace gas chromatography was used in a 650 mL headspace vial at an ambient temperature of 30 °C. 15 μL of different types of liquid VOCs (including toluene, acetone, ethyl acetate, dimethyl disulfide, and p-xylene) were precisely injected into the preheated headspace vial wall using a microsyringe to simulate the actual VOCs release environment. The kelp-based aerogel SW@G-NTP-Ca prepared in Example 1 was selected as the adsorbent at a dosage of 0.10 g / L, with an adsorption time of 120 minutes. The results are as follows: Figure 3 As shown in the figure. Experiments show that the adsorption process tends to reach equilibrium at 120 minutes. The adsorption capacities of SW@G-NTP-Ca for different VOCs are as follows: p-xylene 149.22 mg / g, ethyl acetate 134.04 mg / g, dimethyl disulfide 155.46 mg / g, toluene 146.38 mg / g, and acetone 115.03 mg / g. This indicates that the aerogel not only exhibits excellent adsorption capacity for non-polar benzene compounds (such as p-xylene and toluene), but also possesses good adsorption performance for oxygen-containing polar molecules (such as acetone and ethyl acetate) and sulfur-containing compounds (such as dimethyl disulfide), demonstrating its broad application potential in the control of complex VOC pollution.

[0093] Table 2. Adsorption capacity of SW@G-NTP-Ca material prepared in Example 1 for different VOCs.

[0094] Experimental Example 3 To systematically evaluate the adsorption performance of the seaweed-based aerogel adsorbent prepared in this invention for PX, static headspace gas chromatography was used for experimental research. Under a controlled ambient temperature of 30 °C, 15 μL of liquid PX was precisely injected into the inner wall of a preheated 650 mL headspace vial using a microsyringe to simulate a real VOCs release environment. Biomass aerogels prepared from different seaweeds in Examples 1-4 were selected as adsorbent materials, and adsorption experiments were conducted for 120 minutes. The results are as follows: Figure 4 As shown in the figure, experimental data indicate that the adsorption process reaches equilibrium at 120 minutes. The adsorption capacities of different seaweed-based aerogels for PX are as follows: kelp-based 149.22 mg / g, *Sargassum fusiforme*-based 71.31 mg / g, *Sargassum fusiforme*-based 53.55 mg / g, and *Sargassum fusiforme*-based 63.94 mg / g. This demonstrates a significant difference in the PX adsorption performance of biomass aerogels prepared from different seaweed sources. Kelp-based aerogel exhibits the best adsorption capacity, its superior performance stemming from the naturally occurring polysaccharides and enriched natural metal salt ions in kelp. These components help regulate the surface properties and pore structure of the material, effectively enhancing the adsorption of PX. Therefore, this study shows that kelp-based biomass aerogels have significant advantages in xylene adsorption, providing a valuable reference for the development of efficient VOCs adsorption materials.

[0095] Table 3. Adsorption capacity of different seaweed-based aerogels for PX

[0096] Test Example 4 To evaluate the reusability of the kelp-based aerogel adsorbent prepared in this invention for PX, a programmed temperature rise was used to perform five adsorption-desorption cycles. Static headspace gas chromatography was employed, and the experiment was conducted in a 650 mL headspace vial at an ambient temperature of 30 °C. 15 μL PX was precisely injected into the preheated inner wall of the headspace vial using a microsyringe to simulate the actual VOCs release environment. The kelp-based aerogel SW@G-NTP-Ca prepared in Example 1 was selected as the adsorbent, with a dosage of 0.10 g / L and an adsorption time of 120 minutes. After adsorption equilibrium was reached, desorption was performed by drying in a 200 °C oven for 1 h. The results are as follows: Figure 5 As shown in the figure, the adsorption capacity of SW@G-NTP-Ca for p-xylene decreased after five adsorption cycles. This may be attributed to the incomplete release of p-xylene due to the chemisorption sites on the aerogel being occupied.

[0097] Experimental Example 5 The surface morphology of SW@G, SW@G-Ca, SW@G-NTP, and SW@G-NTP-Ca prepared in Example 1 and Comparative Examples 1-3 was observed using a Verios G4 field emission scanning electron microscope. The results are as follows: Figure 6 As shown in the image above. Figure 6 The results show that under the cross-linking effect of gelatin, kelp particles are bound and shaped by SW@G, exhibiting an irregular morphology with interwoven layers, fibers and folds, and forming large pores. Figure 6 In b, the addition of CaCl2 solution to SW@G-Ca affected the gelation process, prompting the formation of a certain number of micropores and mesoporous structures inside the material. Figure 6 As can be seen, micropores and mesopores appear on the surface of the SW@G-NTP material. This is mainly due to the etching effect of high-energy active particles generated by NTP ionization on the material surface, and the grafting of oxygen-containing functional groups (-COOH, -C=O, -OH) generated by ionized water onto the material surface. During the subsequent carbonization process, these functional groups decompose to produce gases such as CO2 and CO, thereby playing a role in pore formation. Figure 6 In d, SW@G-NTP-Ca exhibits a more diverse range of pore structures. This is attributed to the introduction of CaCl2 regulating the gelation behavior, while the high-energy particle bombardment brought about by NTP treatment and the decomposition of oxygen-containing functional groups grafted on the surface during carbonization jointly promote the formation of hierarchical pore structures.

[0098] Experimental Example 6 The specific surface area and pore structure of the SW@G, SW@G-Ca, SW@G-NTP, and SW@G-NTP-Ca materials prepared in Example 1 and Comparative Examples 1-3 were tested, and the results are shown in Table 4. The introduction of CaCl2 solution alone can affect the gel behavior of the materials, resulting in a significantly larger specific surface area (503.8 m²) for SW@G-Ca. 2 g -1 The specific surface area of ​​SW@G-NTP, which is modified only by NTP, is higher than that of SW@G. 2 g -1 The specific surface area of ​​the NTP-modified Ca@G aerogel was lower than that of SW@G. This is likely due to the higher surface temperature during NTP treatment, which led to a decrease in the material's moisture content and reduced the amount of water that could be removed during the freeze-drying stage, resulting in a more limited pore structure. In contrast, the SW@G-NTP-Ca aerogel, which was simultaneously treated with CaCl2 solution and modified with NTP, showed a significantly increased specific surface area of ​​595.7 m². 2 g -1 Furthermore, the pore volume also increases accordingly. The average pore size of this material is 1.85 nm (<2.0 nm), and the richer specific surface area and pore structure provide more active sites for its adsorption of PX.

[0099] Table 4 Specific surface area and pore volume of kelp-based biomass aerogel adsorbents

[0100] Experimental Example 7 To evaluate the adsorption performance of the kelp-based biomass aerogel prepared in this invention for PX, its hydrophobicity was tested using the seated drop method (instrument: JY-82C). The droplet volume was 16 μL, and the contact angle was determined by goniometric method. The results are as follows: Figure 7 As shown, the contact angle of SW@G is 122.13°. Figure 7 a) exhibits hydrophobicity; however, after treatment with CaCl2 solution, the contact angle of SW@G-Ca decreased to 22.88° ( Figure 7 (b) indicates that it has become hydrophilic. After NTP modification, the contact angle of SW@G-NTP further increased to 136.04° ( Figure 7 c), indicating that this treatment significantly enhanced the hydrophobicity of the material. However, the adsorption performance of all three materials for PX was weak. Notably, the contact angle of SW@G-NTP-Ca was 122.74° ( Figure 7 d). The results indicate that NTP modification based on the introduction of CaCl2 solution, while partially reducing the hydrophobicity of the material, can effectively improve its adsorption performance for PX; and NTP modification itself can significantly enhance the hydrophobic properties of the material.

[0101] Comparative Study Example 1 Different metals were introduced into the NTP-modified kelp-based biomass aerogel (SW@G-NTP-Cu) process, including the following steps: (1) The kelp is pretreated by washing and drying, and then uniform kelp powder is obtained by sieving through an 80-mesh sieve.

[0102] (2) Weigh 0.3 g of gelatin into a 100 mL beaker, add 10 mL of deionized water, and dissolve the gelatin in an oven at 50 °C.

[0103] (3) After the gelatin is dissolved, add 2.0 g of kelp powder, then add 5 mL of 0.1 M CuCl2 or MgCl2 solution and 5 mL of deionized water, and then stir magnetically for 15 min.

[0104] (4) Weigh about 10 g of the well-stirred biomass material and place it in a dielectric barrier discharge (DBD) NTP modification device. Under nitrogen atmosphere, the modification voltage is 40 V, the modification time is 10 min, and the discharge current is 1.95-2.05 A to carry out NTP modification.

[0105] (5) The NTP-modified material was filled into a mold and subjected to vacuum freeze-drying at -60 ℃ for 24 h.

[0106] (6) Finally, the sample was placed in a tube furnace and heated at a rate of 5 °C / min under a nitrogen atmosphere, and calcined at 800 °C for 1 h. Then, it was cooled to room temperature at a rate of 5 °C / min. After removal, the sample was washed with HCl and then washed with deionized water until neutral. Finally, it was dried in an oven at 100 °C for 4 h to obtain biomass aerogel.

[0107] At an ambient temperature of 30 ℃ and a relative humidity of 0%, gaseous p-xylene with a concentration of 19.671 mg / L was used as the target pollutant. 0.1 g of SW@G-NTP-Cu biomass aerogel was placed in a 650 mL headspace vial. Figure 8 After 120 min of adsorption, the adsorption capacity of SW@G-NTP-Cu for p-xylene was 69.6 mg / g. However, the adsorption capacity of SW@G-NTP-Cu was lower than that of SW@G-NTP, which may be due to the collapse of the pore structure caused by the interaction between NTP and CuCl2 and MgCl2, thus affecting its adsorption of p-xylene.

[0108] Comparative Study Example 2 This example refers to patent publication number CN116553517A, patent title: Preparation and application of a bio-waste-derived carbon aerogel material, and the experiment includes the following steps: (1) Physically crush the rice husk biomass containing polysaccharides to make the particle size less than 200 μm.

[0109] (2) The crushed biomass is subjected to alkaline hydrolysis by treating it with 10%-12% NaOH solution for 12-16 hours.

[0110] (3) The suspension after alkaline hydrolysis is dissolved and purified, and microwaved at 130°C for 30 minutes using an organic solvent (such as phenol or acetone) to obtain the precursor.

[0111] (4) The precursor is immersed in a salt solution and placed at -30 ℃ to -25 ℃ for 24-32 hours to gel, thus obtaining a salt-containing aerogel.

[0112] (5) The salt-containing aerogel is heated to 500 ℃ at a heating rate of 5 ℃ / min under an inert atmosphere (such as nitrogen) and held at the temperature for 1-3 hours to carbonize it, thus obtaining carbon aerogel material.

[0113] CN116553517A proposes a method that utilizes citric acid carboxylation to introduce carboxylic acid groups onto the material surface. Alkali metals are then introduced to the material surface via ion exchange between the base and carboxyl groups, and the carboxyl groups anchor the alkali metal ions at specific locations. High-temperature activation melts the metal ions, thus creating microporous carbon. However, observation of the experimental results in this case reveals that, compared to the plasma-modified seaweed-based aerogel preparation of this invention, the seaweed-based biomass aerogel SW@G-NTP-Ca obtained in this example has a longer experimental cycle and utilizes more chemical reagents.

[0114] Comparative Study Example 3 This example refers to patent publication number CN115990463A, patent title: A method for preparing and applying modified biomass carbon aerogel for adsorbing antibiotics, and the experiment includes the following steps: (1) Cut the fresh grapefruit peel into 1 cm pieces. 3 The blocks were dried in an oven at 30 ℃ until constant weight.

[0115] (2) Place the dried grapefruit peel into a hydrothermal reactor and react at 180 °C for 12 h, then let it cool naturally to room temperature.

[0116] (3) Take out the solid obtained from the reaction, immerse it in a 1:1 aqueous solution of ethanol and deionized water for 12 h, and then wash it with deionized water until the cleaning solution is colorless and transparent.

[0117] (4) The solid was frozen at -18 ℃ for 12 h, and then placed in a freeze dryer and dried at -60 ℃ for 50 h to obtain grapefruit peel carbon aerogel (GPH).

[0118] (5) Take 0.5 g GPH and 0.5 g dopamine, add 250 mL pH buffer (pH=8.5), and stir at 70 °C for 5 h.

[0119] (6) After vacuum filtration, the gel was dried in a vacuum drying oven at 50 °C for 8 h to obtain dopamine modified aerogel (MGPH).

[0120] Method CN115990463A proposes using grapefruit peel as raw material. After cutting and drying, grapefruit peel carbon aerogel (GPH) is prepared by hydrothermal reaction at 180 °C for 12 hours, solvent washing, and freeze-drying. Subsequently, GPH is modified by stirring and reacting with dopamine at a 1:1 mass ratio in a buffer solution at pH 8.5 at 70 °C for 5 hours to finally obtain MGPH. However, observation of the experimental results shows that compared with the plasma-modified seaweed-based aerogel preparation method of this invention, the kelp-based biomass aerogel SW@G-NTP-Ca obtained in this example has more complex preparation conditions and uses a large number of chemical reagents.

[0121] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of preparing a plasma-modified seaweed-based aerogel, characterized by, The method comprises the following steps: (1) taking seaweed biomass raw materials, washing, drying, screening, and obtaining seaweed biomass powder; (2) taking gelatin, adding water, mixing, and obtaining a gelatin solution; (3) adding the seaweed biomass powder of step (1) to the gelatin aqueous solution of step (2), and then adding a calcium chloride solution, stirring, and obtaining a precursor; (4) placing the precursor of step (3) in a dielectric barrier discharge NTP modification device, and performing NTP modification in a nitrogen atmosphere; (5) filling a mold with the NTP-modified material of step (4), and performing vacuum freeze-drying treatment; (6) placing the material obtained in step (5) in a tube furnace and performing calcination and carbonization in a nitrogen atmosphere; taking out, pickling, and then washing with water until neutral, and drying to obtain a plasma-modified seaweed-based aerogel.

2. The method for preparing a plasma-modified seaweed-based aerogel according to claim 1, characterized in that: in step (1), the seaweed biomass is at least one of green sargassum, copper algae, and sea tangle; in step (1), the drying temperature is 90-110 ℃, and the drying time is 7-9 h; and the mesh size of the screening is 80-100 mesh.

3. The method of claim 1, wherein the plasma-modified seaweed-based aerogel is prepared by the steps of: in step (2), the mass-volume ratio of the gelatin to water is 0.20-0.40 g:5-20 mL, and the mixing temperature is 50-55 ℃.

4. The method of claim 1, wherein the plasma-modified seaweed-based aerogel is prepared by the steps of: in step (3), the concentration of the calcium chloride solution is 0.1-0.3 mol / L; in step (3), the mass-volume ratio of the seaweed biomass powder to the calcium chloride solution is 1-3 g:3-6 mL; in step (3), after adding the calcium chloride solution, water is also added, and the mass-volume ratio of the seaweed biomass powder to water is 1-3 g:1-6 mL; in step (3), the stirring time is 10-20 min.

5. The method of claim 1, wherein the plasma-modified seaweed-based aerogel is prepared by the steps of: in step (4), the modification voltage is 25-50 V, and the modification time is 5-20 min.

6. The method of claim 1, wherein the plasma-modified seaweed-based aerogel is prepared by the steps of: in step (5), the vacuum freeze-drying conditions are -50~-70 ℃ for 20-28 h.

7. The method for preparing a plasma-modified seaweed-based aerogel according to claim 1, characterized in that: in step (6), the calcination temperature is 750-850 ℃, and the calcination time is 0.8-1.2 h; in step (6), the drying temperature is 100-105 ℃, and the drying time is 3-5 h.

8. A plasma-modified seaweed-based aerogel, characterized in that, obtained by the preparation method of any one of claims 1-7.

9. The plasma-modified seaweed-based aerogel of claim 8 for use in adsorbing volatile organic compounds.

10. Use according to claim 9, characterized in that, The volatile organic compounds are at least one of p-xylene, toluene, dimethyl disulfide, ethyl acetate, and acetone.

Images