Preparation method and application of bacterial cellulose modified biomass solar evaporator

Abstract

The present invention provides a method for preparing a biomass solar evaporator modified with bacterial cellulose, which uses a luffa with hydrophilicity and a three-dimensional pore structure as a substrate, forms bacterial cellulose inside and outside the luffa by a dynamic culture method, and loads a photothermal material in the bacterial cellulose to obtain a biomass solar evaporator with high photothermal conversion efficiency, high water transport and evaporation efficiency, stable evaporation performance, good surface salt rejection performance, and biodegradable. In the above technical scheme, by loading the photothermal material in the process of growing and forming bacterial cellulose on the luffa, the photothermal material is evenly distributed in the evaporator, and the photothermal material can be ensured to be stably combined with the substrate, so that the evaporation performance of the evaporator is more stable; secondly, the pore structure of the luffa provides a fast channel for water replenishment, improves the water supply capacity, thereby effectively solving the problem of salt deposition on the surface of the photothermal material, and further improves the evaporation performance of the evaporator.

Description

Technical Field

[0001] The present invention relates to the technical field of seawater desalination, and in particular to a preparation method and application of a bacterial cellulose-modified biomass solar evaporator. Background Art

[0002] Desalination is a clean and effective solution to address water pollution and water shortages. Traditional desalination technologies, such as adsorption, multi-stage flash evaporation, ultrafiltration, membrane distillation, reverse osmosis, and electrodialysis, have established highly mature, large-scale water supply systems. However, these technologies require large-scale thermal and electrical infrastructure, resulting in concentrated production capacity. Furthermore, the production process generates significant amounts of greenhouse gases, posing environmental risks. Furthermore, during the desalination and purification process, salt accumulates on the device surface, forming crystals that block water channels, impacting water supply and reducing desalination efficiency, rendering traditional desalination devices "disposable" waste. To address the common challenges of traditional desalination and reduce energy consumption and pollution, researchers have proposed solar-driven interfacial evaporation desalination technology. This technology utilizes solar energy to continuously generate fresh water. It offers the advantages of low cost, miniaturization, recyclability, sustainability, and environmental friendliness. It avoids the large-scale, centralized, and energy-intensive nature of traditional desalination, offering a green and sustainable solution to the current water scarcity problem.

[0003] The solar interfacial evaporator used to construct an efficient solar-driven interfacial evaporation system consists of a photothermal layer and a water transport layer. The photothermal layer acts as an efficient light absorber, absorbing solar energy for photothermal conversion and thus promoting water evaporation; the water transport layer can transport water from bottom to top to the photothermal layer, and plays a role in supporting the photothermal material and providing insulation. In order to improve the evaporation efficiency, researchers are based on the development of photothermal materials with high photothermal conversion efficiency and low heat conduction loss. However, excessively fast steam generation rates also significantly increase the local salt water concentration at the interface, which also causes the problem of salt accumulation. In recent years, due to the extensive resource conditions, rich internal structure and operability, as well as the advantages of renewable resources, the development of sustainable biomass-based solar interfacial evaporators with high photothermal conversion efficiency and water evaporation efficiency, and balanced or inhibited salt accumulation has become an inevitable research trend.

[0004] In view of this, it is necessary to design an improved preparation method and application of a bacterial cellulose-modified biomass solar evaporator to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method and application of a bacterial cellulose-modified biomass solar evaporator.

[0006] To achieve the above-mentioned object of the invention, on the one hand, the present invention provides a method for preparing a bacterial cellulose-modified biomass solar evaporator, comprising the following steps:

[0007] S1. Mix glucose, peptone, yeast extract, citric acid, disodium hydrogen phosphate dodecahydrate, and deionized water to obtain HS medium;

[0008] S2. Add the photothermal material and loofah to the HS culture medium prepared in step S1, sterilize, inoculate Acetobacter xylinum, and dynamically culture at 25-30°C to form bacterial cellulose inside and outside the loofah, and load the photothermal material in the bacterial cellulose to obtain a functionalized bacterial cellulose hydrogel that grows directionally on the loofah; finally, sterilize and freeze-dry to obtain the biomass solar evaporator.

[0009] As an embodiment of the present invention, in step S2, the pore density of the loofah is 79-93%.

[0010] As an embodiment of the present invention, in step S2, the process of inoculating Acetobacter xylinum is carried out in the following manner: adding Acetobacter xylinum solution to the sterilized HS culture medium, wherein the mass percentage of the Acetobacter xylinum solution is 3-15 wt%.

[0011] As an embodiment of the present invention, in step S2, the photothermal material is one or more of a carbon material, a polymer coating and a nano-inorganic metal coating, and the rule for adding the photothermal material is: 2.5-12.5 mg of the photothermal material is added to every 1 mL of the HS culture medium; the carbon material is one or more of carbon black, carbon nanotubes, and graphene; the polymer coating is an acrylic or fluorocarbon coating; and the nano-inorganic metal coating is iron black or cobalt black.

[0012] As an embodiment of the present invention, in step S1, the addition rule of each raw material in the HS medium is: 1.5-2g glucose, 0.5-0.6g peptone, 0.5-0.6g yeast extract, 0.5-1g disodium hydrogen phosphate dodecahydrate, and 0.1-0.15g citric acid are added to every 100mL of deionized water.

[0013] As an embodiment of the present invention, in step S2, the temperature of the sterilization treatment is 100-140°C, and the sterilization time is 10-30 minutes.

[0014] As an embodiment of the present invention, in step S2, the sterilization treatment is performed by boiling the functionalized bacterial cellulose hydrogel in a sodium hydroxide solution; preferably, the concentration of the sodium hydroxide solution is 1-2 g / 100 mL.

[0015] As an embodiment of the present invention, in step S2, the dynamic culture time is 5-10 days.

[0016] On the other hand, the present invention provides a biomass solar evaporator, which is prepared by the above-mentioned preparation method, and the material can be applied to the field of seawater purification.

[0017] The beneficial effects of the present invention are:

[0018] 1. The preparation method of the bacterial cellulose-modified biomass solar evaporator provided by the present invention is to use the biomass material loofah with hydrophilicity and three-dimensional pore structure as the substrate, adopt a dynamic culture method to grow bacterial cellulose inside and outside, and load photothermal material in the bacterial cellulose to obtain a biomass solar evaporator with high photothermal conversion efficiency, high water transport and evaporation efficiency, stable evaporation performance, good surface salt rejection performance and biodegradable. In the above technical solution, by loading photothermal material in the process of growing bacterial cellulose on loofah, the photothermal material is evenly distributed in the evaporator, and it can ensure that the photothermal material is stably combined with the substrate, avoid the photothermal material from falling off during the application process, and ensure that the evaporation performance of the evaporator is stable during the evaporation process; secondly, the pore structure of the loofah provides a fast channel for water replenishment, improves the water supply capacity, thereby effectively solving the problem of salt deposition on the surface of the photothermal material, and the network structure of the bacterial cellulose promotes the multi-level reflection of sunlight, improves the photothermal conversion ability of the material, promotes the escape of water vapor, and further improves the evaporation performance of the evaporator.

[0019] 2. The preparation method of the bacterial cellulose-modified biomass solar evaporator provided by the present invention adopts a dynamic culture method, and simultaneously regulates the culture time and the amount of Acetobacter xylinum added in the culture process, so that bacterial cellulose coated with photothermal material is directionally grown inside and outside the loofah; by using the in situ fermentation of microorganisms, photothermal conversion functional materials and compressible biomass substrates are added to the bacterial culture medium, and functional biological modification is carried out during the secretion of bacterial cellulose, which is conducive to the directional growth of ultra-fine functional fibers and one-step efficient assembly with biomass-based solar evaporation devices, providing a preparation method with great application value for preparing evaporators with high evaporation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The preparation principle of the preparation method of the bacterial cellulose modified biomass solar evaporator proposed in the present invention;

[0021] Figure 2 This is a comparison chart of the evaporation rates of pure water by the evaporators prepared at different polypyrrole addition amounts in Example 1 of the present invention;

[0022] Figure 3 is the evaporation rate of the evaporator prepared in Example 1 of the present invention in NaCl solutions of different concentrations;

[0023] Figure 4 for Figure 3 Optical photographs of the evaporator at different evaporation times in 15.0 wt% NaCl solution;

[0024] Figure 5 This is a comparison chart of the evaporation performance of the evaporators prepared in Example 1 of the present invention and Comparative Example 1;

[0025] Figure 6 This is a comparison diagram of optical photographs of the evaporators prepared in Example 1 of the present invention and Comparative Example 2. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] It should also be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0028] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0029] See also Figure 1 As shown, on the one hand, the present invention provides a method for preparing a bacterial cellulose-modified biomass solar evaporator, comprising the following steps:

[0030] S1. Prepare HS medium: mix glucose, peptone, yeast extract, citric acid, disodium hydrogen phosphate dodecahydrate, and deionized water to obtain HS medium;

[0031] S2. Preparation of a biomass solar evaporator: Adding the photothermal material and the loofah to the HS culture medium prepared in step S1, sterilizing it, inoculating it with Acetobacter xylinum, and dynamically culturing it at 25-30°C for 5-10 days to form bacterial cellulose in the loofah, while simultaneously loading the photothermal material to obtain a functionalized bacterial cellulose hydrogel that directionally grows on the loofah; finally, sterilizing it and freeze-drying it to obtain a biomass solar evaporator.

[0032] The above technical solution uses loofah as the base material and adopts a dynamic culture method to modify the loofah. In this process, by regulating the culture time, culture environment and the amount of added Acetobacter xylinum, bacterial cellulose coated with photothermal material is oriented and grown inside and outside the loofah, and in the process of forming bacterial cellulose, the photothermal material is integrated into the cellulose network structure, so that the photothermal material in the evaporator is evenly distributed, greatly improving the utilization rate of the photothermal material; secondly, because the loofah itself is hydrophilic and has a unique pore structure inside, the above structural characteristics accelerate the transport of water during evaporation and improve the evaporation efficiency of the evaporator. At the same time, the network structure of bacterial cellulose can produce multi-level reflection of sunlight, improve the photothermal conversion capacity of the evaporator, promote the rapid escape of water vapor, effectively reduce the possibility of salt deposition on the surface of the evaporator, and improve the sustainable and efficient salt rejection capacity of the evaporator; furthermore, the dynamic culture method can make the bacterial cellulose carrying the photothermal material evenly distributed, avoid the photothermal material being adsorbed on the surface of the loofah in the early stage of bacterial reproduction and covered by the subsequently grown bacterial cellulose, resulting in a decrease in the photothermal conversion capacity of the photothermal material.

[0033] It should be noted that in the above preparation process, other biomass materials with hydrophilicity and pore structure can also be used as the substrate, as long as the same effect of the evaporator made with loofah as the substrate can be achieved. Under this premise, those skilled in the art can also use other substrates. In addition, the size of the loofah used in the present invention is: length × width × height = (1-3) cm × (1-3) cm × (1-3) cm. In other embodiments, it can also be adjusted according to actual needs and experimental conditions, which is not limited here.

[0034] In one embodiment of the present invention, in step S1, the ingredients in the HS culture medium are added in the following manner: 1.5-2 g glucose, 0.5-0.6 g peptone, 0.5-0.6 g yeast extract, 0.5-1 g sodium hydrogen phosphate dodecahydrate, and 0.1-0.15 g citric acid per 100 mL of deionized water. By selecting and combining these ingredients within the aforementioned concentration range, a culture medium capable of providing sufficient nutrients for the subsequent growth of bacterial cellulose is obtained.

[0035] As one embodiment of the present invention, in step S2, the photothermal material includes, but is not limited to, one or more of a carbon material, a polymer coating, or a nano-inorganic metal coating. Carbon materials include, but are not limited to, carbon black, carbon nanotubes, and graphene; polymer coatings include, but are not limited to, acrylic and fluorocarbon coatings; and nano-inorganic metal coatings include, but are not limited to, iron black or cobalt black. The photothermal material is added as follows: 2.5-12.5 mg of the material is added per 1 mL of HS medium.

[0036] As an embodiment of the present invention, in step S2, the pore density of the loofah is 79-93%.

[0037] As an embodiment of the present invention, in step S2, the process of inoculating Acetobacter xylinum is carried out as follows: a solution of Acetobacter xylinum is added to a sterilized HS culture medium, wherein the mass percentage of the Acetobacter xylinum solution is 3-15wt%. By controlling the concentration of Acetobacter xylinum within the above range and combining the control of the culture time, the growth degree of bacterial cellulose can be regulated to avoid insufficient growth of bacterial cellulose on the loofah, thereby preventing the fibers in the loofah from being covered and the photothermal material from being fully coated, or excessive growth of bacterial cellulose in the loofah, thereby clogging the network structure of the loofah. Both of the above situations affect the evaporation performance of the evaporator.

[0038] As an embodiment of the present invention, in step S2, the temperature of the sterilization treatment is 100-140°C, and the sterilization time is 10-30 minutes.

[0039] As an embodiment of the present invention, in step S2, the sterilization treatment is performed by boiling the functionalized bacterial cellulose hydrogel in a sodium hydroxide solution. Preferably, the concentration of the sodium hydroxide solution is 1-2 g / 100 mL.

[0040] As an embodiment of the present invention, in step S2, the freeze-drying time is 24-72 hours.

[0041] On the other hand, the present invention also provides the application of the biomass solar evaporator prepared by the above preparation method in the field of seawater purification.

[0042] The preparation method and application of the bacterial cellulose modified biomass solar evaporator of the present invention are further described below with reference to specific examples:

[0043] Example 1

[0044] This embodiment prepares a bacterial cellulose-modified biomass solar evaporator, and the specific preparation method includes the following steps:

[0045] S1. Mix 2 g of glucose, 0.5 g of peptone, 0.5 g of yeast extract, 0.15 g of citric acid monohydrate, 0.68 g of disodium hydrogen phosphate dodecahydrate, and 100 mL of deionized water to obtain HS medium.

[0046] S2. Add 1000 mg of polypyrrole (PPy) and a loofah with a length × width × height = 3.0 × 3.0 × 1.5 cm to the HS medium prepared in step S1, mix well and sterilize at high temperature at 120°C for 20 minutes; then, inoculate with 5 wt% of Acetobacter xylinum, place in a shaker, and culture at 30°C for 7 days to obtain a functionalized bacterial cellulose hydrogel that grows directionally on the loofah; finally, place the functionalized bacterial cellulose hydrogel in a sodium hydroxide solution with a concentration of 2 g / 100 mL and boil for 20 minutes for sterilization, and then freeze-dry in a freeze dryer for 48 hours to obtain a biomass solar evaporator. It should be noted that the reagents used in this application, unless otherwise specified, can be purchased on the market.

[0047] In the above preparation process, in order to determine the optimal addition amount of polypyrrole, the evaporation performance of the solar evaporator prepared with different addition amounts of polypyrrole was also explored. The specific concentrations of polypyrrole were 0, 2.5, 5.0, 7.5, 10.0, and 12.5 mg / mL. The evaporation rate of pure water by the evaporator prepared with different addition amounts was as follows: Figure 2 The results show that the performance of the solar evaporator prepared when the addition amount is 10 mg / mL is the best (the water evaporation rate is 2.52 kg·m -2 ·h -2 ).

[0048] In order to explore the evaporation performance and salt rejection performance of the biomass solar evaporator prepared in this embodiment when used for seawater evaporation, a xenon lamp was used to simulate sunlight, and the light path was perpendicular to the evaporator surface to simulate the evaporation process. The weight loss during the evaporation process was measured by a high-precision balance, and the real-time data was received by a desktop calculator. The specific evaporation experiment was carried out as follows: NaCl solution was used to simulate seawater to explore the evaporation performance of the solar evaporator under different salt concentrations. The concentrations of NaCl solution were 3.5wt%, 5.0wt%, 10.0wt% and 15.0wt%, respectively. The evaporation rate in NaCl solution with different concentrations is as follows: Figure 3 As shown in the figure, the water evaporation rate of the evaporator shows a negligible decrease with the increase of NaCl concentration, and in the 15.0wt% NaCl solution, it still has a high water evaporation rate (water evaporation rate is 2.35kg·m -2 ·h -2 ), generally speaking, the salt concentration of seawater is about 3.5wt% (see the description in https: / / doi.org / 10.1016 / j.solener.2023.04.016), so the evaporator prepared in this embodiment also has a high water evaporation rate when used for seawater evaporation; during the evaporation process, the optical photos of the solar evaporator at different time periods are as follows Figure 4As shown in the figure, it can be seen that no salt precipitation / salt accumulation phenomenon occurs on the surface of the evaporator after evaporation for 8 hours. This result further proves that the evaporator prepared in this embodiment has excellent salt rejection performance.

[0049] Comparative Example 1

[0050] The only difference between Comparative Example 1 and Example 1 is that the bacterial fermentation system was not cultured (ie, the step of inoculating Acetobacter xylinum was omitted). Other operating steps and experimental conditions were basically the same as those in Example 1 and will not be repeated here.

[0051] The evaporation performance of the solar evaporator prepared in Comparative Example 1 and Example 1 and the untreated loofah were measured for pure water evaporation using the evaporation experimental conditions in Example 1. The water evaporation rates under the three conditions were as follows: Figure 5 As shown in the figure, it is calculated that the evaporation rate of the NaCl solution by the evaporator prepared in Comparative Example 1 is 1.56 kg·m -2 ·h -2 This result is significantly lower than 2.52 kg·m in Example 1. -2 ·h -2 This is because: in Example 1, dynamic culture is adopted to form bacterial cellulose in the loofah sponge, and the photothermal material can be coated in the network structure of the bacterial cellulose during the formation of the bacterial cellulose. Therefore, not only can the photothermal material be evenly distributed in the evaporator, but the multi-level reflection of multiple lights of the bacterial cellulose network structure can be utilized to improve the utilization rate of solar energy and accelerate the evaporation rate of water in the evaporator.

[0052] Comparative Example 2

[0053] The only difference between Comparative Example 2 and Example 1 is that in step S2, after inoculation of Acetobacter xylinum, dynamic culture is not adopted, but static culture is carried out in an incubator. The other operating steps and experimental conditions are basically the same as those in Example 1 and will not be repeated here. The optical photographs of the evaporators prepared in Example 1 and Comparative Example 2 are as follows: Figure 6 As shown in the figure, it can be clearly seen that the three-dimensional structure of the evaporator prepared by the dynamic culture method (Example 1) is better and fluffier. This is because: in the preparation process of static culture, the bacterial cellulose carrying the photothermal material is unevenly distributed, and a large amount of photothermal material is adsorbed on the surface of the loofah in the early stage of bacterial reproduction, and the growth of bacterial cellulose covers the photothermal material, which reduces the photothermal conversion capacity; at the same time, the static culture of bacterial cellulose is mainly concentrated at the gas-liquid interface (i.e., the upper surface of the loofah). Due to the difference in the growth time of bacterial cellulose and the adsorption time of the photothermal material, a white film is produced on the surface of the solar evaporator, which reduces the light absorption efficiency and evaporation efficiency.

[0054] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a bacterial cellulose-modified biomass solar evaporator, characterized in that: The steps include: S1. Evenly mix glucose, peptone, yeast extract, citric acid, disodium hydrogen phosphate dodecahydrate and deionized water to obtain HS medium; S2, adding the photothermal material and the loofah into the HS culture medium prepared in step S1, inoculating Acetobacter xylinum after sterilization, and dynamically culturing for 5-10 days at 25-30° C. to form bacterial cellulose inside and outside the loofah, and loading the photothermal material in the bacterial cellulose to obtain a functionalized bacterial cellulose hydrogel that grows directionally on the loofah; finally, sterilizing and freeze-drying to obtain the biomass solar evaporator.

2. The method for preparing a bacterial cellulose-modified biomass solar evaporator according to claim 1, characterized in that: In step S2, the pore density of the loofah is 79-93%.

3. The method for preparing a bacterial cellulose-modified biomass solar evaporator according to claim 1, characterized in that: In step S2, the process of inoculating Acetobacter xylinum is carried out in the following manner: adding Acetobacter xylinum solution into the sterilized HS culture medium, wherein the mass percentage of the Acetobacter xylinum solution is 3-15wt%.

4. The method for preparing a bacterial cellulose-modified biomass solar evaporator according to claim 1, characterized in that: In step S2, the photothermal material is one or more of a carbon material, a polymer coating and a nano-inorganic metal coating, and the rule for adding the photothermal material is: 2.5-12.5 mg of the photothermal material is added to every 1 mL of the HS culture medium; the carbon material is one or more of carbon black, carbon nanotubes, and graphene; the polymer coating is an acrylic or fluorocarbon coating; and the nano-inorganic metal coating is iron black or cobalt black.

5. The method for preparing a bacterial cellulose-modified biomass solar evaporator according to claim 1, characterized in that: In step S1, the addition rule of each raw material in the HS medium is: 1.5-2g glucose, 0.5-0.6g peptone, 0.5-0.6g yeast extract, 0.5-1g disodium hydrogen phosphate dodecahydrate, and 0.1-0.15g citric acid are added to every 100mL deionized water.

6. The method for preparing a bacterial cellulose-modified biomass solar evaporator according to claim 1, characterized in that: In step S2, the temperature of the sterilization treatment is 100-140°C, and the sterilization time is 10-30 minutes.

7. The method for preparing a bacterial cellulose-modified biomass solar evaporator according to claim 1, characterized in that: In step S2, the sterilization treatment is carried out by boiling the functionalized bacterial cellulose hydrogel in a sodium hydroxide solution; the concentration of the sodium hydroxide solution is 1-2 g / 100 mL.

8. A bacterial cellulose modified biomass solar evaporator, characterized in that: The invention is prepared by the preparation method described in any one of claims 1 to 7.

9. Application of a biomass solar evaporator modified with bacterial cellulose obtained by the preparation method according to any one of claims 1 to 7 in the field of seawater purification.

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