Water collecting / releasing material taking biomass material as matrix

Abstract

The invention discloses a water collecting / releasing material taking a biomass material as a matrix, and a preparation method of the water collecting / releasing material comprises the following steps: mixing galactomannan, cellulose, an ethanolamine salt-based moisture absorption compound solution, a photo-thermal material dispersion liquid and a silane coupling agent, fully mixing under magnetic stirring at normal temperature, freeze-drying, and standing to obtain the water collecting / releasing material. According to the invention, galactomannan and cellulose are selected as a polymer matrix to accommodate a uniformly dispersed ethanolamine salt-based moisture absorption compound solution, so that active moisture capture and water vapor transmission are realized; meanwhile, the photo-thermal material dispersion liquid endows the water collecting / releasing material with photo-thermal conversion capacity, and the water is released under the driving of solar energy.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical materials, and particularly relates to a water collection / release material based on biomass materials. Background Art

[0002] All life on land depends on fresh water. However, affected by monsoon climate and topographic and geological conditions, the temporal and spatial distribution of precipitation is uneven in each place, resulting in water shortage in inland arid areas. At the same time, with the continuous aggravation of water pollution, fresh water resources such as seawater, lakes, and rivers have been damaged to varying degrees. The atmospheric water collection technology that produces fresh water by collecting water in the air and then realizes sustainable fresh water transportation is an important means to solve the water shortage problem in arid areas.

[0003] The atmospheric water collection technology can be realized by three different methods: fog collection, dew collection, and adsorption-based atmospheric water collection. Fog collection and dew collection are only applicable to high-humidity areas and have limitations. Adsorption-based atmospheric water collection realizes water vapor adsorption / release in a wider humidity range and has a wide application.

[0004] Among them, polyacrylamide is often used as a framework network to accommodate liquid desiccants and realize the adsorption and release of water vapor. However, polyacrylamide causes certain pollution to the environment, and its raw material acrylamide has certain toxicity, so its application has certain limitations. Biomass materials have better sustainable development due to their low production cost and environmental friendliness, and have broad application prospects. Commonly used biomass materials include guar gum, locust bean gum, nanocellulose, wood cellulose, etc. Using them as network skeletons, a water collection / release material is prepared through the steps of freeze-drying, impregnating with a salt solution, and drying. However, its synthesis process is complex, and there are often problems of salt leakage and low adsorption / desorption kinetics. Especially, it takes a long time for the material to release water, usually 2 - 4 hours. Therefore, it is still a challenge to prepare a water collection / release material with excellent adsorption / desorption ability and effective solution to the salt leakage problem using biomass materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a water collection / release material based on biomass materials, which is prepared by the following steps: Step 1: Dissolve a salt-based hygroscopic compound in ethanol, then add ethanolamine and stir, and obtain an ethanolamine salt-based hygroscopic compound after drying. Step 2: Mix a dispersant and water, then add a photothermal material and grind to obtain a photothermal material dispersion. Step 3: Mix a galactomannan solution, cellulose, the photothermal material dispersion, a silane coupling agent, and an ethanolamine salt-based hygroscopic compound solution, stir and then stand, and obtain the water collection / release material through freeze-drying. The basic moisture-absorbing compound is lithium chloride (LiCl), calcium chloride (CaCl2), magnesium chloride (MgCl2), or cobalt chloride (CoCl2); The dispersant is alkynediol (TMDD), polyethylene glycol ether (PEG), or fatty alcohol polyoxyethylene ether (AEO); The photothermal material is carboxyl carbon nanotube (FCNT), graphene oxide (GO), polypyrrole (PPy), or carbon black (CB); The galactomannan is guar gum (GG), locust bean gum (LBG), or honey locust bean gum (GSG); The cellulose is nanocellulose (CNF), bacterial cellulose (CB), or hydroxypropyl cellulose (HPC); The silane coupling agent is methyltrimethoxysilane (MTMS), methyltriacetoxysilane (KH-310), γ-aminopropyltriethoxysilane (KH-550), γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), or γ-methacryloxypropyltrimethoxysilane (KH-570).

[0006] Further, in step one, the dosage ratio of the basic moisture-absorbing compound, ethanol, and ethanolamine is 1-5 g: 15-30 mL: 0.1-0.5 mL.

[0007] Further, in step two, the dosage ratio of the dispersant, water, and photothermal material is 5-15 g: 50-100 g: 5-20 g.

[0008] Further, in step three, the dosage ratio of the galactomannan solution, cellulose, ethanolamine basic moisture-absorbing compound solution, silane coupling agent, and photothermal material dispersion is 5-15 mL: 1-6 mL: 1-15 mL: 0.01-0.1 mL: 0.01-0.09 g.

[0009] Further, the concentration of the galactomannan solution is 1.0-3.0 wt%, and the solvent is deionized water; the concentration of the ethanolamine basic moisture-absorbing compound solution is 3.0-6.0 wt%, and the solvent is deionized water.

[0010] Further, the stirring time in step one is 0.5-1.5 h; the grinding time in step two is 7-12 h; the stirring time in step three is 1-4 h, and the standing time is 1-3 h.

[0011] In the present invention, galactomannan and cellulose are used as the polymer matrix to construct a porous network structure through hydrogen bonding to accommodate a uniformly dispersed ethanolamine salt-based hygroscopic compound solution; the silane coupling agent is used as a crosslinking agent to carry out hydroxy-silylation with the hydroxyl groups of galactomannan and cellulose, further enhancing the stability of the network structure. The porous network enables active water capture and water vapor transmission, and the photothermal material dispersion endows it with the ability of photothermal conversion to release water under the drive of solar energy. At the same time, the ethanolamine salt-based hygroscopic compound forms hydrogen bonds or chemical coordination with the oxygen in the network to achieve the anchoring of salt ions, which can effectively prevent the aggregation and leakage of the hygroscopic salt. It solves the problems of low hygroscopic rate, difficulty in releasing water, poor cycle stability, and salt leakage in the existing atmospheric water collection technology.

[0012] In the present invention, galactomannan and cellulose are selected as the polymer matrix to accommodate a uniformly dispersed ethanolamine salt-based hygroscopic compound solution, thereby achieving active water capture and water vapor transmission; at the same time, the photothermal material dispersion endows the water collection / water release material with the ability of photothermal conversion to release water under the drive of solar energy.

[0013] Compared with the prior art, the present invention has the following advantages: The water collection / water release material prepared by the present invention has a simple synthesis process and is easy to realize industrial production.

[0014] (2) The raw materials of the water collection / water release material prepared by the present invention are widely sourced and inexpensive. Galactomannan is a renewable material with good hydrophilicity and biocompatibility, which is green and environmentally friendly and conforms to the concept of sustainable development.

[0015] (3) The water collection / water release material prepared by the present invention utilizes the ethanolamine salt-based hygroscopic compound to form hydrogen bonds or chemical coordination with the O in the network to achieve the anchoring of salt ions, which can effectively prevent the aggregation and leakage of the hygroscopic salt ( Figure 3 )

[0016] (4) The water collection / water release material prepared by the present invention efficiently utilizes solar energy and has excellent desorption ability. Compared with other reported water collection / water release materials ( Figure 7 ), this water collection / water release material has a water release rate as high as 89.22% in a short time (100 min) under one sun (1.0 sun), showing good atmospheric water collection ability. Description of the Drawings

[0017] Figure 1 It is the scanning electron microscope image (SEM) of the water collection / water release material GG-CNF / CB@E-LiCl.

[0018] Figure 2FTIR spectra of LiCl, E-LiCl, GG, CNF, GG-CNF@E-LiCl, and GG-CNF / CB@E-LiCl.

[0019] Figure 3 There is salt leakage and caking in GG-CNF / CB@LiCl, while there is no salt leakage and caking in GG-CNF / CB@E-LiCl.

[0020] Figure 4 Water absorption rates of the water-collecting / water-releasing material GG-CNF / CB@E-LiCl at 25 °C, relative humidity of 30%, 50%, and 70%.

[0021] Figure 5 Water release amounts and surface temperatures of GG-CNF@E-LiCl and GG-CNF / CB@E-LiCl as functions of time under one sun intensity.

[0022] Figure 6 Surface temperatures and weight changes of the water-collecting / water-releasing material under different light intensities.

[0023] Figure 7 Comparison chart of water release amounts with reported water-collecting / water-releasing materials.

[0024] Figure 8 Air dehumidification performances of 4A molecular sieve, silica gel, and GG-CNF / CB@E-LiCl. Detailed implementation manners

[0025] The preferred implementation manners of the present invention will be described in detail below in conjunction with embodiments. It should be understood that the following embodiments are given only for the purpose of illustration and are not used to limit the scope of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0026] Unless otherwise specified, the experimental methods used in the following embodiments are all conventional methods.

[0027] Unless otherwise specified, the materials, reagents, etc. used in the following embodiments can all be obtained from commercial channels. Example 1

[0028] Step 1: Dissolve 3.0 g of LiCl in 20 mL of ethanol, then add 0.2 mL of ethanolamine and stir for 30 min. Secondly, dry at 80 °C to obtain E-LiCl. Then dissolve 0.35 g of E-LiCl in 10 mL of deionized water to obtain an E-LiCl solution for standby.

[0029] Step 2: Uniformly mix 10 g of TMDD and 80 g of deionized water, then add 10 g of CB and grind for 10 h using a grinder to obtain a CB dispersion.

[0030] Step 3: Mix 10 mL of GG solution (0.2 g dissolved in 10 mL of deionized water), 2 mL of CNF, 0.025 g of CB dispersion, 0.01 mL of MTMS, and 10 mL of E-LiCl solution, stir magnetically at room temperature for 4 h, let stand for 1 h, and freeze-dry to obtain the water collection / water release material GG-CNF / CB@E-LiCl.

[0031] As Figure 1 shown, GG-CNF / CB@E-LiCl has a reticulated porous structure, reducing the resistance to water vapor transmission. These structures endow the material with a large specific surface area, providing more attachment points for the adsorbent and facilitating the adsorption and release of water vapor.

[0032] As Figure 2 shown, in the Fourier transform infrared spectrum of ethanolamine, the peak at 1069 cm -1 is attributed to the stretching vibration of the C-O group in ethanolamine, the peak at 1025 cm -1 is attributed to the stretching vibration of C-N, the peak at 1563 cm -1 is attributed to the stretching vibration of N-H, the peak at 1380 cm -1 is attributed to the bending vibration of O-H, and the peak at 1497 cm -1 is attributed to the stretching of C-H of the methyl group. In the Fourier transform infrared spectrum of E-LiCl, compared with the Fourier transform infrared spectrum of ethanolamine, the positions of each peak have changed. The characteristic peak of C-O stretching vibration at 1060 cm -1 and the characteristic peak of C-N stretching vibration at 995 cm -1 have both undergone blue shifts. The characteristic peak of O-H bending vibration at 1409 cm -1 the characteristic peak of C-H stretching vibration at 1522 cm -1 and the characteristic peak of N-H stretching vibration at 1640 cm -1 have all undergone red shifts. These changes in peak positions all prove that the metal has effectively coordinated with the O atom in the hydroxyl group and the N atom in the amino group of ethanolamine. In the Fourier transform infrared spectra of GG-CNF / CB@E-LiCl and GG-CNF / CB@E-LiCl, the enhancement of the characteristic peak of O-H stretching vibration at 3460 cm -1 indicates a strong ionic bond between Li + and the GG-CNF network. The characteristic peak at 1090 cm -1The absorption peak at [location] is attributed to the stretching vibration of the Si-O-C bond, confirming the crosslinking reaction between GG, CNF, and the silane agent. In addition, the characteristic peak of C-O stretching vibration at 1060 cm -1 and the characteristic peak of C-N stretching vibration at 995 cm -1 confirm the successful introduction of E-LiCl.

[0033] The dried water-collecting / water-releasing material was placed in an environment with a temperature of 25 °C and relative humidities of 30%, 50%, and 70% respectively. Its mass was measured every hour for 25 h. As Figure 4 shown, at 25 °C and relative humidities of 30%, 50%, and 70%, the water absorption rates of the water-collecting / water-releasing material were 0.73 g×g -1 , 1.31 g×g -1 , and 2.05 g×g -1 .

[0034] The dried water-collecting / water-releasing material was placed in an environment with a temperature of 25 °C and a relative humidity of 70% for 25 h of moisture absorption; the xenon lamp source was adjusted to 0.5 sun, 1.0 sun, and 1.5 sun respectively with a light power meter, and the temperature and mass of the sample were measured every 5 min. As Figure 5 shown, under 0.5 sun, 1.0 sun, and 1.5 sun, the surface temperatures of the water-collecting / water-releasing material reached 64.80 °C, 82.00 °C, and 107.00 °C respectively after 100 min, indicating that the CB dispersion has good photothermal conversion ability. As Figure 6 shown, after 100 min, the water contents of the material decreased to 25.63%, 10.78%, and 8.03% respectively, showing good desorption kinetic characteristics. As Figure 7 shown, compared with other reported water-collecting / water-releasing materials, under one sun (1.0 sun), the water release rate of this material reached 89.22%, having superior atmospheric water collection ability.

[0035] As Figure 8As shown, the dehumidification capabilities of GG-CNF / CB@E-LiCl, silica gel, and 4A molecular sieve with the same mass were compared. Under the condition of a relative humidity of 90%, silica gel and 4A molecular sieve could only reduce the relative humidity of the drying oven from 90% to 89.9% and 91.40% respectively within 100 min, with a small decrease; after 700 min, they only reached 58.60% and 57.50% respectively. However, the humidity in the box tended to stabilize at 19.40% after 100 min for GG-CNF / CB@E-LiCl. Compared with silica gel and 4A molecular sieve, the humidity decreased by 70.5%, indicating the good dehumidification ability of GG-CNF / CB@E-LiCl, which can be used as a desiccant to dehumidify in various enclosed environments (such as wardrobes or indoors). Example 2

[0036] Step 1: Dissolve 4.0 g of CaCl2 in 20 mL of ethanol, then add 0.2 mL of ethanolamine and stir for 30 min. Secondly, dry it at 80 °C to obtain E-CaCl2. Finally, dissolve 0.4 g of E-CaCl2 in 10 mL of deionized water to obtain an E-CaCl2 solution.

[0037] Step 2: Uniformly mix 12 g of PEG and 80 g of deionized water, then add 10 g of GO, and grind with a grinder for 8 h to obtain a graphene oxide dispersion.

[0038] Step 3: Mix 10 mL of GG solution (0.13 g dissolved in 10 mL of deionized water), 3 mL of CNF, 0.01 g of graphene oxide dispersion, 0.01 mL of MTMS, and 6 mL of E-CaCl2 solution, stir magnetically at room temperature for 4 h, let it stand for 1 h, and freeze-dry to obtain a water-absorbing / water-releasing material. Example 3

[0039] Step 1: Dissolve 4.0 g of CoCl2 in 20 mL of ethanol, then add 0.2 mL of ethanolamine and stir for 30 min. Secondly, dry it at 80 °C to obtain E-CoCl2. Finally, dissolve 0.35 g of E-CoCl2 in 10 mL of deionized water to obtain an E-CoCl2 solution.

[0040] Step 2: Uniformly mix 12 g of PEG and 80 g of deionized water, then add 10 g of CB, and grind with a grinder for 8 h to obtain a CB dispersion.

[0041] Step 3: Mix 10 mL of LBG solution (0.13 g dissolved in 10 mL of deionized water), 3 mL of BC, 0.01 g of CB dispersion, 0.01 mL of KH-310, and 8 mL of E-CoCl2 solution, stir magnetically at room temperature for 4 h, let stand for 1 h, and freeze-dry to obtain the water-absorbing / water-releasing material. Example 4

[0042] Step 1: Dissolve 4.0 g of CoCl2 in 20 mL of ethanol, then add 0.2 mL of ethanolamine and stir for 30 min. Secondly, dry at 80 °C to obtain E-CoCl2. Finally, dissolve 0.45 g of E-CoCl2 in 10 mL of deionized water to obtain the E-CoCl2 solution.

[0043] Step 2: Uniformly mix 11 g of AEO and 80 g of deionized water, then add 10 g of CB, and grind with a grinder for 8 h to obtain the CB dispersion.

[0044] Step 3: Mix 10 mL of GG solution (0.13 dissolved in 10 mL of deionized water), 3 mL of HPC, 0.01 g of CB dispersion, 0.05 mL of KH-310, and 5 mL of E-CoCl2 solution, stir magnetically at room temperature for 4 h, let stand for 1 h, and freeze-dry to obtain the water-absorbing / water-releasing material. Comparative Example 1

[0045] The difference between this example and Example 1 is that LiCl was not modified.

[0046] Step 1: Dissolve 0.35 g of LiCl in 10 mL of deionized water to obtain the LiCl solution.

[0047] Step 2: Uniformly mix 10 g of TMDD and 80 g of deionized water, then add 10 g of CB, and grind with a grinder for 10 h to obtain the CB dispersion.

[0048] Step 2: Mix 10 mL of GG solution (0.2 g dissolved in 10 mL of deionized water), 2 mL of CNF, 0.025 g of CB dispersion, 0.01 mL of MTMS, and 10 mL of LiCl solution, stir magnetically at room temperature for 4 h, let stand for 1 h, and freeze-dry to obtain the water-absorbing / water-releasing material.

[0049] As Figure 3As shown, compared with the water-collecting / water-releasing material without modification of lithium chloride, no salt leakage or agglomeration occurred after the material was dried. This is mainly because ethanolamine lithium chloride forms hydrogen bonds or chemical coordination with O in the network, realizing the anchoring of salt ions and effectively preventing the aggregation and leakage of hygroscopic salts. Comparative Example 2

[0050] The difference between this example and Example 1 is that no CB dispersion was added.

[0051] Step 1: Dissolve 3.0 g of LiCl in 20 mL of ethanol, then add 0.2 mL of ethanolamine and stir for 30 min. Secondly, dry at 80 °C to obtain E-LiCl. Finally, dissolve 0.35 g of E-LiCl in 10 mL of deionized water to obtain an E-LiCl solution.

[0052] Step 2: Mix 10 mL of GG solution (0.2 g dissolved in 10 mL of deionized water), 2 mL of CNF, 0.01 mL of MTMS, and 10 mL of E-LiCl solution, stir magnetically at room temperature for 4 h, let stand for 1 h, and freeze-dry to obtain the water-collecting / water-releasing material GG-CNF@E-LiCl.

[0053] As Figure 5 shown, compared with the water-collecting / water-releasing material without the addition of CB dispersion, the water-collecting / water-releasing material exhibits a very high light absorption intensity across the entire solar spectrum. When the light intensity is 1.0 sun, the surface temperature of the water-collecting / water-releasing material reaches 82.8 °C after 100 min, which is 37 °C higher than the surface temperature of the material without carbon black dispersion. This result indicates that the added carbon black collects all the sunlight falling on the water-collecting / water-releasing material for photothermal conversion, providing sufficient energy to release the adsorbed water.

[0054] The above are only specific embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various modifications and substitutions can be made to the present invention without departing from the purpose and spirit of the present invention, and all belong to the protection scope of the present invention.

Claims

1. A water collection / release material based on biomass material, characterized in that: The preparation was carried out by the following steps: Step 1, dissolving the salt-based hygroscopic compound in ethanol, then adding ethanolamine and stirring, and drying to obtain the ethanolamine salt-based hygroscopic compound; Step 2, mixing the dispersant and water, then adding the photothermal material, and grinding to obtain a photothermal material dispersion; Step 3, mixing the galactomannan solution, cellulose, photothermal material dispersion, silane coupling agent and ethanolamine salt-based hygroscopic compound solution, stirring and then standing, and freeze-drying to obtain the water collection / release material; The salt-based hygroscopic compound is lithium chloride, calcium chloride, magnesium chloride or cobalt chloride; The dispersant is acetylenic glycol, polyethylene glycol ether or fatty alcohol polyoxyethylene ether; The photothermal material is carboxyl carbon nanotubes, graphene oxide, polypyrrole or carbon black; The galactomannan is guar gum, locust bean gum or sapodilla bean gum; The cellulose is nanocellulose, bacterial cellulose or hydroxypropyl cellulose; The silane coupling agent is methyltrimethoxysilane, methyltriacetoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane.

2. The water collection / release material based on biomass material according to claim 1, characterized in that: In step 1, the amount ratio of the base hygroscopic compound, ethanol and ethanolamine is 1-5 g: 15-30 mL: 0.1-0.5 mL.

3. The water collection / release material based on biomass material according to claim 1, characterized in that: In step 2, the usage ratio of the dispersant, water and photothermal material is 5-15 g: 50-100 g: 5-20 g.

4. The water collection / release material based on biomass material according to claim 1, characterized in that: In step three, the dosage ratio of the galactomannan solution, cellulose, ethanolamine salt-based hygroscopic compound solution, silane coupling agent and photothermal material dispersion is 5-15 mL: 1-6 mL: 1-15 mL: 0.01-0.1 mL: 0.01-0.09 g.

5. The water collection / release material based on biomass material according to claim 4, characterized in that: The concentration of the galactomannan solution is 1.0-3.0 wt %, and the solvent is deionized water; the concentration of the ethanolamine salt-based hygroscopic compound solution is 3.0-6.0 wt %, and the solvent is deionized water.

6. The water collection / release material based on biomass material according to claim 1, characterized in that: The stirring time in step 1 is 0.5-1.5 h; the grinding time in step 2 is 7-12 h; the stirring time in step 3 is 1-4 h, and the standing time is 1-3 h.

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