An amphoteric ion hydrogel for collecting high-salt-resistant all-weather fresh water and generating electricity, and its preparation method and application

Abstract

The present invention discloses an amphoteric ion hydrogel integrating high-salt tolerance, all-weather fresh water collection and power generation, and a preparation method and application thereof. The present invention not only improves the intrinsic salt tolerance of the evaporator through the chemical structure design of related molecules to make up for the defect that the solar water vapor evaporation system is not resistant to high-salt environments, greatly reduces the manufacturing difficulty and cost of the solar-driven water vapor evaporation system, and at the same time avoids physical damage to the device morphology, but also improves its time utilization rate and the daily fresh water production capacity of the device, and further enriches the SVG function with the performance of chelating power generation.

Description

Technical Field

[0001] The present invention relates to the fields of solar water evaporation, atmospheric water collection, water-power cogeneration, and in particular to a zwitterionic hydrogel that integrates high-salt-resistant all-weather freshwater collection and electricity generation, and a preparation method and application thereof. Background Art

[0002] The development of economical, efficient, green and sustainable freshwater production technology has become a research focus in related fields. The solar-powered water vapor evaporation system (Solar Vapor Generation, SVG) has attracted special attention from researchers around the world, not only because solar energy has the unique advantages of being inexhaustible, green and sustainable, but also because SVG can make use of seawater and wastewater that are difficult to use directly, and produce water and electricity at the same time.

[0003] At present, relevant research on water vapor evaporation systems driven by solar energy is constantly advancing. On the one hand, SVG is mostly used in pure water or low-concentration salt water. However, in practical applications, long-term seawater / high-concentration salt water environment will cause the precipitation and accumulation of salt crystals on the surface of SVG, thereby covering the absorption of sunlight and blocking the pore structure for transmitting water. In addition, free salt molecules are easy to combine with water, increasing the evaporation enthalpy required for water evaporation, thereby reducing the evaporation efficiency. To this end, researchers have improved the salt accumulation problem by setting up higher longitudinal hydrophobic pipes to hinder the transmission of salt molecules to the evaporation surface, designing the device geometry so that salt is precipitated preferentially at the edge of the surface to ensure the cleanliness of the central area, and setting up a reflux channel connecting the high-salinity area and the surrounding seawater to re-dissolve the precipitated salt crystals. However, 1) the complex structural design involved in the above-mentioned devices (hierarchical channels, specific distribution of pores and complex surface morphology) will increase the difficulty and cost of manufacturing, and may cause distortion or even failure during the long evaporation process; 2) longitudinal pipes, reflux channels, etc. are easy to take away the heat from the evaporation surface, causing unnecessary heat loss; 3) the problem of high evaporation enthalpy of brine is not well solved; 4) the production capacity is low at night when solar energy is weak.

[0004] It can be seen that there is still a huge room for improvement in the functional design of existing solar evaporators. Furthermore, the salt difference and temperature difference generated during the operation of SVG have great potential in the field of power generation. Therefore, it is urgent to develop a zwitterionic hydrogel that integrates high-salinity-resistant all-weather freshwater collection and power generation. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a zwitterionic hydrogel that integrates high-salt-resistant all-weather freshwater collection and electricity production, as well as a preparation method and application thereof.

[0006] The technical solution of the present invention is as follows:

[0007] A preparation method of an amphoteric ion hydrogel integrating high-salt tolerance, all-weather fresh water collection and power generation, comprising the following steps:

[0008] (1) Disperse the amphoteric ion monomer, initiator, and crosslinker in pure water to obtain a reaction precursor solution. Inject the reaction precursor solution into a mold with a syringe and place it at 20-90 °C (preferably 50 °C). Polymerization reaction is initiated by irradiating with ultraviolet light of 365 nm (preferably 32 W) for 0.1-48 h (preferably 3 h) to achieve curing, and a pure amphoteric ion gel preform is obtained;

[0009] Preferably, in the reaction precursor solution, the concentration of the amphoteric ion monomer is 1-10 mmol / mL, the mass fraction of the initiator is 0.1-1%, and the mass fraction of the crosslinker is 0.1-1%;

[0010] The amphoteric ion monomer includes but is not limited to: 2-methacryloyloxyethyl phosphorylcholine (MPC), 3-[[2-(methacryloyloxy)ethyl]dimethylammonium] propionate (CBMA), [3-(methacrylamido)propyl]dimethyl(3-thiopropyl) ammonium hydroxide (SBAA), 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium] propane-1-sulfonate inner salt (SBMA), dimethyl-(4-vinylphenyl) propane sulfonate ammonium (DVBAPS), or 3-(1-(4-vinylbenzyl)-1H-imidazol-3-ium) propane-1-sulfonate (VBIPS), etc. Monomer molecules with the same repeating unit containing equal amounts of cationic and anionic groups, preferably VBIPS;

[0011] The initiator is a photoinitiator, including but not limited to: 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, a,a-dimethoxy-a-phenylacetophenone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone, 2-methyl-1-(4-methylthiophenyl)-2-morpholin-1-propanone, or lithium phenyl-2,4,6-trimethylbenzoylphosphite, preferably 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone;

[0012] The crosslinker includes but is not limited to: ethyl dimethacrylate, N,N'-methylenebisacrylamide, divinylbenzene, diisocyanate, dicumyl peroxide, benzoyl peroxide, or di-tert-butyl peroxide, etc. Molecules containing 2 or more double bonds, preferably N,N'-methylenebisacrylamide;

[0013] (2) Immerse the pure amphoteric ion gel preform obtained in step (1) in a photothermal absorber solution to absorb the photothermal absorber to obtain the amphoteric ion hydrogel;

[0014] The mass fraction of the photothermal absorber solution is 0.01 to 100%;

[0015] The photothermal absorber includes but is not limited to: inorganic carbon materials such as carbon black, carbon nanotubes, graphite, graphene; organic materials such as aniline, pyrrole; and metal materials such as silver nanoparticles, gold nanorods, multiple-twinned nanogold; preferably, the photothermal absorber is pyrrole;

[0016] When the photothermal absorber is an organic material such as aniline or pyrrole, an oxidant is needed to induce its in-situ polymerization reaction in the preform; the oxidant includes but is not limited to: ammonium persulfate, potassium persulfate, ferric chloride, ferric nitrate, azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, diisopropylbenzene peroxide, tert-butyl peroxybenzoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, etc., preferably ammonium persulfate;

[0017] The soaking method of the pure zwitterionic gel preform in the photothermal absorber solution can be complete immersion or partial immersion, and the soaking time is 0.1 to 72 h; different soaking methods can obtain zwitterionic hydrogels with different photothermal absorber distributions, specifically: complete immersion obtains a zwitterionic hydrogel with a uniform photothermal absorber concentration distribution, and partial immersion obtains a zwitterionic hydrogel with a photothermal absorber concentration gradient distribution;

[0018] The preferred soaking process is as follows:

[0019] Completely immerse the pure zwitterionic gel preform in a photothermal absorber solution with a mass fraction of 0.1 to 100% (preferably a pyrrole phytic acid solution of 10 to 60%) for 1 to 48 h (preferably 24 h), so that the photothermal absorber is uniformly distributed in the pure zwitterionic gel, and then induce its in-situ polymerization reaction with an oxidant (preferably ammonium persulfate) for 1 to 48 h (preferably 24 h) to obtain a zwitterionic hydrogel integrating high-salt tolerance, all-weather fresh water collection and power generation with a uniform photothermal absorber distribution;

[0020] Or, immerse 1 / 8 to 7 / 8 (preferably 1 / 4) of the height of the pure zwitterionic gel preform in a photothermal absorber solution with a mass fraction of 0.1 to 100% (preferably a pyrrole phytic acid solution of 30 to 80%) for 1 to 48 h (preferably 24 h), so that the photothermal absorber is gradient-distributed in the pure zwitterionic gel, and then induce its in-situ polymerization reaction with an oxidant (preferably ammonium persulfate) for 1 to 48 h (preferably 24 h) to obtain a zwitterionic hydrogel integrating high-salt tolerance, all-weather fresh water collection and power generation with a gradient photothermal absorber distribution.

[0021] The present invention relates to an amphoteric ion hydrogel prepared by the above preparation method, and the amphoteric ion hydrogel described in the present invention is black in color.

[0022] The present invention also relates to the application of the amphoteric ion hydrogel in solar seawater evaporation, including applications in atmospheric water collection and combined heat and power generation. The specific application methods are as follows:

[0023] Implementation method of hydrogel seawater evaporation: Place the amphoteric ion hydrogel in a container filled with a certain amount of seawater, so that the lower end of the hydrogel is fully wetted with the seawater in the container, while the upper end is exposed to the air to absorb sunlight; under simulated sunlight irradiation, monitor the mass change and its change rate during the evaporation process through an electronic balance to evaluate the solar seawater evaporation efficiency of the hydrogel; at the same time, a transparent support shell is arranged outside the above container to condense water vapor and realize the collection of fresh water;

[0024] Implementation method of hydrogel combined heat and power generation: During the above seawater evaporation process, electrodes are connected to the upper and lower surfaces of the gel and connected to an electricity storage device, and the collection function of the generated direct current can be realized by utilizing the salt difference and temperature heat difference generated by the gel while the water evaporates, realizing combined heat and power generation;

[0025] Implementation method of hydrogel water vapor collection: Use a constant temperature and humidity chamber to control the humidity and temperature in the environment where the gel is located, simulate the environment of no light at night, expose the amphoteric ion hydrogel to this environment, realize water vapor collection and evaluate the absorption of atmospheric water vapor by the amphoteric ion hydrogel.

[0026] The technical principle of the present invention is as follows:

[0027] The method of the present invention first studies the anti-polyelectrolyte effect of amphoteric ions from a molecular perspective, and utilizes the anti-polyelectrolyte effect of amphoteric ion polymer hydrogels, that is, salt ions can act with the anionic and cationic groups in the side chains of amphoteric ion polymers. 1) Make the amphoteric ion polymer transform from a coiled chain conformation to a straight chain conformation, increasing the hydration volume; 2) Reduce the ionic interaction cross-linking sites between polymer chains, lower the cross-linking density, thereby enhancing the overall hydration ability of the gel and reducing the evaporation enthalpy of the water therein. Therefore, the present invention constructs a pure amphoteric ion gel using amphoteric ion monomers with strong anti-polyelectrolyte effects, and in-situ introduces a photothermal absorber to obtain an amphoteric ion hydrogel that integrates high-salt tolerance, all-weather fresh water collection and power generation, and provides a specific implementation method for the amphoteric ion hydrogel.

[0028] The evaporation rate of the amphoteric ion gel in natural seawater can reach 3.22 kg m -2 h -1 , and it maintains long-term (~10 h) and stable water evaporation performance (2.65 kg m-2 h -1 );Meanwhile, during the solar water evaporation process, an open-circuit voltage of ~130 mV can be stably output; furthermore, the water vapor collection amount in the water vapor collection device in the dark state at night with a relative humidity of 90% is 1.1 g g -1 . Therefore, this zwitterionic gel can not only improve the intrinsic salt tolerance of the evaporator through the chemical structure design of related molecules, greatly reducing the manufacturing difficulty and cost, and avoiding physical damage to the device; but also greatly improve the utilization rate of the device through night atmospheric water collection to increase its total daily water production; at the same time, the salt concentration difference and temperature difference generated during the operation of the device can be used to generate electricity.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] Compared with the existing solar-driven water vapor evaporation system, this method (1) studies the anti-polyelectrolyte effect of zwitterions from a molecular perspective, which is necessary for seawater evaporation devices; and further improves the intrinsic salt tolerance of the evaporator through the chemical structure design of related molecules. The obtained zwitterionic hydrogel can have an evaporation rate of 3.22 kg m -2 h -1 in natural seawater, and maintain stable water evaporation performance (2.65 kg m -2 h -1 ) for a long time (about 10 h) in a high-salt environment (10 wt% NaCl); (2) greatly reduce the manufacturing difficulty and cost of the solar-driven water vapor evaporation system, and avoid physical damage to the device; (3) at the same time, during the process of solar seawater evaporation, direct current can be stably output by using the salt concentration difference and temperature difference generated during the operation of the device, realizing combined production of water and electricity; (4) furthermore, through night atmospheric water collection (1.1 g·g -1 ) greatly improve the utilization rate of the device to increase its total daily water production and the production capacity of fresh water. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 shows the swelling properties of various zwitterionic hydrogels in seawater.

[0032] Figure 2 is a schematic diagram of the preparation process of the zwitterionic hydrogel device of the present invention.

[0033] Figure 3 is a graph of the seawater evaporation performance of the zwitterionic hydrogels (uniform polypyrrole structure) prepared in Examples 2-4.

[0034] Figure 4 is a graph of the seawater evaporation performance of the zwitterionic hydrogels (gradient polypyrrole structure) prepared in Examples 5-8.

[0035] Figure 5 Atmospheric water collection performance diagram of the zwitterionic hydrogel described in Examples 2-4.

[0036] Figure 6 Atmospheric water collection performance diagram of the zwitterionic hydrogel described in Examples 5-8.

[0037] Figure 7 Long-term water evaporation performance diagram of the zwitterionic hydrogel described in Example 9 in different water body environments.

[0038] Figure 8 Comparison diagram of the seawater evaporation performance of the zwitterionic hydrogel described in Example 9 with that of the same type of SVG; the data in the figure are from the following literature:

[0039] Wei Zhou, Cailong Zhou*, Chengfei Deng, Li Chen, Xinjuan Zeng, Yaoxin Zhang, Luxi Tan, Baoshan Hu, Shuai Guo, Lichun Dong, Swee Ching Tan*. Advanced Functional Materials, 2022, 32, 2113264.

[0040] Zhen Yu, Ruonan Gu, Yue Tian, Pengfei Xie, Beichen Jin, Shaoan Cheng*. Advanced Functional Materials, 2022, 32, 2108586.

[0041] Xiaojiang Mu, Jianhua Zhou, Pengfei Wang, Huan Chen, Tingting Yang, Siyi Chen, Lei Miao*, Takao Mori*. Energy & Environmental Science, 2022, 15, 3388.

[0042] Miaomiao Zou, Yu Zhang, Zheren Cai, Chuxin Li, Zhiyuan Sun, Cunlong Yu, Zhichao Dong, Lei Wu*, Yanlin Song*. Advanced Materials, 2021, 33, 2102443.

[0043] Zechang Wei, Yibo Wang, Chenyang Cai, Yaoxin Zhang, Shuai Guo, Yu Fu*, Swee Ching Tan*. Advanced Functional Materials, 2022, 32, 2206287.

[0044] Lingyu Zhao, Liu Wang, Jidong Shi, Xingyu Hou, Qi Wang, Yuan Zhang, Yan Wang, Ningning Bai, Junlong Yang, Jianming Zhang, Bo Yu, Chuan Fei Guo*. ACS Nano, 2021, 15, 5752.

[0045] Xiangyang Dong, Yang Si, Chaoji Chen, Bin Ding*, Hongbing Deng*. ACS Nano, 2021, 15, 12256.

[0046] Figure 9 It is the power generation performance diagram of the zwitterionic hydrogel described in Example 9. Detailed implementation manners

[0047] The present invention will be further described in detail below in conjunction with the drawings and embodiments. It should be understood that the following description is only the most preferred implementation manner of the present invention and should not be considered as a limitation on the protection scope of the present invention.

[0048] Example 1

[0049] First, 2 mmol of zwitterionic monomer (selected from one of MPC (1.18 g) / CBMA (0.92 g) / SBMA (1.12 g) / SBAA (1.17 g) / DVBAPS (1.13 g) / VBIPS (1.22 g)), 0.003 g (0.02 mmol) of N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator) were dispersed in 1 mL of pure water and ultrasonically treated at 40 KHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel. Then, the prepolymer solution was injected into a mold composed of an open cuboid formed by sandwiching a 0.5-mm-thick polytetrafluoroethylene plate between two glass plates with a height of 0.5 mm, a width of 2 mm, and a length of 35 mm. Then, the above reaction system was placed at 50 °C and photocured and polymerized under UV light at 365 nm for 3 h to obtain a pure zwitterionic hydrogel. And the pure zwitterionic monomer obtained above was completely immersed in 20 mL of natural seawater to test its swelling performance in seawater respectively to reflect the strength of the anti-polyelectrolyte effect of zwitterions ( Figure 1 ).

[0050] Example 2

[0051] First, 1.22 g (2 mmol) of VBIPS, 0.003 g (0.02 mmol) of N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator) were dispersed in 1 mL of pure water and ultrasonically treated at 40 KHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel. Then, the prepolymer solution was injected into a mold. Then, the above reaction system was placed at 50 °C and photocured and polymerized under UV light at 365 nm for 3 h to obtain a pure zwitterionic hydrogel.

[0052] The above pure zwitterionic hydrogel was completely immersed in a pyrrole-phytic acid solution with mass fractions of pyrrole and phytic acid of 40 wt% and 30 wt% respectively for 24 h to make the pyrrole monomer uniformly distributed in the pure zwitterionic gel, and then it was immersed in 0.1 M ammonium persulfate aqueous solution to initiate in-situ polymerization of pyrrole for 1 h to obtain a zwitterionic hydrogel integrating high-salt tolerance, all-weather fresh water collection and power generation with a uniform photothermal absorber structure ( Figure 2 ).

[0053] The seawater evaporation experiment of the zwitterionic hydrogel with a uniform photothermal absorber structure was carried out under laboratory conditions with a room temperature of 25 °C and a humidity of 50 RH%. A solar simulator was used to simulate sunlight under natural conditions for irradiation (radiation intensity is 1 kW m -2) Place the amphoteric ion hydrogel in a container filled with seawater. The lower end of the amphoteric ion hydrogel is fully wetted by the seawater in the container, while the upper end is exposed to the air to absorb sunlight. Under simulated sunlight irradiation, monitor the mass change and its change rate during the evaporation process using an electronic balance to evaluate the solar seawater evaporation efficiency of the hydrogel. At the same time, a transparent support shell is arranged outside the container to condense water vapor and collect fresh water. Figure 3 )

[0054] The implementation method of water vapor collection of an amphoteric ion hydrogel with a uniform photothermal absorber structure is carried out in a constant temperature and humidity chamber with a room temperature of 25 °C and a humidity of 90 RH%. Simulate the environment of the night without light. Expose the amphoteric ion hydrogel to this environment to achieve water vapor collection and evaluate the water vapor absorption of the amphoteric ion hydrogel. Figure 5 )

[0055] Example 3

[0056] First, disperse 1.22 g (2 mmol) of VBIPS, 0.003 g (0.02 mmol) of N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator) in 1 mL of pure water, and ultrasonically treat it at 40 KHz for 5 min at room temperature to obtain a prepolymer solution of a pure amphoteric ion gel. Then, inject the prepolymer solution into a mold using a syringe. Then, place the above reaction system at 50 °C and irradiate it with UV light at 365 nm for 3 h for photocuring polymerization to obtain a pure amphoteric ion hydrogel.

[0057] Immerse the above pure amphoteric ion hydrogel completely in a pyrrole-phytic acid solution with a mass fraction of pyrrole and phytic acid of 50 wt% and 25 wt% respectively for 24 h, so that pyrrole monomers are uniformly distributed in the pure amphoteric ion gel, and then immerse it in a 0.1 M ammonium persulfate aqueous solution to initiate in-situ polymerization of pyrrole for 1 h to obtain an amphoteric ion hydrogel with a uniform photothermal absorber structure for all-weather fresh water collection and power generation resistant to high salt. Figure 2 )

[0058] The seawater evaporation experiment of the amphoteric ion hydrogel with a uniform photothermal absorber structure is carried out under laboratory conditions with a room temperature of 25 °C and a humidity of 50 RH%. Use a solar simulator to simulate sunlight under natural conditions for irradiation (radiation intensity is 1 kW m -2), place the zwitterionic hydrogel in a container filled with seawater. The lower end of the zwitterionic hydrogel is fully immersed in the seawater in the container, while the upper end is exposed to the air to absorb sunlight. Under simulated sunlight irradiation, monitor the mass change and its rate during the evaporation process using an electronic balance to evaluate the solar seawater evaporation efficiency of the hydrogel; at the same time, a transparent support shell is arranged outside the container to condense water vapor and collect fresh water. Figure 3 )

[0059] The implementation method of water vapor collection of the zwitterionic hydrogel with a uniform photothermal absorber structure is carried out in a thermostatic and humidified chamber with a room temperature of 25 °C and a humidity of 90 RH%. Simulate the environment of the night without light. Expose the zwitterionic hydrogel to this environment to achieve water vapor collection and evaluate the water vapor absorption of the zwitterionic hydrogel. Figure 5 )

[0060] Example 4

[0061] First, disperse 1.22 g (2 mmol) of VBIPS, 0.003 g (0.02 mmol) of N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator) in 1 mL of pure water, and ultrasonically treat it at 40 KHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel. Then, inject the prepolymer solution into a mold using a syringe. Then, place the above reaction system at 50 °C and irradiate it with UV light at 365 nm for 3 h for photocuring polymerization to obtain a pure zwitterionic hydrogel.

[0062] Completely immerse the above pure zwitterionic hydrogel in a pyrrole-phytic acid solution with a mass fraction of pyrrole and phytic acid of 60 wt% and 20 wt% respectively for 24 h, so that pyrrole monomers are evenly distributed in the pure zwitterionic gel, and then immerse it in a 0.1 M ammonium persulfate aqueous solution to initiate in-situ polymerization of pyrrole for 1 h to obtain a zwitterionic hydrogel with a uniform photothermal absorber structure for high-salt-tolerant all-weather fresh water collection and power generation integration. Figure 2 )

[0063] The seawater evaporation experiment of the zwitterionic hydrogel with a uniform photothermal absorber structure is carried out under laboratory conditions with a room temperature of 25 °C and a humidity of 50 RH%. Use a solar simulator to simulate sunlight under natural conditions for irradiation (radiation intensity is 1 kW m -2) Place the amphoteric ion hydrogel in a container filled with seawater. The lower end of the amphoteric ion hydrogel is fully wetted by the seawater in the container, while the upper end is exposed to the air to absorb sunlight. Under simulated sunlight irradiation, monitor the mass change and its change rate during the evaporation process using an electronic balance to evaluate the solar seawater evaporation efficiency of the hydrogel. At the same time, a transparent support shell is arranged outside the container to condense water vapor and collect fresh water. Figure 3 )

[0064] The implementation method of water vapor collection of amphoteric ion hydrogel with a uniform photothermal absorber structure is carried out in a thermostatic and humidified chamber with a room temperature of 25 °C and a humidity of 90 RH%. Simulate the environment of no light at night. Expose the amphoteric ion hydrogel to this environment to achieve water vapor collection and evaluate the water vapor absorption of the amphoteric ion hydrogel. Figure 5 )

[0065] Example 5

[0066] First, disperse 1.22 g (2 mmol) of VBIPS, 0.003 g (0.02 mmol) of N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator) in 1 mL of pure water, and ultrasonically treat it at 40 KHz for 5 min at room temperature to obtain a prepolymer solution of pure amphoteric ion gel. Then, inject the prepolymer solution into a mold using a syringe. Then, place the above reaction system at 50 °C and irradiate it with UV light at 365 nm for 3 h for photocuring polymerization to obtain a pure amphoteric ion hydrogel.

[0067] Immerse 1 / 4 of the height of the above pure amphoteric ion hydrogel in a pyrrole-phytic acid solution with a mass fraction of pyrrole and phytic acid of 50 wt% and 25 wt% respectively for 24 h, so that pyrrole monomers are distributed in the pure amphoteric ion gel in a gradient manner. Then, immerse the gel in 0.1 M ammonium persulfate aqueous solution to initiate in-situ polymerization of pyrrole for 1 h to obtain an amphoteric ion hydrogel with a gradient photothermal absorber structure for all-weather fresh water collection and power generation resistant to high salt. Figure 2 )

[0068] The seawater evaporation experiment of the amphoteric ion hydrogel with a gradient photothermal absorber structure is carried out under laboratory conditions with a room temperature of 25 °C and a humidity of 50 RH%. Use a solar simulator to simulate sunlight under natural conditions for irradiation (radiation intensity is 1 kW m -2), place the zwitterionic hydrogel in a container filled with seawater. The lower end of the zwitterionic hydrogel is fully wetted by the seawater in the container, while the upper end is exposed to the air to absorb sunlight. Under simulated sunlight irradiation, monitor the mass change and its change rate during the evaporation process using an electronic balance to evaluate the solar seawater evaporation efficiency of the hydrogel; at the same time, a transparent support shell is provided outside the container to condense water vapor and collect fresh water. Figure 4 )

[0069] The implementation method of water vapor collection of the zwitterionic hydrogel with a gradient photothermal absorber structure is carried out in a thermostatic and humidified chamber with a room temperature of 25 °C and a humidity of 90 RH%. Simulate the environment of a dark state at night. Expose the zwitterionic hydrogel to this environment to achieve water vapor collection and evaluate the water vapor absorption of the zwitterionic hydrogel. Figure 6 )

[0070] Example 6

[0071] First, disperse 1.22 g (2 mmol) of VBIPS, 0.003 g (0.02 mmol) of N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator) in 1 mL of pure water, and ultrasonically treat it at 40 KHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel. Then, inject the prepolymer solution into a mold using a syringe. Then, place the above reaction system at 50 °C and irradiate it with ultraviolet light at 365 nm for 3 h to carry out photocuring polymerization to obtain a pure zwitterionic hydrogel.

[0072] Immerse 1 / 4 of the height of the above pure zwitterionic hydrogel in a pyrrole-phytic acid solution with a mass fraction of pyrrole and phytic acid of 60 wt% and 20 wt% respectively for 24 h, so that pyrrole monomers are gradiently distributed in the pure zwitterionic gel, and then immerse the gel in 0.1 M ammonium persulfate aqueous solution to initiate in-situ polymerization of pyrrole for 1 h to obtain a zwitterionic hydrogel with a gradient photothermal absorber structure for high-salt-tolerant all-weather fresh water collection and power generation integration. Figure 2 )

[0073] The seawater evaporation experiment of the zwitterionic hydrogel with a gradient photothermal absorber structure is carried out under laboratory conditions with a room temperature of 25 °C and a humidity of 50 RH%. Use a solar simulator to simulate sunlight under natural conditions for irradiation (radiation intensity is 1 kW m -2), place the zwitterionic hydrogel in a container filled with seawater. The lower end of the zwitterionic hydrogel is fully immersed in the seawater in the container, while the upper end is exposed to the air to absorb sunlight. Under simulated sunlight irradiation, monitor the mass change and its change rate during the evaporation process using an electronic balance to evaluate the solar seawater evaporation efficiency of the hydrogel; at the same time, a transparent support shell is arranged outside the container to condense water vapor and collect fresh water ( Figure 4 ).

[0074] The implementation method of water vapor collection of the zwitterionic hydrogel with a gradient photothermal absorber structure is carried out in a thermostatic and humidified chamber with a room temperature of 25 °C and a humidity of 90 RH%. Simulate the environment of the night without light. Expose the zwitterionic hydrogel to this environment to achieve water vapor collection and evaluate the absorption of water vapor by the zwitterionic hydrogel ( Figure 6 ).

[0075] Example 7

[0076] First, disperse 1.22 g (2 mmol) of VBIPS, 0.003 g (0.02 mmol) of N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator) in 1 mL of pure water, and perform ultrasonic treatment at 40 KHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel. Then, inject the prepolymer solution into a mold using a syringe. Then, place the above reaction system at 50 °C and irradiate it with UV light at 365 nm for 3 h for photocuring polymerization to obtain a pure zwitterionic hydrogel.

[0077] Immerse 1 / 4 of the height of the above pure zwitterionic hydrogel in a pyrrole-phytic acid solution with mass fractions of pyrrole and phytic acid of 70 wt% and 15 wt% respectively for 24 h, so that pyrrole monomers are gradiently distributed in the pure zwitterionic gel, and then immerse the gel in 0.1 M ammonium persulfate aqueous solution to initiate in-situ polymerization of pyrrole for 1 h to obtain a zwitterionic hydrogel with a gradient photothermal absorber structure that integrates high-salt tolerance, all-weather fresh water collection, and power generation ( Figure 2 ).

[0078] The seawater evaporation experiment of the zwitterionic hydrogel with a gradient photothermal absorber structure is carried out under laboratory conditions with a room temperature of 25 °C and a humidity of 50 RH%. Use a solar simulator to simulate sunlight under natural conditions for irradiation (radiation intensity is 1 kW m -2), place the zwitterionic hydrogel in a container filled with seawater. The lower end of the zwitterionic hydrogel is fully wetted by the seawater in the container, while the upper end is exposed to the air to absorb sunlight. Under simulated sunlight irradiation, monitor the mass change and its rate during the evaporation process using an electronic balance to evaluate the solar seawater evaporation efficiency of the hydrogel. At the same time, a transparent support shell is provided outside the container to condense water vapor and collect fresh water. Figure 4 )

[0079] The implementation method of water vapor collection of the zwitterionic hydrogel with a gradient photothermal absorber structure is carried out in a constant temperature and humidity chamber with a room temperature of 25 °C and a humidity of 90 RH%. Simulate the environment of no light at night. Expose the zwitterionic hydrogel to this environment to achieve water vapor collection and evaluate the absorption of water vapor by the zwitterionic hydrogel. Figure 6 )

[0080] Example 8

[0081] First, disperse 1.22 g (2 mmol) of VBIPS, 0.003 g (0.02 mmol) of N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator) in 1 mL of pure water, and ultrasonically treat it at 40 KHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel. Then, inject the prepolymer solution into a mold using a syringe. Then, place the above reaction system at 50 °C and irradiate it with ultraviolet light at 365 nm for 3 h for photocuring polymerization to obtain a pure zwitterionic hydrogel.

[0082] Immerse 1 / 4 of the height of the above pure zwitterionic hydrogel in a pyrrole-phytic acid solution with a mass fraction of pyrrole and phytic acid of 80 wt% and 10 wt% respectively for 24 h, so that pyrrole monomers are gradient-distributed in the pure zwitterionic gel. Then, immerse the gel in a 0.1 M ammonium persulfate aqueous solution to initiate in-situ polymerization of pyrrole for 1 h to obtain a zwitterionic hydrogel with a gradient photothermal absorber structure for all-weather fresh water collection and power generation resistant to high salt. Figure 2 )

[0083] The seawater evaporation experiment of the zwitterionic hydrogel with a gradient photothermal absorber structure is carried out under laboratory conditions with a room temperature of 25 °C and a humidity of 50 RH%. Use a solar simulator to simulate sunlight under natural conditions for irradiation (radiation intensity is 1 kW m -2) Place the zwitterionic hydrogel in a container filled with seawater. The lower end of the zwitterionic hydrogel is fully wetted by the seawater in the container, while the upper end is exposed to the air to absorb sunlight. Under simulated sunlight irradiation, monitor the mass change and its rate during the evaporation process using an electronic balance to evaluate the solar seawater evaporation efficiency of the hydrogel. At the same time, a transparent support shell is arranged outside the container to condense water vapor and collect fresh water. Figure 4 )

[0084] The implementation method of water vapor collection of the zwitterionic hydrogel with a gradient photothermal absorber structure is carried out in a thermostatic and humidified chamber with a room temperature of 25 °C and a humidity of 90 RH%. Simulate the environment of a dark state at night. Expose the zwitterionic hydrogel to this environment to achieve water vapor collection and evaluate the absorption of water vapor by the zwitterionic hydrogel. Figure 6 )

[0085] Example 9

[0086] First, disperse 1.22 g (2 mmol) of VBIPS, 0.003 g (0.02 mmol) of N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator) in 1 mL of pure water, and ultrasonically treat it at 40 KHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel. Then, inject the prepolymer solution into a mold using a syringe. Then, place the above reaction system at 50 °C and irradiate it with ultraviolet light at 365 nm for 3 h for photocuring polymerization to obtain a pure zwitterionic hydrogel.

[0087] Immerse 1 / 4 of the height of the above pure zwitterionic hydrogel in a pyrrole-phytic acid solution with a mass fraction of pyrrole and phytic acid of 60 wt% and 20 wt% respectively for 24 h, so that pyrrole monomers are gradiently distributed in the pure zwitterionic gel. Then, immerse the gel in 0.1 M ammonium persulfate aqueous solution to initiate in-situ polymerization of pyrrole for 1 h to obtain a zwitterionic hydrogel with a gradient photothermal absorber structure that integrates high-salt tolerance, all-weather fresh water collection, and power generation. Figure 2 )

[0088] The water evaporation experiment of the zwitterionic hydrogel with a gradient photothermal absorber structure is carried out under laboratory conditions with a room temperature of 25 °C and a humidity of 50 RH%. Use a solar simulator to simulate sunlight under natural conditions for irradiation (radiation intensity is 1 kW m -2), place the zwitterionic hydrogel in a container filled with different water bodies (pure water / seawater / 10 wt% sodium chloride solution). The lower end of the zwitterionic hydrogel is fully immersed in the seawater in the container, while the upper end is exposed to the air to absorb sunlight. Under simulated sunlight irradiation, monitor the mass change and its change rate during the evaporation process using an electronic balance to evaluate the solar seawater evaporation efficiency of the hydrogel; at the same time, a transparent support shell is arranged outside the above container to condense water vapor and collect fresh water ( Figure 7 ).

[0089] Compare the seawater evaporation performance of this zwitterionic hydrogel with that of similar SVGs reported in the literature, and it is found that the seawater evaporation performance of the adhesive described in the present invention is relatively prominent ( Figure 8 ).

[0090] At the same time, during the solar seawater evaporation experiment, electrodes are connected to the upper and lower surfaces of the gel and connected to an electricity storage device, so that the function of collecting the generated direct current can be realized while the water evaporates, and the function of combined heat and power production of the zwitterionic hydrogel can be realized ( Figure 9 ).

[0091] Unless otherwise specified, the raw materials and equipment used in the present invention are all common raw materials and equipment in the art; unless otherwise specified, the methods used in the present invention are all conventional methods in the art.

[0092] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent transformations made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. Preparation method of zwitterionic hydrogel integrating high-salt tolerance, all-weather fresh water collection and power generation, characterized in that, it comprises the following steps: (1) Dispersing zwitterionic monomer, initiator and crosslinking agent in pure water to obtain a reaction precursor solution, injecting the reaction precursor solution into a mold with a syringe, placing it at 50-90 °C, and irradiating with ultraviolet light of 365 nm for 0.1-48 h to initiate a polymerization reaction to achieve curing, obtaining a pure zwitterionic gel preform; The zwitterionic monomer is: 3-(1-(4-vinylbenzyl)-1H-imidazol-3-ium) propane-1-sulfonate; The initiator is a photoinitiator, selected from: 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, a,a-dimethoxy-a-phenylacetophenone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone, 2-methyl-1-(4-methylthiophenyl)-2-morpholin-1-propanone or lithium phenyl-2,4,6-trimethylbenzoylphosphite; The crosslinking agent is selected from: ethylene dimethacrylate, N,N'-methylenebisacrylamide or divinylbenzene; (2) Immersing the pure zwitterionic gel preform obtained in step (1) in a photothermal absorber solution to absorb the photothermal absorber to obtain the zwitterionic hydrogel; The photothermal absorber is selected from: inorganic carbon materials, organic materials or metal materials; the inorganic carbon materials are carbon black, carbon nanotubes, graphite or graphene; the organic materials are aniline or pyrrole; the metal materials are silver nanoparticles, gold nanorods or multiple twinned nanogolds; When the photothermal absorber is an organic material, an oxidant is used to induce its in-situ polymerization reaction in the preform; the oxidant is selected from: ammonium persulfate, potassium persulfate, ferric chloride, ferric nitrate, azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, diisopropylbenzene peroxide, tert-butyl peroxybenzoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxydicarbonate or dicyclohexyl peroxydicarbonate.

2. The preparation method according to claim 1, characterized in that, in the reaction precursor solution in step (1), the concentration of the zwitterionic monomer is 1-10 mmol / mL, the mass fraction of the initiator is 0.1-1%, and the mass fraction of the crosslinking agent is 0.1-1%.

3. The preparation method according to claim 1, characterized in that, the mass fraction of the photothermal absorber solution in step (2) is 0.01-100%.

4. The preparation method according to claim 1, characterized in that, in step (2), the immersion method of the pure zwitterionic gel preform in the photothermal absorber solution is complete immersion or partial immersion, and the immersion time is 0.1-72 h.

5. The preparation method according to claim 4, characterized in that, the process of complete immersion is as follows: Completely immerse the pure zwitterionic gel preform in a photothermal absorbent solution with a mass fraction of 0.1% to 100% for 1 to 48 hours, so that the photothermal absorbent is evenly distributed in the pure zwitterionic gel, and then induce its in-situ polymerization reaction for 1 to 48 hours with an oxidant to obtain a zwitterionic hydrogel that integrates high-salt-resistant all-weather fresh water collection and power generation with uniform photothermal absorbent distribution; Alternatively, the process of partial immersion is as follows: Immerse 1 / 8 to 7 / 8 of the height of the pure zwitterionic gel preform in a photothermal absorbent solution with a mass fraction of 0.1% to 100% for 1 to 48 hours, so that the photothermal absorbent is gradient-distributed in the pure zwitterionic gel, and then induce its in-situ polymerization reaction for 1 to 48 hours with an oxidant to obtain a zwitterionic hydrogel that integrates high-salt-resistant all-weather fresh water collection and power generation with gradient photothermal absorbent distribution.

6. A zwitterionic hydrogel prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the zwitterionic hydrogel according to claim 6 in solar seawater evaporation, as well as in atmospheric water collection and co-generation of electricity and water.

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