Preparation method and application of sandwich type solar driven interface evaporator

Abstract

The invention relates to a preparation method and application of a sandwich type solar driven interface evaporator, and belongs to the technical field of high polymer materials. According to the invention, a hydrophilic-hydrophobic-hydrophilic sandwich type wetting gradient aerogel is constructed, a two-dimensional material molybdenum disulfide with a high photothermal conversion effect is sprayed on the upper surface of a porous electrostatic spinning polyimide aerogel, and the bottom surface of a super-hydrophobic three-dimensional polyimide aerogel is subjected to hydrophilic treatment; and water supply and transmission are facilitated. Due to the reasonable design, the evaporator has excellent photo-thermal conversion efficiency, and the photo-thermal conversion efficiency can reach 98.8% under the sunlight intensity. The prepared sandwich-type solar-driven interface evaporator is applied to the field of seawater desalination, has good cycling stability, salt resistance and structural stability, and provides a new way for efficiently and stably obtaining fresh water driven by solar energy.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a preparation method and application of a sandwich-type solar-driven interface evaporator. Background Art

[0002] With the serious aggravation of the world energy crisis and water pollution, the shortage of fresh water resources has become a global problem that cannot be ignored. As we all know, the ocean occupies more than 97% of the water resources on the earth. Therefore, seawater desalination is an effective strategy to solve the existing problems. Solar-driven evaporation technology provides a new solution to the problem of seawater desalination. Compared with traditional seawater desalination technology that relies heavily on fossil energy, solar energy, a widely available and sustainable green and environmentally friendly energy, has attracted widespread attention from researchers. At present, the solar-driven interfacial evaporation technology has attracted much attention, placing the photothermal material on the gas-liquid interface for heating and evaporation. This method can reduce the loss of heat into the water body. The methods for achieving interfacial evaporation include utilizing the hydrophobicity and porous or hollow structural characteristics of the evaporator. However, after long-term use, due to the reduction of capillary force, salt accumulation still inevitably occurs, resulting in a decrease in evaporation effect. Therefore, the construction of aerogel materials with different wetting structures, excellent photothermal conversion effects and salt tolerance has become the focus of research. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a method for preparing a sandwich-type solar-driven interface evaporator.

[0004] The technical solution of the present invention to solve the above technical problem is as follows: A method for preparing a sandwich-type solar-driven interface evaporator comprises the following steps:

[0005] Step 1: Preparation of rice disulfide nanoflowers by hydrothermal method;

[0006] Step 2: electrospinning a polyamic acid nanofiber membrane, cutting it into pieces and dispersing it in water for uniform dispersion, adding a certain amount of triethylamine to the dispersion for cross-linking, freeze-drying and thermal imidization to obtain a polyimide aerogel;

[0007] Step three: prepare a dispersion of the molybdenum disulfide nanoflowers and polyvinyl pyrrolidone obtained in step one, prepare a polyvinyl alcohol solution, spray the molybdenum disulfide / polyvinyl pyrrolidone dispersion on the top surface of the polyimide aerogel prepared in step two, spray the polyvinyl alcohol solution on the bottom surface of the polyimide aerogel prepared in step two, and obtain a solar-driven interface evaporator with a sandwich-type wetting structure after drying.

[0008] Beneficial effects:

[0009] The aerogel prepared by electrospinning in the present invention has light-to-heat conversion performance and salt resistance performance;

[0010] Based on the above technical solution, the present invention can also be improved as follows.

[0011] Preferably, the hydrothermal temperature in step 1 is 220-280°C.

[0012] Preferably, the hydrothermal time in step 1 is 6-10 hours.

[0013] Preferably, the electrospinning parameter in step 2 is a voltage of 26-32 kV.

[0014] Preferably, the receiving distance in step 2 is 15-17 cm.

[0015] Preferably, the feeding amount in step 2 is 0.5-1.0 mL / h.

[0016] Preferably, the air humidity in step 2 is controlled at 20-30% RH.

[0017] Preferably, the receiving roller in step 2 rotates at a speed of 10-20 rpm.

[0018] Preferably, the concentration of the polyamic acid dispersion in step 2 is 0.5wt%-1.5wt%.

[0019] Preferably, the mass ratio of triethylamine in step 2 is 50%-70% of the mass of the polyamic acid.

[0020] Preferably, the concentration of the molybdenum disulfide / polyvinyl pyrrolidone dispersion in step three is 5%-20%.

[0021] The purpose of the present invention is to provide an application of a sandwich-type solar-driven interface evaporator, wherein the sandwich-type solar-driven interface evaporator is prepared by the preparation method of the sandwich-type solar-driven interface evaporator.

[0022] Beneficial effect: The prepared sandwich-type solar-driven interface evaporator is applied to seawater desalination, and light-heat conversion is carried out under light conditions, and clean fresh water resources are obtained based on this characteristic. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a SEM picture of the sandwich-type solar-driven interface evaporator obtained in Example 1 of the present invention;

[0025] Figure 2 The evaporation rate and photothermal conversion efficiency of the sandwich-type solar-driven interface evaporator of Example 1 at one sunlight intensity;

[0026] Figure 3 The evaporation rate and photothermal conversion efficiency of the sandwich-type solar-driven interface evaporator of Example 1 in a water environment with different salt contents under one sunlight intensity;

[0027] Figure 4 The comparison of ion concentration in water before and after desalination by the sandwich-type solar-driven interface evaporator of Example 1; DETAILED DESCRIPTION

[0028] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0029] Example 1

[0030] A method for preparing a sandwich-type solar-driven interface evaporator comprises the following steps:

[0031] Step 1: Preparation of rice disulfide nanoflowers by hydrothermal method;

[0032] Step 2: electrospinning a polyamic acid nanofiber membrane, cutting it into pieces and dispersing it in water for uniform dispersion, adding a certain amount of triethylamine to the dispersion for cross-linking, freeze-drying and thermal imidization to obtain a polyimide aerogel;

[0033] Step three: prepare a dispersion of the molybdenum disulfide nanoflowers and polyvinyl pyrrolidone obtained in step one, prepare a polyvinyl alcohol solution, spray the molybdenum disulfide / polyvinyl pyrrolidone dispersion on the top surface of the polyimide aerogel prepared in step two, spray the polyvinyl alcohol solution on the bottom surface of the polyimide aerogel prepared in step two, and obtain a solar-driven interface evaporator with a sandwich-type wetting structure after drying.

[0034] The sandwich-type solar-driven interface evaporator prepared in Example 1 was observed under an electron microscope. Figure 1 As shown, the molybdenum disulfide / polyvinyl pyrrolidone dispersion sprayed on the top surface of the polyimide aerogel presents a uniform stacked coating, and polyvinyl pyrrolidone as a binder can make the coating not easy to fall off at high temperatures.

[0035] The photothermal conversion capability of the sandwich-type solar-driven interface evaporator prepared in Example 1 was investigated. First, a photothermal evaporation test was conducted on it and seawater. The test results are as follows: Figure 3 As shown in Figure 2, the water evaporation rate of the sandwich-type solar-driven interface evaporator under one sun radiation in air is 1.46 kg m -2 h -1 , and its photothermal conversion efficiency is 93.6%.

[0036] The salt tolerance of the sandwich-type solar-driven interface evaporator prepared in Example 1 was tested, and the test results are as follows: Figure 3 As shown in Figure 2, the water evaporation rates of the sandwich-type solar-driven interface evaporator at salt concentrations of 5, 10, 15, and 20% are 1.541, 1.537, 1.488, and 1.481 kg m, respectively. -2 h -1 , the photothermal conversion efficiencies are 96.8, 96.6, 93.2, and 92.8%, respectively. With the gradual increase in salt content, the evaporation rate decreases slightly, but still maintains a good evaporator effect.

[0037] The desalination capacity of the polyimide solar-driven interface evaporator prepared in Example 1 was investigated. In order to detect its desalination performance, the evaporated water vapor was collected. The collection device was as follows: Figure 4 As shown in the figure. Under the radiation of one sun, obvious water vapor accumulation appeared on the glass cover after 20 minutes. The concentration changes of the four main ions before and after seawater desalination were detected by ICP. Compared with the simulated seawater before desalination, Na, K + , Ca 2+ Mg 2+ The four ions were significantly reduced by several orders of magnitude in the desalinated seawater, which is far below the drinking water standards set by the World Health Organization (WHO).

[0038] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a sandwich-type solar-driven interface evaporator, characterized in that: The following steps are involved: Step 1: Preparation of rice disulfide nanoflowers by hydrothermal method; Step 2: electrospinning a polyamic acid nanofiber membrane, cutting it into pieces and dispersing it in water for uniform dispersion, adding a certain amount of triethylamine to the dispersion for cross-linking, freeze-drying and thermal imidization to obtain a polyimide aerogel; Step three: prepare a dispersion of the molybdenum disulfide nanoflowers and polyvinyl pyrrolidone obtained in step one, prepare a polyvinyl alcohol solution, spray the molybdenum disulfide / polyvinyl pyrrolidone dispersion on the top surface of the polyimide aerogel prepared in step two, spray the polyvinyl alcohol solution on the bottom surface of the polyimide aerogel prepared in step two, and obtain a solar-driven interface evaporator with a sandwich-type wetting structure after drying.

2. The method for preparing a sandwich-type solar-driven interface evaporator according to claim 1, characterized in that: The raw materials used in the step 1 are ammonium molybdate and thiourea, the hydrothermal temperature is 220-280° C., and the hydrothermal time is 6-10 h.

3. The method for preparing a sandwich-type solar-driven interface evaporator according to claim 1, characterized in that: The electrospinning parameters in step 2 are as follows: voltage of 26-32 kV, receiving distance of 15-17 cm, liquid feeding volume of 0.5-1.0 mL / h, air humidity controlled at 20-30% RH, and the receiving roller collecting the nanofiber membrane at a rotation speed of 10-20 rpm.

4. The method for preparing a sandwich-type solar-driven interface evaporator according to claim 1, characterized in that: The concentration of the polyamic acid dispersion in step 2 is 0.5wt%-1.5wt%.

5. The method for preparing a sandwich-type solar-driven interface evaporator according to claim 1, characterized in that: The mass ratio of triethylamine in the step 2 is 50%-70% of the mass of the polyamic acid.

6. The method for preparing a sandwich-type solar-driven interface evaporator according to claim 1, characterized in that: The concentration of the molybdenum disulfide / polyvinyl pyrrolidone dispersion in step 3 is 5%-20%.

7. The method for preparing a sandwich-type solar-driven interface evaporator according to claim 1, characterized in that: The concentration of the polyvinyl alcohol solution in the composite aerogel in step 3 is 2-4 wt %.

8. The method for preparing a sandwich-type solar-driven interface evaporator according to claim 1, characterized in that: The spraying distance in step 3 is 10-20 cm, and the spraying intensity is 15-25 psi.

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