CN113308026A

CN113308026A - Evaporator and preparation method and application thereof

Info

Publication number: CN113308026A
Application number: CN202110684377.3A
Authority: CN
Inventors: 陈雯雯; 景高星; 朱国帅
Original assignee: Shenzhen University
Current assignee: Shenzhen University
Priority date: 2021-06-21
Filing date: 2021-06-21
Publication date: 2021-08-27
Anticipated expiration: 2041-06-21
Also published as: CN113308026B

Abstract

The invention provides an evaporator and a preparation method and application thereof, wherein the evaporator has a porous structure; the material of the evaporator comprises a combination of gold nanoparticles, aqueous polyurethane and nanocellulose. The preparation method comprises the following steps: and mixing the gold nanoparticle solution, the nanocellulose solution and the aqueous polyurethane emulsion, and drying to obtain the evaporator. The evaporator provided by the invention has the advantages of high evaporation rate, good reusability and high stability, and can be applied to seawater desalination materials.

Description

Evaporator and preparation method and application thereof

Technical Field

The invention belongs to the technical field of photo-thermal conversion materials, and particularly relates to an evaporator and a preparation method and application thereof.

Background

Due to widespread environmental pollution, shortage of fresh water resources has become one of the most pressing problems worldwide. Today, more than one third of the world's population lives in areas with freshwater shortages. However, compared with the scarce fresh water resource, the seawater resource on the earth is quite abundant, which accounts for about 97% of the total water resource on the earth, and the solar energy resource is often also abundant in the arid region where the fresh water is in short supply. Therefore, the seawater desalination technology based on solar evaporation has become a research hotspot in recent years and has very important research significance.

In the technical field of seawater desalination, interface type solar evaporators appeared in recent years can absorb solar energy at a seawater-air interface by using a light absorber floating on the water surface, so that the energy conversion efficiency from solar energy to water evaporation is greatly improved. Currently, there are many researches on interface type solar evaporators, for example, CN110777561A a metal nanoparticle-polymer composite material and a preparation method and application thereof, the composite material includes a solid matrix and a filler, the filler includes metal nanoparticles, the solid matrix has pores with a pore diameter of 2-500 nm, the solid matrix includes a polymer fiber material, the filler is dispersedly filled in the pores inside the solid matrix, the pores are used for dispersing the filler and preventing the filler from agglomerating; the metal nano-particle-polymer composite material is obtained by preparing metal seeds in the internal pores of the solid matrix and then putting the metal seeds into a metal nano-particle growth solution for growth. CN112429798A discloses a method for preparing a salt-tolerant evaporator by assembling nanoparticles on vertically arranged fibers, which disperses nanoparticles with a particle size of less than 50nm and capable of capturing solar energy as a photo-thermal conversion agent in a polar solvent, permeates the dispersion into regularly shaped fiber bundles, and obtains the salt-tolerant evaporator by baking and carbonizing. Although these materials have a certain photothermal conversion efficiency, there are still problems of clogging due to salt deposition, poor recycling properties, and less than ideal photothermal conversion efficiency.

Therefore, it is an urgent need to solve the problem of research and preparation of a solar evaporator with high photo-thermal conversion efficiency, high evaporation rate, good stability and good reusability.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide the evaporator and the preparation method and the application thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides an evaporator having a porous structure; the material of the evaporator comprises a combination of gold nanoparticles, aqueous polyurethane and nanocellulose.

In the invention, the nano-cellulose has good hygroscopicity, which is beneficial to absorbing seawater, but the hygroscopicity is too strong, so that gold nano-particles are easy to separate out, the evaporation rate is reduced, and the reusability is poor. Therefore, the nanocellulose and the hydrophobic waterborne polyurethane are compounded, gold nanoparticles are prevented from being separated out, and the gold nanoparticles with high light conversion efficiency are added, so that the evaporator is high in evaporation efficiency, good in reusability and high in stability.

In the present invention, the thickness of the evaporator is 0.5-2.5 cm, for example, 0.6cm, 1cm, 1.2cm, 1.5cm, 2cm, 2.2cm or 2.4cm, and the specific values therebetween are limited by space and for the sake of brevity, and the specific values included in the range are not exhaustive.

Preferably, the pore diameter of the porous structure is 20 to 300 μm, for example, 50 μm, 100 μm, 120 μm, 150 μm, 200 μm, 220 μm, 250 μm or 290 μm, and the specific values therebetween are not exhaustive, and the invention is not limited to the specific values included in the range for brevity and conciseness.

In the present invention, the mass ratio of the gold nanoparticles to the nanocellulose is 1 (500 to 2600), and may be, for example, 1:600, 1:800, 1:1000, 1:1200, 1:1500, 1:2000, 1:2200, 1:2500, or the like, and more preferably 1 (1000 to 1200).

The mass ratio of the aqueous polyurethane to the nanocellulose is preferably 1 (2-9), and may be, for example, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, or 1:8.5, and more preferably 1 (3-5).

In the invention, the weight average molecular weight of the waterborne polyurethane is 80000-200000, for example, 80000, 100000, 120000, 140000, 160000, 180000 or 190000, and the specific values therebetween are limited to space and for the sake of brevity, and the invention is not exhaustive.

Preferably, the length of the nanocellulose is 10-100 nm, for example, it may be 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm or 90nm, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive.

In the present invention, the particle size of the gold nanoparticle is 20 to 100nm, for example, it may be 25nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm or 90nm, and specific values therebetween are limited to space and for simplicity, and the invention is not exhaustive.

Preferably, the gold nanoparticles are prepared by a method comprising the steps of: (1) soaking tea in water to obtain tea soaking solution; (2) and (2) mixing the tea soaking solution obtained in the step (1) with a chloroauric acid solution, and reacting to obtain the gold nanoparticles.

Preferably, the tea leaves are commercially available tea leaves.

Preferably, the tea leaves are selected from green tea and/or black tea.

Preferably, the mass ratio of the tea leaves to the water in the step (1) is 1 (50-500), and may be, for example, 1:100, 1:150, 1:200, 1:250, 1:300, 1:350, 1:400, 1:450, or the like.

Preferably, the temperature of the soaking in the step (1) is 25 to 100 ℃, and for example, it may be 30 ℃, 40 ℃, 50 ℃, 60 ℃, 65 ℃, 70 ℃, 80 ℃, 85 ℃, 90 ℃ or 95 ℃, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive list of the specific values included in the range.

Preferably, the soaking time in step (1) is 0.5-2 h, for example, 0.6h, 1h, 1.2h, 1.5h, 1.6h, 1.8h or 1.9h, and the specific values therebetween are limited by the space and for the sake of brevity, and the invention is not exhaustive list of the specific values included in the range.

Preferably, the soaking step further comprises the steps of taking supernatant and filtering.

In the present invention, the volume ratio of the tea leaf soaking solution and the chloroauric acid solution in the step (2) is 1 (0.3-1), and may be, for example, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, or 1: 0.9.

Preferably, the concentration of the chloroauric acid solution is 0.04-4 mM, for example, 0.05mM, 1mM, 1.2mM, 1.5mM, 2.5mM, 3.2mM or 3.5mM, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive list of the specific values included in the range, and further preferably 2-3 mM.

Preferably, the solvent of the chloroauric acid solution is water.

Preferably, the method of mixing is mechanical agitation.

Preferably, the rotation speed of the mechanical stirring is 400-800 rpm, such as 420rpm, 450rpm, 500rpm, 550rpm, 600rpm, 650rpm, 700rpm or 750rpm, and specific values therebetween, which are not exhaustive and included in the range for brevity.

Preferably, the mechanical stirring time is 30-90 min, such as 35min, 40min, 50min, 60min, 70min, 80min or 90min, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive.

Preferably, the reaction time is 1 to 3 hours, for example, 1.2 hours, 1.5 hours, 1.6 hours, 1.8 hours, 2 hours, 2.5 hours, 2.6 hours or 2.9 hours, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive.

Preferably, the reaction is carried out under standing conditions.

Preferably, after the reaction, centrifugation is further included.

Preferably, the rotation speed of the centrifugation is 4000 to 10000rpm, for example 4200rpm, 4500rpm, 5000rpm, 5500rpm, 6000rpm, 6500rpm, 7000rpm, 7500rpm, 8000rpm, 8500rpm, 9000rpm or 9500rpm, and specific values therebetween, which are not intended to be exhaustive for reasons of space and simplicity, are included in the present invention.

Preferably, the centrifugation time is 5-20 min, such as 6min, 8min, 10min, 12min, 14min, 16min or 18min, and the specific values therebetween are limited by space and for simplicity, and the invention is not exhaustive.

Preferably, the temperature of the mixing, reacting and centrifuging is 15-40 ℃, for example, 16 ℃, 18 ℃, 20 ℃, 22 ℃, 24 ℃, 30 ℃ or 35 ℃, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive.

In a second aspect, the present invention provides a method for manufacturing the evaporator according to the first aspect, the method comprising the steps of: and mixing the gold nanoparticle solution, the nanocellulose solution and the aqueous polyurethane emulsion, and drying to obtain the evaporator.

Preferably, the concentration of the gold nanoparticle solution is 3-15 mg/mL, for example, 4mg/mL, 5mg/mL, 6mg/mL, 7mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL, 12mg/mL, 13mg/mL or 14mg/mL, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive list of the specific values included in the range.

Preferably, the mass concentration of the nanocellulose solution is 2-6%, for example, it may be 2.2%, 2.5%, 3%, 3.2%, 3.5%, 4%, 4.2% or 4.5%, and the specific values therebetween are limited by space and for brevity, the present invention is not exhaustive list of the specific values included in the range.

Preferably, the mass concentration of the aqueous polyurethane emulsion is 30-50%, for example, 32%, 35%, 38%, 40%, 42%, 45%, 48% or 49%, and the specific values therebetween are limited to the space and for the sake of brevity, and the invention is not exhaustive.

Preferably, the solvent of the gold nanoparticle solution, the nanocellulose solution and the aqueous polyurethane emulsion is water.

Preferably, the drying is selected from any one or a combination of at least two of freeze drying, normal temperature drying and high temperature drying, and further preferably freeze drying.

Preferably, the temperature of the freeze-drying is-100 to-70 ℃, for example, -99 ℃, -90 ℃, -85 ℃, -82 ℃, -80 ℃, -75 ℃ or-72 ℃, and the specific values therebetween, are limited to space and for the sake of brevity, and the invention is not exhaustive of the specific values included in the ranges.

Preferably, the freeze-drying time is 10-25 h, for example, 12h, 13h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h or 23h, and the specific values therebetween are limited by space and for brevity, the invention is not exhaustive of the specific values included in the range.

In a third aspect, the present invention provides the use of an evaporator according to the first aspect in a seawater desalination material.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides an evaporator, which is prepared by compounding waterborne polyurethane and nano-cellulose and adding gold nanoparticles:

(1) the evaporation rate is high, and the evaporation rates of pure water, actual seawater and brine with the concentration of 3.5 percent, 10 percent and 20 percent are respectively 2.24 kg.m^-2·h^-1、2.18kg·m^-2·h^-1、2.07kg·m^-2·h^-1、1.96kg·m^-2·h^-1、1.71kg·m^-2·h^-1；

(2) The salt has strong self-cleaning property, and 0.3g of salt on the surface of the evaporator is completely absorbed after 30 min;

(3) the surface of the material is not cracked and changed after ultrasonic treatment for 2 hours in water and soaking for 1 hour in 95 ℃ water and manual pressing for 10 times of circulation, and the material has excellent thermal stability, mechanical stability and ultrasonic stability.

(4) When the evaporator provided by the invention is used for seawater desalination, the ion concentration in the desalinated water meets the regulations of the world health organization.

Drawings

FIG. 1 is a scanning electron microscope photograph of the evaporator surface provided in example 1;

FIG. 2 is a UV absorption spectrum of the water-soaking solution and pure water of the evaporator provided in example 1 and comparative example 1;

FIG. 3 is a graph of the evaporation rate of the evaporator provided in example 1 at different salt concentrations;

FIG. 4 is a graph of the evaporation rate of the evaporator provided in example 1 in pure water and brine at various time points;

FIG. 5 is a graph showing a test of salt self-cleaning property of the evaporator provided in example 1;

FIG. 6 is a graph showing the thermal stability test of the evaporator provided in example 1;

FIG. 7 is a test chart of the ultrasonic stability of the evaporator provided in example 1;

FIG. 8 is a mechanical stability test chart of the evaporator provided in example 1;

fig. 9 is a test chart of a seawater desalination application of the evaporator provided in example 1;

fig. 10 is a graph of the evaporation rate of the evaporator provided in example 1 at different time points under actual sunlight.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The following examples and comparative examples of the present invention use materials including:

aqueous polyurethane: shanghai Michelin Biochemical technology, Inc., A909856;

nano-cellulose: the preparation method of the nano-cellulose comprises the following steps: firstly, 100g of cotton pulp is added into 1L of sulfuric acid with the mass concentration of 64 percent, and the mixture is stirred for 2 hours at the temperature of 45 ℃ to obtain a mixed solution; then diluting the mixed solution by 10 times with water to terminate the reaction; and finally, centrifuging at the rotating speed of 1000rpm for 15min, repeatedly cleaning, dialyzing, removing free acid to obtain a nano cellulose colloidal solution, and freeze-drying to obtain the nano cellulose.

Preparation example 1

The preparation example provides a gold nanoparticle, and the preparation method of the gold nanoparticle comprises the following steps:

(1) according to the mass ratio of the green tea to the water of 1:100, soaking the green tea in water of 100 ℃ for 2 hours to obtain a green tea soaking solution; (2) mixing the green tea soaking solution obtained in the step (1) with a chloroauric acid solution with the concentration of 2mM according to the volume ratio of 3:2, reacting for 2 hours under a standing condition, and then centrifuging for 10min at the rotating speed of 7000rpm to obtain the gold nanoparticles; the temperature of the mixing, reaction and centrifugation was 25 ℃.

Preparation examples 2 to 6

The present preparation example provides gold nanoparticles, which are prepared by a method different from that of preparation example 1 in that the concentrations of the chloroauric acid solution of step (2) are 0.05mM, 0.1mM, 0.5mM, 1mM, and 4mM, respectively.

And (3) performance testing:

(1) and (3) testing the dispersion performance: respectively taking the gold nanoparticle solution subjected to standing reaction in the step (2) in the preparation examples 1-6, observing whether a coagulation phenomenon exists, and if no coagulation exists within 1 hour, indicating that the gold nanoparticle solution has good dispersibility; if the coagulation phenomenon appears within 1 hour, the dispersion of the gold nanoparticle solution is poor. The test results are shown in table 1. As can be seen from the data in Table 1, the solutions of gold nanoparticles provided in preparation examples 1 to 5 have good dispersibility and no coagulation, and when the concentration of the chloroauric acid solution is 4mM, the prepared solutions of gold nanoparticles have coagulation phenomena and poor dispersibility.

TABLE 1

	Dispersing Properties
		Preparation example 1	Good taste
Preparation example 2	Good taste
		Preparation example 3	Good taste
Preparation example 4	Good taste
		Preparation example 5	Good taste
Preparation example 6	Difference (D)

(2) Ultraviolet and visible light absorption spectrum test: the gold nanoparticles provided in preparation examples 1 to 6 were subjected to ultraviolet-visible absorption spectrum tests using a microplate reader (Tecan, Infinite 200PRO), respectively, and the test results are shown in table 2.

TABLE 2

As can be seen from Table 2, when the mass concentration of the chloroauric acid solution is 2mM, the prepared gold nanoparticles have a strong visible light absorption effect, which is only slightly inferior to the gold nanoparticles prepared by the chloroauric acid solution with the mass concentration of 4 mM.

Therefore, the gold nanoparticles provided in preparation example 1 were used in each example of preparing the evaporator according to the dispersibility of the gold nanoparticle solution and the visible light absorption effect of the gold nanoparticles.

Example 1

The embodiment provides an evaporator and a preparation method thereof, wherein the evaporator is provided with a porous structure; the material of the evaporator comprises a composition of gold nanoparticles, aqueous polyurethane and nanocellulose; the gold nanoparticles are provided by preparation example 1. The mass ratio of the gold nanoparticles to the nanocellulose is 1:1200, and the mass ratio of the waterborne polyurethane to the nanocellulose is 1: 4. The thickness of the evaporator was 1.2 cm.

The preparation method of the evaporator comprises the following steps: uniformly mixing a gold nanoparticle solution with the concentration of 6.4mg/mL, a nano-cellulose solution with the concentration of 3.4% and a waterborne polyurethane emulsion with the concentration of 40% to obtain a mixed solution, wherein the mass ratio of the gold nanoparticles to the nano-cellulose is 1:1200, and the mass ratio of the waterborne polyurethane to the nano-cellulose is 1: 4; and (3) freeze-drying the mixed solution at-80 ℃ for 16h to obtain the evaporator.

Examples 2 to 5

This example provides an evaporator and a method for manufacturing the same, and the evaporator is different from example 1 only in that the mass ratio of the aqueous polyurethane to the nanocellulose is 1:12, 1:9, 3:7 and 2:3, respectively. The preparation method is the same as in example 1.

Examples 6 to 10

This example provides an evaporator and a method for preparing the same, which are different from example 1 only in that the mass ratio of the gold nanoparticles to the nanocellulose is 1:300, 1:600, 1:800, 1:2400 and 1:3000, respectively. The preparation method differed from example 1 only in that the concentrations of the gold nanoparticle solutions were 15mg/mL, 12.8mg/mL, 9.6mg/mL, 3.2mg/mL, and 3 mg/mL.

Examples 11 and 12

Examples 11 and 12 provide an evaporator and a method for manufacturing the same, which are different from example 1 only in that the thickness of the evaporator is 0.6cm and 2.4cm, respectively. The preparation method is the same as in example 1.

Comparative example 1

The present comparative example provides an evaporator and a method of manufacturing the same, the evaporator having a porous structure; the material of the evaporator comprises a combination of gold nanoparticles and nanocellulose; the gold nanoparticles are provided by preparation example 1. The mass ratio of the gold nanoparticles to the nanocellulose is 1: 1200.

The preparation method of the evaporator comprises the following steps: (1) and (3) carrying out freeze drying on the gold nanoparticle solution with the concentration of 6.4mg/mL and the nano-cellulose solution with the concentration of 3.4% at-80 ℃ for 16h to obtain the evaporator.

Comparative example 2

The present comparative example provides an evaporator and a method of manufacturing the same, the evaporator having a porous structure; the material of the evaporator comprises a combination of gold nanoparticles and aqueous polyurethane; the gold nanoparticles are provided by preparation example 1. The mass ratio of the gold nanoparticles to the waterborne polyurethane is 1: 1200.

The preparation method of the evaporator comprises the following steps: (1) and (3) carrying out freeze drying on the gold nanoparticle solution with the concentration of 6.4mg/mL and the aqueous polyurethane emulsion with the concentration of 40% at-80 ℃ for 16h to obtain the evaporator.

And (3) performance testing:

(1) and (3) testing a scanning electron microscope: the evaporator provided in example 1 was scanned for surface topography using a scanning electron microscope (zeiss Sigma 300) and the results are shown in fig. 1. As can be seen from FIG. 1, the evaporator prepared by the present embodiment has a porous structure with pores of 20-400 μm.

(2) And (3) testing the precipitation performance of the gold nanoparticles: the evaporators provided in example 1 and comparative example 1 were immersed in water for 12 hours, and then the evaporators were taken out to measure the ultraviolet absorption spectra of the immersion liquid and pure water. As shown in fig. 2, the absorption spectrum of the immersion liquid of the evaporator (example 1) immersed with the aqueous polyurethane in the component was substantially identical to that of pure water, compared with the immersion liquid of the evaporator (comparative example 1) immersed with the component not containing the aqueous polyurethane, indicating that the gold nanoparticles in the evaporator were hardly precipitated and the stability in the evaporator was good.

(3) And (3) testing the evaporation rate: the evaporators provided in examples 1 to 12 and comparative examples 1 and 2 were subjected to an evaporation rate test according to the following procedure: the evaporators provided in the above examples and comparative examples were each placed in a glass dish by simulating the intensity of sunlight with an artificial sun, pure water was supplied to the evaporator using a sponge, the evaporator was floated on the water surface by a foam pad, and the change in mass during evaporation of the evaporation apparatus was continuously recorded on an electronic balance. The test time is 60min, the mass of the evaporator at 0min and 60min is recorded respectively, and the evaporation rate of the evaporator to pure water is measured. The test results are shown in table 3.

TABLE 3

As can be seen from Table 3, in the preparation process of the evaporator, the addition of a proper amount of aqueous polyurethane into the nanocellulose helps to increase the evaporation rate of the evaporator, and the evaporation rate is not obviously increased after the content of the aqueous polyurethane reaches a certain value (examples 1 to 5); the higher the content of the gold nanoparticles added into the evaporator, the better the photothermal effect and the faster the evaporation rate (example 1, examples 6 to 10), but in view of cost, the evaporator is prepared by selecting the appropriate content of the gold nanoparticles; the larger the thickness of the evaporator, the higher the evaporation rate (example 1, example 11, 12), but the thicker the evaporator, the more difficult it is to freeze-dry, and the longer the freeze-drying time is required, so the thickness of the evaporator is set to 1.2 cm.

The evaporator provided in example 1 was subjected to evaporation rate tests for solutions of different salt concentrations, namely pure water, sea water and brine at concentrations of 3.5%, 10%, 20%, respectively. The testing time is 60min, and the quality of the evaporation device at 0min, 10min, 20min, 30min, 40min, 50min and 60min is recorded respectively. The test results are shown in fig. 3: it can be seen that the evaporation rate of the evaporator is the greatest for pure water, and the higher the salt concentration in the water, the smaller the evaporator is relative to its evaporation rate.

Illustratively, the evaporator provided in example 1 was tested for evaporation rates of pure water and 3.5% brine, respectively, for a test time of 8 hours, and the mass and rate of the evaporation apparatus were recorded for 0, 1h, 2h, 3h, 4h, 5h, 6h, 7h, and 8h, respectively, with the results shown in fig. 4: the evaporation rates of the evaporators at each time point were comparable and substantially identical for pure water and 3.5% brine; meanwhile, the evaporation rate of the evaporator for pure water is greater than that of 3.5% brine.

(4) And (3) testing the reusability: the evaporators provided in example 1 and comparative examples 1 and 2 were tested for reusability by the following procedure: the evaporators provided in the above examples and comparative examples were subjected to evaporation test for 1 hour per day under 3.5% saline for 7 consecutive days, see "(3) evaporation rate test" for test procedure, and the test results are shown in table 4.

TABLE 4

As can be seen from the data in table 4, the evaporator provided in example 1 still has a high evaporation rate after 7 consecutive evaporation tests, which is almost not different from the first evaporation rate, indicating that the gold nanoparticles are not precipitated from the evaporator, and has excellent stability, which is consistent with the results shown in fig. 2; comparative example 1 as can be seen from fig. 2, the stability of the gold nanoparticles in the evaporator is poor, and precipitation occurs, so that the evaporation rate of the evaporator gradually decreases with the increase of the number of evaporation tests, the evaporation rate in the seventh test is close to that of the evaporator without the addition of the gold nanoparticles, and the evaporation rate of the evaporator provided in comparative example 1 is also significantly lower than that of example 1. In comparative example 2, the evaporation rate was low because the moisture absorption of the evaporator was poor due to the absence of nanocellulose, but the evaporation rate was decreased more slowly in the evaporator subjected to the evaporation rate test of 7 times because the stability of the gold nanoparticles in the evaporator was high due to the presence of the aqueous polyurethane.

(5) Testing the self-cleaning property of salt: as shown in FIG. 5, 0.3g of NaCl was weighed and uniformly sprinkled on the wetted evaporator surface provided in example 1, and it was found that NaCl particles on the evaporator surface were significantly reduced after 15min and that NaCl on the evaporator surface was completely absorbed after 30min, indicating that the evaporator had good salt self-cleaning properties.

(6) And (3) stability testing: as shown in fig. 6, the evaporator provided in example 1 was soaked in water at 95 ℃ for 1 h; as shown in fig. 7, the evaporator provided in example 1 was sonicated in water for 2 h; as shown in FIG. 8, the manual pressure rebounds continuously, cycling 10 times. It can be observed that the evaporator provided by the invention has no cracking, no fading and no shape change no matter under high temperature, ultrasonic or repeated mechanical stress, which shows that the evaporator provided by the invention has excellent thermal stability, ultrasonic stability and mechanical stability.

(7) Sea water desalination application test: as shown in FIG. 9, the simple condensed water collecting device is composed of a base, a water tank and a glass cover. The test procedure was as follows: firstly, a layer of plastic film is laid on a base; then, a water tank which is provided with an evaporator and is filled with a proper amount of seawater is arranged on a plastic film of a base, and a glass cover is covered above the water tank and is arranged below an artificial solar lamp; the condensed water can be gathered on the glass cover and flows down along the inner wall of the glass cover, and finally the condensed water can be collected on the plastic film of the base; the condensed water evaporated by the evaporator provided in example 1 and comparative examples 1 and 2 was collected, and then the ion concentrations of the seawater and the collected condensed water were measured by a mass spectrometer, and the test results are shown in table 5.

TABLE 5

As can be seen from the data in Table 5, in the condensed water obtained by evaporating seawater and condensing it by using the evaporator provided in example 1, Na was contained⁺、Mg⁺、K⁺And Ca⁺The concentration of each ion is greatly reduced, the concentration of each ion meets the requirements of the world health organization on the concentration of the related ions in the fresh water, and the desalination efficiency reaches 97.72-99.68%. While the evaporator provided in comparative example 1 can evaporate seawater, the evaporation rate is low, the pores are larger than those of the evaporator doped with the aqueous polyurethane, and the ion rejection rate is low; comparative example 2, on the other hand, had poor water absorption, a lower evaporation rate and a slightly lower ion rejection than example 1.

(7) Actual solar evaporation test: the evaporator provided in example 1 was subjected to an actual solar evaporation test outdoors and recorded as 8:00 to 18: the evaporation rate of 00 was varied and the test results are shown in fig. 10, starting in the morning at 8:00, with increasing light intensity, the evaporation rate of the evaporator gradually increased, reaching a maximum at 14:00, and then the light intensity started to gradually decrease, with the rate of the evaporator gradually decreasing.

The applicant states that the present invention is illustrated by the above embodiments of the evaporator of the present invention, and the preparation method and application thereof, but the present invention is not limited to the above embodiments, i.e. it does not mean that the present invention must be implemented by the above embodiments. It will be apparent to those skilled in the art that any modification of the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific modes and the like, which are within the scope and disclosure of the present invention, are contemplated by the present invention.

Claims

1. An evaporator, characterized in that the evaporator has a porous structure; the material of the evaporator comprises a combination of gold nanoparticles, aqueous polyurethane and nanocellulose.

2. The evaporator according to claim 1, wherein the thickness of the evaporator is 0.5 to 2.5 cm;

preferably, the pore diameter of the porous structure is 20-300 μm.

3. The evaporator according to claim 1 or 2, wherein the mass ratio of the gold nanoparticles to the nanocellulose is 1 (500-2600), and is further preferably 1 (1000-1200);

preferably, the mass ratio of the waterborne polyurethane to the nanocellulose is 1 (2-9), and more preferably 1 (3-5).

4. An evaporator according to any one of claims 1 to 3 wherein the aqueous polyurethane has a weight average molecular weight of 80000 to 200000;

preferably, the length of the nano-cellulose is 10-100 nm.

5. The evaporator according to any one of claims 1 to 4, wherein the gold nanoparticles have a particle size of 20 to 100 nm;

6. The evaporator of claim 5, wherein the mass ratio of the tea leaves to the water in the step (1) is 1 (50-500);

preferably, the soaking temperature in the step (1) is 25-100 ℃;

preferably, the soaking time in the step (1) is 0.5-2 h;

7. The evaporator according to claim 5 or 6, wherein the volume ratio of the tea soaking solution to the chloroauric acid solution in the step (2) is 1 (0.3-1);

preferably, the concentration of the chloroauric acid solution is 0.04-4 mM, and more preferably 2-3 mM;

preferably, the solvent of the chloroauric acid solution is water;

preferably, the method of mixing is mechanical stirring;

preferably, the rotation speed of the mechanical stirring is 400-800 rpm;

preferably, the mechanical stirring time is 30-90 min;

preferably, the reaction time is 1-3 h;

preferably, the reaction is carried out under standing conditions;

preferably, after the reaction, centrifugation is further included;

preferably, the rotating speed of the centrifugation is 4000-10000 rpm;

preferably, the centrifugation time is 5-20 min;

preferably, the temperature of the mixing, the reaction and the centrifugation is 15-40 ℃.

8. A method for manufacturing an evaporator according to any one of claims 1 to 7, comprising the steps of: and mixing the gold nanoparticle solution, the nanocellulose solution and the aqueous polyurethane emulsion, and drying to obtain the evaporator.

9. The method according to claim 8, wherein the concentration of the gold nanoparticle solution is 3 to 15 mg/mL;

preferably, the mass concentration of the nano-cellulose solution is 2-6%;

preferably, the mass concentration of the aqueous polyurethane emulsion is 30-50%;

preferably, the solvent of the gold nanoparticle solution, the nano-cellulose solution and the aqueous polyurethane emulsion is water;

preferably, the drying is selected from any one or a combination of at least two of freeze drying, normal temperature drying or high temperature drying, and further preferably freeze drying;

preferably, the temperature of the freeze drying is-100 to-70 ℃;

preferably, the freeze drying time is 10-25 h.

10. Use of an evaporator according to any one of claims 1 to 7 in a seawater desalination material.