Polyolefin-based flexible solar driving interface evaporator as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of water evaporator material preparation, and particularly relates to a polyolefin-based flexible solar driving interface evaporator and a preparation method and application thereof. The invention provides the low-cost, high-efficiency and large-area integrated flexible polyolefin-based solar-driven interface evaporator and the preparation method, and the integrated flexible polyolefin-based solar-driven interface evaporator can be applied to seawater desalination, wastewater treatment and concentration and extraction of water-soluble lithium, magnesium, sodium and rare-earth salts. The preparation method comprises the following steps: by taking aniline oligomer, polyaniline, polypyrrole, polydopamine, a carbon material or nano metal particles as a photo-thermal conversion material and dicyclopentadiene and cyclooctene as polymer matrixes, quickly polymerizing by utilizing olefin metathesis reaction and by virtue of a sodium chloride template, and cleaning sodium chloride in an obtained blocky solid through ultrasonic waves, thereby obtaining the photo-thermal conversion material. And the polyolefin-based solar driven interface evaporator with the photo-thermal conversion effect is prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of water evaporator materials, and particularly relates to a polyolefin-based flexible solar-driven interfacial evaporator, a preparation method thereof, and an application thereof. Background Art

[0002] Fresh water resources are one of the important natural resources on which human beings depend for survival. However, due to the rapid growth of the world population, the high-speed development of the global economy, and the rapid increase in water use caused by industrialization, as well as factors such as environmental pollution and climate change, the problem of fresh water resource shortage has become increasingly serious. Therefore, it is crucial to seek green, economic, and sustainable processes and methods to solve the problem of fresh water resource shortage. The solar-driven interfacial evaporation technology provides an effective way to solve the problem of fresh water resource shortage by desalinating seawater and purifying sewage to obtain precious fresh water resources.

[0003] During the desalination of seawater by solar-driven interfacial evaporators, the precipitation of salts often occurs. Utilizing the property of water evaporation and salt precipitation of solar-driven interfacial evaporators can not only obtain pure water but also obtain precious mineral resources. It is reported that 1 liter of seawater contains abundant resources such as chlorine, sodium, magnesium, and bromine, and in addition, there are also a small amount of metal ions such as lithium, uranium, and gold. Although the content of resources such as lithium, uranium, and gold is relatively low, the total amount of seawater is huge, making the total amount of these resources in seawater very considerable, and also making it possible to extract resources such as lithium, uranium, and gold from seawater. At the same time, it is required that the solar-driven interfacial evaporator must have high efficiency. In addition, currently 70% of lithium products come from salt lakes, but the concentration of lithium in salt lakes is relatively low, and industrial extraction of lithium from salt lakes requires prior concentration of salt lake water. Salt lakes are usually located in deserts or semi-desertified areas with little rainfall and large evaporation, and the industrial foundation is relatively weak, so only the natural evaporation method can be used for concentration, but this process is very time-consuming, often up to 12 - 18 months. Utilizing solar-driven interfacial evaporators can accelerate the evaporation of water and shorten the time for concentrating salt lake water. This requires that the solar-driven interfacial evaporator not only has a high water evaporation rate but also has a function of screening ions.

[0004] The area of the currently reported solar-driven interfacial evaporators is relatively small, and it is difficult to achieve large-scale preparation. Moreover, the preparation process is relatively complex, time-consuming, and laborious, and the cost is relatively high. These factors have restricted the wide use of solar interfacial evaporators. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a low-cost, high-efficiency, large-area integrated flexible polyolefin-based solar-driven interfacial evaporator and its preparation method, which can be applied to seawater desalination, wastewater treatment, and the concentration and extraction of water-soluble lithium, magnesium, sodium, and rare earth salts. Using aniline oligomers, polyaniline, polypyrrole, polydopamine, carbon materials, or nano metal particles as the photothermal conversion materials, and dicyclopentadiene and cyclooctene as the polymer matrix, through olefin metathesis reaction, with the aid of sodium chloride template, rapid polymerization is carried out. The obtained bulk solid is ultrasonically cleaned to remove the internal sodium chloride, and a polyolefin-based solar-driven interfacial evaporator with photothermal conversion effect is prepared.

[0006] Specifically, the first technical solution of the present application discloses a polyolefin-based flexible solar-driven interfacial evaporator, which includes a photothermal conversion material and a polyolefin-based polymer matrix. Among them, the photothermal conversion material is uniformly dispersed in the polyolefin-based polymer matrix.

[0007] Furthermore, the photothermal conversion material is one or more of aniline oligomers, polypyrrole, polydopamine, carbon materials, or nano metal particles having a photothermal conversion effect.

[0008] Furthermore, the aniline oligomer is an amine-terminated aniline trimer.

[0009] Furthermore, the polyolefin-based polymer matrix is obtained by ring-opening polymerization of one or several monomers of dicyclopentadiene, cyclooctene, and methyl dicyclopentadiene through olefin metathesis reaction.

[0010] The second technical solution of the present application discloses a preparation method of the above polyolefin-based flexible solar-driven interfacial evaporator. Using the salt template method, the photothermal conversion material is dispersed in the sodium chloride template, and then the polyolefin-based polymer matrix monomer containing a catalyst is poured into the gaps of the sodium chloride template. After heating and polymerization, the sodium chloride is removed by washing with water.

[0011] The salt template method described in this technical solution refers to using sodium chloride crystals to solidify into a mold in a humid environment; the above technical solution is specifically as follows: First, the photothermal conversion material and sodium chloride are mixed evenly and filled into the template, and then placed in a closed system containing saturated potassium sulfate solution to solidify to obtain the sodium chloride template; then the polyolefin-based polymer matrix monomers are mixed evenly, the Grubbs catalyst is dissolved in a small amount of cyclohexylbenzene and added to the monomers, and the above monomers are dropped into the sodium chloride template, and the monomers are allowed to self-initiate polymerization at room temperature or heated reaction until the reaction is completed.

[0012] Furthermore, the molar ratio of the photothermal conversion material to the polyolefin-based polymer matrix monomer is 0.1% to 100%.

[0013] Further, the catalyst is a Grubbs catalyst, and its addition amount is 0.001% - 90% of the mass of the polyolefin-based polymer matrix monomer.

[0014] Further, the heating polymerization temperature is 20 - 100 °C, and the reaction completion time is within 5 minutes.

[0015] And a polyolefin-based flexible solar-driven interfacial evaporator prepared by the above preparation method.

[0016] The third technical solution of this application discloses the application of the above polyolefin-based flexible solar-driven interfacial evaporator in seawater desalination, wastewater treatment, or the concentration and extraction of water-soluble lithium, magnesium, sodium, and rare earth salts.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The polyolefin-based flexible solar-driven interfacial evaporator prepared in this application can float on the water surface by itself and has good heat insulation effect.

[0019] (2) This application can quickly prepare a large-area solar-driven interfacial evaporator.

[0020] (3) The polyolefin-based flexible solar-driven interfacial evaporator prepared in this application has excellent water evaporation rate and efficiency, and has obvious effects in seawater desalination and wastewater treatment.

[0021] (4) The polyolefin-based flexible solar-driven interfacial evaporator prepared in this application can be used for the concentration and separation extraction of water-soluble lithium, magnesium, sodium, and rare earth salts. Description of the Drawings

[0022] Figure 1 is a physical diagram of a large-area integrated polyolefin-based flexible solar-driven interfacial evaporator;

[0023] Figure 2 is an absorption diagram of the sunlight spectrum by the aniline trimer-based solar-driven interfacial evaporator capped with amine groups;

[0024] Figure 3 is a temperature change curve detected by an infrared camera of the aniline trimer-based and activated carbon-based solar-driven interfacial evaporator under 1 sun intensity;

[0025] Figure 4 is a water evaporation rate diagram of the aniline trimer-based solar-driven interfacial evaporator in different concentrations of salt water;

[0026] Figure 5 is the stability test result of the aniline trimer-based solar-driven interfacial evaporator;

[0027] Figure 6 For the common Zn 2+ , Cd 2+ , Cr 3+ Comparison results of the effects before and after wastewater treatment;

[0028] Figure 7 For the mass change results of the corresponding crystals obtained by separating and treating magnesium chloride, sodium chloride, and lithium chloride solutions with an amine-terminated aniline trimer solar-driven interfacial evaporator;

[0029] Figure 8 For the ion ratios in the mother liquor after treating the mixed solution of magnesium chloride and lithium chloride with an amine-terminated aniline trimer solar-driven interfacial evaporator;

[0030] Figure 9 For the outdoor verification experimental result diagram of an amine-terminated aniline trimer solar-driven interfacial evaporator. Detailed implementation manners

[0031] The present invention will be specifically described below in conjunction with embodiments to facilitate the understanding of those skilled in the art of the present invention. It is necessary to specifically point out here that the embodiments are only used to further illustrate the present invention and should not be construed as limiting the protection scope of the present invention. Those skilled in the art, based on the above-mentioned invention content, make non-essential improvements and adjustments to the present invention, which should still fall within the protection scope of the present invention. At the same time, for the raw materials not described in detail, they are all commercially available products; for the process steps or preparation methods not mentioned in detail, they are all process steps or preparation methods known to those skilled in the art.

[0032] Example 1 Preparation of a polyolefin-based flexible solar-driven interfacial evaporator

[0033] Using amine-terminated aniline trimer (ACAT) as the photothermal conversion material to prepare a low-cost, high-efficiency, large-area integrated flexible solar-driven interfacial evaporator, the specific steps are as follows:

[0034] Preparation of sodium chloride template: Take 3.40 g of NaCl and 0.58 g of ACAT and spread them flat in a polytetrafluoroethylene mold (30x30x5 mm), then place the mold in a sealed container filled with saturated potassium sulfate solution for 4 h. After the template is cured, take it out and dry the excess moisture for standby.

[0035] Preparation of Porous Polymer Foam: Weigh 2.00 g of dicyclopentadiene and 0.09 g of 5-ethylidene-2-norbornene into a 100 mL beaker, then add 0.55 g of cyclooctene and mix well. Dissolve 1.8 mg of Grubbs second-generation catalyst in 0.5 mL of cyclohexylbenzene solution and add it to the above mixture. Then, drop the mixture into the sodium chloride template in the previous step and heat and polymerize it at 50 °C. After taking it out of the mold, ultrasonically clean the sodium chloride in the template and dry it to obtain an ACAT-based solar-driven interfacial evaporator.

[0036] The physical object obtained by its preparation is as Figure 1 shown.

[0037] Example 2 Preparation of Polyolefin-Based Flexible Solar-Driven Interfacial Evaporator

[0038] Using carbon materials as photothermal conversion materials to prepare low-cost, high-efficiency, large-area integrated polyolefin-based flexible solar-driven interfacial evaporators. The specific steps are as follows:

[0039] Preparation of Sodium Chloride Template: Take 3.40 g of NaCl and 0.58 g of activated carbon and spread them flat in a polytetrafluoroethylene mold (30x30x5 mm). Then, place the mold in a sealed container filled with saturated potassium sulfate solution for 3 h. After the template is cured, take it out and dry the excess moisture for standby.

[0040] Preparation of Porous Polymer Foam: Weigh 2.00 g of dicyclopentadiene and 0.09 g of 5-ethylidene-2-norbornene into a 100 mL beaker, then add 0.55 g of cyclooctene and mix well. Dissolve 1.8 mg of Grubbs second-generation catalyst in 0.5 mL of cyclohexylbenzene solution and add it to the above mixture. Then, drop the mixture into the sodium chloride template in the previous step and heat and polymerize it at 50 °C. After taking it out of the mold, ultrasonically clean the sodium chloride in the template and dry it to obtain an activated carbon-based solar-driven interfacial evaporator.

[0041] Example 3 Sunlight Absorption and Photothermal Conversion Experiment

[0042] The ACAT-based solar-driven interfacial evaporator prepared in Example 1 was measured by a solid ultraviolet-visible-near-infrared spectrometer with an integrating sphere, and its light absorption efficiency was above 98%, as Figure 2 shown. The surface temperatures of the ACAT-based solar-driven interfacial evaporator prepared in Example 1 and the carbon-based solar-driven interfacial evaporator prepared in Example 2 were measured under 1 standard sunlight irradiation for 60 min, as Figure 3As shown, the evaporators all heat up rapidly within 1 minute. After 10 minutes of illumination, the surface temperature of the samples begins to stabilize. The surface temperature of the ACAT-based solar-driven interfacial evaporator is 71.4 °C after 30 minutes of illumination, and the surface temperature of the carbon-based solar-driven interfacial evaporator is 62.1 °C after 30 minutes of illumination.

[0043] Example 4 Seawater Evaporation Experiment

[0044] Seawater desalination is an important way to obtain fresh water. The ACAT-based solar-driven interfacial evaporator prepared in Example 1 was placed in salt water with different concentrations and irradiated under 1 standard sunlight to measure the water evaporation rate. The results are as Figure 4 shown. In pure water with a salt content of 0 wt%, the water evaporation rate of the evaporator is 3.67 kg . m -2. h -1 . The average salinity of global seawater is 3.5%. At this concentration, the water evaporation rate of the ACAT-based solar-driven interfacial evaporator is 3.44 kg m -2 h -1 . As the salt concentration in the solution gradually increases, the water evaporation rate gradually decreases. In salt water with a relatively high salt content (20 wt%), the water evaporation rate is still 2.74 kg . m -2. h -1 , and this data still exceeds most of the current solar evaporators.

[0045] The ACAT-based solar-driven interfacial evaporator has excellent stability. Ten cyclic water evaporation tests were carried out in simulated seawater with a NaCl concentration of 3.5 wt%. The water evaporation rate of the evaporator was basically stable at about 3.27 kg m -2 h -1 ; and after 6 months, the water evaporation rate of the solar interfacial evaporator in salt water with a NaCl concentration of 3.5 wt% is 3.21 kg m -2 h -1 . Compared with the initial water evaporation rate of the evaporator, this is a 6.63% decrease. In 10 wt% salt water, the water evaporation rate decreased by 4.22%, and in 20 wt% salt water, the water evaporation rate basically did not change, indicating that the solar interfacial evaporator has excellent stability (as Figure 5 shown).

[0046] Example 5 Wastewater Treatment Experiment

[0047] Water pollution is one of the important reasons for the shortage of fresh water resources on Earth. Among them, dye wastewater and heavy metal wastewater are relatively common. The ACAT-based solar-driven interfacial evaporator prepared in Example 1 was placed in Zn 2+ 、Cr3+ , Cd 2+ and other common heavy metal wastewaters and their mixed solutions, and under 1 standard sunlight irradiation, the water evaporation rate and ion concentrations before and after treatment were measured. The water evaporation rate of the evaporator in the above wastewater solutions was maintained at 3.3 kg . m -2. h -1 or so. For Zn 2+ , Cr 3+ , Cd 2+ ion concentrations were measured by inductively coupled plasma optical emission spectrometer (ICP-OES), as Figure 6 shown. After purification, the concentrations of Zn 2+ , Cd 2+ , Cr 3 + ions decreased sharply by 3 - 4 orders of magnitude compared with the initial concentrations, and the removal rates of the above ions were all above 99%, showing excellent heavy metal wastewater treatment ability.

[0048] Example 6 Sodium, Magnesium, and Lithium Ion Separation Experiment

[0049] Currently, 60% of lithium products in the industry come from salt lakes, but the lithium concentration in salt lakes is only between 0.025% - 0.16%. Therefore, to extract lithium from salt lakes, it is necessary to first concentrate the salt lake water and then use the differences in the properties of various ions to stepwise extract resources such as lithium, boron, and bromine in the brine. At the same time, since salt lakes are usually located in deserts or semi-desertified areas with little rainfall and large evaporation, and the industrial foundation is relatively weak, only the natural evaporation method can be used for concentration, but this process is very time-consuming, often taking 12 - 18 months.

[0050] The ACAT-based solar-driven interfacial evaporator prepared in Example 1 was placed in three solutions of saturated sodium chloride, saturated magnesium chloride, and saturated lithium chloride, and irradiated under 1 sunlight for 12 h. Solid sodium chloride and magnesium chloride were successively collected in the evaporator and its surrounding area, while lithium chloride was always enriched in the brine. The separation of lithium chloride from other metal ions can be achieved. The relationship between the weights of the precipitated sodium chloride, magnesium chloride, and lithium chloride solids and the illumination time is as Figure 7 shown, and no solid was collected from the saturated lithium chloride solution throughout the process. In the first 5 h of illumination, more solid was collected from the saturated sodium chloride solution than from the precipitated saturated magnesium chloride, but after 5 h of illumination, the rate of collecting magnesium chloride solid was greater than that of sodium chloride solid.

[0051] An aqueous solution close to saturation was prepared with magnesium chloride and lithium chloride, and the ACAT-based solar-driven interfacial evaporator was placed therein. The change in the concentration ratio of magnesium to lithium ions in the brine was measured by ICP-OES as Figure 8 shown. In the first 10 hours, Mg2+ / Li + The mass concentration ratio of / Li rapidly decreases from 5.0:1 to 3.2:1. After that, the rate of change gradually decreases and reaches 2.6:1 after 30 hours. If a solar photothermal conversion water evaporator is used, it can not only accelerate the evaporation of water and shorten the time for concentrating salt lake water, but also is expected to selectively separate lithium and improve the efficiency of lithium extraction from salt lakes.

[0052] Example 7: Water Evaporation Performance Test under Natural Light

[0053] The ACAT-based solar-driven interfacial evaporator prepared in Example 1 was placed under natural light irradiation to test its water evaporation performance. As Figure 9 shown, from 9:30 am to 5:30 pm in the experiment, the water evaporation rate, solar flux, ambient humidity, and ambient temperature of the evaporator were recorded every hour. The water evaporation rate and solar flux of the ACAT-based solar-driven interfacial evaporator were the highest in the interval of 12:30 - 13:30. The highest solar flux was 0.807 kw m -2 , at this time the ambient temperature was 45.2 °C, the ambient humidity was 22%, and the highest evaporation rate was 3.33 kgm -2 h -1 , and this water evaporation rate is close to the water evaporation rate tested in the laboratory (brine with a salinity of 3.5%: 3.43 kgm -2 h -1 ).

[0054] Finally, it should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combinations of these technical features do not conflict, they should all be considered as the scope described in this specification.

[0055] Specific examples are used in this article to elaborate on the principles and implementation methods of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A polyolefin-based flexible solar-driven interface evaporator, characterized in that: It comprises a photothermal conversion material and a polyolefin-based polymer matrix, wherein the photothermal conversion material is uniformly dispersed in the polyolefin-based polymer matrix.

2. The polyolefin-based flexible solar-driven interface evaporator according to claim 1, characterized in that: The photothermal conversion material is one or more of aniline oligomers, polyaniline, polypyrrole, polydopamine, carbon materials or nano-metal particles having a photothermal conversion effect.

3. The polyolefin-based flexible solar-driven interface evaporator according to claim 2, characterized in that: The aniline oligomer is an aniline trimer terminated by an amine group.

4. The polyolefin-based flexible solar-driven interface evaporator according to claim 1, characterized in that: The polyolefin-based polymer matrix is ​​obtained by ring-opening polymerization of one or more monomers selected from dicyclopentadiene, cyclooctene and methyldicyclopentadiene through olefin metathesis reaction.

5. A method for preparing a polyolefin-based flexible solar-driven interface evaporator according to any one of claims 1 to 4, characterized in that: The salt template method is adopted to disperse the photothermal conversion material in the sodium chloride template, and then the polyolefin-based polymer matrix monomer containing the catalyst is poured into the gap of the sodium chloride template, and then the sodium chloride is removed by washing after heating and polymerization.

6. The preparation method according to claim 5, characterized in that: The molar ratio of the photothermal conversion material to the polyolefin-based polymer matrix monomer is 0.1%-100%.

7. The preparation method according to claim 5, characterized in that: The catalyst is a Grubbs catalyst, and the added amount thereof is 0.001% to 90% of the mass of the polyolefin-based polymer matrix monomer.

8. The preparation method according to claim 5, characterized in that: The heating polymerization temperature is 20-100°C.

9. A polyolefin-based flexible solar-driven interface evaporator prepared according to any one of the preparation methods of claims 5-8.

10. Use of the polyolefin-based flexible solar-driven interface evaporator according to any one of claims 1 to 4 and claim 9 in seawater desalination, wastewater treatment or concentration and extraction of water-soluble lithium, magnesium, sodium and rare earth salts.

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