PHOTOTHERMAL SEAWATER DESALINATION MATERIAL WITH MULTI-STAGE STRUCTURE AND PREPARATION METHOD AND USE THEREOF

Abstract

A photothermal seawater desalination material with a multi-stage structure and a preparation method and application thereof. The photothermal seawater desalination material includes a light-absorbing material having a C/WO3-x heterogeneous junction, which is obtained by depositing a nano-C material on a porous metal foam material using plasma enhanced chemical vapor deposition (PECVD), and then synthesizing WO3-x with plasma resonance effect by a solvothermal reaction.

Claims

1. A photothermal seawater desalination material with a multi-stage structure, comprising a light-absorbing material, wherein the light-absorbing material is a C/WO3-x heterogeneous junction obtained by depositing a nano-C material on a porous metal foam material using plasma enhanced chemical vapor deposition (PECVD), and then synthesizing WO3-x with plasma resonance effect by a solvothermal reaction.

2. The photothermal seawater desalination material with a multi-stage structure according to claim 1, wherein the porous metal foam material is a porous metal material of Ti, Ni or Cu.

3. A method for preparing the photothermal seawater desalination material with a multi-stage structure according to claim 1, comprising: depositing a nano-C material on a surface of a pretreated porous metal foam material by PECVD: placing the pretreated porous metal foam material in a cavity of a tubular furnace, using CH4 as a C source, H2 as a carrier gas and Ar as a protective gas, and carrying out a reaction at 800-1000° C. with a reaction time and a gas flow velocity of CH4 and H2 being controlled to obtain a porous material coated with the nano-C material, wherein the nano-C material has a sheet-like structure with a nano-scale thickness; placing the porous material coated with the nano-C material obtained above in a reaction kettle, adding an organic solution of WCl6 to the reaction kettle, and carrying out a reaction at a constant temperature of 160-200° C. for 16 h, followed by cooling naturally, washing and drying to obtain the C/WO3-x light-absorbing material.

4. The method according to claim 3, wherein a pretreatment to the porous metal foam material includes an ultrasonic washing procedure with 3 mol HCl, anhydrous ethanol and deionized seawater in sequence.

5. The method according to claim 3, wherein the reaction time is 5-10 min, and the gas flow velocity of CH4 is 10-20 sccm and the gas flow velocity of H2 is 100-200 sccm.

6. The method according to claim 3, wherein a solvent used for the organic solution of WCl6 is isopropyl alcohol or ethanol, and a concentration of the solution is 1.25-5 g/L.

7. The method according to claim 3, wherein the drying is carried out at 45-55° C. for 5-7 hr.

8. The method according to claim 3, wherein the porous metal foam material is a porous metal material of Ti, Ni or Cu.

9. A method for using a photothermal seawater desalination material with a multi-stage structure, comprising: combining a photothermal seawater desalination material with a polyethylene foam and cotton to form a light absorber, placing the light absorber in a polytetrafluoroethylene container loaded with seawater, then placing the polytetrafluoroethylene container on a balance and irradiating with a simulated light source, and recording changes in mass at different times to calculate a seawater evaporation rate and further obtain a photothermal conversion efficiency, wherein the polystyrene foam is used to insulate heat and the cotton is used to transport moisture.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are, therefore, not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. It is emphasized that the figures are not necessarily to scale and certain features and certain views of the figures can be shown exaggerated in scale or in schematic for clarity and/or conciseness.

[0010] FIG. 1a and FIG. 1b are the SEM image of contact angle and surface image after illumination for 10 h of the light absorber in Example 5 of the present disclosure, respectively.

[0011] FIG. 2 is a graph of the evaporation rate of the light absorber in Example 5 of the present disclosure.

[0012] FIG. 3a and FIG. 3b are the morphology scanning images of the light absorber in Example 5 of the present disclosure with magnification of 500 times and 350,000 times, respectively.

[0013] FIG. 4 is a XRD diffraction pattern of the light absorber of the present disclosure.

DETAILED DESCRIPTION

[0014] In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” The phrase “consisting essentially of” means that the described/claimed composition does not include any other components that will materially alter its properties by any more than 5% of that property, and in any case does not include any other component to a level greater than 3 mass %.

[0015] Unless otherwise indicated, all numerical values are “about” or “approximately” the indicated value, meaning the values take into account experimental error, machine tolerances and other variations that would be expected by a person having ordinary skill in the art. It should also be understood that the precise numerical values used in the specification and claims constitute specific embodiments. Efforts have been made to ensure the accuracy of the data in the examples. However, it should be understood that any measured data inherently contains a certain level of error due to the limitation of the technique and/or equipment used for making the measurement.

[0016] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims. Each of the inventions will now be described in greater detail below, including specific embodiments, versions and examples, but the inventions are not limited to these embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the inventions, when the information in this disclosure is combined with publicly available information and technology.

[0017] A photothermal seawater desalination material with a multi-stage structure on the basis of ensuring corrosion resistance and methods for making the same are provided herein. The photothermal seawater desalination material of the present disclosure can be hydrophobic as a whole. The light absorber of a C/WO3-x heterogeneous junction can have has a strong light absorption ability and photothermal conversion capacity, which is beneficial to convert the absorbed light energy into heat energy for seawater desalination in time. During seawater evaporation, the moisture may not reach the surface of the light absorber to cause salt accumulation, and thus the material has a long service life.

[0018] In one or more embodiments, the photothermal seawater desalination material with a multi-stage structure can include a light-absorbing material, wherein the light-absorbing material is a C/WO3-x heterogeneous junction obtained by depositing a nano-C material on a porous metal foam material by plasma enhanced chemical vapor deposition (PECVD), and then synthesizing WO3-x with plasma resonance effect by a solvothermal reaction. The porous metal foam material can be Ti, Ni or Cu.

[0019] The present disclosure also provides a preparation method of the material. In a first step, a nano-C material can be deposited on a surface of a pretreated porous metal foam material by PECVD. The pretreated porous metal foam material can be placed in a cavity of a tubular furnace, using CH4 as a C source, H2 as a carrier gas and Ar as a protective gas, and reacted at 800-1000° C. with a reaction time and a gas flow velocity of CH4 and H2 being controlled to obtain a porous material coated with the nano-C material. The term “nano-C material”, as used herein, refers to a C material having a sheet-like structure with a nano-scale thickness. In a subsequent step or step 2, a C/WO3-x light-absorbing material can be prepared by a solvothermal reaction. The porous material coated with the nano-C material obtained above can be placed in a reaction kettle. An organic solution of WCl.sub.6 can be added to the reaction kettle, and reacted at a constant temperature of 160-200° C. for 16 hr, followed by cooling naturally, washing and drying to obtain the C/WO3-x light-absorbing material.

[0020] In some embodiments, in step 1), the porous metal foam material can be pretreated using an ultrasonic washing procedure with 3 mol HCl anhydrous ethanol and deionized seawater in sequence.

[0021] In some embodiments, in step 1), the reaction time is 5-10 min, and the gas flow velocity of CH4 and H2 is (10-20) sccm and (100-200) sccm, respectively.

[0022] In some embodiments, in step 2), a solvent used for the organic solution of WC.sub.6 is isopropyl alcohol or ethanol, and a concentration of the solution is 1.25-5 g/L.

[0023] In some embodiments, in step 2), the drying is carried out at 45-55° C. for 5-7 hr.

[0024] The photothermal seawater desalination material with a multi-stage structure of the present disclosure can be used in seawater desalination. For example, the photothermal seawater desalination material provided herein can be used by combining the photothermal seawater desalination material with a polyethylene foam and cotton to form a light absorber, placing the light absorber in a polytetrafluoroethylene container loaded with seawater, then placing the polytetrafluoroethylene container on a balance and irradiating with a simulated light source, and recording changes in mass at different times to calculate a seawater evaporation rate and further to obtain a photothermal conversion efficiency, wherein the polystyrene foam is used to insulate heat and the cotton is used to transport seawater.

[0025] In the photothermal seawater desalination material provided herein, the corrosion-resistant and hydrophobic porous metal foam material can be used as a support. The coated carbon material can be hydrophobic, so the material can be hydrophobic as a whole. Moreover, the light absorber of C/WO3-x heterogeneous junction finally obtained has a strong light absorption ability and photothermal conversion capacity, which is beneficial to convert the absorbed light energy into heat energy for seawater desalination in time. During seawater evaporation, the seawater may not reach the surface of the light absorber to cause salt accumulation, and may not damage the material due to the salt accumulation, and thus the material has a long service life.

[0026] The porous material coated with C material can be synthesized by a deposition method. The light absorber can be synthesized by a one-step solvothermal method, thereby forming a multi-stage structure of foamed nickel, graphene and defective tungsten oxide. The present disclosure is simple in process, low in cost, and is suitable for a large-scale production, providing a reliable way to solve the global freshwater resource crisis.

[0027] The morphology of the light absorber described herein has a three-dimensionally interconnected pore structure, which is beneficial to the transportation of moisture and escape of steam. The testing result shows that the solar utilization efficiency of the synthesized material is up to 94%. From the change in balance reading after irradiation at one solar intensity for one hour, it is calculated that the seawater evaporation rate of the light absorber is as high as 2.1 kg m−2 h−1, which is about 4.78 times that of pure seawater, and the photothermal conversion efficiency is as high as 85%.

EXAMPLES

[0028] The technical solution of the present disclosure will be further illustrated by specific examples below. Although the following examples are directed to specific embodiments, they are not to be viewed as limiting in any specific respect. In each example, a porous nickel foam material was used as the substrate. The porous nickel foam material had a size of 2×2 cm2, a pore diameter of 100-400 μm and a porosity of 96-98%.

Example 1

[0029] Step 1): Pretreatment to Porous Metal Material

[0030] The porous foam Ni material was ultrasonically washed with 3 M HCl, anhydrous ethanol and deionized seawater for 5 min to activate the surface thereof, which was beneficial to better deposition of nano-C materials.

[0031] Step 2): Deposition of Nano-C Material by PECVD Method

[0032] The pretreated porous foam Ni material was placed in a cavity of a tubular furnace. CH4 was used as a C source, H2 as a carrier gas and Ar as a protective gas, and the gas flow velocity of CH4 and H2 were 15 sccm and 150 sccm, respectively. The materials above were kept at 1000° C. for 5 min, and then naturally cooled to obtain a porous foam Ni material coated with nano-C material.

[0033] Step 3): Preparation of C/WO3-x Light-Absorbing Material by Solvothermal Reaction

[0034] The porous foam Ni material coated with nano-C material obtained above was placed in a 50 mL reaction kettle. 0.05 g of WCl6 powder was weighed and dissolved in 40 mL of isopropanol, stirred with ultrasonic for 1 h, and poured into the reaction kettle after a uniform and stable solution was formed. The materials above were kept at 180° C. for 16 h. After cooling naturally, the porous Ni material was taken out, then washed with anhydrous ethanol and deionized water, and dried in an oven at 50° C. for 6 h to obtain a C/WO3-x light-absorbing material.

[0035] Testing results showed that the light-absorbing material in Example 1 had a solar utilization efficiency as high as 85%, a seawater evaporation rate as high as 1.85 kg m−2 h−1, which was about 4.02 times that of pure seawater, and a photothermal conversion efficiency as high as 77%.

Example 2

[0036] Example 2 was different from Example 1 only in that: the temperature kept in step 3) was changed to 200° C. The rest of the processes and parameters were the same as those of Example 1.

[0037] Testing results showed that the light-absorbing material in Example 2 had a solar utilization efficiency as high as 81%, a seawater evaporation rate as high as 1.78 kg m−2 h−1, which was about 3.87 times that of pure seawater, and a photothermal conversion efficiency as high as 73%.

Example 3

[0038] Example 3 was different from Example 1 only in that: the temperature kept in step 3) was changed to 160° C. The rest of the processes and parameters were the same as those of Example 1.

[0039] Testing results showed that the light-absorbing material in Example 3 had a solar utilization efficiency as high as 82%, a seawater evaporation rate as high as 1.8 kg m−2 h−1, which was about 3.91 times that of pure seawater, and a photothermal conversion efficiency as high as 74%.

[0040] By comparing Examples 1-3, it may be seen that under other conditions unchanged, the effect of solvothermal reaction temperature on the performances of the final material cannot be ignored. An excessively low or high temperature will cause a decrease in the light absorption performance, and thus a decrease in the seawater evaporation rate.

Example 4

[0041] Example 4 was different from Example 1 in that: in step 2), the gas flow velocity of CH4 and H2 were 10 sccm and 100 sccm, respectively, and the temperature was kept at 800° C. for 10 min; in step 3), the amount of WCl6 was changed to 0.2 g, and the drying was changed to be conducted at 45° C. for 7 h. The rest of the processes and parameters were the same as those of Example 1.

[0042] Testing results showed that the light-absorbing material in Example 4 had a solar utilization efficiency as high as 90%, a seawater evaporation rate as high as 2.0 kg m−2 h−1, which was about 4.3 times that of pure seawater, and a photothermal conversion efficiency as high as 83%.

Example 5

[0043] Example 5 was different from Example 1 in that: in step 2), the gas flow velocity of CH4 and H2 were 20 sccm and 200 sccm, respectively, and the temperature was kept at 900° C. for 8 min; in step 3), the amount of WC16 was changed to 0.125 g, and the drying was changed to be conducted at 55° C. for 5 h. The rest of the processes and parameters were the same as those of Example 1. The performances of the obtained light absorber are shown in FIG. 1a, FIG. 1b, FIG. 2, FIG. 3a and FIG. 3b.

[0044] Testing results showed that the light-absorbing material in Example 5 had a solar utilization efficiency as high as 94%, a seawater evaporation rate as high as 2.1 kg m−2 h−1, which was about 4.78 times that of pure seawater, and a photothermal conversion efficiency as high as 85%.

Example 6

[0045] Example 6 was different from Example 5 only in that: the amount of WCl6 in step 3) was changed to 0.2 g. The rest of the processes and parameters were the same as those of Example 5.

[0046] Testing results showed that the light-absorbing material in Example 6 had a solar utilization efficiency as high as 89%, a seawater evaporation rate as high as 1.95 kg m−2 h−1, which was about 4.24 times that of pure seawater, and a photothermal conversion efficiency as high as 81%.

[0047] By comparing Examples 5 and 6, it is found that an excessive addition of WCl6 will adversely affect the light absorption performance in turn, under other conditions unchanged.

Example 7

[0048] Example 7 was different from Example 5 only in that: the isopropanol in step 3) was changed to anhydrous ethanol. The rest of the processes and parameters were the same as those of Example 5.

[0049] Testing results showed that the light-absorbing material in Example 7 had a solar utilization efficiency as high as 89%, a seawater evaporation rate as high as 1.96 kg m−2 h−1, which was about 4.26 times that of pure seawater, and a photothermal conversion efficiency as high as 81%.

[0050] By comparing the test results of Examples 7 and 5, it is found that the choice of solvent in the solvothermal step is important. Compared with anhydrous ethanol, isopropanol is more beneficial to the test results.

[0051] FIG. 1a and FIG. 1b are SEM images of contact angle and surface image after illumination for 10 hr of the light absorber in Example 5 of the present disclosure. FIG. 2 is a graph of the evaporation rate of the light absorber in Example 5 of the present disclosure. FIG. 3a and FIG. 3b are the morphology scanning images of the light absorber in Example 5 of the present disclosure with magnification of 500 times and 350,000 times, respectively. FIG. 4 is a XRD diffraction pattern of the light absorber of the present disclosure.

[0052] From FIG. 1a and FIG. 1b, that is, the SEM image of contact angle and the surface image after 10 h of illumination of the light absorber in Example 5 of the present disclosure, it may be seen that the light absorber of the present disclosure is hydrophobic on surface, and during seawater evaporation, the moisture will not reach the surface of the light absorber to cause salt accumulation.

[0053] It may be seen from FIG. 2 of an evaporation rate curve of the light absorber in Example 5 of the present disclosure that the synthesized material has a solar utilization efficiency as high as 94%, a seawater evaporation rate as high as 2.1 kg m−2 h−1, which is about 4.78 times that of pure seawater, and a photothermal conversion efficiency as high as 85%.

[0054] It may be seen from the morphology scanning images of the light absorber in Example 5 of the present disclosure with magnification of 500 times and 350,000 times shown in FIG. 3 that the synthesized material has a three-dimensionally interconnected pore structure, which is beneficial to the transportation of moisture and the escape of steam.

[0055] It may be seen from the diffraction diagram shown in FIG. 4 that the synthesized material contains the components of carbon and tungsten oxide, indicating that the technical solution of the present disclosure is feasible.

[0056] The above is only specific embodiments of the present disclosure, and the protection scope of the present disclosure is not limited thereto. Any modification or substitution made without creative work should be included within the scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the scope of protection defined by the claims that follow.