Preparation method of efficient photo-thermal conversion nanofiber membrane for solar seawater desalination

Abstract

The invention discloses a preparation method of an efficient photo-thermal conversion black body membrane for solar seawater desalination, and relates to the technical field of solar seawater desalination. The preparation method comprises the following steps: (1) preparing a spinning solution; the preparation method comprises the following steps: dispersing a certain amount of polyacrylonitrile, zinc acetate, carbon nanotubes and carbon black in N-N dimethylformamide, and stirring to obtain a polyacrylonitrile / zinc acetate / carbon black / carbon nanotube mixed solution; and (2) spinning preparation. And spinning the spinning solution by using an electrostatic spinning device under a certain spinning condition to obtain the nanofiber membrane. And (3) growing the nanowire. The nanofiber membrane is subjected to heat treatment at a certain temperature, then the nanofiber membrane subjected to heat treatment is completely soaked in the growth solution, and hydrothermal growth is performed for enough time at a certain temperature. The efficient photo-thermal conversion nanofiber membrane is obtained. The high-efficiency photo-thermal conversion nanofiber membrane is prepared by combining an electrostatic spinning technology and a hydrothermal growth method, the solar energy absorption efficiency is high, the solar energy water evaporation rate is high, and surface salt crystals are few.

Description

Technical Field

[0001] The invention belongs to the technical field of solar water distillation, and in particular relates to a method for preparing a high-efficiency photothermal conversion nanofiber membrane for solar seawater desalination. Background Art

[0002] With the rapid development of industry and the rapid growth of population, the shortage of drinking water resources is becoming a very serious problem in many areas. In terms of water resources, more than 70% of the earth's area is covered by water, of which only 2.5% is fresh water. Purifying fresh water from seawater or wastewater provides a solution to the above global problems. At the same time, sustainable technologies and renewable energy sources need to be considered to reduce the burden on the environment. Compared with various clean energy sources such as wind energy, nuclear energy, tidal energy, biomass energy, geothermal energy, etc., solar energy is the most abundant and convenient energy on earth. In recent years, solar water distillation technology has received widespread attention in dealing with environmental problems such as seawater desalination and wastewater purification. This technology aims to collect solar energy and convert it into thermal energy, and collect fresh water by using thermal energy to heat water bodies to produce water vapor.

[0003] At present, most research institutes use solar interfacial heating methods. The photothermal conversion effect only acts on the interface between the solution and the air, rather than the entire water body, which effectively improves the efficiency of solar water evaporation. However, the solar collector used has a complex structure, and the absorption band is mostly limited to visible light. The absorption rate of the ultraviolet and infrared bands that contain huge energy is not high. As the solar water distillation process proceeds, a large amount of crystalline salt precipitates on the surface of the solar collector, limiting the light absorption performance, resulting in a decrease in solar absorption efficiency and photothermal conversion efficiency, thereby affecting the efficiency of solar seawater desalination. At the same time, cleaning the large amount of salt crystals on the surface of the solar collector will also cause a waste of water resources and cumbersome operating procedures. Some collectors cannot even be reused many times.

[0004] This patent aims to broaden the absorption range of the solar spectrum, reduce surface salt crystallization, and provide a method for preparing an efficient photothermal conversion nanofiber membrane for solar water distillation. Summary of the invention

[0005] The problem to be solved by the present invention is to provide a method for preparing an efficient photothermal conversion nanofiber membrane for solar water distillation, achieve broad-spectrum absorption of solar energy, and solve the problem of salt crystallization on the membrane surface.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] A method for preparing a high-efficiency photothermal conversion nanofiber membrane for solar water distillation, the preparation process comprising:

[0008] S1. Spinning solution preparation: Disperse polyacrylonitrile and zinc acetate in NN dimethylformamide, with the mass fraction of polyacrylonitrile being 10-20% and the mass fraction of zinc acetate being 2-6%, and stir to obtain a polyacrylonitrile / zinc acetate mixed solution. Add carbon nanotubes and carbon black to the mixed solution, with the mass ratio of the two being 1:1.5-3, to obtain a mixed solution of polyacrylonitrile / zinc acetate / carbon black / carbon nanotubes.

[0009] S2. Spinning preparation: Under the conditions of a high voltage electric field of 9kV to 18kV, a spinning distance of 5cm to 17cm and a syringe pump propulsion speed of 0.1mL / h to 5mL / h, the spinning solution is spun using an electrospinning device, and then a drum collection method with a collection speed of 100 to 300rpm is used to obtain a nanofiber membrane.

[0010] S3, nanowire growth: Place the nanofiber membrane in an oven at 100-150°C for heat treatment. Then completely immerse the heat-treated nanofiber membrane in a growth solution, in which the mass ratio of hexamethylenetetramine to zinc nitrate hexahydrate is 1:2-4, and hydrothermally grow at a certain temperature for 2-4 hours. After taking it out, put it in distilled water, wash the zinc oxide floating on the surface, and dry it at low temperature.

[0011] In one example of the present invention, the polymer used in S1 is polyacrylonitrile.

[0012] In one embodiment of the present invention, the spinning method used in S2 is electrospinning.

[0013] In one example of the present invention, the growth time used in S3 is 2 hours.

[0014] The present invention adopts the electrostatic spinning technology and the hydrothermal growth method to prepare the high-efficiency light-heat conversion nanofiber membrane, which has high solar energy absorption efficiency, fast solar energy water evaporation rate and less surface salt crystallization. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the preparation process in the present invention.

[0016] Figure 2 This is the ultraviolet-visible-near-infrared spectrum of the high-efficiency light-to-heat conversion nanofiber membrane in the present invention.

[0017] Figure 3 The high-efficiency light-to-heat conversion nanofiber membrane in the present invention is 1kW / m 2 Curve of water evaporation mass changing with time after irradiation at the same light intensity for 60 minutes.

[0018] Figure 4 This is the surface of the high-efficiency photothermal conversion nanofiber membrane in the present invention after simulating seawater desalination for 24 hours. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the examples of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Embodiment 1:

[0021] See also Figure 1 The present invention discloses a method for preparing a high-efficiency photothermal conversion nanofiber membrane for solar water distillation, comprising the following steps:

[0022] (1) Spinning solution preparation

[0023] Polyacrylonitrile and zinc acetate are dispersed in NN dimethylformamide, the mass fraction of polyacrylonitrile is 10%, the mass fraction of zinc acetate is 2%, and the polyacrylonitrile / zinc acetate mixed solution is obtained by stirring. Carbon nanotubes and carbon black are added to the mixed solution, and the mass ratio of the two is 1:1.5-3 to obtain a mixed solution of polyacrylonitrile / zinc acetate / carbon black / carbon nanotubes.

[0024] (2) Spinning preparation

[0025] Under the conditions of a high voltage electric field of 9 kV, a spinning distance of 10 cm and a syringe pump propulsion speed of 0.1 mL / h, the spinning solution was spun using an electrospinning device, and then a drum collection method with a collection speed of 100 rpm was used to obtain a nanofiber membrane.

[0026] (3) Nanowire Growth

[0027] The nanofiber membrane was placed in an oven at 100°C for heat treatment. The heat-treated nanofiber membrane was then completely immersed in a growth solution in which the mass ratio of hexamethylenetetramine to zinc nitrate hexahydrate was 1:2, and hydrothermally grown at a certain temperature for 2 hours. After being taken out, it was placed in distilled water, the zinc oxide floating on the surface was washed, and then dried at low temperature.

[0028] Comparative Example 1:

[0029] (1) Spinning solution preparation

[0030] Polyacrylonitrile is dispersed in N,N-dimethylformamide with a mass fraction of 10% to obtain a polyacrylonitrile solution.

[0031] (2) Spinning preparation

[0032] Under the conditions of a high voltage electric field of 9 kV, a spinning distance of 10 cm and a syringe pump propulsion speed of 0.1 mL / h, the spinning solution was spun using an electrospinning device, and then a drum collection method with a collection speed of 100 rpm was used to obtain a nanofiber membrane.

[0033] Experimental results: Figure 2 As shown, according to the samples in Example 1 and Comparative Example 1, the light absorption performance of Example 1 is stronger.

[0034] The above description is only a preferred embodiment of the present invention, which is only used to help understand the method of the present invention and its core essence, but the protection scope of the present invention is not limited thereto. For those skilled in the art in this technical field, equivalent replacement or change according to the technical solution and inventive concept of the present invention within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. In summary, the content of this specification should not be understood as limiting the present invention. The protection scope of the present invention is defined by the attached claims.

Claims

1. A method for preparing a highly efficient photothermal conversion nanofiber membrane for solar water distillation, characterized in that: The steps include: S1. Spinning solution preparation: Disperse polyacrylonitrile and zinc acetate in NN dimethylformamide, with the mass fraction of polyacrylonitrile being 10-20% and the mass fraction of zinc acetate being 2-6%, and stir to obtain a polyacrylonitrile / zinc acetate mixed solution. Add carbon nanotubes and carbon black to the mixed solution, with the mass ratio of the two being 1:1.5-3, to obtain a mixed solution of polyacrylonitrile / zinc acetate / carbon black / carbon nanotubes. S2. Spinning preparation: Under the conditions of a high voltage electric field of 9kV to 18kV, a spinning distance of 5cm to 17cm and a syringe pump propulsion speed of 0.1mL / h to 5mL / h, the spinning solution is spun using an electrospinning device, and then a drum collection method with a collection speed of 100 to 300rpm is used to obtain a nanofiber membrane. S3, nanowire growth: Place the nanofiber membrane in an oven at 100-150°C for heat treatment. Then completely immerse the heat-treated nanofiber membrane in a growth solution, in which the mass ratio of hexamethylenetetramine to zinc nitrate hexahydrate is 1:2-4, and hydrothermally grow at a certain temperature for 2-4 hours. After taking it out, put it in distilled water, wash the zinc oxide floating on the surface, and dry it at low temperature.

2. The method for preparing a highly efficient photothermal conversion nanofiber membrane for solar water distillation according to claim 1, characterized in that: The polymer used in S1 is polyacrylonitrile.

3. The method for preparing a highly efficient photothermal conversion nanofiber membrane for solar water distillation according to claim 1, characterized in that: The light absorbing material used in S1 is a mixture of carbon black and carbon nanotubes.

4. The method for preparing a highly efficient photothermal conversion nanofiber membrane for solar water distillation according to claim 1, characterized in that: The spinning method used in S2 is electrospinning.

5. The method for preparing a highly efficient photothermal conversion nanofiber membrane for solar water distillation according to claim 1, characterized in that: The growth time used in S3 is 2 to 4 hours.

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