阅读说明：本技术 一种高导热及传输水的复合薄膜材料及其制备方法和应用 (High-thermal-conductivity and water-transmission composite film material and preparation method and application thereof ) 是由 张帆 魏巍巍 于 2020-05-13 设计创作，主要内容包括：本发明公开了一种高导热及传输水的复合薄膜材料及其制备方法和应用,涉及材料工程技术领域,所述复合薄膜材料包含石墨烯和纤维素纳米纤维,通过将石墨烯和纤维素纳米纤维配置成混合溶液,然后超声分散、磁力搅拌均匀后抽滤并晾干成膜。本发明制备的复合薄膜材料具有丰富的亲水纳米孔道和紧密的石墨烯片层堆积,可以实现快速水传递和高热导率,可以快速的将光热转化所产生的热量传递给石墨烯层间的水纳米流体,从而加速水的蒸发。本发明的复合薄膜材料作为太阳能蒸发器应用时,在1倍太阳光的光强下,蒸发速率可以达到1.47kg m<Sup>-2</Sup>h<Sup>-1</Sup>,在3倍太阳光光强下其蒸发速率为4.51kg m<Sup>-2</Sup>h<Sup>-1</Sup>,而蒸发效率均保持在95％。(The invention discloses a composite film material with high heat conductivity and water transmission, a preparation method and application thereof, and relates to the technical field of material engineering. The composite film material prepared by the invention has rich hydrophilic nano-pore channels and compact graphene lamellar stack, can realize rapid water transfer and high thermal conductivity, and can rapidly transfer heat generated by photothermal conversion to water nanofluid among graphene layers, thereby accelerating the evaporation of water. The composite film material of the invention is madeWhen the solar evaporator is applied, the evaporation rate can reach 1.47kg m under the light intensity of 1 time of sunlight ‑2 h ‑1 The evaporation rate is 4.51kg m under 3 times of sunlight intensity ‑2 h ‑1 While the evaporation efficiency was kept at 95%.)

1. The composite film material with high heat conductivity and water transmission is characterized by comprising graphene and cellulose nanofibers.

2. The method for preparing the composite thin film material with high thermal conductivity and water transmission according to claim 1, wherein the method comprises the following steps:

step 1, preparing the graphene and the cellulose nano-fibers into a mixed solution;

step 2, ultrasonically dispersing the mixed solution in an ultrasonic cleaner, stirring by using a magnetic stirrer, and repeating the ultrasonic dispersion and stirring processes to finally obtain a uniform graphene-nano cellulose fiber dispersed solution;

and 3, carrying out suction filtration on the graphene-nano cellulose fiber dispersion solution to form a film, and airing to obtain the composite film material.

3. The method according to claim 2, wherein the graphene in the mixed solution in the step 1 is 60-90% by mass.

4. The method of claim 2, wherein the cellulose nanofibers in the mixed solution of step 1 are needle-like nanofibers with a high aspect ratio of 5-15nm in diameter.

5. The method for preparing a composite film material with high thermal conductivity and water transport according to claim 2, wherein the ultrasonic dispersion time of step 2 is 2 hours.

6. The method according to claim 2, wherein the stirring time in step 2 is 10 minutes.

7. The method according to claim 2, wherein the number of the repetition of the step 2 is 5.

8. The method as claimed in claim 2, wherein the filtration step 3 is performed with a 220nm pore size polypropylene filter membrane as a substrate.

9. The method according to claim 2, wherein the drying temperature in step 3 is room temperature.

10. Use of the high thermal conductivity and water transport composite film material of claim 1 or 2 in a solar evaporator.

Technical Field

The invention relates to the technical field of material engineering, in particular to a high-heat-conductivity and water-transmission composite film material, and a preparation method and application thereof.

Background

Aiming at the ubiquitous existence of the photo-thermal energy conversion of sunlight in the nature, the solar water evaporation material is inspired by the water circulation in the terrestrial biosphere, and a composite material film is prepared by assembling a high-thermal-conductivity nano carbon material (graphene) and a hydrophilic nano biological polymer (nano cellulose fiber) and is used for improving the water evaporation process driven by solar energy, so that the high water evaporation efficiency under the lower light intensity is realized. As the material does not need additional energy or chemical reagents in the evaporation process, a cheap and environment-friendly solution can be provided for seawater desalination and sewage treatment, and convenience is provided for solving the increasingly serious problems of shortage of fresh water resources, pollution of waste water and the like in the human society.

At present, research aiming at solar water evaporation materials mainly focuses on assembly of cellulose material carbonized semiconductor nano particles, solar energy is converted into heat energy by utilizing infrared absorption of the carbon material and the semiconductor material, and the heat energy is transferred to water to realize evaporation by compounding with hydrophilic materials (such as cellulose or water-absorbing paper materials).

However, as a part of the cavity of the traditional material must be reserved to ensure the diffusion of water vapor and the transfer of liquid water, the heat generated by sunlight absorbed by the surface layer of the material is blocked by the air in the cavity and cannot be transferred to the inside of the material, and the improvement of the evaporation efficiency is limited, especially under the low sunlight intensity (1 time of sun intensity/1 kW m)^-2) The evaporation efficiency is mostly lower than 1.47kg m^{- 2}h^-1. Therefore, innovative material design ideas are urgently needed to simultaneously obtain high sunlight absorption rate, efficient contact of water molecules and heat conduction materials, effective transfer of surface light and heat in a material system and a rapid water molecule transmission channel.

Accordingly, those skilled in the art have been devoted to developing a composite film material having high thermal conductivity and water transport.

Disclosure of Invention

In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to develop a composite film material with high thermal conductivity and water transmission, so as to improve the evaporation efficiency when the composite film material is used as a solar water evaporation material.

In order to achieve the above object, the present invention provides a composite thin film material with high thermal conductivity and water transmission, which comprises graphene and cellulose nanofibers.

The preparation method of the composite film material with high heat conductivity and water transmission comprises the following steps: step 1, preparing the graphene and the cellulose nano-fibers into a mixed solution; step 2, ultrasonically dispersing the mixed solution in an ultrasonic cleaner, stirring by using a magnetic stirrer, and repeating the ultrasonic dispersion and stirring processes to finally obtain a uniform graphene-nanocellulose fiber dispersed solution; and 3, carrying out suction filtration on the graphene-nano cellulose fiber dispersion solution to form a film, and airing to obtain the composite film material.

Further, the mass percentage of the graphene in the mixed solution in the step 1 is 50-90%.

Further, the cellulose nanofibers in the mixed solution in the step 1 are needle-shaped nanofiber with a high aspect ratio and a diameter of 5-15 nm.

Further, the ultrasonic dispersion time in step 2 is 2 hours.

Further, the stirring time in step 2 is 10 minutes.

Further, the number of times of repetition in step 2 is 5.

Further, the filtration in step 3 takes a polypropylene filter membrane with a pore diameter of 220nm as a substrate.

Further, the airing temperature in the step 3 is room temperature.

The composite film material with high heat conductivity and water transmission is applied to a solar evaporator.

The technical effects of the invention are as follows:

1) the composite film material prepared by the invention has a compact layered structure, the compact packing of graphene nanosheets is utilized to realize the rapid inward transfer of surface layer photo-induced heat, the compact packing of the graphene nanosheets can promote the efficient heat transfer quantity in the film, the high heat conductivity is obtained at room temperature, and the heat conductivity can reach 614W m at room temperature^-1k^-1(ii) a At the same time, since the cellulose itself has 5 to 15The diameter of nm forms a supporting effect between graphene sheet layers to form a hydrophilic pore channel with a nano size, so that water molecule nano fluid is formed conveniently, and the rapid transfer and the heated evaporation of water molecules are promoted. Sunlight with light intensity of 1 time (1KW m)^-2) Under the condition, the evaporation efficiency of water can reach 1.47kg m^-2h^-1The evaporation rate is 4.51kg m under 3 times of sunlight intensity^-2h^-1And the evaporation efficiency is kept at 95 percent, so that the material is an extremely excellent photo-thermal water evaporation material.

2) The raw materials are commercial products based on natural species, the price is low, the composite material is simple to operate, and no toxic or harmful substances are involved.

The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings to fully understand the objects, the features and the effects of the present invention.

Drawings

FIG. 1a) is an AFM image of cellulose nanofibers used in a preferred embodiment of the present invention; 1b) is a graphene SEM image used in a preferred embodiment of the present invention

FIG. 2 is a schematic view of the 1D/2D van der Waals heterostructure of the composite thin film material of the preferred embodiment of the present invention;

FIG. 3 is an SEM cross-sectional image of a composite thin film material according to a preferred embodiment of the invention;

FIG. 4 is a graph of the light absorption spectrum of the composite thin film material at 200-2000nm according to the preferred embodiment of the present invention;

FIG. 5 is a graph of the thermal conductivity of the composite film material of the preferred embodiment of the present invention;

FIG. 6a) is a top view of the composite thin film material of the preferred embodiment of the present invention as applied to a solar water evaporator; b) is a side view of the application of the composite film material of the preferred embodiment of the present invention as a solar water evaporator;

FIG. 7 is a graph of thermal imaging of a composite film material of a preferred embodiment of the present invention in 1 x sunlight for 0-600 seconds;

FIG. 8a) is a graph of the evaporation efficiency of the composite film material of the preferred embodiment of the present invention at 1 time solar intensity; b) the evaporation efficiency of the composite film material of the preferred embodiment of the invention is shown in a graph under 3 times of sunlight intensity; c) the composite film material of the preferred embodiment of the invention has stable evaporation efficiency under 1-3 times of sunlight intensity; d) the composite film material of the preferred embodiment of the invention has a water vapor effect pattern under 3 times of sunlight.

Detailed Description

The technical contents of the preferred embodiments of the present invention will be more clearly and easily understood by referring to the drawings attached to the specification. The present invention may be embodied in many different forms of embodiments and the scope of the invention is not limited to the embodiments set forth herein.