Photo-thermal evaporation material based on black titanium dioxide as well as preparation method and application of photo-thermal evaporation material

Abstract

The invention provides a photo-thermal evaporation material based on black titanium dioxide as well as a preparation method and application of the photo-thermal evaporation material. The preparation method comprises the following steps: mixing urea, absolute ethyl alcohol and tetrabutyl titanate into a solution A, mixing absolute ethyl alcohol, ultrapure water and hydrochloric acid into a solution B, dropwise adding the solution B into the solution A, mixing to form a white colloid, heating in a water bath, drying, and calcining in a nitrogen atmosphere to obtain black titanium dioxide powder; the preparation method comprises the following steps: fully mixing a certain amount of black titanium dioxide, sodium alginate and ultrapure water to form a uniform dispersion liquid, dipping the pretreated polyurethane sponge in the dispersion liquid, and crosslinking with a calcium chloride solution to prepare the photo-thermal evaporation material of the black titanium dioxide-calcium alginate composite hydrogel. The photo-thermal evaporation material breaks through the photo-thermal application bottleneck of traditional titanium dioxide, has excellent evaporation rate and seawater desalination performance, and can effectively remove various printing and dyeing wastewater to obtain clean water.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photothermal evaporation, in particular to a black titanium dioxide-based photothermal evaporation material, a preparation method and application thereof. BACKGROUND

[0002] With the global population growth, environmental pollution and climate change, many regions are facing serious freshwater shortage problems, although more than 70% of the earth's surface is covered by water, but less than 0.3% of the direct available freshwater resources, so developing a green, renewable and eco-friendly sustainable clean water production technology has become an urgent demand of current research. Traditional seawater desalination technologies, such as distillation, electrodialysis and membrane separation, usually have high cost and are complex and inefficient. In recent years, with the development of solar-driven interfacial evaporation technology, which has environmental friendliness, renewable characteristics and high energy conversion efficiency, by efficiently converting light energy into heat energy to drive water phase change to realize seawater desalination, it shows great potential in freshwater production.

[0003] The core of the solar-driven interfacial evaporation technology lies in the development of high-performance photothermal materials. The ideal photothermal material should have the characteristics of wide spectrum absorption, high-efficiency photothermal conversion, good thermal positioning and stable water transport channel. At present, a variety of photothermal material systems including metal nanomaterials, semiconductors, polymers and carbon-based materials have been developed, but the preparation process of these materials is complicated and the cost is high, which seriously limits the application of these materials in actual water treatment. Among them, titanium dioxide as a semiconductor material has excellent energy band structure and strong redox capacity, but due to its large band gap, it has poor ultraviolet light absorption ability, which limits its application. SUMMARY

[0004] Compared with conventional white titanium dioxide, black titanium dioxide introduces oxygen vacancies, Ti 3 + defects or hydrogenation treatment, which significantly reduces the band gap and realizes full-spectrum absorption from ultraviolet to near-infrared. Black titanium dioxide has excellent photothermal conversion efficiency and good chemical stability, and has broad application prospects in solar-driven interfacial evaporation, and can be used as a new type of photothermal material.

[0005] The present application discloses a black titanium dioxide-based photothermal evaporation material, a preparation method and application thereof, which aims to prepare a photothermal evaporation material with excellent photothermal performance by using black titanium dioxide as a precursor. The photothermal evaporation material has excellent evaporation rate and seawater desalination performance, and can effectively remove various printing and dyeing wastewater to obtain clean water.

[0006] The present application adopts the following scheme:

[0007] A method for preparing a photothermal evaporation material based on black titanium dioxide, comprising the following steps:

[0008] S1. Mixing urea, anhydrous ethanol and tetrabutyl titanate in a mass ratio to form an A solution, then mixing anhydrous ethanol, ultrapure water and hydrochloric acid in a mass ratio to form a B solution; then adding the B solution dropwise into the A solution, after the dropwise addition is completed, stirring the mixture gently with a glass rod to form a white colloid;

[0009] S2. First heating the prepared white colloid in a water bath, and then drying it in an oven to form light yellow particles;

[0010] S3. Grinding the light yellow particles into powder, and then calcining the powder in a tube furnace under a nitrogen atmosphere to obtain black titanium dioxide powder;

[0011] S4. Mixing the black titanium dioxide powder, sodium alginate and ultrapure water in a mass ratio, and then stirring after heating in a water bath to form a uniform dispersion liquid, immersing the pretreated polyurethane sponge in the dispersion liquid, and repeating the immersion and extrusion;

[0012] S5. Crosslinking the immersed polyurethane sponge in a calcium chloride solution, repeatedly washing the obtained sample with deionized water, and obtaining a photothermal evaporation material of polyurethane sponge loaded black titanium dioxide-calcium alginate composite hydrogel.

[0013] Preferably, in step S1, the mass ratio of urea, anhydrous ethanol and tetrabutyl titanate in the A solution is 0.8:15.8:14; the mass ratio of anhydrous ethanol, ultrapure water and hydrochloric acid in the B solution is 7.9:5:1.2.

[0014] Preferably, in step S2, the temperature of the water bath heating for the white colloid is 35℃, and the time is 30min; when drying, the oven drying temperature is 80℃, and the drying time is 12h.

[0015] Preferably, in step S3, the calcination temperature is 600℃, the heating rate is 5℃ / min, and the calcination time is 3h.

[0016] Preferably, in step S4, in the dispersion liquid, the mass ratio of black titanium dioxide, sodium alginate and ultrapure water is 2:1:97, and the water bath heating temperature is 65℃.

[0017] Preferably, in step S4, the pretreatment is ultrasonic cleaning and oven drying of the polyurethane sponge with deionized water for subsequent use.

[0018] Preferably, in step S5, the mass fraction of calcium chloride in the calcium chloride solution is 2wt.%, and the crosslinking time is 12h.

[0019] The application also provides a black titania-based photothermal evaporation material prepared by the preparation method.

[0020] The application also provides application of the black titania-based photothermal evaporation material in seawater desalination.

[0021] The application also provides application of the black titania-based photothermal evaporation material in wastewater treatment.

[0022] By adopting the technical solution, the application can achieve the following technical effects:

[0023] (1) The photothermal evaporation material breaks through the photothermal application bottleneck of traditional titania, and the synthesized photothermal evaporation material has excellent photothermal conversion performance.

[0024] (2) The black titania-based photothermal evaporation material has excellent pore structure and mechanical properties, and in combination with the relaxation effect of black titania semiconductor, the material has a high evaporation rate.

[0025] (3) The black titania-based photothermal evaporation material has excellent seawater desalination performance, and the material can effectively remove organic pollutants methyl blue and rhodamine B dye in wastewater, achieving the effect of wastewater treatment. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation to the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0027] Figure 1 is a steam production performance characterization diagram of the black titania-based photothermal evaporation material of the application embodiments 1, 2, 3 and 4;

[0028] Figure 2 is a pore size distribution diagram of the black titania-based photothermal evaporation material of the application embodiment 2;

[0029] Figure 3 is a seawater desalination effect comparison diagram of the black titania-based photothermal evaporation material of the application embodiment 2;

[0030] Figure 4 is an organic matter removal effect comparison diagram of the black titania-based photothermal evaporation material of the application embodiment 2. DETAILED DESCRIPTION

[0031] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0032] First, urea, anhydrous ethanol and tetrabutyl titanate are mixed in a mass ratio of 0.8:15.8:14 to form a solution A, then anhydrous ethanol, ultrapure water and hydrochloric acid are mixed in a mass ratio of 7.9:5:1.2 to form a solution B, and then the solution B is added dropwise into the solution A without stirring, and after the dropwise addition is completed, the mixture is gently stirred with a glass rod to form a white colloid; then the prepared white colloid is heated in a water bath at 35°C for 30 min, and then placed in an oven for drying at 80°C for 12 h to form a light yellow granule. Finally, the light yellow granule is ground into a powder, and then heated to 600°C at a speed of 5°C / min in a tube furnace under a nitrogen atmosphere, and calcined for 3 h to obtain a black titanium dioxide powder. The subsequent preparation process is carried out according to the processes of Examples 1-4.

[0033] Example 1

[0034] In this embodiment, a black titanium dioxide-based photothermal evaporation material is provided, and the preparation method thereof can be obtained according to the following steps:

[0035] (1) Black titanium dioxide, sodium alginate and ultrapure water are mixed in a mass ratio of 1:1:98, and after stirring in a water bath at 65°C, a uniform dispersion liquid is formed. The pretreated polyurethane sponge is immersed in the dispersion liquid and repeatedly immersed and squeezed.

[0036] (2) The immersed polyurethane sponge is soaked in a 2wt.% calcium chloride solution for crosslinking for 12 h, and the obtained sample is repeatedly washed with deionized water to finally obtain a polyurethane sponge loaded black titanium dioxide-calcium alginate composite hydrogel photothermal evaporation material.

[0037] Example 2

[0038] The photothermal evaporation material based on black titanium dioxide provided in this embodiment can be prepared by the following steps:

[0039] (1) Black titanium dioxide, sodium alginate and ultrapure water are mixed in a mass ratio of 2:1:97. After being heated and stirred in a water bath at 65°C, a uniform dispersion is formed. The pretreated polyurethane sponge is then immersed in the dispersion and repeatedly immersed and squeezed.

[0040] (2) The impregnated polyurethane sponge was immersed in a calcium chloride solution with a mass fraction of 2 wt.% for 12 h for crosslinking. The resulting sample was repeatedly washed with deionized water to finally obtain a black titanium dioxide-calcium alginate composite hydrogel photothermal evaporation material supported by polyurethane sponge.

[0041] Example 3

[0042] The photothermal evaporation material based on black titanium dioxide provided in this embodiment can be prepared by the following steps:

[0043] (1) Black titanium dioxide, sodium alginate and ultrapure water are mixed in a mass ratio of 3:1:96. After being heated and stirred in a water bath at 65°C, a uniform dispersion is formed. The pretreated polyurethane sponge is then immersed in the dispersion and repeatedly immersed and squeezed.

[0044] (2) The impregnated polyurethane sponge was immersed in a calcium chloride solution with a mass fraction of 2 wt.% for 12 h for crosslinking. The resulting sample was repeatedly washed with deionized water to finally obtain a black titanium dioxide-calcium alginate composite hydrogel photothermal evaporation material supported by polyurethane sponge.

[0045] Example 4

[0046] The photothermal evaporation material based on black titanium dioxide provided in this embodiment can be prepared by the following steps:

[0047] (1) Mix black titanium dioxide, sodium alginate and ultrapure water in a mass ratio of 4:1:95. Heat and stir in a water bath at 65°C to form a uniform dispersion. Immerse the pretreated polyurethane sponge in the dispersion and repeatedly immerse and squeeze.

[0048] (2) The impregnated polyurethane sponge was immersed in a calcium chloride solution with a mass fraction of 2 wt.% for 12 h for crosslinking. The resulting sample was repeatedly washed with deionized water to finally obtain a black titanium dioxide-calcium alginate composite hydrogel photothermal evaporation material supported by polyurethane sponge.

[0049] The performance of the photothermal evaporation materials in the above embodiments will be compared and explained through some experimental examples.

[0050] Experimental Example 1

[0051] Photoevaporation tests were conducted using indoor xenon lamps to simulate sunlight. The differences in photothermal performance of the photothermal evaporation materials provided in different embodiments were determined by comparing their evaporation rates.

[0052] The photoevaporation test was simulated using Perfectlight (PLS-SXE300+), which simulated a solar flux of 500 to 3000 W / m². 2 The spectrum was calibrated using a standard AM 1.5G filter. The light intensity was always calibrated using an automatic optical power meter (Aulight, CEL-NP2000-2(10)A) before testing. A 2cm x 2cm x 3cm hydrogel-like photothermal evaporation material was laid on the surface of a sponge. The sponge provided a continuous water supply for the evaporation of the photothermal evaporation material. To reduce heat loss, they were placed in vacuum-sealed glass beakers. The weight loss of the entire apparatus was tracked using an electronic mass balance. The evaporation process was measured over 3 hours under simulated sunlight conditions at a temperature of 25°C and a relative humidity of 40%.

[0053] from Figure 1 As can be seen from the data, the evaporation rate of the photothermal evaporation material in Example 2 can reach 3.331 kg / m³. -2 h -1 Its evaporation rate is higher than that of the materials provided in other embodiments.

[0054] Experimental Example 2

[0055] The pore structure of the photothermal evaporation material provided in Example 2 was analyzed using a mercury porosimetry porosimeter. Figure 2 The pore size distribution of the macropores inside the photothermal evaporation material was measured by a mercury porosimetry porosimeter. It can be seen that the photothermal evaporation material has a well-developed pore structure. These pore structures can promote material transport, and incident light can be continuously reflected within the pore structure, thus enhancing light absorption.

[0056] Experimental Example 3

[0057] Using the photothermal evaporation material prepared in Example 2, actual seawater (taken from Xiamen First Wharf) was added to the photothermal evaporation device constructed in Example 1 and irradiated. The generated steam condensed into liquid and entered the recovery container. Then, flame atomic absorption spectrometry was used to detect the ion concentration in the collected water.

[0058] from Figure 3 As can be seen from the above, after the evaporation and desalination treatment by the photothermal evaporation material in Example 2, the Na+ in the seawater... + K + Ca 2+ and Mg 2+The ion concentrations all decreased significantly and were below the World Health Organization's standards, proving that photothermal evaporation materials can be well applied in the field of seawater desalination.

[0059] Test Example 4

[0060] Using the photothermal evaporation material prepared in Example 2, 20 mg / L of methylene blue and rhodamine B solution was added to the photothermal evaporation device constructed in Example 1, and the device was irradiated. The generated vapor condensed into liquid and entered the recovery container. Then, the dye removal effect in the collected water was detected by ultraviolet-visible absorption spectroscopy.

[0061] from Figure 4 As can be seen from the evaporation treatment by the photothermal evaporation material of Example 2, methylene blue and rhodamine B were completely removed. This is mainly due to the excellent pore structure of the photothermal evaporation material, which retained the dye. This proves that the photothermal evaporation material of Example 2 can be well applied in the field of dye wastewater treatment.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for preparing a photothermal evaporation material based on black titanium dioxide, characterized in that, Includes the following steps: S1. Mix urea, anhydrous ethanol and tetrabutyl titanate in a certain mass ratio to form solution A. Then mix anhydrous ethanol, ultrapure water and hydrochloric acid in a certain mass ratio to form solution B. Add solution B dropwise to solution A. After the addition is complete, gently stir the mixture with a glass rod to form a white colloid. S2. The obtained white colloid is first heated in a water bath, and then dried in an oven to form light yellow granules; S3. Grind the pale yellow particles into powder, and then calcine them in a tube furnace under a nitrogen atmosphere to obtain black titanium dioxide powder; S4. The black titanium dioxide powder, sodium alginate and ultrapure water are mixed in a certain mass ratio and heated and stirred in a water bath to form a uniform dispersion. The pretreated polyurethane sponge is then immersed in the dispersion and repeatedly immersed and squeezed. S5. The impregnated polyurethane sponge is immersed in calcium chloride solution for crosslinking. The resulting sample is repeatedly washed with deionized water to obtain a photothermal evaporation material of black titanium dioxide-calcium alginate composite hydrogel supported on polyurethane sponge.

2. The method for preparing a photothermal evaporation material based on black titanium dioxide according to claim 1, characterized in that, In step S1, the mass ratio of urea, anhydrous ethanol and tetrabutyl titanate in solution A is 0.8:15.8:14; The mass ratio of anhydrous ethanol, ultrapure water and hydrochloric acid in solution B is 7.9:5:1.

2.

3. The method for preparing a photothermal evaporation material based on black titanium dioxide according to claim 1, characterized in that, In step S2, the water bath heating temperature of the white colloid is 35°C and the time is 30 min; during drying, the oven drying temperature is 80°C and the drying time is 12 h.

4. The method for preparing a photothermal evaporation material based on black titanium dioxide according to claim 1, characterized in that, In step S3, the calcination temperature is 600℃, the heating rate is 5℃ / min, and the calcination time is 3h.

5. The method for preparing a photothermal evaporation material based on black titanium dioxide according to claim 1, characterized in that, In step S4, the mass ratio of black titanium dioxide, sodium alginate, and ultrapure water in the dispersion is 2:1:97, and the water bath heating temperature is 65°C.

6. The method for preparing a photothermal evaporation material based on black titanium dioxide according to claim 1, characterized in that, In step S5, the calcium chloride solution contains 2 wt.% calcium chloride by mass, and the crosslinking time is 12 h.

7. A photothermal evaporation material based on black titanium dioxide, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 6.

8. The application of a photothermal evaporation material based on black titanium dioxide as described in claim 7 in seawater desalination.

9. The application of a photothermal evaporation material based on black titanium dioxide as described in claim 7 in wastewater treatment.

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