MIL-100(Fe) / Ti3C2 composite aerogel and preparation and application thereof

Abstract

The application relates to the technical field of photothermal and photocatalysis, in particular to a MIL-100(Fe) / Ti3C2 composite aerogel as well as preparation and application thereof. MIL-100(Fe) powder is added into Ti3C2 concentrated solution, mixed and stirred for 18-24 hours, ultrasonically treated for 1-2 hours, frozen in liquid nitrogen for 5-10 minutes, and then placed in a freeze dryer for 18-24 hours, so that the composite aerogel is obtained. The Ti3C2 / MIL-100(Fe) composite aerogel can efficiently absorb sunlight, has high photothermal conversion efficiency and photocatalytic degradation capacity, simultaneously has photothermal and photocatalytic properties, can effectively obtain distilled water from sewage, and can realize efficient degradation of volatile organic pollutants in water.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photothermal and photocatalysis, and in particular to a MIL-100(Fe) / Ti3C2 composite aerogel and a preparation and application thereof. BACKGROUND

[0002] With the growth of population and water pollution, water shortage has become one of the most severe global challenges. Solar-driven interfacial distillation has the smallest environmental and resource footprint, and has attracted wide attention in the fields of fresh water production and purification, wastewater treatment, power generation, etc. Solar distillation is becoming a powerful and energy-saving tool for water purification and fresh water production. However, many water sources contain harmful volatile organic compounds, which will evaporate with water and thus enrich in distilled water, which will threaten human health. Photocatalysis has the prospect of degrading volatile organic compounds, because photocatalysis is also a solar-driven interfacial process. The synergistic effect of photothermal distillation and photocatalysis can be shown.

[0003] Metal-organic framework (MOF) as a new type of material has greater specific surface area, controllable crystal structure and special active site compared with traditional adsorbents, and shows great potential in wastewater treatment. However, it is difficult to recycle and reuse due to its powder form, so it needs to be loaded on a carrier to achieve reuse and facilitate recycling. Professor Dong Wang's research group of Wuhan Textile University prepared MIL-100(Fe) / Ti3C2 MXene composite photocatalyst, but the prepared MIL-100(Fe) / Ti3C2 MXene composite photocatalyst is two-dimensional flake, and it is used to realize photocatalytic nitrogen fixation, and it is not disclosed that it can be used for treating wastewater, and the two-dimensional flake structure is not easy to recycle after dispersion in water. Therefore, there is no report on MIL-100(Fe) composite material for treating wastewater in the prior art. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application aims to provide a preparation and application of a solar-driven photothermal / photocatalytic composite aerogel (Ti3C2 / MIL-100(Fe)), which can obtain pure distilled water through the synergistic effect of photothermal and photocatalysis in the treatment of volatile organic wastewater.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] A preparation method of a MIL-100(Fe) / Ti3C2 composite aerogel, wherein MIL-100(Fe) powder is added to Ti3C2 concentrated solution, mixed and stirred for 18-24 h, ultrasonically treated for 1-2 h, frozen in liquid nitrogen for 5-10 min, and then placed in a freeze dryer for 18-24 h to obtain the composite aerogel.

[0007] The preparation of the Ti3C2 concentrated solution: after adding hydrochloric acid and lithium fluoride, Ti3AlC2 powder is added, after etching, the product is treated to obtain the Ti3C2 concentrated solution, the concentration of the Ti3C2 concentrated solution is 10 mg / g-50 mg / g, preferably 30 mg / g.

[0008] The preparation of the MIL-100(Fe): ferrous sulfate and trimesic acid are dissolved in deionized water, after ultrasonic treatment for 5-10 min, hydrothermal reaction is carried out, the reaction product is washed, vacuum dried, and high-temperature activated to obtain MIL-100(Fe) powder.

[0009] The mass ratio of the hydrochloric acid, lithium fluoride and Ti3AlC2 is 32-34:8:5;

[0010] The etching condition is: temperature 20-25 DEG C, time 46-48 h;

[0011] The post-treatment is that the product is washed with deionized water until the pH value of the supernatant is greater than 5, ice-bath ultrasonic stripping is carried out for 10-12 h, centrifugation is carried out at 3500 rpm for 15-20 min, centrifugation is carried out at 10000 rpm for 30-40 min, and the precipitate is the Ti3C2 concentrated solution.

[0012] The molar ratio of the ferrous sulfate and trimesic acid is 1:1;

[0013] The hydrothermal reaction temperature is 150-160 DEG C, and heating is carried out for 22-24 h;

[0014] The vacuum drying temperature is 60-70 DEG C, and the high-temperature activation is carried out at 150-160 DEG C for 10-12 h.

[0015] The mass ratio of the MIL-100(Fe) and Ti3C2 is 1:10-1:2, preferably 3:10.

[0016] The thickness of the composite aerogel is 10 mm.

[0017] The MIL-100(Fe) / Ti3C2 composite aerogel is used as a solar-driven photothermal material.

[0018] The MIL-100(Fe) / Ti3C2 composite aerogel is used as a solar-driven photocatalytic material.

[0019] The beneficial effects of the present application are as follows:

[0020] (1) The Ti3C2 / MIL-100(Fe) composite aerogel of the application can efficiently absorb sunlight, has high light-heat conversion efficiency and photocatalytic degradation capacity, simultaneously has photo-thermal and photocatalytic properties, can effectively obtain distilled water from sewage, and can efficiently degrade volatile organic pollutants in water.

[0021] (2) The disordered porous structure of the Ti3C2 / MIL-100(Fe) composite aerogel of the application can effectively adsorb and intercept phenol molecules volatilized with water vapor, meanwhile, the network structure of Ti3C2 connected with each other also provides sufficient active sites for MIL-100(Fe), the mesoporous structure inside MIL-100(Fe) can efficiently adsorb phenol molecules, and due to the irradiation of simulated sunlight, can excite MIL-100(Fe) to generate more hydroxyl radicals and active oxygen, so that it can effectively catalyze and degrade phenol molecules, so that the phenol content of the collected pure water is greatly reduced, and compared with the traditional water purification technology, the solar-driven photo-thermal / photocatalytic composite aerogel for treating sewage has the advantages of high efficiency, energy saving, no secondary pollution and carbon dioxide emission.

[0022] (3) The MIL-100(Fe) / Ti3C2 composite aerogel prepared in the application can stably float on the water surface, the aerogel structure provides sufficient active sites for the loading of MIL-100(Fe), so that it can fully intercept volatile pollutants in water, achieve the effect of efficient water purification, and can be used stably for a long time.

[0023] (4) The MIL-100(Fe) / Ti3C2 composite aerogel of the application is simple and feasible to prepare, safe and efficient, expands the light absorption range of the MIL-100(Fe) catalyst, and improves the photocatalytic activity. The composite aerogel has good photocatalytic performance and photo-thermal conversion performance, hydrophilicity, good stability, and can be reused. It has broad application prospects in water treatment. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is the optical photograph of the MIL-100(Fe) / Ti3C2 composite aerogel H3 of the application.

[0025] Figure 2 It is the morphology diagram of the MIL-100(Fe) / Ti3C2 composite aerogel H3 of the application.

[0026] Figure 3 It is the water evaporation rate of the MIL-100(Fe) / Ti3C2 composite aerogel of the embodiment.

[0027] Figure 4 It is the standard curve of the phenol standard sample.

[0028] Figure 5 Phenol rejection efficiency of the MIL-100(Fe) / Ti3C2 composite aerogel for the example. DETAILED DESCRIPTION

[0029] The specific embodiments of the present application are further described in conjunction with the examples below.

[0030] EXAMPLE

[0031] Preparation of MIL-100(Fe) / Ti3C2 composite aerogel

[0032] (1) Preparation of Ti3C2 concentrated solution: 80 mL of hydrochloric acid with a concentration of 9 mol / L was added to a polytetrafluoroethylene beaker, 6.4 g of lithium fluoride was added, and after the mixture was stirred thoroughly, 4 g of Ti3AlC2 powder was slowly added. After etching at 25°C for 48 h, 100 mL of water was added to the beaker to stop the reaction. The product was washed with deionized water until the pH value of the supernatant was > 5, and then was ultrasonically stripped in an ice bath for 10 h. The precipitate was removed by centrifugation at 3500 rpm for 20 min and at 10000 rpm for 40 min to obtain pure Ti3C2 concentrated solution. The concentration of the Ti3C2 concentrated solution was 30 mg / g.

[0033] (2) Preparation of MIL-100(Fe): ferrous sulfate and trimesic acid with a molar ratio of 1:1 were dissolved in deionized water. The mixed solution was ultrasonically treated for 5 min and then poured into a polytetrafluoroethylene-lined hydrothermal reaction kettle. The kettle was heated at 150°C for 24 h. After the reaction was completed and the kettle was cooled, the product was separated by centrifugation, washed with water and ethanol for 5 times, and dried at 60°C. The dried sample was activated at 150°C for 10 h to obtain MIL-100(Fe) powder.

[0034] (3) MIL-100(Fe) powder was added to the Ti3C2 concentrated solution at a mass ratio of 1:10, 1:5, 3:10, 1:2.5, and 1:2, respectively, and the mixture was stirred for 24 h and ultrasonically treated for 2 h. The mixtures were named H1, H2, H3, H4, and H5, respectively. The mixtures were placed in a mold after being frozen by liquid nitrogen and then were placed in a freeze dryer for 24 h to obtain black cylindrical composite aerogels with a diameter of 20 mm and a thickness of 10 mm. The optical photograph of H3 is shown in Figure 1 .

[0035] The composite aerogel H3 has a morphology as shown in Figure 2 , in which MIL-100(Fe) with a regular hexagonal morphology (marked by a red circle) is loaded on the surface of the three-dimensional network structure composed of Ti3C2.

[0036] APPLICATION EXAMPLE 1

[0037] The MIL-100(Fe) / Ti3C2 composite aerogel prepared in the embodiment of the application is used as a solar-driven photothermal material. The preparation method comprises the following steps:

[0038] (1) The solar distillation system is composed of polystyrene foam, an acetic acid fiber water guide cotton stick, a beaker and the MIL-100(Fe) / Ti3C2 composite aerogel. The circular polystyrene foam is embedded in the top of the beaker to isolate the heat transfer between the MIL-100(Fe) / Ti3C2 composite aerogel and the water in the beaker. The acetic acid fiber water guide cotton stick is fixed in the central hole of the polystyrene foam to connect the lower water and the upper MIL-100(Fe) / Ti3C2 composite aerogel, and to transfer the lower water to the upper MIL-100(Fe) / Ti3C2 composite aerogel.

[0039] (2) The solar evaporation system is irradiated under a solar simulator (AM 1.5G). The weight change is monitored by an electronic balance (with an accuracy of 1 mg).

[0040] (3) Under the irradiation of 1kW / m 2 , the water evaporation rate is measured by recording the weight change of water with time under simulated sunlight irradiation.

[0041] The evaporation rates of the H1, H2, H3, H4 and H5 aerogels can reach 1.70kg / m 2 / h, 1.78kg / m 2 / h, 1.85kg / m 2 / h, 1.73kg / m 2 / h and 1.65kg / m 2 / h (see Figure 3 ), respectively. As a control, the water evaporation rate of pure water without the aerogel is only 0.23kg / m 2 / h.

[0042] Application Example 2

[0043] The MIL-100(Fe) / Ti3C2 composite aerogel prepared in the application is used as a solar-driven photocatalytic material. The preparation method comprises the following steps

[0044] (1) The beaker in the solar distillation system is designed as a closed dome-shaped double-layer quartz glass cup. The inner layer is filled with 1mg / L phenol wastewater. The light intensity is 2kW / m 2Under the simulated sunlight irradiation, the temperature of MIL-100(Fe) / Ti3C2 composite aerogel rises, making water vapor and phenol molecules vaporize, and water vapor is generated at the top. Due to the temperature difference, water droplets are condensed here, and under the action of gravity, they flow to the outer layer along the circular top to form distilled water. The retention rate of phenol is measured by analyzing the concentration of phenol in the collected distilled water, and the photocatalytic effect of MIL-100(Fe) / Ti3C2 composite aerogel is evaluated.

[0045] (2) The quantitative method of the collected distilled water and phenol is as follows: a C18 reverse phase chromatographic column with octadecylsilane bonded silica gel as the filler is used, and a high performance liquid chromatograph is used to detect the collected liquid phase; the high performance liquid chromatograph uses an Agilent ZORBAX SB-C18 column (5 μm, 4.6*150 mm), the column temperature is 25°C, and the sample injection volume is 10 μL; the mobile phases A and B are water:methanol=40:60, and the flow rate is 0.7 mL / min; the ultraviolet detection conditions are that the detection wavelength is 270 nm, and the detection time is 10 min.

[0046] (3) A standard curve is drawn: 1 mg of phenol standard is accurately weighed and dissolved in 1 L of ultrapure water to prepare a 1 mg / L standard stock solution, which is stored in a refrigerator. The standard series with concentrations of 0.2 mg / L, 0.4 mg / L, 0.6 mg / L, 0.8 mg / L, and 1 mg / L are prepared by dilution, and then detected by high performance liquid chromatography. The response value (peak area) of the standard substance is taken as y, and the corresponding concentration is taken as x, linear fitting is performed, and a standard curve is drawn as follows: Figure 4 .

[0047] (4) The distilled water of H1, H2, H3, H4, and H5 is collected, and the collected liquid phase is detected by a high performance liquid chromatograph. According to the standard curve, the concentration of phenol in the distilled water is quantitatively calculated, so that the efficiency of MIL-100(Fe) / Ti3C2 composite aerogel in retaining phenol can be calculated.

[0048] The phenol retention efficiencies of composite aerogels H1, H2, H3, H4, and H5 are 40.1%, 57.5%, 84.4%, 84.4%, and 83.3% respectively (see Figure 5 ).

[0049] As can be seen from the above examples, the composite aerogels H1, H2, H3, H4, and H5 can achieve excellent effects as solar-driven photothermal materials and solar-driven photocatalytic materials, and in particular, the evaporation rate of composite aerogel H3 can reach 1.85 kg / m 2 / h, and the phenol retention efficiency can reach 84.4%.

[0050] The above-mentioned embodiments are preferred application cases of the present application, but do not limit the present application in any form. In actual application, some more changes or modifications can be made within the scope of the technical solutions of the present application, and equivalent embodiments with equivalent changes can be obtained based on the disclosed technical content.

Claims

1. A method for preparing MIL-100(Fe) / Ti3C2 composite aerogel, characterized in that, The MIL-100(Fe) powder is added to the Ti3C2 concentrated solution, mixed and stirred for 18-24 h, ultrasonically treated for 1-2 h, frozen in liquid nitrogen for 5-10 min, and then placed in a freeze dryer for 18-24 h to obtain the composite aerogel; The mass ratio of MIL-100(Fe) to Ti3C2 is 1:10-1:

2.

2. The preparation method of the MIL-100(Fe) / Ti3C2 composite aerogel according to claim 1, characterized in that, The Ti3C2 concentrated solution is prepared by adding hydrochloric acid and lithium fluoride, then adding Ti3AlC2 powder, etching, and then treating the product to obtain the Ti3C2 concentrated solution; The mass ratio of the hydrochloric acid, lithium fluoride and Ti3AlC2 is 32-34:8:5; The etching conditions are: temperature 20-25 °C, time 46-48 h; The post-treatment is washing the product with deionized water until the pH value of the supernatant is greater than 5, ice-bath ultrasonic stripping for 10-12 h, centrifugation at 3500 rpm for 15-20 min, centrifugation at 10000 rpm for 30-40 min, and the precipitate is the Ti3C2 concentrated solution.

3. Use of the MIL-100(Fe) / Ti3C2 composite aerogel according to claim 1, characterized in that, The MIL-100(Fe) / Ti3C2 composite aerogel is used as a solar-driven photothermal material.

4. The use of the MIL-100(Fe) / Ti3C2 composite aerogel according to claim 1, characterized in that, The MIL-100(Fe) / Ti3C2 composite aerogel is used as a solar-driven photocatalytic material. The MIL-100(Fe) / Ti3C2 composite aerogel is used as a solar-driven photocatalytic material.

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