Nano photocatalyst, concrete containing nano photocatalyst and application of nano photocatalyst

Abstract

The invention discloses a ZnS / ZnO nano photocatalyst, concrete containing the ZnS / ZnO nano photocatalyst and application of the ZnS / ZnO nano photocatalyst. The ZnS / ZnO nano photocatalyst is constructed by performing high-temperature calcination on ZnS in air; the method is applied to concrete. The nano photocatalyst designed by the invention not only has excellent photocatalytic performance, but also is simpler and more efficient in preparation method, and pervious concrete with excellent photocatalytic performance can be prepared within a shorter time; meanwhile, the adopted ZnS / ZnO nano photocatalytic material is low in price and environment-friendly, has better capability of degrading an anti-inflammatory drug pollutant diclofenac sodium, has excellent sunlight activity and pollutant removal capability after being used for the pervious concrete, is particularly suitable for the field of sponge cities, effectively reduces refractory organic pollutants in rainwater runoff, and has a good application prospect. The method is of great significance to improvement of urban water environment.

Description

Technical Field

[0001] The invention relates to the technical field of materials and sewage treatment, and more particularly to a ZnS / ZnO nano photocatalyst, concrete containing the same and application thereof. Background Art

[0002] With the rapid growth of population and the expansion of infrastructure construction, runoff from road systems, impervious pavements and open spaces has increasingly become one of the main sources of pollution in urban water environments. Non-point source pollutants can be dissolved, carried and transported by runoff and eventually enter the urban water environment. Among various rainwater-induced runoff pollutants, anti-inflammatory drug pollutants (diclofenac sodium) are ubiquitous and have significant accumulation, threatening public health and the sustainability of ecosystems. Thanks to the abundant pores in the structure, permeable concrete has excellent permeability, large specific surface area and biocompatibility, which provides conditions for its good rainwater purification ability and is expected to become an effective way to control new pollutants in urban water environments. Permeable concrete can be used to remove common pollutants in urban runoff and significantly reduce persistent organic pollutants and microorganisms in urban runoff.

[0003] Photocatalytic technology has shown great potential in solving environmental pollution problems due to its advantages such as simple operation and green environmental protection. However, in the current heterogeneous photocatalysis, the metal photocatalyst TiO2 has a narrow absorption range and poor electron mobility, which leads to reduced stability in removing organic pollutants and limited mineralization efficiency. And it can only degrade dye wastewater. Natural minerals can be obtained directly from nature, with the outstanding advantages of low price and environmental friendliness. The necessary condition for photocatalytic reaction is the adsorption of target compounds. Due to the large surface area of ​​natural minerals and their strong adsorption of pollutants, they can be used as carriers. At the same time, the active sites exposed on the surface of natural minerals can provide a structural basis for improving photocatalytic activity.

[0004] Therefore, developing and utilizing natural minerals with low market prices to prepare modified photocatalysts and further improving their photocatalytic performance has become an urgent problem to be solved. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a nano photocatalyst, concrete containing the same and application thereof. The photocatalyst designed by the present invention not only has excellent photocatalytic performance, but also has a simpler and more efficient preparation method, and can prepare permeable concrete with excellent photocatalytic performance in a relatively short time; at the same time, the ZnS / ZnO nanomaterials used are inexpensive, environmentally friendly, and have a good ability to degrade diclofenac sodium, i.e., DCF, an anti-inflammatory drug pollutant. After being used in permeable concrete, it has excellent solar activity and pollutant removal ability, is particularly suitable for the field of sponge cities, and can effectively reduce difficult-to-degrade organic pollutants in rainwater runoff, which is of great significance to the improvement of urban water environment.

[0006] In order to achieve the above-mentioned object, one of the objects of the present invention is to provide a nano photocatalyst, comprising: constructing a ZnS / ZnO nano photocatalyst by calcining ZnS at high temperature under air;

[0007] Preferably, the purity of the raw material ZnS is ≥99.9%.

[0008] The second object of the present invention is to provide a method for preparing a ZnS / ZnO nano-photocatalyst.

[0009] Specifically, the raw materials are heated to 800°C in a ZnS muffle furnace at a heating rate of 15°C / min and kept at a constant temperature for 2 hours, then taken out, cooled to room temperature, ground through a 10 μm sieve, and a ZnS / ZnO nano-photocatalyst is obtained.

[0010] For example, 3-5 g of raw material is heated to 800°C in a muffle furnace at a rate of 15°C / min and kept at a constant temperature for 2 hours, then taken out and cooled to room temperature and ground through a 10 μm sieve to obtain 1-3 g of ZnS / ZnO nano-photocatalyst.

[0011] The beneficial effects of adopting the above technical solution include at least: improving the photocatalytic performance of ZnS, calcining at 800°C to produce ZnO; not only can it effectively promote the interaction between ZnS and ZnO to form a more stable structure, but also compared with other treatment temperatures, 800°C helps to improve the crystallinity of ZnS / ZnO particles, optimize the light absorption and electron migration properties of the material, thereby enhancing its photocatalytic activity. This temperature helps to achieve more efficient solar light catalytic degradation of pollutants, especially organic pollutants, preferably DCF; it can fully exert the photocatalytic performance of ZnS / ZnO, and ensure the crystallinity, stability and catalytic activity of the material, thereby optimizing its application effect in permeable concrete coatings.

[0012] The third object of the present invention is to provide a concrete comprising the nano-photocatalyst described above.

[0013] A fourth object of the present invention is to provide a method for preparing concrete.

[0014] Specifically, it comprises: preparing a ZnS / ZnO nano-photocatalyst solution, coating it on the surface of uncured permeable concrete after ultrasonic dispersion, placing a glass sheet on the surface and curing it at room temperature for several days to obtain highly efficient solar-active concrete;

[0015] Furthermore, the coating has a thickness of 0.2-0.3 cm.

[0016] The beneficial effects of adopting the above technical solution include at least: After the photocatalytic concrete is made, it is necessary to explore the aging and falling off problems on the surface of the concrete material. The catalyst on the concrete surface will gradually fall off over time, resulting in a decrease in photocatalytic performance. Therefore, the coating thickness of the photocatalyst on the concrete surface determines the durability of the photocatalytic concrete. The coating thickness of the photocatalyst is about 2 mm or more to maintain its photocatalytic ability until a certain degree of aging occurs. Thus, the penetration thickness of the photocatalyst is determined. Rub the concrete surface with a polisher until the photocatalyst no longer exists, and then measure the change in thickness. The change in the thickness of the concrete surface represents the coating thickness of the photocatalyst.

[0017] Preferably, the concentration of the ZnS / ZnO nano-photocatalyst solution is 0-0.05 g / ml;

[0018] Furthermore, the concentration of the ZnS / ZnO nano photocatalyst solution is 0.03-0.04 g / ml.

[0019] Furthermore, the ZnS / ZnO nano-photocatalyst is dissolved in pure water to form a solution with a certain mass concentration, wherein the mass concentration of the solution is 0.01 g / mL-0.05 g / mL.

[0020] The ultrasonic dispersion treatment temperature is 10-20°C and the time is 10-40 minutes;

[0021] Furthermore, the room temperature is controlled at 24°C-27°C, and the humidity is 95%-98%.

[0022] A fifth object of the present invention is to provide an application of concrete in degrading the pharmaceutical pollutant diclofenac sodium.

[0023] By adopting the above technical solution, the technical effects achieved by the present invention include at least:

[0024] 1) The present invention uses zinc sulfide, the main component of sphalerite, which is cheap and easily available, to prepare a photocatalyst, and calcines and modifies it in the air, and loads the modified ZnS / ZnO nanoparticles on the surface and pores of permeable concrete to prepare a porous concrete natural mineral material composite permeable paving material with high strength and water conductivity. It can not only use visible light to catalyze and degrade organic pollutants attached to the surface, but also solve the problem of urban waterlogging by virtue of its own permeability, and also purify surface runoff to avoid groundwater pollution, which plays an important role in promoting sponge city construction;

[0025] 2) The ZnS / ZnO nanoparticle photocatalyst prepared by the present invention is successfully loaded on the surface of permeable concrete, wherein the ZnS / ZnO nanoparticle catalyst promotes the migration and separation of photoinduced carriers and reduces the complexation of photoinduced carriers;

[0026] 3) The highly efficient sunlight-active ZnS / ZnO nano-photocatalytic layer permeable concrete provided by the present invention has good cyclic applicability and mechanical friction performance. The pores on the surface of the permeable concrete can provide sufficient active sites for the photocatalyst and protect the photocatalyst from rain erosion and mechanical friction.

[0027] 4) The preparation process of the high-efficiency sunlight-active ZnS / ZnO nano-photocatalytic layer permeable concrete provided by the present invention is simple, environmentally friendly, and has low production cost, and is suitable for industrial mass production; it has good practical value and promotion and application prospects in the field of sponge cities. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0029] Figure 1 The attached figure is a microstructure diagram of ZnS / ZnO and a surface diagram of ZnS / ZnO photocatalytic permeable concrete;

[0030] Figure 2 The attached figure is a comparison image of Fourier transform infrared spectra of ZnS and ZnS / ZnO before and after calcination;

[0031] Figure 3 The attached figure shows the removal efficiency of DCF by ZnS under calcination at different temperatures;

[0032] Figure 4 The attached figure shows the change of pollutant removal capacity at different ZnS / ZnO particle concentrations;

[0033] Figure 5 The attached figure shows the change of pollutant removal capacity of ZnS / ZnO photocatalytic layer permeable concrete under different lighting conditions;

[0034] Figure 6 The attached figure shows the change of DCF removal rate of ZnS / ZnO photocatalytic layer permeable concrete after 20 cycles of rainwater flushing;

[0035] Figure 7 The attached figure is a schematic diagram of a device for photocatalytic reduction of DCF in ZnS / ZnO photocatalytic layer permeable concrete. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments 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.

[0037] Example 1

[0038] This embodiment discloses a concrete, which specifically includes the following components:

[0039] Cement: 48g,

[0040] Water: 19.6g,

[0041] Coarse aggregate: 175g,

[0042] The cement is 42.5 grade ordinary Portland cement, and its physical properties and chemical properties conform to the ASTM C150-07 standard (ASTM, 2007).

[0043] The coarse aggregate is stone with a particle size of 5-10 mm, conforming to ASTM size 67.

[0044] At the same time, this embodiment provides a ZnS / ZnO nano photocatalyst, specifically,

[0045] Zinc sulfide (99.9%) is used as raw material.

[0046] The preparation method of ZnS / ZnO nano-photocatalyst is as follows:

[0047] 5 g of zinc sulfide powder was placed in a crucible, heated to 800°C in a muffle furnace at a heating rate of 15°C / min for 2 hours, then taken out, cooled to room temperature, ground and sieved to 10 μm, and 2.8 g of ZnS / ZnO nano-photocatalyst was prepared for use;

[0048] This embodiment also provides a highly efficient solar-active concrete, the preparation method of which includes the following steps:

[0049] Step 1: weigh each raw material component according to the above concrete ratio;

[0050] Step 2: Add coarse aggregate and cement into a container and stir evenly, then add water and continue to stir evenly, pour the mixture into a mold (150mm*150mm*300mm) to make permeable concrete and cure it into shape;

[0051] Step 3: De-mould the concrete after curing at room temperature for 2 hours. At this time, the cement slurry on the surface has just begun to solidify.

[0052] Step 4: Dissolve 0.4g ZnS / ZnO nano-photocatalyst powder in 10ml pure water, disperse it by ultrasonic for 10min, and then apply 0.3cm on the surface of uncured permeable concrete. The treatment temperature of ultrasonic dispersion is 10-20℃ and the time is 10-40min.

[0053] Step 5: Place a 100g glass plate on the concrete and press the ZnS / ZnO nano-photocatalyst into the concrete.

[0054] Step 6: After curing in a curing room at room temperature (24-27°C, humidity 95-98%) for 7 days, remove the glass plate to expose the photocatalyst.

[0055] Effect data test:

[0056] The microstructure of the material was observed using a SU8000 scanning electron microscope (SEM) from Hitachi, Japan.

[0057] The infrared spectra of the samples were measured using a PerkinElmer Spectrum 3 Fourier transform infrared spectrophotometer (FTIR).

[0058] Acquity UPLC H-class from Waters, USA was used.

[0059] Effect experiment 1: Removal rate of DCF by ZnS at different calcination temperatures

[0060] Step 1: Calcination to prepare ZnS / ZnO nano-photocatalyst:

[0061] 5 g of zinc sulfide powder was placed in a crucible, and heated to 200, 400, 600, 800, and 1000°C at a rate of 15°C / min in a muffle furnace, and then taken out and cooled to room temperature, and then ground and sieved to 10 μm to obtain photocatalysts at different temperatures for use;

[0062] The experimental steps are as follows:

[0063] (1) Prepare 2.5 mg / L DCF solution;

[0064] (2) 0.02 g of ZnS nano-photocatalyst powder calcined at different temperatures was placed in a 50 ml beaker, 2.5 mg / L of DCF solution was added, and a xenon lamp was turned on to conduct a photocatalytic experiment.

[0065] (3) After a certain period of photocatalysis, the residual concentration of the solution is measured by ultra-high performance liquid chromatography;

[0066] (4) The photocatalytic efficiency of the photocatalyst is characterized by the change in DCF concentration: (initial concentration - residual concentration) / initial concentration. Figure 3 shown.

[0067] The results show that the removal effect of zinc sulfide powder is best when calcined at 800℃.

[0068] Effect experiment 2: Photocatalytic performance of photocatalytic permeable concrete under different concentrations of ZnS / ZnO nanophotocatalysts.

[0069] Photocatalytic permeable concrete at low concentration of ZnS / ZnO nanoparticles, and a preparation method thereof, comprising the following steps:

[0070] Step 1: Calcination to prepare ZnS / ZnO nano-photocatalyst.

[0071] 5 g of zinc sulfide powder was placed in a crucible, heated to 800°C in a muffle furnace at a rate of 15°C / min for 2 hours, then taken out, cooled to room temperature, ground and sieved to 10 μm to prepare a photocatalyst for use;

[0072] The method for preparing the modified photocatalytic permeable concrete with high efficiency solar activity comprises the following steps:

[0073] Step 1: weigh each raw material component according to the ratio;

[0074] Step 2: Add coarse aggregate and cement into a bucket and mix well, then add water and continue to mix well, pour the mixture into a mold (150mm*150mm*300mm) to make permeable concrete and cure it into shape;

[0075] Step 3: De-mould the concrete after curing at room temperature for 2 hours. At this time, the cement paste on the surface has just begun to solidify.

[0076] Then, 0, 0.1, 0.2, 0.3, 0.4, and 0.5 g of ZnS / ZnO nano-photocatalyst powder were dissolved in 10 ml of pure water, respectively. After ultrasonic dispersion for 10 min, the powder was evenly coated on the concrete surface and pores with a brush, and the coating thickness was 0.2 cm.

[0077] A 100 g glass plate was placed on the concrete to press ZnS / ZnO into the concrete. After curing in a room temperature (24°C, 95% humidity) for 7 days, the glass plate was removed to expose the photocatalyst.

[0078] like Figure 1 As shown, ZnS / ZnO particles formed on the surface and in the pores of permeable concrete;

[0079] like Figure 2 As shown; the infrared spectrum of Zn-O is at 465cm -1 617cm appeared in the range -1 The vibration peaks at can be assigned to ZnS. These results confirm the successful synthesis of ZnS / ZnO nanophotocatalysts.

[0080] The experimental steps are as follows:

[0081] (1) Prepare 2.5 mg / L DCF solution;

[0082] (2) ZnS / ZnO photocatalytic permeable concrete prepared at concentrations of 0, 0.01, 0.02, 0.03, 0.04, and 0.05 g / ml were placed in the device, respectively. Figure 7 The device shown was added with 2.5 mg / L DCF solution and the xenon lamp was turned on to conduct the photocatalytic experiment;

[0083] (3) After a certain period of photocatalysis, the residual concentration of the solution is measured by ultra-high performance liquid chromatography;

[0084] (4) The photocatalytic efficiency of the photocatalyst is characterized by the change in DCF concentration: (initial concentration - residual concentration) / initial concentration;

[0085] like Figure 4 As shown in the figure, with the increase of the amount of nanoparticles added in the solution, the degradation efficiency of the pollutant DCF by the coated permeable concrete gradually increased, reaching the highest at 0.04g / ml and decreasing at 0.05g / ml. This may be because excessive catalyst loading will lead to agglomeration, thereby limiting the generation of electron-hole pairs and reducing the photocatalytic efficiency. Therefore, keeping the catalyst dosage below the saturation threshold is the key to ensuring effective photon absorption and maximizing degradation performance.

[0086] Effect experiment 3: Pollutant removal effect of ZnS / ZnO photocatalytic permeable concrete at different pH values

[0087] The experimental steps are as follows:

[0088] (1) Prepare 2.5 mg / L DCF solution;

[0089] (2) The ZnS / ZnO photocatalytic permeable concrete prepared with a concentration of 0.04 g / ml was placed in the device. Figure 7 The device shown was added with 2.5 mg / L DCF solution, the pH was adjusted to 5, 6, 8, 9 by HCl and NaOH, and the xenon lamp was turned on to conduct the photocatalytic experiment;

[0090] (3) After a certain period of photocatalysis, the residual concentration of the solution is measured by ultra-high performance liquid chromatography;

[0091] (4) The photocatalytic efficiency of the photocatalyst is characterized by the change in DCF concentration: (initial concentration - residual concentration) / initial concentration; the results are as follows Figure 5 As shown;

[0092] ZnS / ZnO photocatalytic permeable concrete exhibited stable catalytic activity over a wide pH range (5-9) by adjusting the pH value through HCl and NaOH, which is contrary to the typical expectation that pH significantly affects chemical reactions. This unexpected behavior may be attributed to the immobilization of the photocatalyst on the concrete surface, which shields it from pH-induced changes. Previous studies have shown that pH can significantly affect the aggregation of photocatalyst particles in solution, affecting the degradation process. However, in this case, the immobilized nature of the photocatalyst offset the effect of pH on particle aggregation. The stability of ZnS / ZnO photocatalytic permeable concrete under different pH conditions highlights its practical application potential in stormwater runoff treatment.

[0093] Effect experiment 4: Photocatalytic performance of ZnS / ZnO photocatalytic permeable concrete after recycling;

[0094] In addition to high photocatalytic performance, the durability of photocatalytic permeable concrete is crucial for practical applications. The stability of the material's ability to degrade DCF was evaluated over multiple cycles.

[0095] The experimental steps are as follows:

[0096] (1) Prepare 2.5 mg / L DCF solution;

[0097] (2) Place ZnS / ZnO photocatalytic permeable concrete with a concentration of 0.04 g / ml into the device. Figure 7 As shown, 2.5 mg / L DCF solution was added, and the xenon lamp was turned on at pH = 7 to carry out photocatalytic experiments; each hour was a cycle, and a test was performed after each cycle. After each test, the sample was rinsed with pure water and placed in an oven at 60°C for 2 hours before being taken out.

[0098] (3) determining the residual concentration of the solution by ultra-high performance liquid chromatography;

[0099] (4) The photocatalytic efficiency of the photocatalyst is characterized by the change in DCF concentration: (initial concentration - residual concentration) / initial concentration; the results are as follows Figure 6 As shown;

[0100] like Figure 6 As shown in Figure 2, after 20 cycles, the DCF degradation efficiency gradually decreased from about 87% to 54%, which is due to the protection of the photocatalyst in the pores.

[0101] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0102] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the concept or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nano photocatalyst, characterized in that: include: ZnS / ZnO nanophotocatalyst was constructed by high-temperature calcination of ZnS in air.

2. A nano photocatalyst according to claim 1, characterized in that: The purity of the raw material ZnS is ≥99.9%.

3. The method for preparing a nano-photocatalyst according to claim 1 or 2, characterized in that: Specifically include: The raw material ZnS was heated to 800°C at a rate of 15°C / min in a muffle furnace and kept at this temperature for 2 hours. The temperature was then taken out, cooled to room temperature, ground through a 10 μm sieve, and a ZnS / ZnO nano-photocatalyst was obtained.

4. A concrete, characterized in that: The invention comprises the nano photocatalyst according to claim 1 or 2 or the ZnS / ZnO nano photocatalyst prepared according to claim 3.

5. The method for preparing concrete according to claim 4, characterized in that: Specifically include: A ZnS / ZnO nano-photocatalyst solution is prepared, and after ultrasonic dispersion, it is coated on the surface of uncured permeable concrete. A glass sheet is placed on the surface and cured at room temperature for several days to obtain highly efficient solar-active concrete.

6. A method for preparing concrete according to claim 5, characterized in that: The concentration of the ZnS / ZnO nano photocatalyst solution is 0-0.05 g / ml.

7. The method for preparing concrete according to claim 5, characterized in that: The concentration of the ZnS / ZnO nano photocatalyst solution is 0.03-0.04 g / ml.

8. The method for preparing concrete according to claim 5, characterized in that: The treatment temperature of the ultrasonic dispersion is 10-20° C. and the time is 10-40 min.

9. Use of the concrete according to claim 4 or the concrete prepared by any one of the preparation methods according to 5-8 in degrading the pharmaceutical pollutant diclofenac sodium.

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