Nano photocatalyst, concrete containing same and application thereof

Abstract

The present invention discloses a ZnS / ZnO nano-photocatalyst, concrete containing the same, and applications thereof. The present invention constructs the ZnS / ZnO nano-photocatalyst by calcining ZnS at high temperature under air; and then applies the ZnS / ZnO nano-photocatalyst to concrete. The nano-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 nano-photocatalytic material used is inexpensive, environmentally friendly, and has a good ability to degrade diclofenac sodium, an anti-inflammatory drug pollutant. After being used in permeable concrete, it has excellent solar activity and pollutant removal capabilities, and is particularly suitable for the field of sponge cities, effectively reducing difficult-to-degrade organic pollutants in rainwater runoff, and is of great significance to the improvement of urban water environment.

Description

Technical Field

[0001] The present 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 applications 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 cumulative properties, threatening public health and the sustainability of ecosystems. Thanks to the abundant pores in its structure, permeable concrete has excellent permeability, large specific surface area and biocompatibility, which provide 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 can also 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 environmental friendliness. However, in current heterogeneous photocatalysis, the metal photocatalyst TiO2 has a narrow absorption range and poor electron mobility, resulting in reduced stability in removing organic pollutants and limited mineralization efficiency. In addition, it can only degrade dye wastewater. Natural minerals can be obtained directly from nature and have the outstanding advantages of being low-cost and environmentally friendly. A necessary condition for photocatalytic reactions is the adsorption of target compounds. Due to their large surface area and strong adsorption capacity for pollutants, natural minerals can serve 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 that needs 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 its application. The photocatalyst designed in 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 good ability to degrade diclofenac sodium (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 sponge city field, effectively reduces difficult-to-degrade organic pollutants in rainwater runoff, and is of great significance to the improvement of urban water environment.

[0006] In order to achieve the above objectives, one of the objectives of the present invention is to provide a nano photocatalyst, comprising: constructing a ZnS / ZnO nano photocatalyst by calcining ZnS at high temperature in 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 ZnS / ZnO nano-photocatalysts.

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

[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 constant 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. Calcination at 800°C produces ZnO. This not only effectively promotes the interaction between ZnS and ZnO, forming a more stable structure, but also, compared to other treatment temperatures, helps increase the crystallinity of ZnS / ZnO particles, optimizes the material's light absorption and electron transfer properties, and thus enhances its photocatalytic activity. This temperature facilitates more efficient solar photocatalytic degradation of pollutants, especially organic pollutants, preferably DCF. It can fully utilize the photocatalytic performance of ZnS / ZnO while ensuring the material's crystallinity, stability, and catalytic activity, thereby optimizing its application in permeable concrete coatings.

[0012] A third object of the present invention is to provide 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, the method comprises: preparing a ZnS / ZnO nano-photocatalyst solution, dispersing the solution by ultrasonication, and coating the solution on the surface of uncured permeable concrete, placing a glass sheet on the surface and curing the solution 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 produced, it is necessary to explore the aging and falling 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. A coating thickness of the photocatalyst of about 2 mm or more can 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 polishing machine 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 nanophotocatalyst 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 readily available, to prepare a photocatalyst. The photocatalyst is then calcined in air for modification. The modified ZnS / ZnO nanoparticles are then loaded onto the surface and pores of permeable concrete to prepare a porous concrete natural mineral composite permeable paving material with high strength and water conductivity. This material not only utilizes visible light to catalytically degrade organic pollutants attached to the surface, but also solves urban waterlogging problems with its inherent water permeability. Furthermore, the material purifies surface runoff and avoids groundwater contamination, which plays an important role in promoting sponge city construction.

[0025] 2) The ZnS / ZnO nanoparticle photocatalyst prepared by the present invention was successfully loaded on the surface of permeable concrete. The ZnS / ZnO nanoparticle catalyst promoted the migration and separation of photoinduced carriers and reduced the complexation of photoinduced carriers.

[0026] 3) The highly efficient solar-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, making it 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0029] Figure 1 The attached figure shows the microstructure of ZnS / ZnO and the surface of ZnS / ZnO photocatalytic permeable concrete;

[0030] Figure 2 The accompanying drawings are comparative images 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 different calcination temperatures;

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

[0033] Figure 5 The attached figure shows the changes in the 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 the device for photocatalytic reduction of DCF in permeable concrete with ZnS / ZnO photocatalytic layer. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment discloses a concrete comprising 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 and conforms 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 the raw material.

[0046] The preparation method of ZnS / ZnO nanophotocatalyst 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 rate of 15 °C / min and kept constant for 2 h, then taken out and cooled to room temperature, ground and sieved to 10 μm to obtain 2.8 g of ZnS / ZnO nano-photocatalyst for use;

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

[0049] Step 1: Weigh the raw material components according to the above concrete ratio;

[0050] Step 2: Add coarse aggregate and cement into a container and mix them evenly, then add water and continue to mix 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 ultrasonically for 10 minutes, and then apply 0.3cm on the surface of uncured permeable concrete. The ultrasonic dispersion treatment temperature is 10-20°C and the time is 10-40 minutes.

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

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

[0055] Effect data test:

[0056] The microstructure of the materials 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 nanophotocatalyst:

[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. The temperature was then kept constant for 2 h, taken out, cooled to room temperature, ground, and sieved to 10 μm to prepare photocatalysts at different temperatures for later use.

[0062] The experimental steps are as follows:

[0063] (1) Prepare a 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 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 was measured using 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. The results are as follows 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 permeable concrete with ZnS / ZnO nanophotocatalyst at different concentrations.

[0069] The preparation method of photocatalytic permeable concrete at low concentration of ZnS / ZnO nanoparticles comprises the following steps:

[0070] Step 1: Calcination to prepare ZnS / ZnO nanophotocatalyst.

[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 and kept constant for 2 h, then taken out and cooled to room temperature, ground and sieved to 10 μm to prepare a photocatalyst for use;

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

[0073] Step 1: weigh the raw material components 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, dispersed by ultrasonic for 10 minutes, and then evenly coated on the concrete surface and pores with a brush to a coating thickness of 0.2 cm.

[0077] A 100-gram 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 peak 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 a 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 into the device, respectively. Figure 7 The device shown was added with 2.5 mg / L DCF solution and the xenon lamp was turned on for photocatalytic experiments;

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

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

[0085] like Figure 4 As shown in the figure, as the amount of nanoparticles added to the solution increases, the degradation efficiency of the pollutant DCF by the coated permeable concrete gradually increases, reaching a maximum at 0.04g / ml and decreasing slightly at 0.05g / ml. This may be because excessive catalyst loading causes agglomeration, which limits the generation of electron-hole pairs and reduces photocatalytic efficiency. Therefore, keeping the catalyst dosage below the saturation threshold is 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 a 2.5 mg / L DCF solution;

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

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

[0091] (4) The photocatalytic efficiency of the photocatalyst is characterized by the change of 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 with HCl and NaOH, 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 offsets 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 a 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 a xenon lamp was turned on at pH = 7 to conduct a photocatalytic experiment; 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 of 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 will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest possible manner consistent with the principles and novel features disclosed herein.

Claims

1. An application of concrete in degrading the pharmaceutical pollutant diclofenac sodium, characterized in that: The concrete includes ZnS / ZnO nano-photocatalyst; The ZnS / ZnO nano-photocatalyst is constructed by calcining ZnS at high temperature in air; The specific preparation method of the ZnS / ZnO nano-photocatalyst comprises: heating the raw material ZnS to 800°C in a muffle furnace at a heating rate of 15°C / min and maintaining the temperature for 2 hours, then taking it out, cooling it to room temperature, and grinding it through a 10 μm sieve to prepare the ZnS / ZnO nano-photocatalyst; The concrete is specifically prepared by preparing a ZnS / ZnO nanophotocatalyst solution, applying the solution to the surface of uncured permeable concrete after ultrasonic dispersion, placing a glass sheet on the surface and curing the solution at room temperature for several days to obtain solar-active concrete.

2. The use of concrete according to claim 1 in degrading the pharmaceutical pollutant diclofenac sodium, characterized in that: The purity of the raw material ZnS is ≥99.9%.

3. The use of concrete according to claim 1 in degrading the pharmaceutical pollutant diclofenac sodium, characterized in that: The concentration of the ZnS / ZnO nanometer photocatalyst solution is 0-0.05 g / ml, and is not 0.

4. The use of concrete according to claim 3 in degrading the pharmaceutical pollutant diclofenac sodium, characterized in that: The concentration of the ZnS / ZnO nanometer photocatalyst solution is 0.03-0.04 g / ml.

5. The use of concrete according to claim 1 in degrading the pharmaceutical pollutant diclofenac sodium, characterized in that: The ultrasonic dispersion treatment temperature is 10-20° C. and the time is 10-40 min.

Images