Sulfide nitride carbon photocatalyst loaded with solid waste metals, and preparation method and application thereof

Abstract

The application discloses a kind of solid waste metal-loaded sulfurized carbon nitride photocatalyst and its preparation method and application, preparation method adopts the following steps: electroplating sludge powder is added into acid solution, and leaching solution is obtained;Take melamine and add it into leaching solution, and obtain sulfurized melamine containing metal elements;Sulfurized melamine is calcined under H2 / Ar atmosphere condition, and light yellow powder is obtained;Finally, the light yellow powder is ball milled in dimethylformamide solution, and the sulfurized carbon nitride photocatalyst loaded with solid waste metal atoms is obtained.The application converts the metal recovered and extracted from solid waste into the active component of photocatalyst, which not only improves the performance of water splitting for hydrogen production, but also realizes the secondary use of electroplating sludge solid waste resources, saves cost, and has simple preparation process, and is worthy of popularization and application.

Description

Technical Field

[0001] This invention relates to the field of photocatalyst technology, specifically to a carbon sulfide nitride photocatalyst supported on solid waste metals, its preparation method, and its application. Background Technology

[0002] Photocatalysis is an emerging interdisciplinary research field, with photocatalytic materials at its core because they can convert solar energy into chemical energy under mild conditions. Under illumination, photocatalytic materials generate electrons and holes; electrons have strong reducing power, while holes have strong oxidizing power, thus enabling redox reactions. Photocatalytic materials have significant application value in areas such as photocatalytic water splitting for hydrogen production, carbon dioxide reduction, and the degradation of organic pollutants.

[0003] Hydrogen energy, with its renewable, clean, and efficient characteristics, is considered one of the environmentally friendly and sustainable alternatives to fossil fuels. In recent decades, photocatalytic water splitting for hydrogen production has received increasing attention as a clean, low-cost, and environmentally friendly method utilizing solar energy. In recent years, a new organic polymer semiconductor—graphitic carbon nitride—has been considered a novel visible light photocatalyst. Due to its significant advantages, such as simple preparation processes, a graphite-like layered structure, well-matched conduction and valence band positions, and stable chemical and physical properties, graphitic carbon nitride has rapidly become a research focus in photocatalysts. Among these, metal atoms, as active sites in photocatalysts for hydrogen production via water splitting (HER), are considered crucial factors in improving HER performance. Currently, most research on the modification of carbon nitride photocatalysts focuses on single noble metal doping, multi-noble metal doping, rare earth metal doping, or co-doping with noble and rare earth metals. However, the noble and rare earth metals used for doping are not only limited in source and difficult to obtain, but also expensive, preventing the large-scale production and application of photocatalysts prepared from them. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a carbon sulfide-nitrogenate photocatalyst loaded with solid waste metals, its preparation method, and its application. By converting metals recovered from solid waste into the active components of the photocatalyst, not only can the photocatalyst's performance in photocatalytic water splitting for hydrogen production be improved, but it can also realize the high-value application of solid waste. The extracted and recovered metals replace the use of important metals such as precious metals or rare earth metals, saving costs and making it worthy of widespread application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a method for preparing a carbon sulfide-nitride photocatalyst supported on solid waste metals, comprising the following steps:

[0007] (1) Add dry electroplating sludge powder to an acid solution, heat and stir to leach, and obtain leachate; add an appropriate amount of melamine to the leachate, and stir at room temperature to obtain sulfide melamine containing metal elements;

[0008] (2) The sulfide melamine containing metal elements was calcined in an atmosphere of H2 and Ar mixed gas, cooled and ground to obtain a light yellow powder.

[0009] (3) The light yellow powder was placed in a dimethylformamide solution and ball-milled, filtered, washed and dried to obtain a carbon sulfide photocatalyst loaded with solid waste metal.

[0010] Preferably, in step (1), the particle size of the electroplating sludge powder is 200-300 mesh.

[0011] Preferably, in step (1), the metal content of the electroplating sludge powder is 20-30 wt%, and the metal element includes one or two of Fe and Al.

[0012] Preferably, in step (1), the acid solution is one or a mixture of several of the following: nitric acid solution, dilute sulfuric acid solution, and hydrochloric acid solution, and the concentration of the acid solution is 3 to 6 mol / L.

[0013] Preferably, in step (1), the leaching temperature is 50-70°C and the leaching time is 5-8 hours.

[0014] Preferably, in step (1), the ratio of melamine to leachate is 0.8-1.5 mg: 15-20 μL.

[0015] Preferably, in step (2), the H2 / Ar ratio in the H2 and Ar mixture is 5% to 20%.

[0016] Preferably, in step (2), the calcination temperature is 450-500℃ and the calcination time is 3-5h.

[0017] In another aspect, the present invention provides a carbon sulfide nitride photocatalyst supported on solid waste metals, which is prepared by the above-described method for preparing the carbon sulfide nitride photocatalyst supported on solid waste metals.

[0018] Another aspect of the present invention provides the application of a carbon sulfide-nitrogenate photocatalyst supported on solid waste metals, wherein the carbon sulfide-nitrogenate photocatalyst is applied to a photocatalytic water splitting reaction to produce hydrogen under neutral conditions.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] Solid wastes such as electroplating sludge generated during steel production contain various metallic elements and inorganic compounds. These sludges must undergo special treatment before discharge; otherwise, they will cause significant heavy metal pollution to the environment. This invention utilizes acid leaching to extract metallic elements from the electroplating sludge. Simultaneously, sulfur in the leachate is used to sulfide melamine, forming melamine sulfide. Metal elements are then incorporated into the melamine sulfide through stirring and adsorption, resulting in melamine sulfide containing metallic elements. This melamine sulfide is then calcined and ground in a dimethylformamide solution to ultimately obtain a carbon nitride photocatalyst loaded with metallic elements from the solid waste. The preparation process is simple, easy to operate, and readily scalable. It not only achieves the secondary utilization of electroplating sludge but also uses recovered iron and aluminum to replace precious or rare earth metals, saving costs and making it worthy of widespread application.

[0021] The solid waste metal-doped carbon nitride photocatalyst synthesized in this invention differs from existing photocatalysts that use ordinary melamine. This technology utilizes sulfur from the leachate of solid waste sludge to sulfide melamine, forming sulfur-carrying melamine sulfide. Using this sulfur-carrying melamine as a supported precursor, the introduction of sulfur atoms and metal elements significantly increases the carrier concentration of the photocatalyst, enhancing the transfer, separation, oxidation, and reduction capabilities of photogenerated electron-hole pairs, thereby greatly improving its catalytic performance in photocatalytic water splitting for hydrogen production. Furthermore, due to the introduction of sulfur atoms and metal elements, this photocatalyst exhibits high absorption performance in the ultraviolet and visible light regions, making its light-capturing ability more sensitive, its activity higher, and its catalytic efficiency better.

[0022] The solid waste metal-doped carbon sulfide and nitride photocatalyst synthesized in this invention is calcined in a mixed gas of H2 and Ar in different proportions. As the proportion of hydrogen increases, the metal-doped carbon sulfide and nitride will gradually separate and peel off. Attached Figure Description

[0023] Figure 1 XRD patterns of the carbon sulfide nitride photocatalysts supported on solid waste metals prepared in Examples 1, 2, and 3, and the catalyst obtained in Comparative Example 1;

[0024] Figure 2 Transmission electron microscope (TEM) images of the carbon sulfide nitride photocatalysts loaded with solid waste metals prepared in Examples 1, 2, and 3, and the catalyst obtained in Comparative Example 1 (a is Comparative Example 1; b is Example 1; c is Example 2; d is Example 3).

[0025] Figure 3 The graph shows the performance of the carbon sulfide and carbon nitride photocatalysts supported on solid waste metals prepared in Examples 1, 2, and 3, and the catalyst obtained in Comparative Example 1 in HER.

[0026] Figure 4 This study examines the recyclability of the carbon sulfide nitride photocatalyst loaded with solid waste metals prepared in Example 2 under visible light photocatalytic hydrogen evolution cycle.

[0027] Figure 5 The images show the electron paramagnetic resonance (EPR) diagrams of the carbon sulfide nitride photocatalyst (S-CN) supported on solid waste metal prepared in Example 2 and Comparative Example 1 (CN).

[0028] Figure 6 The UV-Vis diffuse reflectance (DRS) spectra of the carbon sulfide nitride photocatalyst (S-CN) supported on solid waste metal prepared in Example 2 and Comparative Example 1 (CN) are shown.

[0029] Figure 7 The Fourier transform infrared (FTIR) spectra of the carbon sulfide nitride photocatalyst (S-CN) supported on solid waste metal prepared in Example 2 and Comparative Example 1 (CN) are shown. Detailed Implementation

[0030] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments can be purchased through conventional commercial channels unless otherwise specified. In some specific embodiments of the present invention, the electroplating sludge powder is derived from electroplating sludge generated during steel production, and its main components after drying include the following components by mass fraction:

[0032]

[0033] The rest are unavoidable impurities.

[0034] This invention provides a method for preparing a carbon sulfide-nitride photocatalyst supported on solid waste metals. The specific overall process is as follows:

[0035] (1) Dry and crush the electroplating sludge solid waste into powder. Weigh 100g of electroplating sludge powder sieved to 200-300 mesh and add it to a prepared 3-6mol / L acid solution. Stir in a water bath at 50-70℃ for 5-8h, and then filter to obtain a leachate. Take 1-2g of melamine and add it to 20-40ml of the leachate. Stir at room temperature for 7-10h to obtain sulfide melamine containing metal elements. In some specific embodiments of the present invention, the acid solution is one or a mixture of several of nitric acid solution, dilute sulfuric acid solution, and hydrochloric acid solution; the metal element includes one or two of Fe and Al.

[0036] (2) The sulfurized melamine containing metallic elements was calcined in a tube furnace under different proportions of H2 and Ar mixed gas atmosphere, cooled, and ground to obtain a light yellow powder. In some specific embodiments of the present invention, the H2 / Ar ratio in the H2 and Ar mixed gas was 5%–20%; the calcination temperature was 500℃; and the calcination time was 3 hours. ICP (Inductively Coupled Plasma Atomic Emission Spectrometry) analysis of the light yellow powder showed that it contained 0.59 wt% S, 0.12 wt% Al, and 0.73 wt% Fe, with the remainder being other elements or metallic elements, such as Ca.

[0037] (3) The light yellow powder obtained in step (2) is added to dimethylformamide (DMF) solution and ball-milled in a planetary ball mill. The ball-to-material ratio is 1:200, the rotation speed is 300-400 rpm, and after ball milling for 2-3 hours, it is dried to obtain carbon sulfide nitride photocatalyst loaded with solid waste metal, i.e., photocatalyst.

[0038] This invention also provides an application of the carbon sulfide nitride photocatalyst prepared by the above-mentioned method for preparing carbon sulfide nitride photocatalyst supported on solid waste metals, specifically applied to the photocatalytic water splitting to produce hydrogen under neutral conditions.

[0039] The present invention will be further described below with reference to specific embodiments, but is not limited thereto.

[0040] Example 1

[0041] This embodiment provides a method for preparing a carbon sulfide-nitride photocatalyst supported on solid waste metals, specifically including the following steps:

[0042] (1) Dry and crush the electroplating sludge solid waste into powder, weigh 100g of electroplating sludge powder sieved to 200 mesh and add it to the prepared 3mol / L nitric acid solution, stir in a water bath at 60℃ for 5h, and then filter to obtain leachate; take 1g of melamine and add it to 20ml of the leachate, stir at room temperature for 8h to obtain sulfide melamine containing Fe and Al metal elements;

[0043] (2) The sulfurized melamine containing Fe and Al metal elements was calcined in a tube furnace at 500°C for 3 hours under a 5% H2 / Ar mixed gas atmosphere, and then cooled and ground to obtain a light yellow powder.

[0044] (3) The light yellow powder obtained in step (2) is added to the DMF solution and ball-milled in a planetary ball mill at a speed of 300 rpm for 3 hours. After ball milling, it is dried to obtain a carbon sulfide nitride photocatalyst loaded with solid waste metal, which is denoted as photocatalyst 1.

[0045] Example 2

[0046] This embodiment provides a method for preparing a carbon sulfide-nitride photocatalyst supported on solid waste metals, specifically including the following steps:

[0047] (1) Dry and crush the electroplating sludge solid waste into powder, weigh 100g of solid waste powder sieved to 250 mesh and add it to the prepared 5mol / L nitric acid solution, stir in a water bath at 60℃ for 6.5h, and then filter to obtain leachate; take 1g of melamine and add it to 20mL of the leachate and stir at room temperature for 8 hours to obtain sulfide melamine containing Fe and Al metal elements;

[0048] (2) The sulfurized melamine containing Fe and Al metal elements was calcined in a tube furnace at 500°C for 3 hours under a 10% H2 / Ar mixed gas atmosphere, and then cooled and ground to obtain a light yellow powder.

[0049] (3) The light yellow powder obtained in step (2) is added to the DMF solution and ball-milled in a planetary ball mill at a speed of 300 rpm for 3 hours. After ball milling, it is dried to obtain the carbon sulfide nitride photocatalyst loaded with solid waste metal, which is denoted as photocatalyst 2.

[0050] Example 3

[0051] This embodiment provides a method for preparing a carbon sulfide-nitride photocatalyst supported on solid waste metals, specifically including the following steps:

[0052] (1) Dry and crush the electroplating sludge solid waste into powder, weigh 100g of electroplating sludge powder sieved to 300 mesh, add it to the prepared 6mol / L nitric acid solution, stir in a water bath at 60℃ for 8h, and then filter to obtain leachate; take 1g of melamine and add it to 20mL of the leachate and stir at room temperature for 8h to obtain sulfide melamine containing Fe and Al metal elements;

[0053] (2) The sulfurized melamine containing Fe and Al metal elements was calcined in a tube furnace at 500°C for 3 hours under a 20% H2 / Ar mixed gas atmosphere, and then cooled and ground to obtain a light yellow powder.

[0054] (3) The light yellow powder obtained in step (2) is added to the DMF solution and ball-milled in a planetary ball mill at a speed of 300 rpm for 3 hours. After ball milling, it is dried to obtain a carbon sulfide nitride photocatalyst loaded with solid waste metal, which is denoted as photocatalyst 3.

[0055] Comparative Example 1

[0056] This comparative example provides a method for preparing a carbon nitride photocatalyst for water splitting to produce hydrogen. The main difference between this method and Example 1 is that it does not add electroplating sludge solid waste. The method specifically includes the following steps:

[0057] (1) Take 1g of melamine and place it in a crucible, then transfer it to a box furnace and calcine it at 500℃ for 3h to obtain carbon nitride;

[0058] (2) Take 100 mg of carbon nitride obtained in step (1) and add it to DMF solution. Then, ball mill it in a planetary ball mill at a speed of 300 rpm for 3 hours. After ball milling, dry it to obtain powder, which is denoted as catalyst 4.

[0059] The catalyst obtained above was subjected to performance testing. The specific testing procedure is as follows:

[0060] (1) Weigh 10 mg of the catalyst powder obtained in Examples 1, 2 and 3 respectively, add 0.2 mg of platinum acid, 16 mL of deionized water and 4 mL of methanol sacrificial agent to each part of the catalyst powder, and sonicate at room temperature for 1 hour to obtain a uniformly dispersed catalyst suspension.

[0061] (2) Weigh 10 mg of the catalyst powder obtained in Comparative Example 1, add 0.2 mg of platinum acid, 16 ml of deionized water and 4 mL of methanol sacrificial agent respectively, and sonicate at room temperature for 1 hour to obtain a uniformly dispersed catalyst suspension.

[0062] (3) In the HER performance test, the suspension obtained in step (1) and step (2) are compared and tested. The specific experimental method is as follows: First, the suspension is poured into a high-transmittance quartz reactor, then the impurity gas is removed by purging with nitrogen and vacuuming. This is repeated three times. The reactor is irradiated with sunlight for 4 hours by simulating sunlight through a 300W xenon lamp to realize the photocatalytic water splitting to hydrogen production reaction system of the catalyst.

[0063] (4) Every hour, the gas generated in the reactor in step (3) is extracted, and then the collected gas is qualitatively and quantitatively analyzed using a TCD detector in a gas chromatograph, such as... Figure 3As can be seen, the HRE catalyst prepared in Example 2 has better performance than that prepared in Examples 1 and 3, and the performance of the catalysts obtained in Examples 1-3 is significantly higher than that of catalyst 4 obtained in Comparative Example 1. Among them, the hydrogen production yield of catalyst 2 in Example 2 is 27.34 mmol·g. -1 ·h -1 The hydrogen production yield of catalyst 1 in Example 1 was 18.38 mmol·g. -1 ·h -1 The hydrogen production yield of catalyst 3 in Example 3 was 16.26 mmol·g. -1 ·h -1 The hydrogen production yield of catalyst 4 in Comparative Example 1 was 3.23 mmol·g. -1 ·h -1 The performance of HRE catalyst 2 prepared in Example 2 is much higher than that of catalyst 4 prepared in Comparative Example 1. Its hydrogen yield is increased by 8.5 times compared with Comparative Example 1, indicating that the carbon nitride photocatalyst prepared by supporting solid waste metal with melamine sulfide can significantly improve the performance of photocatalytic water splitting to produce hydrogen.

[0064] Conclusions and analysis of the catalyst:

[0065] (1) Figure 2 The morphological characteristics of the photocatalysts obtained in various embodiments and comparative examples of the present invention are shown. Figure 2 (b)(c)(d) It can be seen that as the proportion of hydrogen increases, the metal-doped carbon sulfide and carbon nitride photocatalysts in the embodiments gradually separate and peel off.

[0066] (2) Figure 5 The figures show the electron paramagnetic resonance (EPR) images of the carbon sulfide nitride photocatalyst (S-CN) supported on solid waste metal prepared in Example 2 and Comparative Example 1 (CN). The figures show that the introduction of S atoms and metal elements into the photocatalyst of Example 2 creates defective oxygen vacancies, significantly increasing the carrier concentration and improving the transfer, separation, oxidation, and reduction capabilities of photogenerated electron-hole pairs.

[0067] (3) Figure 6The UV-Vis diffuse reflectance (DRS) spectra of the carbon sulfide nitride photocatalyst (S-CN) supported on solid waste metals prepared in Example 2 and Comparative Example 1 (CN) are shown. The figures demonstrate that photocatalyst S-CN exhibits high absorption performance in the UV region below 400 nm, showing good absorption performance for UV light. In the visible light region above 400 nm, due to the introduction of S atoms and metal elements, the absorption band intensity of photocatalyst S-CN increases, and its visible light absorption region is larger than that of catalyst CN in Comparative Example 1. This indicates that photocatalyst S-CN has stronger absorption performance for visible light than catalyst CN, meaning that photocatalyst S-CN is more sensitive to light capture, resulting in better catalytic efficiency.

[0068] (4) Figure 7 The Fourier transform infrared (FTIR) spectra of the carbon sulfide nitride photocatalyst (S-CN) supported on solid waste metals prepared in Example 2 and Comparative Example 1 (CN) are shown. The S-CN and CN structures exhibit FTIR values ​​in the 1100–1600 cm⁻¹ range. -1 Vibrational peaks typical of triazine heterocyclic structures can be observed, specifically at 1613 cm⁻¹. -1 Tensile vibrations of the CN bonds at 1250, 1333 and 1365 cm⁻¹ -1 The aromatic CN bond stretching vibration at 1615 cm -1 SCN bond tensile vibrations at 1262, 1322 and 1362 cm⁻¹ -1 The aromatic SCN tensile vibration at 810 cm⁻¹. Furthermore, at 810 cm⁻¹... -1 A significant triazine bending vibration peak can be observed at 3000–3700 cm⁻¹. -1 The stretching vibration peak of NH can be observed. The above infrared analysis results indicate that both substances contain extended C=N triazine rings. Moreover, the infrared absorption peak of S-CN is significantly narrower than that of ordinary CN, indicating that it has better crystallinity, a wider range of delocalized π bonds in its structure, better electron mobility, and thus stronger oxidation and reduction capabilities.

[0069] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a solid waste metal-loaded carbon nitride sulfide photocatalyst, characterized by, The method comprises the following steps: (1) adding dry electroplating sludge powder into an acid solution, heating and stirring to leach, to obtain a leaching solution; adding an appropriate amount of melamine into the leaching solution, and sulfidizing the melamine by using sulfur in the leaching solution, to obtain sulfurized melamine containing metal elements under stirring at room temperature; wherein the electroplating sludge powder contains 47.22% of SO3 by mass fraction; the metal elements include one or both of Fe and Al; (2) calcining the sulfurized melamine containing metal elements under the atmosphere of a mixed gas of H2 and Ar, cooling and grinding, to obtain a light yellow powder; (3) placing the light yellow powder into a dimethylformamide solution for continuous ball milling, filtering, washing and drying, to obtain a solid waste metal-loaded sulfurized nitrided carbon photocatalyst.

2. The method for preparing the carbon sulfide-nitride photocatalyst supported on solid waste metals according to claim 1, characterized in that, In the step (1), the particle size of the electroplating sludge powder is 200-300 mesh.

3. The method for preparing the carbon sulfide-nitride photocatalyst supported on solid waste metals according to claim 1, characterized in that, In the step (1), the content of metal elements in the electroplating sludge powder is 20-30 wt%.

4. The method for preparing the carbon sulfide-nitride photocatalyst supported on solid waste metals according to claim 1, characterized in that, In the step (1), the acid solution is one or a mixture of several of nitric acid solution, dilute sulfuric acid solution and hydrochloric acid solution, and the concentration of the acid solution is 3-6 mol / L.

5. The method for preparing the carbon sulfide-nitride photocatalyst supported on solid waste metals according to claim 1, characterized in that, In the step (1), the leaching temperature is 50-70℃, and the leaching time is 5-8 h.

6. The method for preparing the carbon sulfide-nitride photocatalyst supported on solid waste metals according to claim 1, characterized in that, In the step (1), the ratio of the amount of melamine to the amount of leaching solution is 0.8-1.5 mg: 15-20 μL.

7. The method for preparing the carbon sulfide-nitride photocatalyst supported on solid waste metals according to claim 1, characterized in that, In the step (2), the ratio of H2 / Ar in the mixed gas of H2 and Ar is 5%-20%.

8. The method for preparing the carbon sulfide-nitride photocatalyst supported on solid waste metals according to claim 1, characterized in that, In the step (2), the calcination temperature is 450-500℃, and the calcination time is 3-5 h.

9. A nitrogen-sulfide-carbon nitride photocatalyst loaded with solid waste metals, characterized by, The solid waste metal-loaded sulfurized nitrided carbon photocatalyst is prepared by the method of any one of claims 1-8.

10. Use of the metal-loaded solid waste sulfide nitride carbon photocatalyst according to claim 9, characterized by, The sulfurized nitrided carbon photocatalyst is applied to a photocatalytic water decomposition reaction for hydrogen production under neutral conditions, wherein the sulfurized nitrided carbon photocatalyst is in the form of a uniformly dispersed catalyst suspension for the hydrogen production reaction.

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