A method for preparing a Bi2S3 / UiO-66-NH2 nanocomposite material integrating adsorption / photocatalysis and its application in methanethiol removal.

Abstract

This invention discloses a method for preparing a Bi₂S₃ / UiO-66-NH₂ nanocomposite material integrating adsorption / photocatalysis and its application in methanethiol removal. Using amino-modified UiO-66-NH₂ as the adsorbent, it is in-situ loaded onto the surface of the semiconductor photocatalyst Bi₂S₃ via a solvothermal method to construct a Zr-O-Bi bonded structure, exhibiting both porous adsorption and photocatalytic properties. This invention solves the problem of easy powder loss and difficult recycling by using agarose gel molding. The nanocomposite material utilizes the UiO-66-NH₂ on its surface to enrich methanethiol, while Bi₂S₃, under light irradiation, is excited to generate active free radicals to achieve in-situ degradation. The adsorption-photocatalysis synergistic effect is significant, exhibiting excellent removal efficiency and cycle stability for methanethiol. It can be widely used for odor gas purification in industrial waste gas, landfills, sewage treatment plants, and other scenarios, showing good engineering application prospects.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials and air pollution control technology, specifically involving a method for preparing a Bi2S3 / UiO-66-NH2 nanocomposite material with dual adsorption / photocatalytic functions, and its application in the degradation and removal of odorous pollutant methanethiol. Background Technology

[0002] Methanethiol, a typical volatile sulfur-containing odorous organic pollutant, has an extremely low olfactory threshold and a strong, irritating odor; even trace amounts can cause significant discomfort to humans. Its sources include natural emissions from the decomposition of plant and animal remains by microorganisms, as well as anthropogenic emissions from industrial waste gases, landfills, and sewage treatment plants. Uncontrolled emissions of methanethiol not only irritate the eyes, respiratory tract, and skin mucous membranes, causing dizziness and nausea, but at high concentrations, it can also suppress the central nervous system and endanger life. Furthermore, its acidic nature easily corrodes industrial pipes and equipment, and its sulfur groups can cause sulfur poisoning and deactivation of catalysts. It can also exacerbate environmental acidification and ecological damage by forming acidic substances with rainwater. Existing methanethiol treatment technologies generally suffer from high operating costs, complex processes, limited removal efficiency, and the potential for secondary pollution, making it difficult to meet the demands for efficient, stable, and long-term treatment under actual working conditions. Therefore, developing a new methanethiol purification technology that is simple, environmentally friendly, and recyclable is of significant practical importance for the prevention and control of atmospheric odor pollution, ecological environmental protection, and public health safeguards.

[0003] Currently, various removal technologies have been developed both domestically and internationally, but they still generally suffer from problems such as high cost, complex processes, low efficiency, and the potential for secondary pollution. To effectively address the limitations of single removal methods, coupling different removal methods has become an important approach to improving removal efficiency.

[0004] Among various removal methods, adsorption is the most widely used. Its core principle is to remove pollutants through two modes of action: physical adsorption and chemical adsorption, which occur between the adsorbent and methanethiol molecules. Physical adsorption relies on intermolecular forces to achieve reversible adsorption, while chemical adsorption achieves efficient removal by forming irreversible chemical bonds between the metal active sites on the material surface and the thiol groups of methanethiol. Porous materials such as carbon-based materials, zeolites, and metal-organic frameworks are commonly used in the field of methanethiol adsorption. This type of technology has advantages such as simple operation, wide applicability, and good short-term purification effect. However, it also has problems such as limited adsorption capacity, easy saturation, difficult regeneration, and poor cycle stability. Metal oxide adsorbents are also prone to structural damage and deactivation during the reaction process.

[0005] Photocatalysis, as a novel green pollution control method, relies on light to excite semiconductor materials to generate electron-hole pairs, producing highly reactive oxidizing species such as holes, superoxide radicals, and hydroxyl radicals, which oxidize and degrade methanethiol into smaller molecule products. It boasts significant advantages such as mild reaction conditions, environmental friendliness, and no secondary pollution. However, traditional photocatalytic materials generally suffer from low specific surface area, weak adsorption and enrichment capacity, and easy particle aggregation, resulting in insufficient methanethiol capture efficiency and rapid recombination rate of photogenerated carriers, directly limiting their actual degradation efficiency and engineering application potential. Therefore, constructing an adsorption-photocatalysis coupled system, utilizing the adsorption and enrichment capacity of porous materials to increase local pollutant concentration, and combining this with in-situ photocatalytic degradation to regenerate adsorption sites, can achieve long-term and stable removal of pollutants, and is currently a research hotspot in the field of methanethiol control. Summary of the Invention

[0006] The purpose of this invention is to provide a Bi2S3 / UiO-66-NH2 nanocomposite material with both adsorption and photocatalytic functions, which has a good removal effect on the organic odor pollutant methanethiol, and thus has broad practical and economic value.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A Bi₂S₃ / UiO-66-NH₂ nanocomposite material with dual adsorption / photocatalytic functions was prepared by first synthesizing UiO-66-NH₂, using thiourea as the sulfur source and bismuth pentahydrate as the bismuth source; thiourea was added to deionized water and stirred to dissolve to obtain solution A; the pre-synthesized UiO-66-NH₂ and bismuth pentahydrate were dispersed in urea-containing deionized water and stirred to obtain suspension B; solution A was slowly added dropwise to suspension B and stirred to carry out a solvothermal reaction; and then the mixture was centrifuged, washed, and vacuum dried to obtain Bi₂S₃ / UiO-66-NH₂ nanocomposite materials with different ratios.

[0008] Furthermore, the amount of both thiourea and bismuth nitrate pentahydrate added is 4 mmol, and the molar ratio between the two is 1:1.

[0009] Furthermore, by adjusting the amount of UiO-66-NH2 added, composite materials with different component ratios were prepared and named BSUN-100, BSUN-200, and BSUN-300, respectively.

[0010] Furthermore, 20 mL of deionized water was used to prepare the thiourea precursor solution, and 40 mL of urea-containing deionized water was used to prepare the bismuth-containing and UiO-66-NH2 mixed suspension. The concentration of the urea solution was 1.0 mol / L.

[0011] Furthermore, after the thiourea solution was added dropwise to the mixed suspension, the mixture was stirred at a constant temperature for 40 minutes.

[0012] Furthermore, the solvothermal reaction is controlled at a temperature of 120 °C and the reaction time is 12 h.

[0013] Furthermore, the reaction product was washed by alternating centrifugation with anhydrous ethanol and ultrapure water, and the vacuum drying temperature was set at 50 °C for 12 h.

[0014] The Bi2S3 / UiO-66-NH2 nanocomposite material can be used to remove harmful pollutants, especially methanethiol.

[0015] Furthermore, its application method involves encapsulating and fixing the Bi2S3 / UiO-66-NH2 nanocomposite material inside an agarose gel for efficient removal of methanethiol under light irradiation.

[0016] Furthermore, the immobilization process involves dispersing 20 mg of the nanocomposite material in 20 mL of deionized water, heating it to 85 °C, adding 0.5 g of agar powder and stirring to form a hot melt. The hot melt is then poured into a petri dish with a diameter of 8.5 cm and cooled to room temperature to solidify, resulting in an agarose gel immobilized sample Bi2S3 / UiO-66-NH2 / AGE.

[0017] Furthermore, the light source used during illumination is 24W of visible light.

[0018] Agarose gel and nanocomposite materials exhibit excellent encapsulation, high light transmittance, and strong mechanical stability. This invention, by immobilizing Bi₂S₃ / UiO-66-NH₂ nanocomposite materials within agarose gel, enables the removal of methanethiol-related pollutants via visible light irradiation. This invention provides mild and stable pollutant removal conditions, eliminates the need for high temperature and pressure, and utilizes low-cost curing carrier materials, thus possessing broad practical and economic value.

[0019] The advantages of this invention are: (1) The Bi2S3 / UiO-66-NH2 nanocomposite material obtained in this invention has both adsorption enrichment and photocatalytic degradation properties. The heterojunction structure effectively improves the separation efficiency of photogenerated carriers, and removes methanethiol efficiently, stably, and in a green and pollution-free manner. (2) The present invention can achieve efficient removal of methanethiol within 60 min, while exhibiting excellent circulation performance; (3) This invention uses visible light for photocatalysis, which results in low reaction cost and simple and mild reaction conditions; (4) The preparation process of the catalytic material of the present invention is simple, the agarose gel molding operation is easy, the material is not easily lost, and it is easy to recycle and reuse, and has broad application prospects. Attached Figure Description

[0020] Figure 1 The images show the XRD patterns of the Bi2S3 / UiO-66-NH2 nanocomposite materials and single materials with different molar ratios in Example 1 of this invention.

[0021] Figure 2 SEM images of the BSUN-200 nanocomposite material in Example 1 and the Bi2S3 material in Comparative Example 1 of the present invention; (a) Bi2S3, (b) BSUN-200 nanocomposite material.

[0022] Figure 3 This is a TEM image of the BSUN-200 nanocomposite material with the optimal molar ratio in Example 1 of the present invention.

[0023] Figure 4 DRS diagrams of Bi2S3 / UiO-66-NH2 nanocomposite material and single material prepared in Example 1 of this invention.

[0024] Figure 5 BET diagrams of Bi2S3 / UiO-66-NH2 nanocomposite materials prepared in Example 1 of this invention: (a) Bi2S3, (b) BSUN-100, (c) BSUN-200, (d) BSUN-300.

[0025] Figure 6 XPS plot of the BSUN-200 nanocomposite material with the optimal molar ratio in Example 1 of this invention.

[0026] Figure 7 The images show the physical appearance (left) and the petri dish (right) of the BSUN-200 / AGE composite material sample immobilized by agarose gel in this invention.

[0027] Figure 8 The graph shows the adsorption-photocatalytic synergistic removal performance of methanethiol by the BSUN-X (X=100, 200 and 300) series composite materials in Example 1 of this invention.

[0028] Figure 9 This is a diagram showing the cyclic stability of the BSUN-X series composite material in Example 1 of the present invention for removing methanethiol.

[0029] Figure 10 Adsorption performance of materials prepared with different components for methanethiol under dark conditions. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the preparation and testing methods used in the present invention are conventional methods in the art.

[0031] A method for preparing a Bi2S3 / UiO-66-NH2 nanocomposite material with both adsorption and photocatalytic functions includes the following steps: 1) Preparation of UiO-66-NH2 precursor: Amino-modified metal-organic framework UiO-66-NH2 material was pre-synthesized by a solvothermal method; 2) Preparation of Bi2S3 / UiO-66-NH2 composite material: Thiourea was used as the sulfur source and bismuth pentahydrate was used as the bismuth source. Thiourea was added to deionized water and stirred to dissolve to obtain solution A. The pre-synthesized UiO-66-NH2 and bismuth pentahydrate were dispersed in urea-containing deionized water and stirred to obtain suspension B. Solution A was slowly added dropwise to suspension B and stirred to carry out a solvothermal reaction. After centrifugation, washing and vacuum drying, Bi2S3 / UiO-66-NH2 nanocomposites with different molar ratios were obtained. 3) Immobilization and molding of agarose gel: The prepared Bi2S3 / UiO-66-NH2 nanocomposite material was dispersed in hot water, agar powder was added to prepare a hot melt gel, and the sample was cooled and solidified to obtain the Bi2S3 / UiO-66-NH2 / AGE immobilized sample.

[0032] The dosage of thiourea and bismuth nitrate pentahydrate was 4 mmol each, with a molar ratio of thiourea to bismuth nitrate pentahydrate of 1:1; the concentration of the urea aqueous solution was 1.0 mol / L; the solvothermal reaction temperature was 120 ℃, the reaction time was 12 h; the vacuum drying temperature was 50 ℃, and the drying was carried out overnight.

[0033] To make the content of this invention easier to understand, the technical solution of this invention will be further described below in conjunction with specific embodiments, but this invention is not limited thereto.

[0034] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods. Example 1

[0035] The specific steps for preparing a Bi2S3 / UiO-66-NH2 nanocomposite material with both adsorption and photocatalytic functions are as follows: (1) Preparation of UiO-66-NH2 precursor: Weigh 420 mg ZrCl4 and an equal amount of 2-aminoterephthalic acid (326.5 mg), add to 50 mL DMF, and add 5 mL glacial acetic acid while magnetically stirring. Stirring continues for 1 h to ensure complete dissolution of the raw materials. The solution is then transferred to a reactor and reacted at 130 ℃ for 12 h, followed by cooling to room temperature. The sample is washed three times by centrifugation using DMF and anhydrous methanol, and then vacuum dried overnight to obtain the final powder sample.

[0036] (2) Preparation of solution A: Weigh 0.3045 g (4 mmol) of thiourea, add 20 mL of deionized water, and stir until completely dissolved; (3) Preparation of suspension B: Weigh 1.94 g (4 mmol) of bismuth nitrate pentahydrate and disperse it with a quantitative amount of UiO-66-NH2 in 40 mL of 1.0 mol / L urea aqueous solution, and stir evenly; (4) Solvent thermal compounding: Slowly add solution A to suspension B, stir continuously for 40 min, transfer to high pressure reactor, and react at 120 ℃ for 12 h; (5) Post-treatment: Natural cooling, alternating centrifugal washing with anhydrous ethanol and ultrapure water, vacuum drying at 50 ℃ overnight; By adjusting the amount of UiO-66-NH2 added, three different molar ratios of Bi2S3 / UiO-66-NH2 nanocomposites, namely BSUN-100, BSUN-200, and BSUN-300, were prepared respectively. In BSUN-X (X=100, 200, 300), X represents the mass of UiO-66-NH2 added during the synthesis of Bi2S3. The mass of UiO-66-NH2 added was obtained by molar ratio conversion. The molar ratio of Bi2S3 to UiO-66-NH2 corresponding to BSUN-100 is 2:0.06. According to UiO-66-NH2 (1667.72 The average molar mass of UiO-66-NH2 (g / mol) is converted to 100 mg. Similarly, the molar ratio of BSUN-200 is 2:0.12, which is equivalent to 200 mg of UiO-66-NH2. The molar ratio of BSUN-300 is 2:0.18, which is equivalent to 300 mg of UiO-66-NH2.

[0037] XRD tests were performed on the obtained BSUN-100, BSUN-200, and BSUN-300 composite materials. The results are shown in the figure. Figure 1 .Depend on Figure 1 As can be seen, all three samples with different ratios simultaneously exhibited characteristic diffraction peaks for Bi2S3 and UiO-66-NH2, with no obvious impurity peaks, indicating that the two-phase composite nanomaterials were successfully prepared.

[0038] The obtained optimal BSUN-200 composite material was subjected to SEM testing, and the results are shown in the figure. Figure 2 .Depend on Figure 2 As can be seen, Bi2S3 exhibits a needle-like self-assembled flower-shaped structure. Figure 2 In the middle (a), UiO-66-NH2 octahedral particles are uniformly dispersed on the surface and in the gaps ( Figure 2 (b)

[0039] The obtained BSUN-200 composite material was subjected to TEM testing, and the results are shown below. Figure 3 .Depend on Figure 3 As can be seen, the two-phase interface is tightly bonded, and the heterojunction structure has been successfully constructed.

[0040] The obtained BSUN-200 composite material was subjected to DRS testing, and the results are shown in the figure. Figure 4 .Depend on Figure 4 It is evident that the visible light absorption range of the composite material is significantly broadened, and its visible light response capability is improved. With increasing UiO-66-NH2 content, the absorption intensity of the material gradually increases across the entire visible light region, indicating that an appropriate composite ratio helps optimize light absorption performance. This is attributed to the heterojunction interface formed between the two components promoting the generation and transfer of photogenerated carriers, while the porous structure of UiO-66-NH2 enhances multiple scattering and absorption of light.

[0041] BET tests were performed on the obtained BSUN-100, BSUN-200, and BSUN-300 composite materials. The results are shown in the table below. Figure 5 .Depend on Figure 5 This indicates that with the addition of UiO-66-NH2, the specific surface area gradually increases and the pore structure becomes richer, which can provide more active sites for the adsorption of methanethiol.

[0042] XPS tests were performed on the obtained BSUN-200 composite material, and the results are shown below. Figure 6 .Depend on Figure 6 This indicates that the formation of Zr-O-Bi chemical bonds between Bi2S3 and UiO-66-NH2 is beneficial for the separation of photogenerated carriers.

[0043] Comparative Example 1 Without adding UiO-66-NH2, and with other operations the same as in Example 1, pure Bi2S3 photocatalytic material was obtained.

[0044] Comparative Example 2 Without adding the Bi2S3 precursor, other operations were the same as in Example 1 to obtain pure UiO-66-NH2 adsorbent material.

[0045] Practical Application Examples The Bi2S3 / UiO-66-NH2 nanocomposite materials prepared in the examples and comparative examples were used for the removal of methanethiol, a malodorous pollutant, under visible light conditions. The operation is as follows: (1) Take 20 mg of Bi2S3 / UiO-66-NH2 composite material and disperse it in 20 mL of deionized water. Heat it to 85 °C, add 0.5 g of agar powder and stir to form a hot melt. Then pour it into a petri dish with a diameter of 8.5 cm and cool it at room temperature to solidify it to obtain agarose gel loaded with nanomaterials. (2) After loading the agarose gel, place it in the reaction platform and switch the valve to put the system into internal circulation mode. Inject a quantitative amount of CH3SH gas using a syringe. During the circulation process, the methanethiol gas is gradually adsorbed and photocatalytically removed. During the experiment, gas samples were collected periodically from the sampling port and injected into a gas chromatograph equipped with an FPD detector. The CH3SH concentration was determined according to the standard curve, and its trend over time was recorded. The blank control experiment used only a carrier without catalyst. The same volume of CH3SH gas was injected, mixed evenly, and the initial concentration was measured as the starting value of the reaction. According to the experimental design, the LED light source (24W visible light) was selectively turned on to conduct comparative tests of the dark reaction and the photocatalytic reaction.

[0046] (3) The reaction time is 60 min, and the residual concentration of methanethiol is recorded. Eight cycles of stability testing are carried out to complete the pollutant removal test.

[0047] Figure 8 A comparison of the methanethiol removal effects of composite materials prepared with different UiO-66-NH2 loadings. Figure 8 As shown in Table 1, the Bi2S3 / UiO-66-NH2 composite material with the BSUN-200 ratio exhibited the best adsorption-photocatalytic synergistic removal activity for methanethiol, achieving degradation within 60 minutes with a residual methanethiol concentration of only 0.83 ppm. When the UiO-66-NH2 loading was too low or too high, the adsorption-photocatalytic synergistic effect weakened, and the removal performance decreased.

[0048] Figure 9 A comparison of the cyclic stability of composite materials prepared with different UiO-66-NH2 loadings for removing methanethiol. (See figure.) Figure 9 As shown in Table 2, BSUN-200 maintained the best removal performance after 8 cycles, with a residual methanethiol concentration of only 1.70 ppm, which was significantly better than BSUN-100, BSUN-300 and pure Bi2S3.

[0049] Figure 10 Performance graphs of methanethiol removal under dark conditions for materials prepared with different components. Figure 10As shown, the blank agarose gel AGE exhibits only weak physical adsorption and has the worst removal effect on methanethiol; UiO-66-NH2 shows a certain adsorption capacity due to its porous structure; pure Bi2S3 has weak adsorption performance; the BSUN-200 sample prepared in this invention has the best adsorption performance and can rapidly enrich methanethiol pollutants, demonstrating the significantly enhanced adsorption and enrichment capacity after UiO-66-NH2 and Bi2S3 are combined, providing favorable conditions for subsequent photocatalytic in-situ degradation.

[0050] Table 1. Data on the first cycle removal of methanethiol from the BSUN-X series composite materials in Example 1 of this invention.

[0051] Table 2. Data on methanethiol removal in the final cycle of the BSUN-X series composite materials in Example 1 of this invention.

[0052] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a Bi₂S₃ / UiO-66-NH₂ nanocomposite material integrating adsorption / photocatalysis dual functions, characterized in that: Includes the following steps: Thiourea was added to deionized water and stirred to dissolve to obtain solution A. The pre-synthesized UiO-66-NH2 and bismuth nitrate pentahydrate were dispersed in urea-containing deionized water and stirred to obtain suspension B. Solution A was slowly added dropwise to suspension B and stirred to carry out a solvothermal reaction. After washing, centrifugation and drying, UiO-66-NH2 / Bi2S3 nanocomposite material was obtained.

2. The method for preparing the UiO-66-NH2 / Bi2S3 nanocomposite material according to claim 1, characterized in that: The molar ratio of thiourea to bismuth nitrate pentahydrate is 1:

1.

3. The method for preparing the UiO-66-NH2 / Bi2S3 nanocomposite material according to claim 1, characterized in that: The concentration of the urea solution is 1.0 mol / L.

4. The method for preparing the UiO-66-NH2 / Bi2S3 nanocomposite material according to claim 1, characterized in that: Solution A was prepared using 20 mL of deionized water, and suspension B was prepared using 40 mL of deionized water.

5. The method for preparing the UiO-66-NH2 / Bi2S3 nanocomposite material according to claim 1, characterized in that: After all of solution A was added dropwise to suspension B, the mixture was stirred continuously for 40 minutes.

6. The method for preparing the UiO-66-NH2 / Bi2S3 nanocomposite material according to claim 1, characterized in that: The solvothermal reaction temperature is 120 °C, and the reaction time is 12 h.

7. The method for preparing the UiO-66-NH2 / Bi2S3 nanocomposite material according to claim 1, characterized in that: Washing was performed by alternating centrifugation with anhydrous ethanol and ultrapure water, and drying was carried out at 50 ℃ under vacuum overnight.

8. A UiO-66-NH2 / Bi2S3 nanocomposite material prepared by the method described in any one of claims 1-7.

9. The application of the UiO-66-NH2 / Bi2S3 nanocomposite material as described in claim 8 in the removal of harmful pollutants, characterized in that: The UiO-66-NH2 / Bi2S3 nanocomposite material was encapsulated inside an agarose gel and used for the removal of organic sulfur-containing pollutants under light irradiation.

10. The application according to claim 9, characterized in that: The organic sulfur-containing pollutant is methanethiol, and the light source used during illumination is 24W visible light.

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