A sulfur-doped lignin-based carbon / bismuth oxybromide photocatalytic material, a preparation method and application thereof
By preparing flower-shaped sulfur-doped lignin-based carbon/bismuth oxybromide photocatalyst, the problems of fast recombination of BiOBr photogenerated carriers and small specific surface area were solved, achieving efficient reduction of Cr(VI) under visible light, which has the advantages of being green, economical and sustainable.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANJING FORESTRY UNIV
- Filing Date
- 2026-01-30
- Publication Date
- 2026-05-29
AI Technical Summary
Existing BiOBr photocatalytic materials have a fast recombination rate of photogenerated carriers, which limits their photocatalytic performance improvement. In addition, carbonaceous materials are derived from fossil fuels and have a demanding preparation process. BiOBr structures have a small specific surface area, resulting in limited light capture capabilities.
A mild solvothermal method was used to prepare flower-shaped sulfur-doped lignin-based carbon/bismuth oxybromide photocatalytic materials using lignin sulfate, a byproduct of papermaking, as the carbon source and waste feathers as the sulfur-doped precursor. The sulfur-doped lignin-based carbon was used as a structure directing agent to improve the separation and transport efficiency of photogenerated carriers.
The specific surface area and photogenerated carrier separation efficiency of the photocatalytic material were improved, the absorption and utilization of visible light were enhanced, and the effect of efficient photocatalytic reduction of Cr(VI) was achieved, with a Cr(VI) reduction rate of 96%.
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Figure CN122098620A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of photocatalysis, specifically to a sulfur-doped lignin-based carbon / bismuth oxybromide catalytic material for the visible light photocatalytic reduction of Cr(VI). Background Technology
[0002] Bismuth oxybromide (BiOBr) is a photocatalytic material with broad application prospects. Its advantages are mainly reflected in the following aspects: (1) good physicochemical stability, low toxicity, low cost, and suitable band structure; (2) unique layered crystal structure, composed of [Bi2O2]. 2+ The alternating arrangement of layers and bilayers of halide ions in BiOBr helps shorten the migration distance of photogenerated carriers and promotes their efficient transport in multiple directions. However, single-structure BiOBr still faces the problem of a relatively fast recombination rate of photogenerated carriers, limiting further improvement in its photocatalytic performance. Carbonaceous materials, due to their excellent visible light absorption and good conductivity, can promote the separation and transport of photogenerated carriers when combined with BiOBr. However, currently commonly used carbonaceous materials are mostly derived from fossil fuels, and their preparation processes are quite demanding. Therefore, developing green and sustainable carbon sources is of great significance. Lignin is the second largest biomass resource in the plant kingdom after cellulose; however, in the pulping and papermaking process, it is the main component of "black liquor," a byproduct, and is mostly directly discharged, causing environmental pollution. Doping carbonaceous materials can further improve the transport efficiency of photogenerated carriers. Keratin can serve as a precursor for sulfur doping, and the main component of feathers on discarded badminton shuttlecocks is keratin. In addition, BiOBr prepared by conventional methods usually exhibits a disordered layered stacked structure with a small specific surface area, resulting in limited light capture capacity. By controlling the structure, a BiOBr with a three-dimensional flower-like morphology is constructed, which can effectively increase the specific surface area of the material and enhance its light absorption and utilization efficiency, thereby improving the photocatalytic reaction performance. This invention uses sulfate lignin from papermaking byproduct "black liquor" as the carbon source and feathers from discarded badminton shuttlecocks as a sulfur-doped precursor. The precursors are carbonized using a mild solvothermal method. The carbonized sulfur-doped lignin-based carbon can also serve as a structure-directing agent, thus preparing a flower-like sulfur-doped lignin-based carbon / bismuth oxybromide photocatalytic material.
[0003] Chromium (Cr) is a common heavy metal pollutant in water bodies, mainly originating from industrial processes such as leather tanning, textiles, electroplating, and steel manufacturing. Chromium typically exists in the environment in two ionic forms: hexavalent chromium (Cr(VI)), which is highly toxic and has carcinogenic and teratogenic effects, and trivalent chromium (Cr(III)), which is less toxic and an essential trace element for humans. Cr(VI) is classified as a Group 1 carcinogen by the World Health Organization, posing a serious threat to the ecological environment and human health. Therefore, reducing highly toxic Cr(VI) to less toxic Cr(III) has become an important approach to treating chromium-containing wastewater. Visible light accounts for approximately 46% of sunlight; therefore, photocatalysis using visible light to reduce Cr(VI) to Cr(III) is a green and sustainable technology, which is of great significance for promoting the application of photocatalysis in environmental remediation. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a catalytic material capable of efficient photocatalytic reduction of Cr(VI) under visible light and its preparation method.
[0005] The technical solution of the present invention is to provide a photocatalytic material, characterized in that: the photocatalytic material is sulfur-doped lignin-based carbon / bismuth oxybromide.
[0006] The present invention also provides a method for preparing the above-mentioned photocatalytic material, comprising the following steps:
[0007] Step 1: Mix lignin and feathers with deionized water, stir and sonicate for more than 3 hours to form a dispersion;
[0008] Step 2: Place the lignin and feather dispersion in an oven and perform a solvothermal reaction at 180-220℃ for 42-54 hours, then filter to obtain a sulfur-doped lignin-based carbon dispersion.
[0009] Step 3: Mix Bi(NO3)3·5H2O with an aqueous acetic acid solution to obtain a homogeneous solution A;
[0010] Step 4: Mix potassium bromide with the sulfur-doped lignin-based carbon dispersion obtained in Step 2 to obtain a homogeneous solution B;
[0011] Step 5: Mix solution A and solution B and then perform a solvothermal reaction at 140-180℃ in an oven for 10-14 hours to obtain the photocatalytic material.
[0012] Specifically, in step 1, lignin and feathers are mixed with deionized water and stirred and sonicated for more than 3 hours to form a dispersion.
[0013] Step 2: Place the lignin and feather dispersion in an oven and perform a solvothermal reaction at 200°C for 48 hours, then filter to obtain a sulfur-doped lignin-based carbon dispersion.
[0014] Step 3: Mix Bi(NO3)3·5H2O with an aqueous acetic acid solution to obtain a homogeneous solution A;
[0015] Step 4: Mix potassium bromide with the sulfur-doped lignin-based carbon dispersion obtained in Step 2 to obtain a homogeneous solution B;
[0016] Step 5: Mix solution A and solution B and then perform a solvothermal reaction at 160°C in an oven for 12 hours to obtain the photocatalytic material.
[0017] In the above technical solution, the lignin in step 1 is sulfate lignin, and the feather size is 25mm*10mm;
[0018] In the above technical solution, the volume of the acetic acid aqueous solution in step 3 is 40 mL, and the mass ratio is 10 wt%.
[0019] In the above technical solution, the molar ratio of Bi(NO3)3·5H2O and potassium bromide in steps 2 and 3 is 1:1;
[0020] In the above technical solution, the volume of the sulfur-doped lignin-based carbon dispersion in step 4 is 40 mL;
[0021] This invention also provides the application of the above-mentioned photocatalytic material in the photocatalytic reduction of Cr(VI) under visible light.
[0022] Compared with the prior art, the present invention has the following advantages after adopting the above solution:
[0023] A flower-like sulfur-doped lignin-based carbon / bismuth oxybromide photocatalyst was prepared in a one-pot solvothermal process using a sulfur-doped lignin-based carbon dispersion as the reaction solvent. The sulfur-doped lignin-based carbon dispersion acted as a structure-directing agent, forming the aforementioned flower-like photocatalyst. Lignin, as the carbon source, and feathers, as the sulfur-doped precursor, possess advantages of being green, economical, and sustainable, mitigating environmental pollution, and improving the recycling of waste resources. Compared to bismuth oxybromide, sulfur-doped lignin-based carbon / bismuth oxybromide has a larger specific surface area, better light absorption, and higher photogenerated carrier separation efficiency, ultimately improving the catalytic activity of the photocatalyst and enabling its application in the photocatalytic reduction of Cr(VI) under visible light. In the photocatalyst material provided by this invention, the sulfur-doped lignin-based carbon / bismuth oxybromide catalyst exhibited the best performance when the amounts of lignin and feathers were 0.27 g and 0.03 g, respectively, achieving a Cr(VI) reduction rate of 96% after 30 min of visible light irradiation. Attached Figure Description
[0024] Figure 1 X-ray diffraction (XRD) pattern (a) and Fourier transform infrared (FTIR) pattern (b) of sulfur-doped lignin-based carbon / bismuth oxybromide, lignin-based carbon / bismuth oxybromide, sulfur-doped lignin-based carbon and BiOBr prepared in Examples 1-3.
[0025] Figure 2 The images are scanning electron microscope (SEM) images of the sulfur-doped lignin-based carbon / bismuth oxybromide prepared in Examples 1-3, respectively.
[0026] Figure 3 The graph shows the photocatalytic reduction performance of sulfur-doped lignin-based carbon / bismuth oxybromide, lignin-based carbon / bismuth oxybromide, sulfur-doped lignin-based carbon, and BiOBr under visible light for the following preparations: Examples 1-3. Detailed Implementation
[0027] The present invention will be further described below with reference to specific embodiments:
[0028] Example 1
[0029] 0.25 g of lignin and 0.05 g of feathers were added to 59.7 g of deionized water. After stirring and sonicating for 3 h, the dispersion was placed in a 100 mL high-pressure reactor and maintained at 200 °C for 48 h. After cooling to room temperature, the dispersion was obtained by filtration through a 0.22 μm filter membrane. 0.403 g of Bi(NO3)3·5H2O was dissolved in 40 mL of acetic acid aqueous solution (10 wt%) to obtain solution A. Simultaneously, 0.099 g of KBr was dissolved in 40 mL of the sulfur-doped lignin-based carbon dispersion to obtain solution B. Solution B was then added dropwise to solution A, and after stirring for 30 min, the mixture was transferred to a 150 mL high-pressure reactor and maintained at 160 °C for 12 h. After cooling to room temperature, the sample was centrifuged, and the solid precipitate was washed with deionized water and ethanol and then dried in an oven at 80 °C. Sulfur-doped lignin-based carbon / bismuth oxybromide material was obtained.
[0030] Example 2:
[0031] 0.27 g of lignin powder and 0.03 g of feathers were added to 59.7 g of deionized water. After stirring and sonicating for 3 h, the dispersion was placed in a 100 mL high-pressure reactor and maintained at 200 °C for 48 h. After cooling to room temperature, the dispersion was obtained by filtration through a 0.22 μm filter membrane. 0.403 g of Bi(NO3)3·5H2O was dissolved in 40 mL of acetic acid aqueous solution (10 wt%) to obtain solution A. Simultaneously, 0.099 g of KBr was dissolved in 40 mL of the sulfur-doped lignin-based carbon dispersion to obtain solution B. Solution B was then added dropwise to solution A, and after stirring for 30 min, the mixture was transferred to a 150 mL high-pressure reactor and maintained at 160 °C for 12 h. After cooling to room temperature, the sample was centrifuged, and the solid precipitate was washed with deionized water and ethanol and then dried in an oven at 80 °C. Sulfur-doped lignin-based carbon / bismuth oxybromide material was obtained.
[0032] Example 3:
[0033] 0.29 g of lignin powder and 0.01 g of feather were added to deionized water, stirred, and sonicated for 3 h. The dispersion was then placed in a 100 mL high-pressure reactor and maintained at 200 °C for 48 h. After cooling to room temperature, the mixture was filtered through a 0.22 μm filter to obtain a sulfur-doped lignin-based carbon dispersion. 0.403 g of Bi(NO3)3·5H2O was dissolved in 40 mL of acetic acid aqueous solution (10 wt%) to obtain solution A. Simultaneously, 0.099 g of KBr was dissolved in 40 mL of the sulfur-doped lignin-based carbon dispersion to obtain solution B. Solution B was then added dropwise to solution A, stirred for 30 min, and then transferred to a 150 mL high-pressure reactor and maintained at 160 °C for 12 h. After cooling to room temperature, the sample was centrifuged, and the solid precipitate was washed with deionized water and ethanol and then dried in an oven at 80 °C. Sulfur-doped lignin-based carbon / bismuth oxybromide material was obtained.
[0034] Figure 1 a is the XRD pattern of the sulfur-doped lignin-based carbon / bismuth oxybromide prepared in Examples 1-3; it can be seen that the crystal structure of bismuth oxybromide remains unchanged, and the sulfur-doped lignin-based carbon / bismuth oxybromide materials prepared in Examples 1-3 contain both sulfur-doped lignin-based carbon and bismuth oxybromide. Figure 1 b is the FTIR spectrum of the sulfur-doped lignin-based carbon / bismuth oxybromide prepared in Examples 1-3; it can be seen that sulfur was successfully doped.
[0035] Figure 2 The images show SEM images of the sulfur-doped lignin-based carbon / bismuth oxybromide prepared in Examples 1-3. It can be seen that the microstructure of the prepared sulfur-doped lignin-based carbon / bismuth oxybromide materials is a regular flower-like structure.
[0036] The photocatalytic test conditions are as follows:
[0037] Photocatalytic reduction of Cr(VI) test: 40 mg of catalyst powder was dispersed in 40 mL of Cr(VI) aqueous solution (30 mg·L⁻¹). -1 The mixed solution was first stirred in the dark for 60 minutes to reach the adsorption-desorption equilibrium of Cr(VI) by the catalyst. Then, the reaction solution was placed in a 300W xenon lamp equipped with a filter (light wavelength range: 400-780nm, light intensity: 62mW·cm²). -2 The photocatalytic reaction was carried out under [a specific environment / condition]. During the photocatalytic reaction, samples were taken at regular intervals, and the catalyst was filtered through a 0.22 μm nylon 66 filter head. The filtrate samples were collected. The Cr(VI) concentration was determined at 540 nm using a UV-Vis spectrophotometer and the diphenylcarbazide spectrophotometric method.
[0038] The results of the photocatalytic reaction in the examples show (e.g.) Figure 3The sulfur-doped lignin-based carbon / bismuth oxybromide material provided by this invention exhibits superior photocatalytic Cr(VI) reduction performance. Among them, Example 2 demonstrates the best catalytic performance, achieving a Cr(VI) reduction rate of 96% after 30 minutes of visible light irradiation.
[0039] This invention utilizes a sulfur-doped lignin-based carbon dispersion as the reaction solvent to prepare a flower-like sulfur-doped lignin-based carbon / bismuth oxybromide photocatalyst in a one-pot solvothermal process. The sulfur-doped lignin-based carbon acts as a structure directing agent, forming the aforementioned flower-like photocatalyst. Furthermore, lignin as the carbon source and feathers as the sulfur-doped precursor offer advantages such as being green, economical, and sustainable, while mitigating environmental pollution and improving the recycling of waste resources. Compared to bismuth oxybromide, sulfur-doped lignin-based carbon / bismuth oxybromide exhibits a larger specific surface area, better light absorption, and higher photogenerated carrier separation efficiency. This photocatalyst is used for the photocatalytic reduction of Cr(VI) under visible light, offering advantages such as simple preparation and high visible light catalytic activity, providing an economical, green, and sustainable pathway for Cr(VI) reduction.
[0040] The above description only illustrates preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. Any equivalent structural or procedural modifications made using this specification are included within the patent protection scope of the present invention.
Claims
1. A photocatalytic material, characterized in that: The photocatalytic material is sulfur-doped lignin-based carbon / bismuth oxybromide.
2. The method for preparing the photocatalytic material according to claim 1, characterized in that: Includes the following steps, Step 1: Mix lignin and feathers with deionized water, stir and sonicate for more than 3 hours to form a dispersion; Step 2: Place the lignin and feather dispersion in an oven and perform a solvothermal reaction at 180-220℃ for 42-54 hours, then filter to obtain a sulfur-doped lignin-based carbon dispersion. Step 3: Mix Bi(NO3)3·5H2O with an aqueous acetic acid solution to obtain a homogeneous solution A; Step 4: Mix potassium bromide with the sulfur-doped lignin-based carbon dispersion obtained in Step 2 to obtain a homogeneous solution B; Step 5: Mix solution A and solution B and then perform a solvothermal reaction at 140-180℃ in an oven for 10-14 hours to obtain the photocatalytic material.
3. The method for preparing the photocatalytic material according to claim 1, characterized in that: Includes the following steps, Step 1: Mix lignin and feathers with deionized water, stir and sonicate for more than 3 hours to form a dispersion; Step 2: Place the lignin and feather dispersion in an oven and perform a solvothermal reaction at 200°C for 48 hours, then filter to obtain a sulfur-doped lignin-based carbon dispersion. Step 3: Mix Bi(NO3)3·5H2O with an aqueous acetic acid solution to obtain a homogeneous solution A; Step 4: Mix potassium bromide with the sulfur-doped lignin-based carbon dispersion obtained in Step 2 to obtain a homogeneous solution B; Step 5: Mix solution A and solution B and then perform a solvothermal reaction at 160°C in an oven for 12 hours to obtain the photocatalytic material.
4. The method for preparing the photocatalytic material according to claim 3, characterized in that: In step 1, the lignin is sulfate lignin, and the feather size is 25mm*10mm.
5. The method for preparing the photocatalytic material according to claim 3, characterized in that: The volume of the acetic acid aqueous solution in step 3 is 40 mL, and the mass ratio is 10 wt%.
6. The method for preparing the photocatalytic material according to claim 3, characterized in that: The molar ratio of Bi(NO3)3·5H2O to potassium bromide in steps 2 and 3 is 1:
1.
7. The method for preparing the photocatalytic material according to claim 3, characterized in that: The volume of the sulfur-doped lignin-based carbon dispersion in step 4 is 40 mL.
8. The application of a catalyst prepared by the photocatalytic material as described in claim 1 or the photocatalytic material prepared by any one of claims 2-7 in the photocatalytic reduction of Cr(VI) under visible light.