Bimetal nanoparticle green synthesis method based on black rice extracting solution

Abstract

The invention relates to the technical field of metal nanoparticles, in particular to a black rice extracting solution-based bimetal nanoparticle green synthesis method, which comprises the following steps: mixing black rice and distilled water according to a mass ratio of 1: 20, boiling to obtain a primary mixed solution, cooling to room temperature, and filtering the primary mixed solution under reduced pressure to obtain a black rice concentrated solution; the preparation method comprises the following steps: diluting black rice to obtain a black rice extracting solution, then mixing the black rice extracting solution with a copper-silver mixed salt solution, reacting for a preset time under illumination of a 350W xenon lamp, synthesizing to obtain a liquid bimetallic nanoparticle solution, then carrying out centrifugal filtration to obtain copper-silver bimetallic nanoparticle wet mud, carrying out vacuum drying at 80 DEG C to obtain copper-silver bimetallic nanoparticles, and finally, carrying out vacuum drying on the copper-silver bimetallic nanoparticles to obtain the copper-silver bimetallic nanoparticles. The wavelength of an absorption peak is monitored through an ultraviolet-visible absorption spectrum to judge whether the synthesized bimetallic nanoparticles meet the standard or not, so that the adjustment amplitude of the molar concentration ratio of copper sulfate to silver nitrate is determined. According to the invention, the synthesis efficiency of the bimetallic nanoparticles is improved.

Description

Technical Field

[0001] This invention relates to the field of metal nanoparticle technology, and in particular to a green synthesis method for bimetallic nanoparticles based on black rice extract. Background Technology

[0002] The nanomaterials market has been on a continuous growth trend, and bimetallic nanoparticles, due to the significant activity of the two metals involved, have attracted considerable attention from researchers. The properties of bimetallic nanoparticles depend on the redox potential of the metal ions, the type of reducing agent used, and the interaction forces between them. These factors determine whether the bimetallic nanoparticles are core-shell alloys, heterostructure alloys, multi-shell alloys, cluster alloys, or random alloys. The synthesis method can also affect the crystal structure, particle size, and distribution of the metals in the bimetallic nanoparticles. The synthesis of bimetallic nanoparticles using chemical and physical methods is time-consuming, inefficient, and often requires toxic reagents. Green methods for synthesizing bimetallic nanoparticles have gained attention due to their environmental friendliness, speed, and environmental friendliness. Green synthesis of bimetallic nanoparticles shows promising application prospects in electronics, catalysis, and antibacterial fields. The synthesis of bimetallic nanoparticles using plant extracts is also highly favored by researchers. Since plants can convert light energy into chemical energy and absorb, accumulate, utilize, and recycle different minerals, plants and their products can serve as an important source of renewable and sustainable supply for the synthesis of nano-metal particles. Plant components can act as reducing agents and stabilizers to synthesize stable bimetallic nanoparticles.

[0003] Chinese Patent Publication No. CN117884644A discloses a green synthesis method for bimetallic nanoparticles, comprising: S1. preparing a plant extract; S2. heating, stirring, and boiling the plant extract to obtain a mixture A; S3. centrifuging the mixture A to remove the deposited biomass and collecting the supernatant; S4. transferring the supernatant to a reactor, immediately adding a stock solution containing two metal salts, and continuing to magnetically stir and heat to boiling, maintaining the boiling point for 5-10 minutes; S5. stopping heating, waiting for the reactor temperature to drop to room temperature, adding the supernatant again, and continuing to stir the reaction to obtain a mixture B; S6. centrifuging the mixture B at high speed, collecting the precipitate, washing, and drying to obtain bimetallic nanoparticles.

[0004] Chinese Patent Publication No. CN105880624A discloses a method for self-assembling spherical gold nanoparticles using bacitracin as a template. The method mainly involves adding bacitracin to a hydrochloric acid solution to prepare an acidic bacitracin solution of 0.35–0.70 mM. This solution is then heat-treated in a metal bath at 40–60 °C for 1–2 h, followed by ultrasonic treatment for 30 s. Next, gold trichloride solution is added to the bacitracin solution, and the mixture is placed in a double-layer gas bath shaker and incubated at 100–150 rpm and 20–25 °C for 20–30 h. Finally, 60–90 μL of sodium borohydride reducing agent is added to the incubated solution, and the reaction temperature is controlled at 21–23 °C for 40–60 min to obtain spherical gold nanoparticles with a particle size of 80–90 nm.

[0005] However, the following problems still exist in the existing technology: Existing technologies do not consider the problems of low synthesis efficiency of copper-silver bimetallic nanoparticles due to the complexity of the process, high energy consumption, requirement of traditional reducing agents, and long reaction time in the preparation of copper-silver bimetallic nanoparticles by traditional chemical synthesis methods. Summary of the Invention

[0006] Therefore, this invention provides a green synthesis method for bimetallic nanoparticles based on black rice extract, which overcomes the problems of high energy consumption in the high-temperature heating process due to the use of chemical reducing agents and harsh reaction synthesis conditions, as well as the environmental pollution caused by cumbersome processing steps and the low efficiency of bimetallic nanoparticle synthesis due to complex processes in the prior art.

[0007] To achieve the above objectives, this invention provides a green synthesis method for bimetallic nanoparticles based on black rice extract, comprising: S1. Mix black rice and distilled water at a mass ratio of 1:20, and boil the mixture for 15 minutes to obtain a primary mixture. S2. The primary mixture cooled to room temperature is filtered under reduced pressure to obtain a black rice concentrate, and the black rice concentrate is diluted to obtain a black rice extract. S3. Using the flavonoids and phenolic compounds in the black rice extract as biological reducing agents, the black rice extract and copper-silver mixed salt solution are mixed at a volume ratio of 6:1 and reacted under a 350W xenon lamp for a predetermined time to synthesize a liquid bimetallic nanoparticle solution. S4. Centrifuge and filter the liquid bimetallic nanoparticle solution to obtain copper-silver bimetallic nanoparticle wet mud. Dry the copper-silver bimetallic nanoparticle wet mud under vacuum at 80°C to obtain copper-silver bimetallic nanoparticles. S5. Perform ultraviolet-visible absorption spectroscopy monitoring on the copper-silver bimetallic nanoparticles, and determine whether the synthesized bimetallic nanoparticles meet the standard based on the monitored absorption peak wavelengths of the copper-silver bimetallic nanoparticles: If the standard is not met, the adjustment range of the molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution is determined based on the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined absorption peak wavelength threshold of the copper-silver bimetallic nanoparticles.

[0008] Furthermore, the copper-silver mixed salt solution is obtained by mixing copper sulfate and silver nitrate at a molar concentration ratio of 2:1 and then stirring magnetically for 20 minutes. The concentration of copper sulfate is 0.1 mol / L, and the concentration of silver nitrate is 0.1 mol / L.

[0009] Furthermore, the predetermined reaction time under the 350W xenon lamp illumination is 20 minutes.

[0010] Preferably, the process for determining whether the synthesized bimetallic nanoparticles meet the standards includes: Determine the absorption peak wavelength of copper-silver bimetallic nanoparticles; If the absorption peak wavelength of the copper-silver bimetallic nanoparticles does not fall within the predetermined absorption peak wavelength threshold for copper-silver bimetallic nanoparticles, then the synthesized copper-silver bimetallic nanoparticles are deemed not to meet the standard.

[0011] Furthermore, in cases where the synthesized copper-silver bimetallic nanoparticles do not meet the standards, the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined absorption peak wavelength threshold of the copper-silver bimetallic nanoparticles is determined as the abnormal characteristic wavelength difference.

[0012] Furthermore, the process of determining the molar ratio of copper sulfate to silver nitrate in a copper-silver mixed salt solution includes: If the difference in the abnormal characteristic wavelength is negative, then it is determined to increase the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution. If the difference in the abnormal characteristic wavelength is positive, then the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is reduced.

[0013] Furthermore, the increase in the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is determined based on the difference in the abnormal characteristic wavelengths.

[0014] Furthermore, the decrease in the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is determined based on the difference in the anomalous characteristic wavelengths.

[0015] Preferably, in step S1, the mass of the black rice is 5g and the mass of the distilled water is 100g; in step S2, the black rice concentrate is diluted to a volume of 250mL to obtain black rice extract; and in step S4, the vacuum drying temperature is 80℃ and the drying time is 24 hours.

[0016] Furthermore, the predetermined wavelength threshold for the absorption peak of the copper-silver bimetallic nanoparticles is a resonant absorption peak wavelength of 440 nanometers.

[0017] Compared with existing technologies, this invention obtains a primary mixture by boiling a solution of black rice and distilled water at a mass ratio of 1:20 for 15 minutes, cooling it to room temperature, and then filtering the primary mixture under reduced pressure to obtain a concentrated black rice solution. After dilution, a black rice extract is obtained. Then, the black rice extract is mixed with a copper-silver mixed salt solution and reacted under a 350W xenon lamp for a predetermined time to synthesize a liquid bimetallic nanoparticle solution. Subsequently, the solution is centrifuged and filtered to obtain a wet sludge of copper-silver bimetallic nanoparticles, which is then vacuum dried at 80°C for 24 hours to obtain copper-silver bimetallic nanoparticles. Finally, by monitoring the absorption peak wavelength of the copper-silver bimetallic nanoparticles using ultraviolet-visible absorption spectroscopy, the synthesized bimetallic nanoparticles are determined to meet the standards, thereby determining the adjustment range of the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution, thus improving the efficiency of bimetallic nanoparticle synthesis.

[0018] In particular, copper-silver bimetallic nanoparticles were successfully synthesized using black rice extract as a bio-reducing agent, demonstrating significant environmental friendliness and technological advantages. Traditional chemical synthesis uses toxic and expensive reducing agents, while the natural bioactive components in black rice, including polyphenols and anthocyanins, rapidly reduce metal salts under 350W xenon lamp irradiation, significantly reducing energy consumption and safety risks. Real-time monitoring of synthesis quality using UV-Vis absorption spectroscopy and the establishment of a feedback adjustment mechanism dynamically adjust the precursor concentration ratio based on absorption peak wavelength deviations, effectively ensuring the uniformity of product particle size, morphology, and structure. The resulting copper-silver bimetallic nanoparticles exhibit a simple, rapid, and low-cost process, improving the efficiency of green synthesis of bimetallic nanoparticles.

[0019] In particular, copper-silver bimetallic nanoparticles were rapidly and successfully synthesized at room temperature under 350W xenon lamp irradiation using black rice extract as a bio-reducing agent and stabilizer. This example is highly environmentally friendly, reducing the use of hazardous chemicals such as sodium borohydride and lowering safety risks and environmental pollution. Black rice is widely available and inexpensive, and the polyphenols and anthocyanins abundant in this example can efficiently reduce copper and silver ions and effectively stabilize the generated bimetallic nanoparticles. The process is simple, efficient, and extremely energy-efficient. The entire synthesis process is completed at room temperature using magnetic stirring and 350W xenon lamp irradiation, with a short reaction time of only 20 minutes. It requires no complex equipment or high-temperature, high-pressure conditions, significantly reducing energy consumption and production costs. The synthesized product is copper-silver bimetallic nanoparticles, expected to have uniform particle size and stable alloy or core-shell structure, improving the efficiency of green synthesis of bimetallic nanoparticles.

[0020] In particular, by employing an online quality monitoring and feedback mechanism based on UV-Vis absorption spectroscopy, precise spectral judgment criteria are constructed, enabling objective and rapid quantitative evaluation of the quality of the synthesized products. The difference between the absorption peak wavelength and the threshold ensures the uniformity and stability of product performance. This judgment mechanism provides a direct basis for process optimization. The adjustment range of the molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution is determined based on the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined threshold wavelength, thus improving the efficiency of the green synthesis of bimetallic nanoparticles. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the steps of the green synthesis method of bimetallic nanoparticles based on black rice extract according to an embodiment of the present invention. Figure 2 The UV-Vis absorption spectra of copper-silver bimetallic nanoparticles, nano-copper, and nano-silver synthesized based on black rice extract in an embodiment of the present invention are shown. Figure 3 The infrared spectra of copper-silver bimetallic nanoparticles synthesized based on black rice extract and the black rice extract are shown in the embodiments of the present invention. Figure 4 This is an X-ray photoelectron spectrum of copper-silver bimetallic nanoparticles synthesized based on black rice extract in an embodiment of the present invention. Figure 5 The TEM and EDX spectra of copper-silver bimetallic nanoparticles synthesized from black rice extract in this embodiment of the invention are shown below. Figure 6 The images show HRTEM images and SAED selected area electron diffraction patterns of copper-silver bimetallic nanoparticles synthesized based on black rice extract in this embodiment of the invention. Figure 7 This is an example of the UV-Vis absorption spectrum of copper-silver bimetallic nanoparticles synthesized from black rice extract for adsorption of crystal violet in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] Please see Figure 1The diagram shows a flowchart of the green synthesis method of bimetallic nanoparticles based on black rice extract according to an embodiment of the present invention. The present invention provides a green synthesis method of bimetallic nanoparticles based on black rice extract, comprising: Step S1: Boil the solution of black rice and distilled water in a mass ratio of 1:20 for 15 minutes to obtain a primary mixture. Step S2: The primary mixture cooled to room temperature is filtered under reduced pressure to obtain black rice concentrate, and the black rice concentrate is diluted to obtain black rice extract. Step S3: Using the flavonoids and phenolic compounds in the black rice extract as biological reducing agents, the black rice extract and copper-silver mixed salt solution are mixed at a volume ratio of 6:1 and reacted under a 350W xenon lamp for a predetermined time to synthesize a liquid bimetallic nanoparticle solution. Step S4: Centrifuge and filter the liquid bimetallic nanoparticle solution to obtain copper-silver bimetallic nanoparticle wet mud, and dry the copper-silver bimetallic nanoparticle wet mud under vacuum at 80°C to obtain copper-silver bimetallic nanoparticles. Step S5: Perform UV-Vis absorption spectroscopy on the copper-silver bimetallic nanoparticles, and determine whether the synthesized bimetallic nanoparticles meet the standards based on the wavelength of the absorption peaks of the copper-silver bimetallic nanoparticles. If the standard is not met, the adjustment range of the molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution is determined based on the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined absorption peak wavelength threshold of the copper-silver bimetallic nanoparticles.

[0025] In the example, a solution of 5g black rice and 100g distilled water was boiled for 15 minutes to obtain a primary mixture. The primary mixture, cooled to room temperature, was subjected to vacuum filtration to obtain a concentrated black rice liquid. The black rice concentrate was diluted to 250 mL to obtain a black rice extract. 45 mL of the black rice extract was mixed with 7.5 mL of copper-silver mixed salt solution and reacted under a 350 W xenon lamp for 20 min to obtain a liquid bimetallic nanoparticle solution. The liquid bimetallic nanoparticle solution was centrifuged and filtered to obtain copper-silver bimetallic nanoparticle wet mud. The copper-silver bimetallic nanoparticle wet mud was dried under vacuum at 80°C for 24 hours to obtain copper-silver bimetallic nanoparticles. The copper-silver bimetallic nanoparticles were subjected to ultraviolet-visible absorption spectroscopy monitoring. Based on the monitored absorption peak wavelengths of the copper-silver bimetallic nanoparticles, it was determined whether the synthesized bimetallic nanoparticles met the standards. If the standard is not met, the adjustment range of the molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution is determined based on the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined absorption peak wavelength threshold of the copper-silver bimetallic nanoparticles. The copper-silver mixed salt solution was prepared by magnetically stirring a solution of 5 mL copper sulfate and 2.5 mL silver nitrate for 20 minutes. The concentrations of copper sulfate and silver nitrate are 0.1 mol / L.

[0026] This embodiment successfully prepared copper-silver bimetallic nanoparticles using black rice extract as a bio-reducing agent, demonstrating significant environmental friendliness and process advantages. By replacing the toxic and expensive reducing agents in traditional chemical synthesis, the metal salts were rapidly reduced at room temperature under 350W xenon lamp irradiation using natural bioactive components in black rice, including polyphenols and anthocyanins and flavonoids, significantly reducing energy consumption and safety risks. The synthesis quality was monitored in real time using UV-Vis absorption spectroscopy, and a feedback adjustment mechanism was established to dynamically adjust the precursor concentration ratio based on absorption peak wavelength deviations, effectively ensuring the uniformity and stability of the product particle size, morphology, and structure. The synthesized copper-silver bimetallic nanoparticles have excellent application potential in catalysis, antibacterial fields, etc. The overall process is simple, rapid, and low-cost, providing a new strategy for the green and large-scale production of nanomaterials and improving the efficiency of green synthesis of bimetallic nanoparticles.

[0027] Specifically, the copper-silver mixed salt solution is obtained by magnetically stirring a solution of copper sulfate and silver nitrate mixed at a molar ratio of 2:1 for 20 minutes. The concentration of copper sulfate is 0.1 mol / L, and the concentration of silver nitrate is 0.1 mol / L.

[0028] Specifically, the predetermined reaction time under the 350W xenon lamp illumination is 20 minutes.

[0029] This example demonstrates the rapid and successful synthesis of copper-silver bimetallic nanoparticles at room temperature under 350W xenon lamp irradiation, using black rice extract as a bio-reducing agent and stabilizer. This method is highly environmentally friendly, reducing the use of hazardous chemicals such as sodium borohydride in traditional chemical synthesis, thus lowering safety risks and environmental pollution. Black rice is widely available and inexpensive, and the process described in this example is simple, efficient, and extremely energy-efficient. The entire synthesis process is completed at room temperature using magnetic stirring and 350W xenon lamp irradiation, with a short reaction time (20 minutes in this example). No complex equipment or high-temperature, high-pressure conditions are required, significantly reducing energy consumption and production costs. The final product is copper-silver bimetallic nanoparticles, expected to have uniform particle size and stable alloy or core-shell structures, exhibiting superior performance and application potential compared to single-metal nanoparticles in fields such as catalysis, antibacterial agents, and sensing. This method improves the efficiency of green synthesis of bimetallic nanoparticles.

[0030] Please see Figure 2 The image shows the UV-Vis absorption spectra of copper-silver bimetallic nanoparticles, nano-copper, and nano-silver synthesized based on black rice extract in an embodiment of the present invention.

[0031] The examples show the UV-Vis absorption spectra of three nanometals. Nanocopper exhibits a distinct plasmon resonance absorption peak at 542 nm, while nanosilver shows a similar peak at 414 nm with symmetrical peak distribution. The copper-silver bimetallic nanoparticles exhibit a broader absorption peak at 440 nm. By comparing the UV-Vis absorption spectra of these three metal nanoparticles, it can be confirmed that copper-silver bimetallic nanoparticles were successfully synthesized using black rice aqueous extract as a reducing agent.

[0032] Please see Figure 3 As shown, it is the infrared spectrum of copper-silver bimetallic nanoparticles based on black rice extract and black rice extract in an embodiment of the present invention.

[0033] In the infrared spectrum of the black rice extract in the example, 3295 cm⁻¹ -1 The vibration at 2920 cm is caused by the stretching vibration of the hydroxyl group. -1 The stretching vibration of methylene-CH2-, 1606 cm⁻¹ -1 Related to the tensile vibrations of carbon-carbon double bonds, 1412 cm -1 This is a variable-angle vibration of the methyl group, 1049 cm⁻¹ -1 The peaks represent stretching vibrations of the CO bond and skeletal vibrations of the C / C single bond. The characteristic peaks in the examples confirm the presence of flavonoids and phenolic compounds in the black rice extract. The reducing properties of the compounds in the examples enabled the successful synthesis of copper-silver bimetallic nanoparticles. The infrared spectrum of the copper-silver bimetallic nanoparticles shows absorption peaks at similar wavenumbers to those of the black rice extract, indicating that their surface is coated with organic compounds from the black rice extract.

[0034] Please see Figure 4 As shown, it is an X-ray photoelectron spectrum of copper-silver bimetallic nanoparticles based on black rice extract in an embodiment of the present invention.

[0035] In the examples, X-ray photoelectron spectroscopy (XPS) was used to systematically characterize and analyze the samples. For example... Figure 4 As shown in Figure a, the full-spectrum scan results of the sample revealed that it mainly contains four elements: C, O, Ag, and Cu. Quantitative analysis yielded the atomic percentages of each element as follows: C - 83.4%, O - 15.3%, Ag - 0.8%, and Cu - 0.5%. The relatively high carbon content may originate from residual organic components in the plant extract or unavoidable surface contamination during the testing process. To further determine the chemical states of Ag and Cu, high-resolution XPS analysis was performed on the Ag 3d and Cu 2p orbitals. Example Figure 4 b shows a detailed spectrum of the Ag3d region, revealing two distinct characteristic peaks: the peak at 368.2 eV is attributed to Ag3d. 5 / 2 The peak at 374.2 eV corresponds to the Ag 3d orbital, while the peak at 374.2 eV corresponds to the Ag 3d orbital. 3 / 2 Orbit. Example: The binding energy of the two peaks and their 3 / 2-5 / 2 spin orbital splitting distance (6.0 eV) compared with metallic silver (Ag). 0 The standard values ​​were completely consistent, indicating that the Ag element in the sample existed in elemental form. Example 4c shows a high-resolution XPS spectrum of the Cu 2p region. Cu 2p was observed at 932.7 eV and 952.8 eV, respectively. 3 / 2 and Cu 2p 1 / 2 The characteristic peaks indicate that Cu in the sample is mainly in the form of CuO or CuO. + It exists in the form of... Based on the above XPS analysis results, combined with the preparation method using plant extracts as reducing agents in the experiment, it can be confirmed that we successfully reduced the silver and copper ion precursors to prepare a product containing elemental Ag and Cu0 / Cu... + Bimetallic nanocomposite materials.

[0036] Please see Figure 5 As shown, it is the TEM image and EDX spectrum of copper-silver bimetallic nanoparticles based on black rice extract in an embodiment of the present invention.

[0037] The synthesized copper-silver bimetallic nanoparticles were characterized by transmission electron microscopy (TEM). The particles were found to be elliptical in shape, with a main particle size distribution around 20 nm. EDX spectroscopy of the sample area revealed characteristic peaks for copper and silver, indicating the presence of both elements. The molybdenum peak was very high due to the sample being measured on a molybdenum grid.

[0038] Please see Figure 6 As shown, it is an HRTEM image and SAED selected area electron diffraction pattern of copper-silver bimetallic nanoparticles based on black rice extract in an embodiment of the present invention.

[0039] The examples demonstrate the atomic arrangement lattice fringes of the silver phase through high-resolution transmission electron microscopy images of copper-silver bimetallic nanoparticles. Figure 6 (b) The Ag phase is identified as (-11-1) and (100), and the corresponding interplanar spacing is d. (-11-1) =0.244nm and d (100) =0.252 nm. Therefore, the presence of silver nanoparticles in the sample can be confirmed from the HRTEM image. Example Figure 6 (c) shows the polycrystalline electron diffraction pattern. Different colored rings correspond to the crystal planes of specific crystal phases, and the crystal phase, crystal plane index, and the reciprocal 1 / d of the interplanar spacing are marked, where d is the interplanar spacing. The red and yellow rings correspond to the (011) and (022) crystal planes of Ag, indicating the presence of the silver phase in the sample. The green ring marks the (110) crystal plane of Cu3Ag, indicating the presence of the Cu3Ag alloy phase in the sample, reflecting the multi-phase composition.

[0040] Please see Figure 7 As shown, it is the UV-Vis absorption spectrum of crystal violet adsorption by copper-silver bimetallic nanoparticles synthesized based on black rice extract in an embodiment of the present invention.

[0041] Crystal violet is an environmental pollutant with applications in medicine, biology, and industry. Its high water solubility and structural stability allow it to persist in water for extended periods and are difficult to degrade. Crystal violet is toxic to aquatic organisms, interfering with their growth and reproduction, disrupting ecological balance, and may also enter the human body through the food chain, exhibiting reproductive toxicity, mutagenicity, and carcinogenicity. This study investigated the synthesis of a copper-silver bimetallic nanoparticle composite, which can rapidly and effectively remove crystal violet from water.

[0042] In this example, 5 mg of copper-silver bimetallic nanoparticles were added to 50 mL of a 10 mg / L aqueous solution of crystal violet for adsorption experiments. The UV-Vis absorption spectra of the remaining crystal violet in the solution were measured after 0 min, 2 min, 5 min, 10 min, and 20 min. The results show that the adsorption rate of crystal violet by the copper-silver bimetallic nanoparticles can reach 53% within 2 min. As time increases, the adsorption rate gradually slows down, reaching 64% within 20 min.

[0043] Specifically, the process for determining whether synthesized bimetallic nanoparticles meet the standards includes: Determine the absorption peak wavelength of copper-silver bimetallic nanoparticles; If the absorption peak wavelength of the copper-silver bimetallic nanoparticles is within the predetermined absorption peak wavelength threshold of the copper-silver bimetallic nanoparticles, then the synthesized copper-silver bimetallic nanoparticles are deemed to meet the standard. If the absorption peak wavelength of the copper-silver bimetallic nanoparticles does not fall within the predetermined absorption peak wavelength threshold for copper-silver bimetallic nanoparticles, then the synthesized copper-silver bimetallic nanoparticles are deemed not to meet the standard.

[0044] It is understood that the wavelength threshold of the absorption peak of copper-silver bimetallic nanoparticles is predetermined. Specifically, the product of the standard wavelength of the absorption peak of the synthesized copper-silver bimetallic nanoparticles (440 nm) and the accuracy coefficient is determined as the wavelength threshold of the absorption peak of the copper-silver bimetallic nanoparticles. In this embodiment, the accuracy coefficient is selected within the range of [0.95, 1.05], and preferably the accuracy coefficient is 1.

[0045] By employing an online quality monitoring and feedback mechanism based on UV-Vis absorption spectroscopy, precise spectral judgment criteria are constructed, enabling objective and rapid quantitative evaluation of the synthesized product quality. The difference between the absorption peak wavelength and the threshold ensures the uniformity and stability of product performance. This judgment mechanism provides a direct basis for process optimization. The adjustment range of the molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution is determined based on the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined threshold wavelength, thereby improving the efficiency of the green synthesis of bimetallic nanoparticles.

[0046] Specifically, when the synthesized copper-silver bimetallic nanoparticles do not meet the standards, the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined absorption peak wavelength threshold of the copper-silver bimetallic nanoparticles is determined as the abnormal characteristic wavelength difference.

[0047] Specifically, the process of determining the molar ratio of copper sulfate to silver nitrate in a copper-silver mixed salt solution includes: If the difference in the abnormal characteristic wavelength is negative, then it is determined to increase the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution. If the difference in the abnormal characteristic wavelength is positive, then the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is reduced.

[0048] The embodiments utilize an online quality monitoring and feedback mechanism based on UV-Vis absorption spectroscopy to precisely construct spectral judgment criteria. This enables objective and rapid quantitative evaluation of the quality of the synthesized products, ensuring the uniformity and stability of product performance based on the difference between the absorption peak wavelength and the threshold. The judgment mechanism provides a direct basis for process optimization. The adjustment range of the molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution is determined based on the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined threshold wavelength, thereby improving the efficiency of the green synthesis of bimetallic nanoparticles.

[0049] Specifically, the increase in the molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution is determined based on the difference in the abnormal characteristic wavelengths.

[0050] In the embodiment, the increase in the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution was increased until the difference in the abnormal characteristic wavelength was close to zero.

[0051] Specifically, the reduction in the molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution is determined based on the difference in the anomalous characteristic wavelengths.

[0052] The reduction in the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution was reduced to the extent that the difference in the abnormal characteristic wavelength was close to zero.

[0053] Specifically, in step S1, the mass of the black rice is 5g and the mass of the distilled water is 100g. In step S2, the black rice concentrate is diluted to a volume of 250mL to obtain black rice extract. In step S4, the vacuum temperature is 80℃ and the drying time is 24 hours.

[0054] Specifically, the predetermined wavelength threshold for the absorption peak of the copper-silver bimetallic nanoparticles is 440 nanometers, which is the resonant absorption peak wavelength. rice .

[0055] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A green synthesis method for bimetallic nanoparticles based on black rice extract, characterized in that, include: S1. Mix black rice and distilled water at a mass ratio of 1:20, and boil the mixture for 15 minutes to obtain a primary mixture. S2. The primary mixture cooled to room temperature is filtered under reduced pressure to obtain a black rice concentrate, and the black rice concentrate is diluted to obtain a black rice extract. S3. Using the flavonoids and phenolic compounds in the black rice extract as biological reducing agents, the black rice extract and copper-silver mixed salt solution are mixed at a volume ratio of 6:1 and reacted under a 350W xenon lamp for a predetermined time to synthesize a liquid bimetallic nanoparticle solution. S4. Centrifuge and filter the liquid bimetal nanoparticle solution to obtain copper-silver bimetal nanoparticle wet mud, and dry the copper-silver bimetal nanoparticle wet mud under vacuum at 80°C to obtain copper-silver bimetal nanoparticles. S5. Perform ultraviolet-visible absorption spectroscopy monitoring on the copper-silver bimetallic nanoparticles, and determine whether the synthesized bimetallic nanoparticles meet the standard based on the monitored absorption peak wavelengths of the copper-silver bimetallic nanoparticles: If the standard is not met, the adjustment range of the molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution is determined based on the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined absorption peak wavelength threshold of the copper-silver bimetallic nanoparticles.

2. The green synthesis method of bimetallic nanoparticles based on black rice extract according to claim 1, characterized in that, The copper-silver mixed salt solution is obtained by mixing copper sulfate and silver nitrate at a molar ratio of 2:1 and then stirring the mixed solution magnetically for 20 minutes. The concentration of copper sulfate is 0.1 mol / L, and the concentration of silver nitrate is 0.1 mol / L.

3. The green synthesis method of bimetallic nanoparticles based on black rice extract according to claim 1, characterized in that, The predetermined reaction time under the illumination of the 350W xenon lamp is 20 minutes.

4. The green synthesis method of bimetallic nanoparticles based on black rice extract according to claim 1, characterized in that, The process for determining whether synthesized bimetallic nanoparticles meet the standards includes: Determine the absorption peak wavelength of copper-silver bimetallic nanoparticles; If the absorption peak wavelength of the copper-silver bimetallic nanoparticles does not fall within the predetermined absorption peak wavelength threshold for copper-silver bimetallic nanoparticles, then the synthesized copper-silver bimetallic nanoparticles are deemed not to meet the standard.

5. The green synthesis method of bimetallic nanoparticles based on black rice extract according to claim 4, characterized in that, When the synthesized copper-silver bimetallic nanoparticles do not meet the standards, the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined absorption peak wavelength threshold of the copper-silver bimetallic nanoparticles is determined as the abnormal characteristic wavelength difference.

6. The green synthesis method of bimetallic nanoparticles based on black rice extract according to claim 5, characterized in that, The process for determining the molar ratio of copper sulfate to silver nitrate in a copper-silver mixed salt solution includes: If the difference in the abnormal characteristic wavelength is negative, then it is determined to increase the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution. If the difference in the abnormal characteristic wavelength is positive, then the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is reduced.

7. The green synthesis method of bimetallic nanoparticles based on black rice extract according to claim 6, characterized in that, The increase in the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is determined based on the difference in the abnormal characteristic wavelengths.

8. The green synthesis method of bimetallic nanoparticles based on black rice extract according to claim 7, characterized in that, The reduction in the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is determined based on the difference in the abnormal characteristic wavelengths.

9. The green synthesis method of bimetallic nanoparticles based on black rice extract according to claim 2, characterized in that, In step S1, the mass of the black rice is 5g and the mass of the distilled water is 100g. In step S2, the black rice concentrate is diluted to a volume of 250mL to obtain black rice extract. In step S4, the vacuum drying temperature is 80℃ and the drying time is 24 hours.

10. The green synthesis method of bimetallic nanoparticles based on black rice extract according to claim 9, characterized in that, The predetermined wavelength threshold for the absorption peak of the copper-silver bimetallic nanoparticles is a resonant absorption peak wavelength of 440 nanometers.

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