A green synthesis method of bimetallic nanoparticles based on black rice extract

Abstract

The present application relates to the technical field of metal nanoparticles, and particularly relates to a green synthesis method of bimetallic nanoparticles based on black rice extract, wherein the primary mixed solution is obtained by mixing and boiling black rice and distilled water according to a mass ratio of 1:20, the black rice concentrate is obtained by reducing pressure filtration of the primary mixed solution after cooling to room temperature, the black rice extract is obtained by dilution, then the black rice extract is mixed with a copper-silver mixed salt solution, the liquid bimetallic nanoparticle solution is synthesized by reacting under the irradiation of a 350W xenon lamp for a predetermined time, then the copper-silver bimetallic nanoparticle wet mud is obtained by centrifugal filtration, the copper-silver bimetallic nanoparticles are obtained by vacuum drying at 80 DEG C, finally, the absorption peak wavelength is monitored by ultraviolet-visible absorption spectrum to determine whether the synthesized bimetallic nanoparticles meet the standard, so as to determine the adjustment range of the molar concentration ratio of copper sulfate and silver nitrate, and the efficiency of the synthesis of bimetallic nanoparticles is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal nanoparticles, in particular to a green synthesis method of bimetallic nanoparticles based on black rice extract. BACKGROUND

[0002] The market of nanomaterials has been in a growing trend. Bimetallic nanoparticles have attracted much attention due to their significant activity caused by the synergistic effect between two metals. The characteristics of bimetallic nanoparticles depend on the redox potential of metal ions, the type of reducing agent used, and the interaction force between them, which determines whether the bimetallic nanoparticles are core-shell alloy, heterostructure alloy, multi-shell alloy, cluster-in-alloy or random alloy of metal atoms. The synthesis method may also affect the crystal structure and particle size and distribution of metals in bimetallic nanoparticles. Bimetallic nanoparticles are synthesized using chemical and physical methods, which are time-consuming, inefficient and often require toxic reagents. Green synthesis of bimetallic nanoparticles has attracted much attention due to its environmental protection, rapidness and environmental friendliness. Green synthesis of bimetallic nanoparticles has promising application prospects in the fields of electronics, catalysis, antibacterial and the like. The synthesis of bimetallic nanoparticles using plant extracts has attracted much attention. Since plants can convert light energy into chemical energy, absorb, accumulate, utilize and recycle different minerals, plants and their products can be an important source of renewable and sustainable supply for the synthesis of nanometal particles. Plant components can be used as reducing agents and stabilizers to synthesize stable bimetallic nanoparticles.

[0003] Chinese Patent Publication No. CN117884644A discloses a green synthesis method of bimetallic nanoparticles, which comprises the following steps: S1. preparing a plant extract; S2. heating and stirring the plant extract to obtain a mixed solution A; S3. centrifuging the mixed solution A to remove the deposited biomass and collect the supernatant; S4. transferring the supernatant to a reactor, immediately adding a solution containing two metal salts, continuing magnetic stirring and heating to boiling for 5-10 min; S5. stopping heating, waiting for the temperature of the reactor to drop to room temperature, then adding the supernatant and continuing stirring reaction to obtain a mixed solution B; and S6. collecting the precipitate after high-speed centrifugation of the mixed solution B, washing and drying to obtain the bimetallic nanoparticles.

[0004] Chinese patent publication No. CN105880624A discloses a method for synthesizing spherical gold nanoparticles by self-assembly using bacitracin as a template. The method mainly involves adding bacitracin into a hydrochloric acid solution to prepare an acidic bacitracin solution with a concentration of 0.35-0.70 mM, and then subjecting the solution to heat treatment at a metal bath temperature of 40-60℃ for 1-2 h and ultrasonic treatment for 30 s. Then, a gold trichloride solution is added to the bacitracin solution, which is then placed in a double-layered air bath oscillator and incubated at 100-150 rpm and 20-25℃ for 20-30 h. Finally, a reducing agent, sodium borohydride, is added to the incubated solution in an amount of 60-90 μL, and the reaction temperature is controlled at 21-23℃. The reaction is allowed to proceed for 40-60 min to obtain spherical gold nanoparticles with a particle size of 80-90 nm.

[0005] However, the prior art still has the following problems:

[0006] The prior art does not consider the problems of complex process, high energy consumption, the need to use traditional reducing agents, and long reaction time in the preparation of copper-silver bimetallic nanoparticles by traditional chemical synthesis method, which leads to low synthesis efficiency of copper-silver bimetallic nanoparticles. SUMMARY

[0007] Therefore, the present application provides a green synthesis method of bimetallic nanoparticles based on black rice extract to overcome the problems of high energy consumption in high-temperature heating process and environmental pollution and complex process due to complicated processing steps caused by harsh reaction and synthesis conditions in the prior art, which leads to low synthesis efficiency of bimetallic nanoparticles.

[0008] To achieve the above-mentioned purposes, the present application provides a green synthesis method of bimetallic nanoparticles based on black rice extract, comprising:

[0009] S1, mixing black rice and distilled water at a mass ratio of 1:20, boiling the mixed solution for 15 minutes to obtain a primary mixed solution;

[0010] S2, subjecting the primary mixed solution cooled to room temperature to reduced pressure filtration to obtain a black rice concentrate, and diluting the black rice concentrate to obtain a black rice extract;

[0011] S3, using flavonoids and phenolic compounds in the black rice extract as a biological reducing agent, mixing the black rice extract and a copper-silver mixed salt solution at a volume ratio of 6:1, and subjecting the mixed solution to light irradiation under a 350 W xenon lamp for a predetermined period of time to synthesize a liquid bimetallic nanoparticle solution;

[0012] S4, subjecting the liquid bimetallic nanoparticle solution to centrifugal filtration to obtain a copper-silver bimetallic nanoparticle wet mud, and drying the copper-silver bimetallic nanoparticle wet mud at 80℃ under vacuum to obtain copper-silver bimetallic nanoparticles;

[0013] S5, monitoring the copper-silver bimetallic nanoparticles by ultraviolet-visible absorption spectroscopy, determining whether the synthesized bimetallic nanoparticles meet the standard based on the monitored absorption peak wavelength of the copper-silver bimetallic nanoparticles:

[0014] 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 copper-silver bimetallic nanoparticles absorption peak wavelength threshold.

[0015] Further, 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;

[0016] wherein the concentration of copper sulfate is 0.1 mol / L, and the concentration of silver nitrate is 0.1 mol / L.

[0017] Further, the predetermined reaction time under 350W xenon lamp illumination is 20 minutes.

[0018] Preferably, the process of determining whether the synthesized bimetallic nanoparticles meet the standard comprises:

[0019] determining the absorption peak wavelength of the copper-silver bimetallic nanoparticles;

[0020] If the absorption peak wavelength of the copper-silver bimetallic nanoparticles does not belong to the predetermined copper-silver bimetallic nanoparticles absorption peak wavelength threshold, it is determined that the synthesized copper-silver bimetallic nanoparticles do not meet the standard.

[0021] Further, in the case where the synthesized copper-silver bimetallic nanoparticles do not meet the standard, the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined copper-silver bimetallic nanoparticles absorption peak wavelength threshold is determined as an abnormal characteristic wavelength difference.

[0022] Further, the process of determining the molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution comprises:

[0023] If the abnormal characteristic wavelength difference is negative, it is determined to increase the mixed molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution;

[0024] If the abnormal characteristic wavelength difference is positive, it is determined to decrease the mixed molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution.

[0025] Further, the increase range of the mixed molar concentration ratio of copper sulfate to silver nitrate in the copper-silver mixed salt solution is determined based on the abnormal characteristic wavelength difference.

[0026] Further, the decrease range of the mixed molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is determined based on the abnormal characteristic wavelength difference.

[0027] 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 concentrated solution is diluted to a volume of 250mL to obtain the black rice extract, and in step S4, the vacuum drying temperature is 80℃ and the drying duration is 24 hours.

[0028] Further, the predetermined copper-silver bimetallic nanoparticle absorption peak wavelength threshold is a resonance absorption peak wavelength of 440 nanometers.

[0029] Compared with the prior art, the present application boils a solution obtained by mixing black rice and distilled water in a mass ratio of 1:20 for 15 minutes to obtain a primary mixed solution, cools it to room temperature, performs vacuum filtration on the primary mixed solution to obtain a black rice concentrated solution, dilutes it to obtain a black rice extract, then mixes the black rice extract with a copper-silver mixed salt solution, and synthesizes a liquid bimetallic nanoparticle solution under 350W xenon lamp light for a predetermined duration. After that, centrifugal filtration is performed to obtain copper-silver bimetallic nanoparticle wet mud, which is then vacuum dried at 80℃ for 24 hours to obtain copper-silver bimetallic nanoparticles. Finally, the synthesis of the bimetallic nanoparticles is monitored by ultraviolet-visible absorption spectroscopy, and whether the synthesized bimetallic nanoparticles meet the standard is determined based on the monitored absorption peak wavelength of the copper-silver bimetallic nanoparticles, so as to determine the adjustment range of the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution, thereby improving the efficiency of the synthesis of bimetallic nanoparticles.

[0030] In particular, the copper-silver bimetallic nanoparticles are successfully synthesized by using the black rice extract as a biological reducing agent, which exhibits significant environmental friendliness and process superiority. Since toxic and expensive reducing agents are used in traditional chemical synthesis, the natural bioactive ingredients in black rice, including polyphenols and anthocyanins, can rapidly reduce metal salts under 350W xenon lamp light, greatly reducing energy consumption and safety risks. The synthesis quality is monitored in real time by ultraviolet-visible absorption spectroscopy, and a feedback adjustment mechanism is established, which can dynamically adjust the precursor concentration ratio according to the absorption peak wavelength deviation, effectively ensuring the uniformity of the particle size, morphology and structure of the product. The finally synthesized copper-silver bimetallic nanoparticles have a simple, fast and low-cost process, which improves the efficiency of green synthesis of bimetallic nanoparticles.

[0031] In particular, the copper-silver bimetallic nanoparticles are successfully synthesized by using the black rice extract as a biological reducing agent and stabilizer under the condition of room temperature and 350W xenon lamp irradiation. The embodiment is environmentally friendly, reduces the use of hazardous chemicals such as sodium borohydride, and reduces the safety risk and environmental pollution. The black rice is widely available and low in cost, and the natural ingredients such as polyphenols and anthocyanins in the embodiment can efficiently reduce copper ions and silver ions and effectively stabilize the generated bimetallic nanoparticles. The embodiment is simple and efficient, and the energy consumption is extremely low. The entire synthesis process is completed by magnetic stirring and 350W xenon lamp irradiation at room temperature, the reaction time is short, and the reaction time is 20 minutes, without the need for complex equipment or high temperature and high pressure conditions, which significantly reduces the energy consumption and production cost. The synthesized product is copper-silver bimetallic nanoparticles, which is expected to have uniform particle size and stable alloy or core-shell structure, thereby improving the efficiency of green synthesis of bimetallic nanoparticles.

[0032] In particular, the online quality monitoring and feedback mechanism of ultraviolet-visible absorption spectrum can accurately construct the spectral determination standard, and can objectively and quickly quantitatively evaluate the quality of the synthesized product. The uniformity and stability of the product performance are ensured according to the difference between the absorption peak wavelength and the threshold value. The determination mechanism provides a direct basis for process optimization, and the adjustment range of the molar concentration ratio of copper sulfate and 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, thereby improving the efficiency of green synthesis of bimetallic nanoparticles. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The step flow chart of the embodiment of the application is based on the green synthesis method of the bimetallic nanoparticles based on the black rice extract;

[0034] Figure 2 The ultraviolet-visible absorption spectrum of the copper-silver bimetallic nanoparticles, nanocopper and nanosilver synthesized based on the black rice extract of the embodiment of the application;

[0035] Figure 3 The infrared spectrum of the copper-silver bimetallic nanoparticles and the black rice extract synthesized based on the black rice extract of the embodiment of the application;

[0036] Figure 4 The X-ray photoelectron spectrum of the copper-silver bimetallic nanoparticles synthesized based on the black rice extract of the embodiment of the application;

[0037] Figure 5 The TEM spectrum and EDX spectrum of the copper-silver bimetallic nanoparticles synthesized based on the black rice extract of the embodiment of the application;

[0038] Figure 6The HRTEM image and the SAED selected area electron diffraction pattern of the copper-silver bimetallic nanoparticles synthesized based on the black rice extract solution according to the embodiment of the present application are shown in the following figure:

[0039] Figure 7 The UV-visible absorption spectrum of the copper-silver bimetallic nanoparticles synthesized based on the black rice extract solution according to the embodiment of the present application on the adsorption of crystal violet is shown in the following figure. DETAILED DESCRIPTION

[0040] In order to make the purpose and advantages of the present application more clear and understandable, the present application will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0041] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application and are not intended to limit the protection scope of the present application.

[0042] Please refer to Figure 1 The step flow chart of the green synthesis method of the bimetallic nanoparticles based on the black rice extract solution according to the embodiment of the present application is shown in the following figure. The present application provides a green synthesis method of bimetallic nanoparticles based on the black rice extract solution, which comprises the following steps:

[0043] In step S1, a solution of black rice and distilled water mixed at a mass ratio of 1:20 is boiled for 15 minutes to obtain a primary mixed solution;

[0044] In step S2, the primary mixed solution cooled to room temperature is subjected to reduced pressure filtration to obtain a black rice concentrate solution, and the black rice concentrate solution is diluted to obtain a black rice extract solution;

[0045] In step S3, the flavonoids and phenolic compounds in the black rice extract solution are used as a biological reducing agent, and a solution of the black rice extract solution and a copper-silver mixed salt solution mixed at a volume ratio of 6:1 is subjected to reaction under irradiation of a 350W xenon lamp for a predetermined time to synthesize a liquid bimetallic nanoparticle solution;

[0046] In step S4, the liquid bimetallic nanoparticle solution is subjected to centrifugal filtration to obtain a copper-silver bimetallic nanoparticle wet mud, and the copper-silver bimetallic nanoparticle wet mud is dried under vacuum at 80℃ to obtain a copper-silver bimetallic nanoparticle;

[0047] In step S5, the copper-silver bimetallic nanoparticles are subjected to UV-visible absorption spectrum monitoring, and whether the synthesized bimetallic nanoparticles meet the standard is determined based on the monitored absorption peak wavelength of the copper-silver bimetallic nanoparticles:

[0048] 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 copper-silver bimetallic nanoparticle absorption peak wavelength threshold value.

[0049] The primary mixed solution is obtained by boiling the solution of 5 g of black rice mixed with 100 g of distilled water for 15 minutes;

[0050] The primary mixed solution cooled to room temperature is subjected to reduced pressure filtration to obtain a black rice concentrate;

[0051] The black rice concentrate is diluted to 250 mL to obtain a black rice extract;

[0052] The black rice extract 45 mL is mixed with the copper-silver mixed salt solution 7.5 mL, and the mixture is reacted under 350 W xenon lamp light for 20 min to obtain a liquid bimetallic nanoparticle solution;

[0053] The liquid bimetallic nanoparticle solution is centrifuged and filtered to obtain copper-silver bimetallic nanoparticle wet mud;

[0054] The copper-silver bimetallic nanoparticle wet mud is dried at 80°C under vacuum for 24 hours to obtain copper-silver bimetallic nanoparticles;

[0055] The copper-silver bimetallic nanoparticles are subjected to ultraviolet-visible absorption spectrum monitoring, and based on the monitored absorption peak wavelength of the copper-silver bimetallic nanoparticles, it is determined whether the synthesized bimetallic nanoparticles meet the standard:

[0056] 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 copper-silver bimetallic nanoparticle absorption peak wavelength threshold value;

[0057] The copper-silver mixed salt solution is prepared by magnetically stirring the mixed solution of 5 mL of copper sulfate and 2.5 mL of silver nitrate for 20 minutes;

[0058] The concentration of copper sulfate is 0.1 mol / L, and the concentration of silver nitrate is 0.1 mol / L.

[0059] The embodiment successfully prepares copper-silver bimetallic nanoparticles by using black rice extract as a biological reducing agent, showing significant environmental friendliness and process superiority. By replacing the toxic and expensive reducing agent in traditional chemical synthesis, the natural bioactive components in black rice, including polyphenol-phenolic compounds and anthocyanin-flavonoid compounds, are used to rapidly reduce metal salts under room temperature 350W xenon lamp illumination, significantly reducing energy consumption and safety risks. The synthesis quality is monitored in real time by ultraviolet-visible absorption spectroscopy, and a feedback regulation mechanism is established to dynamically adjust the precursor concentration ratio according to the wavelength deviation of the absorption peak, effectively ensuring the uniformity and stability of the particle size, morphology and structure of the product. The finally synthesized copper-silver bimetallic nanoparticles have excellent application potential in catalysis, antibacterial and other fields, and the overall process is simple, fast and low-cost, providing a new strategy for green large-scale production of nanomaterials and improving the efficiency of green synthesis of bimetallic nanoparticles.

[0060] Specifically, the copper-silver mixed salt solution is a solution obtained by mixing copper sulfate and silver nitrate at a molar concentration ratio of 2:1 and stirring magnetically for 20 minutes;

[0061] The concentration of the copper sulfate is 0.1 mol / L, and the concentration of the silver nitrate is 0.1 mol / L.

[0062] Specifically, the predetermined reaction time under 350W xenon lamp illumination is 20 minutes.

[0063] The embodiment successfully prepares copper-silver bimetallic nanoparticles by using black rice extract as a biological reducing agent and stabilizer under room temperature and 350W xenon lamp illumination. The embodiment is highly environmentally friendly, reducing the use of hazardous chemicals such as sodium borohydride in traditional chemical synthesis and reducing safety risks and environmental pollution. Black rice is widely available and low-cost, and the embodiment process is simple, efficient, and has very low energy consumption. The entire synthesis process is completed at room temperature by magnetic stirring and 350W xenon lamp illumination, with a short reaction time of 20 minutes, without the need for complex equipment or high temperature and pressure conditions, significantly reducing energy consumption and production costs. The final product is copper-silver bimetallic nanoparticles, which are expected to have uniform particle size and stable alloy or core-shell structure, and exhibit more excellent performance application potential than single-metal nanoparticles in catalysis, antibacterial, sensing and other fields. The efficiency of green synthesis of bimetallic nanoparticles is improved.

[0064] Please refer to Figure 2 As shown in the figure, it is the ultraviolet-visible absorption spectrum of the copper-silver bimetallic nanoparticles, nanocopper and nanosilver synthesized based on black rice extract in the embodiment of the application.

[0065] The embodiment is three kinds of nano metal ultraviolet-visible absorption spectrum, nano copper has a very obvious plasmon resonance absorption peak at 542nm, nano silver has an obvious plasmon resonance absorption peak at 414nm, the peak shape is symmetrically distributed, and the absorption peak of the copper-silver bimetallic nanoparticles is relatively wide and is located at 440nm. By comparing the ultraviolet-visible absorption spectrum of the three kinds of metal nanoparticles, it can be confirmed that the copper-silver bimetallic nanoparticles are successfully synthesized by using the black rice water extract as a reducing agent.

[0066] Please refer to Figure 3 The figure is the infrared spectrum of the copper-silver bimetallic nanoparticles based on the black rice extract of the embodiment of the application.

[0067] In the infrared spectrum of the black rice extract of the embodiment, 3295cm -1 is caused by the stretching vibration of hydroxyl, 2920cm -1 is the stretching vibration of methylene-CH2-, 1606cm -1 is related to the stretching vibration of carbon-carbon double bond, 1412cm -1 is the variable angle vibration of methyl, and 1049cm -1 is the stretching vibration of C-O bond and the skeleton vibration of C-C single bond. The characteristic peaks of the embodiment confirm that flavonoids and phenolic compounds exist in the black rice extract, and the reducing property of the compound of the embodiment enables the copper-silver bimetallic nanoparticles to be successfully synthesized. Compared with the black rice extract, the infrared spectrum of the copper-silver bimetallic nanoparticles has absorption peaks at similar wave numbers, which indicates that the surface of the copper-silver bimetallic nanoparticles is covered with organic compound components of the black rice extract.

[0068] Please refer to Figure 4 The figure is the X-ray photoelectron spectrum of the copper-silver bimetallic nanoparticles based on the black rice extract of the embodiment of the application.

[0069] The embodiment adopts X-ray photoelectron spectroscopy (XPS) technology to perform systematic characterization analysis on the sample. As shown in Figure 4 a, the full spectrum scanning result of the sample shows that it mainly contains four elements of C, O, Ag and Cu, and the atomic percentage of each element obtained by quantitative analysis is as follows: C-83.4%, O-15.3%, Ag-0.8% and Cu-0.5%. The higher content of carbon element may be derived from the residual organic components in the plant extract or the inevitable surface pollution in the testing process. In order to further determine the chemical state of Ag and Cu, high-resolution XPS analysis is performed on Ag 3d and Cu 2p orbits. The embodiment Figure 4 b shows the fine spectrum of the Ag 3d region, and two obvious characteristic peaks can be observed: the peak at 368.2 eV is attributed to Ag 3d 5 / 2 orbit, and the peak at 374.2 eV corresponds to Ag 3d3 / 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] Referring to Figure 7 Fig. 6 is a UV-Vis absorption spectrum of the copper-silver bimetallic nanoparticles synthesized based on the black rice extract according to an embodiment of the present application, showing the adsorption of crystal violet.

[0075] Crystal violet is an environmental pollutant and can be applied in many fields such as medicine, biology and industry. It has high water solubility and structural stability, making it exist in water for a long time and difficult to degrade. Crystal violet can be toxic to aquatic organisms, interfere with their growth and reproduction, and destroy the ecological balance. It can also enter the human body through the food chain, causing reproductive toxicity, mutagenicity and carcinogenicity, etc. The copper-silver bimetallic nanoparticle complex synthesized in the embodiment can quickly and effectively remove crystal violet in water.

[0076] In the embodiment, 5 mg of copper-silver bimetallic nanoparticles were added to 50 mL of crystal violet aqueous solution with a concentration of 10 mg / L for adsorption experiment, and the UV-Vis absorption spectrum of the remaining crystal violet in the solution was measured at 0 min, 2 min, 5 min, 10 min and 20 min, respectively. From the results, it can be seen that the adsorption rate of copper-silver bimetallic nanoparticles to crystal violet can reach 53% within 2 min, and the adsorption rate gradually slows down with time, and the adsorption rate can reach 64% within 20 min.

[0077] Specifically, the process of determining whether the synthesized bimetallic nanoparticles meet the standard includes:

[0078] determining the absorption peak wavelength of the copper-silver bimetallic nanoparticles;

[0079] if the absorption peak wavelength of the copper-silver bimetallic nanoparticles belongs to the predetermined copper-silver bimetallic nanoparticle absorption peak wavelength threshold, it is determined that the synthesized copper-silver bimetallic nanoparticles meet the standard;

[0080] if the absorption peak wavelength of the copper-silver bimetallic nanoparticles does not belong to the predetermined copper-silver bimetallic nanoparticle absorption peak wavelength threshold, it is determined that the synthesized copper-silver bimetallic nanoparticles do not meet the standard.

[0081] It can be understood that the copper-silver bimetallic nanoparticle absorption peak wavelength threshold is predetermined, wherein the product of the standard wavelength 440 nm of the synthesized copper-silver bimetallic nanoparticles and the precision coefficient is determined as the copper-silver bimetallic nanoparticle absorption peak wavelength threshold, and the precision coefficient in the embodiment is selected within the interval [0.95, 1.05], preferably the precision coefficient is 1.

[0082] By means of the online quality monitoring and feedback mechanism of the ultraviolet-visible absorption spectrum, the spectral determination standard is accurately constructed, the quality of the synthesis product can be objectively and quickly quantitatively evaluated, and the uniformity and stability of the product performance are ensured according to the difference between the absorption peak wavelength and the threshold value. The determination mechanism provides a direct basis for process optimization, the adjustment range of the molar concentration ratio of copper sulfate and 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 value of the copper-silver bimetallic nanoparticles, and the efficiency of the green synthesis of the bimetallic nanoparticles is improved.

[0083] Specifically, in the case that the synthesized copper-silver bimetallic nanoparticles do not meet the standard, the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticles and the predetermined absorption peak wavelength threshold value of the copper-silver bimetallic nanoparticles is determined as an abnormal characteristic wavelength difference.

[0084] Specifically, the process of determining the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution includes:

[0085] If the abnormal characteristic wavelength difference is negative, it is determined to increase the mixed molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution.

[0086] If the abnormal characteristic wavelength difference is positive, it is determined to decrease the mixed molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution.

[0087] The embodiment can objectively and quickly quantitatively evaluate the quality of the synthesis product by means of the online quality monitoring and feedback mechanism of the ultraviolet-visible absorption spectrum, and ensure the uniformity and stability of the product performance according to the difference between the absorption peak wavelength and the threshold value. The determination mechanism provides a direct basis for process optimization, the adjustment range of the molar concentration ratio of copper sulfate and 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 value of the copper-silver bimetallic nanoparticles, and the efficiency of the green synthesis of the bimetallic nanoparticles is improved.

[0088] Specifically, the increase range of the mixed molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is determined based on the abnormal characteristic wavelength difference.

[0089] The embodiment increases the increase range of the mixed molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution to the point that the abnormal characteristic wavelength difference approaches zero.

[0090] Specifically, the decrease range of the mixed molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is determined based on the abnormal characteristic wavelength difference.

[0091] The embodiment reduces the reduction range of the mixed molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution to near zero.

[0092] Specifically, in step S1, the mass of the black rice is 5 g, and the mass of the distilled water is 100 g; in step S2, the black rice concentrated solution is diluted to a volume of 250 mL to obtain a black rice extract; and in step S4, the vacuum drying temperature is 80°C, and the drying duration is 24 hours.

[0093] Specifically, the predetermined copper-silver bimetallic nanoparticle absorption peak wavelength threshold is a resonance absorption peak wavelength of 440 nm Rice .

[0094] So far, the technical solutions of the present application have been described in combination with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after these changes or replacements will all fall within the protection scope of the present application.

Claims

1. A green synthesis method of bimetallic nanoparticles based on black rice extract, characterized by, Comprise: S1, mix black rice with distilled water according to the mass ratio 1:20, boil the mixed solution for 15 minutes to obtain a primary mixed solution; S2, cool the primary mixed solution to room temperature, and then perform vacuum filtration to obtain a black rice concentrate, and dilute the black rice concentrate to obtain a black rice extract; S3, the flavonoids and phenolic compounds in the black rice extract are used as a biological reducing agent, and the black rice extract is mixed with a copper-silver mixed salt solution according to a volume ratio of 6:1 to synthesize a liquid bimetallic nanoparticle solution under irradiation of a 350W xenon lamp for a predetermined time; S4, centrifugal filtration of the liquid bimetallic nanoparticle solution to obtain a copper-silver bimetallic nanoparticle wet mud, and drying the copper-silver bimetallic nanoparticle wet mud under vacuum at 80°C to obtain a copper-silver bimetallic nanoparticle; S5, the copper-silver bimetallic nanoparticle is monitored by ultraviolet-visible absorption spectroscopy, and whether the synthesized bimetallic nanoparticle meets the standard is determined based on the absorption peak wavelength of the copper-silver bimetallic nanoparticle: If it does not meet the standard, the adjustment range of the molar concentration ratio of copper sulfate and 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 nanoparticle and the predetermined copper-silver bimetallic nanoparticle absorption peak wavelength threshold.

2. The green synthesis of bimetallic nanoparticles based on black rice extract of claim 1, wherein, The copper-silver mixed salt solution is obtained by mixing copper sulfate and silver nitrate according to a molar concentration ratio of 2:1, and the mixed solution is subjected to magnetic stirring for 20 minutes to obtain the copper-silver mixed salt solution; Wherein, 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 of bimetallic nanoparticles based on black rice extract of claim 1, wherein, The predetermined time for reaction under irradiation of the 350W xenon lamp is 20 minutes.

4. The green synthesis of bimetallic nanoparticles based on black rice extract of claim 1, wherein, The process of determining whether the synthesized bimetallic nanoparticle meets the standard comprises: Determine the absorption peak wavelength of the copper-silver bimetallic nanoparticle; If the absorption peak wavelength of the copper-silver bimetallic nanoparticle does not belong to the predetermined copper-silver bimetallic nanoparticle absorption peak wavelength threshold, it is determined that the synthesized copper-silver bimetallic nanoparticle does not meet the standard.

5. The green synthesis of bimetallic nanoparticles based on black rice extract of claim 4 wherein, In the case where the synthesized copper-silver bimetallic nanoparticle does not meet the standard, the difference between the absorption peak wavelength of the copper-silver bimetallic nanoparticle and the predetermined copper-silver bimetallic nanoparticle absorption peak wavelength threshold is calculated to determine the abnormal characteristic wavelength difference.

6. The green synthesis of bimetallic nanoparticles based on black rice extract of claim 5 wherein, The process of determining the molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution comprises: If the abnormal characteristic wavelength difference is negative, it is determined to increase the mixed molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution; If the abnormal characteristic wavelength difference is positive, it is determined to decrease the mixed molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution.

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

8. The green synthesis of bimetallic nanoparticles based on black rice extract of claim 7 wherein, The decrease range of the mixed molar concentration ratio of copper sulfate and silver nitrate in the copper-silver mixed salt solution is determined based on the abnormal characteristic wavelength difference.

9. The green synthesis of bimetallic nanoparticles based on black rice extract of claim 2, wherein, 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 the black rice extract. In step S4, the vacuum drying temperature is 80°C, and the drying time is 24 hours.

10. The green synthesis of bimetallic nanoparticles based on black rice extract of claim 9, wherein, The predetermined copper-silver bimetallic nanoparticle absorption peak wavelength threshold is a resonance absorption peak wavelength of 440 nm. The predetermined copper-silver bimetallic nanoparticle absorption peak wavelength threshold is a resonance absorption peak wavelength of 440 nm.

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