A method for green synthesis of copper nanoparticles using black rice extract and its uses

Abstract

The present invention relates to the technical field of the preparation of metal nanomaterials, and in particular to a method and use for the green synthesis of nano copper using black rice extract, including: mixing black rice powder with distilled water for extraction to obtain black rice extract; when it is determined that the preparation of the black rice extract is not up to standard according to the absorbance, simultaneously increasing the temperature of the heating extraction; diluting the black rice extract and mixing it with a CuSO4 solution for reaction to obtain a nano copper solution; when it is determined that the preparation of the nano copper solution is not up to standard according to the particle size uniformity characteristic value of the nano copper, secondarily determining whether the preparation of the nano copper solution is up to standard according to the density of the nano copper solution, or increasing the stirring rate; centrifuging, washing, and vacuum drying the qualified nano copper solution and then sieving it to obtain nano copper, and when it is determined that the preparation of the nano copper is not up to standard according to the weight percentage, reducing the centrifugal speed, thereby improving the preparation quality of the nano copper.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of metal nanomaterials, and particularly to a method and use for green synthesis of nano copper using black rice extract. Background Art

[0002] Nano copper is a new type of nanomaterial, specifically referring to copper particles or copper nanocrystals with a diameter between 1 and 100 nanometers, which can be prepared by physical or chemical methods, resulting in different nanoparticle structures and properties. However, toxic chemicals and preparations that are prone to environmental pollution need to be used in the preparation process. Therefore, replacing harmful components with non-toxic, biocompatible, and eco-friendly materials to synthesize metal nano copper particles is an important research direction at present.

[0003] In addition, tetracycline pollutants in water bodies pose a serious threat to aquatic ecosystems, plants, aquatic organisms, and human health. Due to their tiny size and high specific surface area, nano copper particles have a certain adsorption capacity for pollutants such as tetracycline.

[0004] Chinese Patent Publication No.: CN102601381A, discloses a copper nano powder and its preparation method. The powder is obtained by the following method: preparing a copper salt solution from a copper salt, adding a drag reducer and an inhibitor, obtaining a copper salt mixture solution and preheating it; preparing a reducing agent solution and adjusting its pH value, and then preheating it; mixing the copper salt mixture solution and the reducing agent solution and stirring evenly, heating to the reaction temperature and reacting for a certain time to obtain a nano copper suspension solution; aging the nano copper suspension solution; performing vacuum filtration on the suspension solution obtained in the previous step to obtain copper nano powder without removing impurities; performing certain treatment on the copper nano powder to obtain copper nano powder wrapped with an organic solvent; performing vacuum filtration on the copper nano powder to obtain wet copper nano powder; and performing low-temperature vacuum drying on the copper nano powder obtained in the previous step to obtain the finished product of copper nano powder.

[0005] It can be seen that the above technical solution does not consider the influence of different concentrations of the solution, the stirring rate, and the centrifugation rate during the reaction process on the dispersion of nano copper, resulting in poor quality of the preparation of nano copper. Summary of the Invention

[0006] Therefore, the present invention provides a method and use for green synthesis of nano copper using black rice extract to overcome the problem that the above prior art does not consider the influence of different concentrations of the solution, the stirring rate, and the centrifugation rate during the reaction process on the dispersion of nano copper, resulting in poor quality of the preparation of nano copper.

[0007] To achieve the above object, on the one hand, the present invention provides a method for green synthesis of nano copper using black rice extract, including:

[0008] Grind black rice, mix the black rice powder with distilled water for heating extraction, perform vacuum filtration after cooling to room temperature to obtain a black rice extract, and obtain the absorbance of the black rice extract;

[0009] When it is determined that the preparation of the black rice extract does not meet the preset standard according to the absorbance, increase the temperature of the heating extraction;

[0010] Add distilled water to the black rice extract that meets the preset standard for dilution, mix and react the diluted black rice extract with CuSO4 solution, stir at room temperature to obtain a nano copper solution, obtain the standard deviation of the particle size and the average particle size of the nano copper, and obtain the particle size uniformity characteristic value of the nano copper;

[0011] When it is determined that the preparation of the nano copper solution does not meet the preset standard according to the particle size uniformity characteristic value of the nano copper, re-determine whether the preparation of the nano copper solution meets the preset standard according to the density of the nano copper solution, or increase the stirring rate;

[0012] Centrifuge, wash and vacuum dry the nano copper solution that meets the preset standard to obtain nano copper, obtain the weight percentage of the nano copper under preset conditions, and when it is determined that the preparation of the nano copper does not meet the preset standard according to the weight percentage, reduce the centrifugation speed of the centrifuge,

[0013] Among them, the preset condition is to weigh the weight of nano copper with a particle size less than or equal to 6nm using an electronic balance.

[0014] Further, the dosage ratio of the black rice powder to the distilled water is 1.0g - 5.0g: 20mL - 100mL, the extraction time is 15min - 30min, and the temperature of the heating extraction is 80°C - 100°C.

[0015] Further, the molar concentration of the CuSO4 solution is 0.01mol / L, the stirring duration at room temperature is 5min, and the stirring rate is 350r / min.

[0016] Further, the centrifugation rate of the centrifuge is 10000rpm - 15000rpm, and the centrifugation time is 9 - 15min.

[0017] Further, the process of determining that the preparation of the black rice extract does not meet the preset standard according to the absorbance includes:

[0018] Compare the absorbance with the preset absorbance;

[0019] If the absorbance is less than the preset absorbance, it is determined that the preparation of the black rice extract does not meet the preset standard, and increase the temperature of the heating extraction according to the difference between the preset absorbance and the absorbance.

[0020] Further, the process of determining that the preparation of the nano - copper solution does not meet the preset standard based on the particle size uniformity eigenvalue of the nano - copper includes:

[0021] Compare the particle size uniformity eigenvalue with the first preset particle size uniformity threshold and the second preset particle size uniformity threshold respectively;

[0022] If the particle size uniformity eigenvalue is greater than or equal to the first preset particle size uniformity threshold and less than the second preset particle size uniformity threshold, it is determined that the preparation of the nano - copper solution does not meet the preset standard, and the preparation of the nano - copper solution is further determined whether it meets the preset standard according to the density of the nano - copper solution;

[0023] If the particle size uniformity eigenvalue is greater than or equal to the second preset particle size uniformity threshold, it is determined that the preparation of the nano - copper solution does not meet the preset standard, and the stirring rate is increased according to the difference between the particle size uniformity eigenvalue and the second preset particle size uniformity threshold;

[0024] The particle size uniformity eigenvalue of the nano - copper is jointly determined by the particle size standard deviation and the average particle size of the nano - copper.

[0025] Further, the preparation of the nano - copper solution is further determined whether it meets the preset standard according to the density of the nano - copper solution, where

[0026] If the density of the nano - copper solution is less than the preset density, it is determined that the preparation of the nano - copper solution meets the preset standard, and the nano - copper solution that meets the preset standard is centrifuged;

[0027] If the density of the nano - copper solution is greater than or equal to the preset density, it is determined that the preparation of the nano - copper solution does not meet the preset standard, and the amount of distilled water added to the black rice extract is increased according to the difference between the density of the nano - copper solution and the preset density.

[0028] Further, the process of determining that the preparation of the nano - copper does not meet the preset standard based on the weight percentage of the nano - copper includes:

[0029] If the weight percentage is greater than or equal to the preset weight percentage, it is determined that the preparation of the nano - copper does not meet the preset standard, and the centrifugal speed of the centrifuge is decreased according to the difference between the weight percentage and the preset weight percentage.

[0030] There are several adjustment methods for reducing the centrifugal speed of the centrifuge, and each adjustment method has a different reduction amplitude for the centrifugal speed.

[0031] On the other hand, the present invention also provides the use of the nano - copper prepared by the method of green synthesis of nano - copper using black rice extract, and the nano - copper is used for the adsorption of tetracycline in water.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows. The present invention uses black rice and copper sulfate solution as raw materials, reducing the use of chemical raw materials. The quality of the black rice extract is inspected by obtaining the absorbance of the black rice extract. The preparation effect of the nano copper solution is inspected by the uniform characteristic value of the particle size of the nano copper and the density of the nano copper solution, and the preparation conditions are adjusted accordingly, reducing the possibility of agglomeration of the nano copper and improving the preparation efficiency. The preparation effect of the nano copper is evaluated by the weight ratio of the nano copper, ensuring that the particle size distribution of the nano copper meets the preparation requirements and improving the preparation quality of the nano copper.

[0033] Furthermore, the present invention uses black rice as a raw material, with relatively less process consumption and no toxic by-products generated, being environmentally friendly, safe, belonging to a green synthesis process, and having a simple preparation method, realizing the effective utilization of resources, reducing the use of chemical raw materials, and thus reducing environmental pollution.

[0034] Furthermore, the present invention determines whether the preparation of the black rice extract meets the preset standard according to the absorbance, and increases the heating extraction temperature when it does not meet the preset standard, precisely controlling the extraction conditions to ensure the quality of the black rice extract, thereby improving the preparation efficiency.

[0035] Furthermore, the present invention determines whether the preparation of the nano copper solution meets the preset standard according to the uniform characteristic value of the particle size of the nano copper, precisely evaluating the preparation effect of the nano copper solution, intuitively reflecting the dispersion of the nano copper particles, and improving the preparation quality of the nano copper.

[0036] Furthermore, the present invention secondarily determines whether the preparation of the nano copper solution meets the preset standard according to the density of the nano copper solution, more accurately evaluating the preparation quality of the nano copper solution, and thus reducing the possibility of misjudgment.

[0037] Furthermore, the present invention determines whether the preparation of the nano copper meets the preset standard according to the weight ratio of the nano copper, and reduces the centrifugal speed of the centrifuge when it does not meet the preset standard, thereby improving the control of the particle size of the nano copper.

[0038] Furthermore, the present invention has several adjustment methods for reducing the centrifugal speed of the centrifuge, and each adjustment method has a different reduction amplitude for the centrifugal speed of the centrifuge, thereby realizing precise control of the reduction amplitude of the centrifugal speed of the centrifuge.

[0039] Furthermore, the nano copper synthesized by the present invention through green synthesis is applied to water purification. The nano copper adsorbs tetracycline pollutants in the water body and has a good adsorption effect on tetracycline, thus providing a new solution and technical support for the field of water purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1Flow chart of the method for green synthesis of nano - copper using black rice extract in the embodiments of the present invention;

[0041] Figure 2 Flow chart of determining whether the preparation of black rice extract meets the preset standard in the embodiments of the present invention;

[0042] Figure 3 UV - Vis absorption spectrum of nano - copper green - synthesized using black rice extract in the embodiments of the present invention;

[0043] Figure 4 High - resolution transmission electron microscope image of nano - copper green - synthesized using black rice extract in the embodiments of the present invention; A is the high - resolution transmission electron microscope image of nano - copper at a scale of 2nm, B is the particle size distribution diagram of nano - copper particles, and C is the transmission electron microscope image of nano - copper at a scale of 100nm;

[0044] Figure 5 Infrared spectrum diagram of the obtained nano - copper and black rice extract of the present invention. Detailed implementation manners

[0045] In order to make the objectives and advantages of the present invention more clear and understandable, the present invention 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 invention and do not limit the present invention.

[0046] The preferred implementation manners of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these implementation manners are only used to explain the technical principle of the present invention and do not limit the protection scope of the present invention.

[0047] It should be noted that the data in this embodiment are obtained through comprehensive analysis and evaluation of the historical test data and corresponding historical test results of the present invention in the three months before this test. Those skilled in the art can understand that the determination method of the present invention for a single above - mentioned parameter can be to select the value with the highest proportion according to the data distribution as the preset standard parameter, use weighted summation to obtain the value as the preset standard parameter, substitute each historical data into a specific formula and use the value obtained by this formula as the preset standard parameter, or other selection methods, as long as it satisfies that the method of the present invention can clearly define different specific situations in a single determination process.

[0048] Please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5As shown, they are respectively the flow chart of the method for green synthesis of nano copper using black rice extract in the embodiments of the present invention; the flow chart for determining whether the preparation of black rice extract meets the preset standard in the embodiments of the present invention; the ultraviolet-visible absorption spectrum of the nano copper green synthesized using black rice extract in the embodiments of the present invention; the high-resolution transmission electron microscope image of the nano copper green synthesized using black rice extract in the embodiments of the present invention; among them, A is the high-resolution transmission electron microscope image of the nano copper at a scale of 2 nm, B is the particle size distribution diagram of the nano copper particles, C is the transmission electron microscope image of the nano copper at a scale of 100 nm; the infrared spectrum diagram of the obtained nano copper and black rice extract in the present invention.

[0049] On the one hand, the embodiments of the present invention provide a method for green synthesis of nano copper using black rice extract, including:

[0050] Step S1, grinding black rice, mixing the black rice powder with distilled water for heating extraction, performing reduced-pressure filtration after cooling to room temperature to obtain black rice extract, and obtaining the absorbance of the black rice extract;

[0051] Step S2, when it is determined that the preparation of the black rice extract does not meet the preset standard according to the absorbance, increasing the temperature of the heating extraction;

[0052] Step S3, adding distilled water to the black rice extract that meets the preset standard for dilution, mixing and reacting the diluted black rice extract with CuSO4 solution, stirring at room temperature to obtain a nano copper solution, obtaining the standard deviation of the particle size of the nano copper and the average particle size of the nano copper, and obtaining the particle size uniformity characteristic value of the nano copper;

[0053] Step S4, when it is determined that the preparation of the nano copper solution does not meet the preset standard according to the particle size uniformity characteristic value of the nano copper, secondarily determining whether the preparation of the nano copper solution meets the preset standard according to the density of the nano copper solution, or increasing the stirring rate;

[0054] Step S5, centrifuging, washing and vacuum drying the nano copper solution that meets the preset standard to obtain nano copper, obtaining the weight ratio of the nano copper under preset conditions, and when it is determined that the preparation of the nano copper does not meet the preset standard according to the weight ratio, reducing the centrifugal speed of the centrifuge,

[0055] Wherein, the preset condition is to weigh the weight of the nano copper with a particle size less than or equal to 6 nm using an electronic balance.

[0056] Specifically, mixing the black rice powder with distilled water and heating to 85 °C.

[0057] Specifically, using a grinder to grind black rice into powder, the grinder is 50 Hz to 70 Hz, and the grinding duration is 25 s to 40 s.

[0058] Specifically, the dosage ratio of black rice powder to distilled water is 1.0 g to 5.0 g: 20 mL to 100 mL, the extraction time is 15 min to 30 min, and the heating extraction temperature is 80 °C to 100 °C.

[0059] Specifically, the molar concentration of the CuSO4 solution is 0.01 mol / L, the normal temperature stirring duration is 5 min, and the stirring rate is 350 r / min.

[0060] Specifically, in step S5, the centrifugation rate of the centrifuge is 10,000 rpm to 15,000 rpm, the centrifugation time is 9 to 15 min; vacuum drying at 85 °C for 24 h;

[0061] Specifically, after centrifuging, washing, and vacuum drying the nano copper solution meeting the preset standards, nano copper with a particle size less than or equal to 6 nm is obtained by an electronic balance.

[0062] Specifically, the process of determining that the preparation of the black rice extract does not meet the preset standards according to the absorbance includes:

[0063] Comparing the absorbance with the preset absorbance of 0.7;

[0064] If the absorbance is less than the preset absorbance, it is determined that the preparation of the black rice extract does not meet the preset standards, and the heating extraction temperature is increased according to the difference between the preset absorbance and the absorbance.

[0065] Specifically, the absorbance of the black rice extract is obtained by an ultraviolet-visible spectrophotometer; the preset absorbance value is 0.7. It can be understood that the preset absorbance value is obtained by taking the average of the absorbance of the black rice extract at 495 nm. In the historical detection data of this detection, there is a very obvious plasma resonance absorption peak at 542 nm, and the peak shape is symmetrically distributed, indicating that a large number of spherical nano coppers are generated in the solution and the particle sizes are relatively uniform. However, the value of the preset absorbance is not limited to this, and those skilled in the art can also adjust this value according to actual needs.

[0066] Specifically, the process of determining that the preparation of the nano copper solution does not meet the preset standards according to the particle size uniformity characteristic value of the nano copper includes:

[0067] Comparing the particle size uniformity characteristic value with the first preset particle size uniformity threshold of 1.03 and the second preset particle size uniformity threshold of 1.21 respectively;

[0068] If the particle size uniformity characteristic value is greater than or equal to the first preset particle size uniformity threshold and less than the second preset particle size uniformity threshold, it is determined that the preparation of the nano copper solution does not meet the preset standards, and the preparation of the nano copper solution is further determined whether it meets the preset standards according to the density of the nano copper solution;

[0069] If the particle size uniformity eigenvalue is greater than or equal to the second preset particle size uniformity threshold, it is determined that the preparation of the nano-copper solution does not meet the preset standard, and the stirring rate is increased according to the difference between the particle size uniformity eigenvalue and the second preset particle size uniformity threshold;

[0070] The average particle size and particle size standard deviation of the nano-copper are obtained by cooperating with a transmission electron microscope and image analysis software such as ImagePro Plus;

[0071] The particle size uniformity eigenvalue of the nano-copper is obtained by the following formula:

[0072]

[0073] In the formula, P represents the particle size uniformity eigenvalue of the nano-copper; D represents the average particle size of the nano-copper; D0 represents the preset average particle size of the nano-copper, and D0 is set to 9 nm; α represents the weight of the average particle size of the nano-copper, α = 0.45; σ represents the particle size standard deviation of the nano-copper; σ0 represents the preset particle size standard deviation of the nano-copper, and σ0 is set to 0.89; β represents the weight of the particle size standard deviation of the nano-copper, and β is set to 0.55.

[0074] In this embodiment, the first preset particle size uniformity threshold is taken as 1.03 and the second preset particle size uniformity threshold is taken as 1.21, which are obtained by comprehensive analysis and evaluation of historical detection data and corresponding historical detection results;

[0075] The particle size uniformity eigenvalue is an important index for evaluating the preparation quality of the nano-copper solution, and can effectively control the particle size distribution uniformity of the nano-copper solution.

[0076] Specifically, the preparation of the nano-copper solution is determined again according to the density of the nano-copper solution, where

[0077] If the density of the nano-copper solution is less than the preset density of 1.05 g / cm³, it is determined that the preparation of the nano-copper solution meets the preset standard, and the nano-copper solution that meets the preset standard is centrifuged;

[0078] If the density of the nano-copper solution is greater than or equal to the preset density, it is determined that the preparation of the nano-copper solution does not meet the preset standard, and the amount of distilled water added to the black rice extract is increased according to the difference between the density of the nano-copper solution and the preset density.

[0079] Specifically, the density of the nano-copper solution is obtained by a hydrometer; the value of the preset density is 1.05 g / cm³, but the value of the preset absorbance is not limited to this, and those skilled in the art can also adjust this value according to actual needs.

[0080] A nano - copper solution with uniform density usually means that the particles are evenly distributed in the solution and the solution has good stability. If the density fluctuates or is abnormal, it indicates unstable phenomena such as particle agglomeration, precipitation, or stratification in the solution.

[0081] Specifically, the process of determining that the preparation of nano - copper does not meet the preset standard according to the weight ratio of nano - copper includes:

[0082] If the weight ratio is greater than or equal to the preset weight ratio of 0.22, it is determined that the preparation of nano - copper does not meet the preset standard, and the centrifugal speed of the centrifuge is reduced according to the difference between the weight ratio and the preset weight ratio.

[0083] Specifically, the weight ratio is the ratio of the weight of nano - copper with a particle size less than or equal to 6 nm to the total weight of nano - copper;

[0084] It can be understood that the magnitude of the centrifugal speed will directly affect the centrifugal force exerted on the nano - copper particles during centrifugation. When the speed is too high, the nano - copper particles will deform or break due to excessive centrifugal force, resulting in damage to the integrity of the nano - structure.

[0085] Specifically, there are several adjustment methods for reducing the centrifugal speed of the centrifuge. Among them,

[0086] If the difference in weight ratio is less than the first preset difference in weight ratio of 0.11, the centrifugal speed of the centrifuge is reduced to the corresponding value using the first adjustment coefficient of 0.99;

[0087] If the difference in weight ratio is greater than or equal to the first preset difference in weight ratio and less than the second preset difference in weight ratio of 0.21, the centrifugal speed of the centrifuge is reduced to the corresponding value using the second adjustment coefficient of 0.97;

[0088] If the difference in weight ratio is greater than or equal to the second preset difference in weight ratio, the centrifugal speed of the centrifuge is reduced to the corresponding value using the third adjustment coefficient of 0.95.

[0089] On the other hand, the present invention provides the use of nano - copper prepared by the method of green synthesis of nano - copper using black rice extract, and the nano - copper is used for the adsorption of tetracycline in water.

[0090] Example 1

[0091] The black rice was ground for 25 s with a grinder at 50 Hz to obtain black rice powder. 5 g of black rice powder was mixed with 100 mL of distilled water, and it was placed in a water bath pot heated to 80 °C and extracted for 20 min. Stirring was continued during the extraction. After cooling to room temperature, it was subjected to vacuum filtration to obtain black rice extract;

[0092] The absorbance of the black rice extract at a wavelength of 495 nm was obtained using a UV-visible spectrophotometer, and the measured absorbance was 0.8, which is greater than the preset absorbance of 0.7. It was determined that the preparation of the black rice extract met the preset standard; the black rice extract that met the preset standard was diluted to 250 mL with distilled water, and the diluted black rice extract was mixed with 250 mL of 0.01 mol / L CuSO4 solution and stirred at room temperature for 5 min to obtain a nano-copper solution. The average particle size and the standard deviation of the particle size distribution of the nano-copper were obtained using a transmission electron microscope and Image Pro Plus. The particle size uniformity characteristic value of the nano-copper was 0.83, which is less than the first preset particle size uniformity threshold of 1.03. It was then determined that the preparation of the nano-copper solution met the preset standard;

[0093] The nano-copper solution that met the preset standard was centrifuged at a speed of 10,000 rpm for 10 min, the supernatant was removed, the precipitate was taken for washing, and vacuum dried at 85 °C for 24 h to obtain nano-copper. The weights of the nano-copper with a particle size less than or equal to 6 nm and the total weight of the nano-copper were weighed using an electronic balance, and the weight ratio was 0.20, which is less than the preset weight ratio of 0.22. It was then determined that the preparation of the nano-copper met the preset standard.

[0094] Figure 3 is the UV-visible absorption spectrum of the nano-copper. The results show that a plasma resonance absorption peak appears at 542 nm, and the peak shape is symmetrically distributed, indicating that a large number of spherical nano-coppers are generated in the solution and the particle sizes are relatively uniform; the black rice aqueous extract acts as a reducing agent to reduce copper particles to nano-copper.

[0095] Figure 4 is the high-resolution transmission electron microscope image of the nano-copper. It can be seen that the nano-copper has good dispersion, is spherical, has a small particle size, and the average particle size is 9.03 nm. The nano-copper with the largest proportion has a particle size between 6 - 8 nm. The interplanar spacings of the marked nano-copper particles in the high-resolution transmission electron microscope image of the illustration were measured, and the distances were 2.05 Å and 2.03 Å respectively. By comparing with the standard PDF card of Cu, it was determined to be the 111 crystal plane of the Cu crystal structure.

[0096] Figure 5 is the infrared spectrum of the nano-copper obtained using the black rice aqueous extract as a reducing agent and the black rice aqueous extract. In the infrared spectrum of the black rice aqueous extract, at 3295 cm -1 is caused by the stretching vibration of the hydroxyl group, and at 2920 cm -1 is the stretching vibration of the methylene -CH2-, at 1606 cm -1 is related to the stretching vibration of the carbon-carbon double bond, at 1412 cm -1 is the bending vibration of the methyl group, and at 1049 cm -1This is the stretching vibration of the C-O bond and the skeletal vibration of the C-C single bond; these characteristic peaks confirm the presence of flavonoid compounds and phenolic compounds in the aqueous extract of black rice. The reducibility of these compounds enables the successful synthesis of copper nanoparticles; the infrared spectrum of copper nanoparticles has the same absorption peaks as those of the black rice extract at similar wavenumbers, indicating that the surface of the copper nanoparticles is covered with certain components of the aqueous extract of black rice.

[0097] Application Example 1

[0098] Weigh 20 mg of the vacuum-dried copper nanoparticle powder obtained in Example 1 and add it to 50 mL of a 20 ppm aqueous solution of tetracycline hydrochloride. Place it in an oscillator at room temperature and oscillate for 50 minutes.

[0099] During the oscillation process, sample once every 10 minutes, each time taking 2 mL. After centrifuging at 10000 rpm for 5 minutes, use a spectrophotometer to measure the absorbance of tetracycline at a wavelength of 365 nm, calculate the adsorption rate, and obtain that the maximum adsorption rate of the vacuum-dried copper nanoparticle powder for 20 ppm tetracycline is 87%.

[0100] This shows that copper nanoparticles can effectively remove pollutants in water.

[0101] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle 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 protection scope of the present invention.

[0102] The above are only the preferred embodiments of the present invention and are not used to limit the present invention; for those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for green synthesis of nano copper using black rice extract, characterized in that: include: Grinding black rice, mixing black rice powder with distilled water for heating extraction, cooling to room temperature and filtering under reduced pressure to obtain a black rice extract, and obtaining the absorbance of the black rice extract; When it is determined according to the absorbance that the preparation of the black rice extract does not meet the preset standard, increasing the temperature of the heating extraction; Add distilled water to a black rice extract that meets a preset standard for dilution, mix the diluted black rice extract with a CuSO4 solution for reaction, and stir at room temperature to obtain a nano copper solution, obtain a particle size standard deviation of the nano copper and an average particle size of the nano copper, and obtain a particle size uniformity characteristic value of the nano copper; When it is determined that the preparation of the nano-copper solution does not meet the preset standard according to the uniform characteristic value of the nano-copper particle size, it is determined again whether the preparation of the nano-copper solution meets the preset standard according to the density of the nano-copper solution, or the stirring rate is increased; If the particle size uniformity characteristic value is greater than or equal to the first preset particle size uniformity threshold value and less than the second preset particle size uniformity threshold value, it is determined that the preparation of the nano copper solution does not meet the preset standard, and a second determination is made based on the density of the nano copper solution whether the preparation of the nano copper solution meets the preset standard; If the particle size uniformity characteristic value is greater than or equal to the second preset particle size uniformity threshold, it is determined that the preparation of the nano copper solution does not meet the preset standard, and the stirring rate is increased according to the difference between the particle size uniformity characteristic value and the second preset particle size uniformity threshold; The nano copper solution that meets the preset standard is centrifuged, washed and vacuum dried to obtain nano copper, and the weight proportion of nano copper under the preset conditions is obtained. When it is determined that the preparation of nano copper does not meet the preset standard according to the weight proportion, the centrifugal speed of the centrifuge is reduced. The preset condition is to use an electronic balance to weigh the weight of nano copper with a particle size less than or equal to 6 nm; The process of determining that the preparation of nano-copper does not meet the preset standard according to the weight proportion of the preset particle size of the nano-copper includes: If the weight proportion is greater than or equal to the preset weight proportion, it is determined that the preparation of the nano copper does not meet the preset standard, and the centrifugal speed of the centrifuge is reduced according to the difference between the weight proportion and the preset weight proportion.

2. The method for green synthesis of nano-copper using black rice extract according to claim 1, characterized in that: The usage ratio of black rice powder to distilled water is 1.0 g to 5.0 g: 20 mL to 100 mL, the extraction time is 15 min to 30 min, and the heating extraction temperature is 80° C. to 100° C.

3. The method for green synthesis of nano-copper using black rice extract according to claim 1, characterized in that: The molar concentration of the CuSO4 solution is 0.01 mol / L, the stirring time at room temperature is 5 min, and the stirring rate is 350 r / min.

4. The method for green synthesis of nano-copper using black rice extract according to claim 1, characterized in that: The centrifugal speed of the centrifuge is 10000rpm~15000rpm, and the centrifugal time is 9~15min.

5. The method for green synthesis of nano-copper using black rice extract according to claim 4, characterized in that: The process of determining that the preparation of the black rice extract does not meet the preset standard according to the absorbance includes: Compare the absorbance with the preset absorbance; If the absorbance is less than a preset absorbance, it is determined that the preparation of the black rice extract does not meet the preset standard, and the temperature of the heating extraction is increased according to the difference between the preset absorbance and the absorbance.

6. The method for green synthesis of nano-copper using black rice extract according to claim 5, characterized in that: The density of the nano-copper solution is used to determine whether the preparation of the nano-copper solution meets the preset standard. If the density of the nano copper solution is less than the preset density, it is determined that the preparation of the nano copper solution meets the preset standard, and the nano copper solution meeting the preset standard is centrifuged; If the density of the nano copper solution is greater than or equal to the preset density, it is determined that the preparation of the nano copper solution does not meet the preset standard, and the amount of distilled water added to the black rice extract is increased according to the difference between the density of the nano copper solution and the preset density.

7. The method for green synthesis of nano-copper using black rice extract according to claim 6, characterized in that: There are several adjustment methods for reducing the centrifugal speed of the centrifuge, and each adjustment method has a different reduction range for the centrifugal speed.

8. A use of nano-copper prepared by the method for green synthesis of nano-copper using black rice extract according to any one of claims 1 to 7, characterized in that: The nano copper is used for adsorbing tetracycline in water.

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