CN103706803A - Method for using grapefruit juice to restore silver ions in silver nitrate solution - Google Patents

Abstract

The invention discloses a method for using grapefruit juice to restore silver ions in silver nitrate solution. The method includes: well mixing about 20mL of freshly squeezed grapefruit juice with about 20mL of 0.01-0.1mol/L silver nitrate solution under the constant-temperature water bath at about 30 DEG C, allowing the two to react in a 50mL small beaker, standing the reaction liquid for 48 hours, using a high-speed centrifuge to separate sedimentation, washing the sedimentation with anhydrous ethanol, and centrifuging the washed sedimentation with the high-speed centrifuge to obtain the products.

Description

A kind of method utilizing grapefruit juice to reduce the silver ion in the silver nitrate solution

technical field

The invention belongs to the field of nano-silver particle manufacture, and in particular relates to a method for reducing silver ions in a silver nitrate solution by using grapefruit juice.

Background technique

和

均降低，而K^Θ增大等。纳米银材料热力学性质在各方面与块体银材料均有一定的差异性，因此研究纳米银材料的热力学性质具有极其重要的科学意义和应用价值。With the rapid development of nano-materials, the application of nano-materials is becoming more and more extensive, such as in nano-coatings, nano-carbon tubes, nano-semiconductors, catalytic materials, as well as in medicine, home appliances, textiles, and environmental protection. In recent years, the research on nano-silver has achieved fruitful results. No matter in terms of preparation, properties, or applications, nano-silver is undoubtedly one of the most extensively researched materials. In addition to the characteristics of general nanomaterials, nano-silver materials have a significant surface plasmon resonance effect in optical materials. This effect can enhance the electromagnetic field inside and around the nano-silver particles, which can be used to develop photonic crystal materials. , such as nano-silver semiconductor. At the same time, due to the strong fluorescence emission characteristics of silver nanoparticles, they can be used in biological detection, labeling, and the development of biological and chemical sensors; in terms of thermodynamic properties, they show size effects and shape effects. As the size of nano-silver materials decreases, the binding energy, melting enthalpy and corresponding standard thermodynamic functions of nano-silver materials such as

and

Both decreased, while K ^Θ increased and so on. The thermodynamic properties of nano-silver materials are different from those of bulk silver materials in various aspects. Therefore, it is of great scientific significance and application value to study the thermodynamic properties of nano-silver materials.

The traditional preparation methods of nano-silver mainly include physical methods, chemical methods and comprehensive methods combining physical and chemical methods. The earliest method of preparing nano-silver is the physical method. The purity of nano-silver prepared by this method is high, but the output is low, the capital investment is large, and the energy consumption is large. The main preparation methods include high-energy mechanical ball milling method, illumination method, radiation method, arc method, evaporation and condensation method, etc. Xu J, Yin J S et al. performed high-energy mechanical ball milling on silver powder at an ultra-low temperature of -196°C, and obtained nano-silver particles with an average particle size of about 20nm; Du Yong et al. placed metallic silver under a Nd:YAG laser with a wavelength of 1064nm , Prepare 5-20nm silver colloidal particles by controlling the illumination time. The stability of the prepared silver colloid is very good, and there is no coagulation after being placed for several weeks; the preparation of nanomaterials by radiation method uses ionizing radiation, generally using gamma high-energy rays produced by cobalt 60 radiation sources to ionize and excite water , generating reducing particle H free radicals and hydrated electrons and oxidizing particle OH free radicals. These reducing particles can gradually reduce silver ions to nano silver particles. Cui Guoshi and others used γ-ray radiation liquid phase reduction to prepare nano-silver sol. At lower absorbed dose, higher polyvinyl alcohol concentration (7.5%), lower silver nitrate concentration (0.01mol/L) and appropriate isopropanol concentration (0.5mol/L) are beneficial to obtain the average particle size Smaller (10-30nm), monodisperse, non-aggregated nano-silver sol; the silver powder prepared by Duan Zhiwei et al. using self-developed DC arc plasma evaporation equipment is pure and pollution-free, with a polycrystalline structure and a spherical chain shape. The average particle size is in the range of 38-220nm. The particle size distribution is narrow. The maximum yield is nearly 17 times higher than similar research results.

Wei Zhiqiang et al. used the anode arc discharge plasma evaporation condensation method to prepare silver nano powder. Under the optimal process conditions: thermal power 3kw, air pressure 0.3-2kPa, Ar atmosphere, arc voltage 20-30V, arc current 70-150A, water cooling preparation The silver nano powder has a particle size of about 20nm, high purity and good dispersibility.

In the face of various disadvantages in the preparation of nano-silver particles by physical and chemical methods, coupled with the low-carbon and green life pursued by today's society. The preparation of nano-silver particles by green reduction has become the direction pursued by people.

Contents of the invention

The purpose of this invention is to propose a kind of method that utilizes grapefruit juice to reduce the silver ion in the silver nitrate solution.

In order to achieve the above object, the present invention adopts the following technical solutions:

A kind of method utilizing grapefruit juice to reduce the silver ion in the silver nitrate solution is characterized in that, comprises the following steps:

(1) Take fresh grapefruit, peel it, take about 30g of grapefruit fruit and add about 60g of distilled water to squeeze it, then filter it with a Buchner funnel to obtain the juice, and centrifuge at a low speed in a centrifuge to obtain a supernatant, the supernatant obtained is It is freshly squeezed grapefruit juice, which is all placed in a beaker and sealed for future use;

(2) In a constant temperature water bath at about 30°C, mix about 20mL of freshly squeezed grapefruit juice with about 20mL of 0.01-0.1mol/L silver nitrate solution, and then react in a small 50mL beaker. After standing for 48 hours, separate the precipitate with a high-speed centrifuge, wash the precipitate with absolute ethanol, and centrifuge in a high-speed centrifuge to obtain the product.

Described a kind of method utilizing grapefruit juice to reduce the silver ion in the silver nitrate solution is characterized in that, comprises the following steps:

(1) Take fresh grapefruit, peel it, take 30g of grapefruit fruit and add 60g of distilled water to press, then filter the juice with a Buchner funnel, and centrifuge at a low speed in a centrifuge to obtain a supernatant, which is now Squeeze the grapefruit juice, put it all in a beaker and keep it sealed for later use;

(2) In a constant temperature water bath at 30°C, mix 20mL of freshly squeezed grapefruit juice with 20mL of 0.01-0.1mol/L silver nitrate solution, and then react in a 50mL small beaker, and place the above reaction solution for 48 hours Finally, separate the precipitate with a high-speed centrifuge, wash the precipitate with absolute ethanol, and centrifuge through a high-speed centrifuge to obtain the product.

Discussion on the formation mechanism of silver nanoparticles:

Grapefruit juice mainly contains carotene, B vitamins, vitamin C, sugar, volatile oil, protein, glutamic acid (Glu), aspartic acid (Asp), lysine (Lys), arginine (Arg ), threonine (Thr) and organic acids and other biomolecules. Due to the reducing properties of biomolecules such as vitamin C and some amino acids, monovalent silver ions can be reduced to elemental silver. During the formation of crystal nuclei and the continuous growth of the crystal nuclei, the generated silver atoms were adsorbed and wrapped by biomolecules in the grapefruit juice, which reduced the surface energy, so that the continued growth of the crystal grains was limited, and finally formed a size of 50 -Spherical small particles of 100 nanometers.

Beneficial effects of the present invention:

(1) The present invention uses freshly squeezed grapefruit juice to reduce the silver ions in the silver nitrate solution, which is easy to operate, simple in steps, environmentally friendly and safe, and the obtained nano-silver has good stability. The raw materials are easy to obtain and non-toxic, and have good application prospects.

(2) Using the reducing organic biomolecules contained in grapefruit juice, the monovalent silver ions in the silver nitrate solution can be reduced under mild conditions (30°C, normal pressure); various analysis tests on the reaction products show that, The elemental silver of the face-centered cubic crystal system with a spherical shape is obtained, and the particle size is between 50-100nm; the organic reducing biomolecules contained in the grapefruit juice play the role of template and reducing agent for the formation of nano-silver particles, and induce and regulate the formation of silver nanoparticles.

Description of drawings

Fig. 1 is the infrared spectrogram of the grapefruit juice of embodiment 1;

Fig. 2 is the ultraviolet-visible spectrogram of the grapefruit juice of embodiment 1;

Fig. 3 is the ultraviolet-visible spectrogram of the reaction solution of embodiment 1;

Fig. 4 is the scanning electron micrograph of the product of the present invention of embodiment 1;

5 is an X-ray diffraction pattern of the product of the present invention in Example 1.

Detailed ways

Embodiment 1,

1 Experimental reagents and instruments

Reagents: silver nitrate, absolute ethanol, elemental iodine, potassium iodide, all of the above are of analytical grade; secondary distilled water; the fruit grapefruit used in the experiment was purchased from a local fruit store;

Instrument: American Nicolet870 Fourier transform infrared spectrometer, solid KBr tablet (scanning range: 4000~400cm ^-1 , 32 scans, resolution 4cm ^-1 );

TU-1901 double-beam UV-Vis spectrophotometer, Beijing General Instrument Co., Ltd. (scanning range: 190~800nm, sampling interval: 1nm, spectral bandwidth: 2nm, scanning speed: medium speed, scanning times: once, photometric mode :Abs);

TD6 desktop multi-tube automatic balancing centrifuge, Changsha Pingfan Instrument Co., Ltd. (accelerating voltage is 80kV);

MAP18XAHF X-ray diffractometer, Dandong Ray Instrument Industry Co., Ltd. (test voltage is 40kV, current is 100mA, scanning speed is 4°/min, continuous scanning);

KYKY-EM3200 digital scanning electron microscope, Beijing Zhongke Keyi Technology Development Co., Ltd. (accelerating voltage: 30kV);

Electronic balance (AB104-N, Max=101g, d=0.1mg);

HH-S6 constant temperature water bath, Jintan Xinnuo Experimental Instrument Factory (water temperature is controlled at 30°C).

2 Extraction of grapefruit juice

Take fresh grapefruit, peel it, take 30g pomelo fruit and add 60g distilled water to squeeze it into juice. The fruit juice was obtained by suction filtration with a Buchner funnel, and centrifuged at a low speed in a centrifuge to obtain 80 mL of supernatant. The experiment was carried out in parallel for 5-10 groups, and all the obtained supernatants were placed in a beaker and sealed for storage for later use.

3 Preparation of silver nanoparticles

Take a certain amount of silver nitrate (1.6990g) solid, put it in a beaker and add distilled water to dissolve it, then transfer it into a 100mL volumetric flask to prepare a 0.1mol/L silver nitrate solution. Dilute this solution into a series of silver nitrate solutions with a volume of 50mL and a concentration not lower than 0.01mol/L. In a constant temperature water bath at 30°C, take 20mL of freshly squeezed grapefruit juice and 20mL of 0.1-0.01mol/L silver nitrate solution and mix them in a 50mL small beaker for reaction. Regularly measure the ultraviolet absorption spectrum of the reaction solution. After the above reaction solution was left for 48 hours, the precipitate was separated by high-speed centrifugation in a centrifuge, and the precipitate was washed with absolute ethanol and centrifuged in a centrifuge to obtain the product. 10-20 groups of the above experiments were carried out in parallel to obtain enough products, which were tested by scanning electron microscope, infrared spectrum and X-ray diffraction after drying.

Rough calculation of 4Vc content

Take 20mL of freshly squeezed grapefruit juice, 100mL of secondary water, 10mL of 2mol/L HAc and 10mL of 0.5% starch, add them all into a 250mL Erlenmeyer flask, mix well, and use I ₂ standard solution [1/2 (I ₂ ) = 0.1mol/L] for titration to determine the content of Vc in the above grapefruit juice. Titrate three times in parallel. The volumes of the _I2 standard solutions used were: 1.51mL, 1.57mL, 1.63mL, and the average volume was 1.57mL.

Therefore, the Vc content is: Vc%=C _I2 V _I2 176.12/20=0.1543mg/mL.

5 Results and Discussion

5.1 Infrared spectroscopy analysis of grapefruit juice

There are many kinds of biomolecules in grapefruit juice, such as proteins, vitamins and polysaccharides. Fig. 1 is the infrared spectrogram that grapefruit juice juice drips on KBr solid, and compresses after drying and records. The absorption peak at 1621cm ^-1 in the figure corresponds to the stretching vibration of the C=O group of the protein amide I band, and the absorption peak at 1250cm ^-1 is the CN bending vibration of the protein amide III band. The absorption peaks at 1413cm ^-1 and 1055cm ^-1 may be the bending vibration of the C-OH group and the asymmetric stretching vibration of the COC group in protein, vitamin or polysaccharide molecules, respectively. The characteristic stretching vibration absorption band of methyl group may be at 2930cm ^-1 . The place at 3379cm ^-1 may be the characteristic absorption band of hydrogen bond in NH.

5.2 UV-Vis spectroscopic analysis of grapefruit juice

Fig. 2 is the measured ultraviolet-visible spectrogram of grapefruit juice. It can be seen from the figure that there are two absorption peaks at 210nm and 280nm, corresponding to the electronic transition of C=O group n-π* on the peptide bond of protein or amino acid and the electron transition of protein tyrosine, tryptophan or Electronic transitions of π-π ^* on phenylalanine residues, indicating the presence of biomolecules such as proteins and amino acids in grapefruit juice.

5.3 UV-visible spectroscopic analysis of the reaction solution

Fig. 3 is the measured ultraviolet-visible spectrum diagram of the reaction solution left for different times. It can be seen from the figure that there is an absorption peak at 440nm, and the intensity of this absorption peak gradually increases with the increase of the reaction time. This absorption peak is considered to be the characteristic absorption peak of silver nanoparticles, which is caused by the radial surface-enhanced Raman resonance of silver nanoparticles in solution. This shows that with the prolongation of the reaction time, the amount of the product silver nanoparticles is increasing.

5.4 SEM analysis of the product

Fig. 4 is a scanning electron micrograph of a product obtained by reacting a reaction solution containing 0.05 mol/L silver nitrate and grapefruit juice at 30° C. for 48 hours. It can be seen from the figure that the product is a small spherical particle with a particle size between 50-100nm. The larger particles that appear in the picture are due to the aggregation of small nanoparticles.

5.5 X-ray diffraction analysis of the product

Fig. 5 is an X-ray diffraction pattern of a product obtained by reacting a reaction solution containing 0.05 mol/L silver nitrate and grapefruit juice at 30° C. for 48 hours. It can be seen from the figure that five diffraction peaks appear when the 2θ is 38.24°, 44.43°, 64.66°, 77.63°, and 81.78°. Compared with the standard card (JCPDS87-0720), it can be found that they correspond to the face-centered cubic silver (111 ), (200), (220), (311) and (222) surface characteristic diffraction, indicating that the product is silver with a face-centered cubic structure.

5.6 Discussion on the formation mechanism of silver nanoparticles

Grapefruit juice mainly contains carotene, B vitamins, vitamin C, sugar, volatile oil, protein, glutamic acid (Glu), aspartic acid (Asp), lysine (Lys), arginine (Arg ), threonine (Thr) and organic acids and other biomolecules. Due to the reducing properties of biomolecules such as vitamin C and some amino acids, monovalent silver ions can be reduced to elemental silver. During the formation of crystal nuclei and the continuous growth of the crystal nuclei, the generated silver atoms were adsorbed and wrapped by biomolecules in the grapefruit juice, which reduced the surface energy, so that the continued growth of the crystal grains was limited, and finally formed a size of 50 -Spherical small particles of 100 nanometers.

6 Conclusion

Using a variety of biomolecules contained in grapefruit juice, the monovalent silver ions in silver nitrate solution were reduced to elemental silver under mild conditions (30°C, normal pressure). After various analysis tests, it is found that the obtained product is elemental silver of the face-centered cubic crystal system, and the particle size is between 50-100nm. The formation mechanism of silver nanoparticles was discussed, and it was shown that the biomolecules contained in grapefruit juice acted as templates and reducing agents for the formation of elemental silver particles, and induced and regulated the formation of silver nanoparticles.

Embodiment 2,

A kind of described method utilizing grapefruit juice to reduce the silver ion in the silver nitrate solution comprises the following steps:

(1) Take fresh grapefruit, peel it, take 30g of grapefruit fruit and add 60g of distilled water to press, then filter the juice with a Buchner funnel, and centrifuge at a low speed in a centrifuge to obtain a supernatant, which is now Squeeze the grapefruit juice, put it all in a beaker and keep it sealed for later use;

(2) In a constant temperature water bath at 30°C, mix 20mL of freshly squeezed grapefruit juice with 20mL of 0.01-0.1mol/L silver nitrate solution, and then react in a 50mL small beaker, and place the above reaction solution for 48 hours Finally, separate the precipitate with a high-speed centrifuge, wash the precipitate with absolute ethanol, and centrifuge through a high-speed centrifuge to obtain the product.

Claims (2)

1. utilize grape fruit juice to restore a method for the silver ion in liquor argenti nitratis ophthalmicus, it is characterized in that, comprise the following steps:

(1) get fresh grape fruit, peeling, gets 30g left and right grape fruit fruit grain and adds after the distilled water squeezing of 60g left and right, with Buchner funnel suction filtration, obtain juice, and making supernatant with centrifuge low-speed centrifugal, gained supernatant is existing squeezing grape fruit juice, is all placed on sealing in beaker and saves backup;

(2) in the water bath with thermostatic control of 30 ℃ of left and right, get about 20mL and now squeeze after grape fruit juice mixes with the liquor argenti nitratis ophthalmicus of the 0.01-0.1mol/L of 20mL left and right and react in the small beaker of 50mL, above-mentioned reactant liquor was placed after 48 hours, with supercentrifuge, isolate precipitation, then with after absolute ethanol washing precipitation and through the centrifugal product that obtains of supercentrifuge.

2. a kind of method of utilizing grape fruit juice to restore the silver ion in liquor argenti nitratis ophthalmicus according to claim 1, is characterized in that, comprises the following steps:

(1) get fresh grape fruit, peeling, gets 30g grape fruit fruit grain and adds after the squeezing of 60g distilled water, with Buchner funnel suction filtration, obtain juice, and making supernatant with centrifuge low-speed centrifugal, gained supernatant is existing squeezing grape fruit juice, is all placed on sealing in beaker and saves backup;

(2) in the water bath with thermostatic control of 30 ℃, getting 20mL now squeezes after grape fruit juice mixes with the liquor argenti nitratis ophthalmicus of the 0.01-0.1mol/L of 20mL and reacts in the small beaker of 50mL, above-mentioned reactant liquor was placed after 48 hours, with supercentrifuge, isolate precipitation, then with after absolute ethanol washing precipitation and through the centrifugal product that obtains of supercentrifuge.

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