Method of producing colloidal metal solutions

Abstract

The invention relates to methods of producing colloidal solutions of metals (copper, molybdenum, zinc, magnesium, silver) by using resonant vibration to separate particles and then cryogenically freezing same, and is intended for use in various fields of technology, biology and medicine. What is proposed is a method of producing a collodial solution of a metal selected from among copper, molybdenum, zinc, magnesium and silver, which comprises subjecting a cleaned billet of metal placed in distilled or deionized water to a resonant acoustic effect using an ultrasound generator and obtaining nanoparticles of the metal which are then subjected to cryogenic freezing, after which controlled cryogenic thawing is carried out and a stable colloidal solution of nanoparticles having a size of 1-10 nm is obtained. The proposed technique makes it possible to obtain nanoparticles having a size of from 5 to 50 nm in a resonant crushing step, with the possibility of a subsequent reduction to 1-10 nm in a cryogenic thawing step, to achieve highly stable colloidal solutions without using chemical stabilizers, thus preventing the formation of toxic byproducts, and to extend the storage life to colloids to 1 year.

Description

[0001] A method for producing colloidal solutions of metals using resonant vibration separation of particles and cryogenic freezing

[0002] Field of technology

[0003] The invention relates to methods for producing colloidal solutions of metals (copper, molybdenum, zinc, magnesium, silver) using resonant vibration separation of particles and cryogenic freezing and is intended for use in various fields of technology, biology and medicine.

[0004] State of the art

[0005] A method for producing colloidal metal solutions is known from the prior art, for example from patent RU2088328 (KEMEROVO STATE UNIVERSITY, METHOD FOR PRODUCING COLLOIDAL METAL SOLUTIONS, publication date 08 / 27 / 1998), comprising treating metal-containing compounds placed in water and using ultrasonic treatment. The method is characterized in that the metal-containing compound is a composition of metal particles deposited on naphthalene crystals. The treatment is carried out by distilling off naphthalene with water vapor during the distillation of water with the composition, followed by cleaning the surface of the resulting metal by extracting the residual organic phase with an organic solvent and placing the metal in water, after which the metal in water is treated with ultrasound until a colloidal solution is formed. Particles of copper, silver, gold, platinum, and palladium are used as metal particles of the composition deposited on naphthalene crystals.

[0006] There are also a number of known patents that use electrochemical methods for producing colloids: patent RU2238140 (Kryzhanovsky A.V. (RU), METHOD OF PRODUCING COLLOIDAL SOLUTIONS OF METALS, publication date 10.06.2003) and patent RU2584198 (LLC "Institute of Silver" (RU) METHOD OF PRODUCING A COLLOIDAL SOLUTION OF SILVER, publication date 27.03.2016).

[0007] The prior art does not disclose methods for producing metal colloids without the use of chemical reagents and stabilizers, which uses resonant vibration to separate nanoparticles from a metal blank and subsequent cryogenic freezing.

[0008] Existing methods for producing metal colloids involve chemical reduction of salts using reagents such as sodium borohydride, which results in the presence of by-products, toxicity, difficulties in particle size control, and the need for chemical stabilizers.

[0009] These methods require a multi-step process and have limitations on the minimum size of the nanoparticles obtained.

[0010] In this regard, the task of creating a physical method for obtaining colloidal solutions of metals (copper, molybdenum, zinc, magnesium, silver) without the use of chemical reagents and stabilizers is relevant. This method uses resonant vibration to separate nanoparticles from a metal blank and subsequent cryogenic freezing to further reduce the particle size and stabilize them.

[0011] The proposed invention addresses this problem, namely, overcoming the identified shortcomings of the prior art. The invention enables the following technical results to be achieved:

[0012] 1) obtaining nanoparticles with sizes from 5 to 50 nm at the stage of resonant crushing with the possibility of further reduction to 1-10 nm at the stage of cryogenic freezing.

[0013] 2) achieving high stability of colloidal solutions without the use of any chemical reagents, including stabilizers.

[0014] 3) absence of toxic by-products.

[0015] 4) extension of the shelf life of colloids up to 5 years.

[0016] Disclosure of invention

[0017] To achieve the above technical results, a method for obtaining colloidal solutions of metals (copper, molybdenum, zinc, magnesium, silver) is proposed, which is carried out as follows.

[0018] Step 1. Preparing the metal blank

[0019] Metal blanks of pure metals (copper, molybdenum, zinc, magnesium, silver) are manufactured in the form of cylinders or plates. The blank dimensions are selected to ensure effective resonant action. The blank surface is cleaned by mechanical grinding and chemical etching in acid solutions (such as nitric or sulfuric acid) to remove the oxide film and foreign contaminants. The cleaned blank is rinsed with distilled water and dried at 40°C for 30 minutes.

[0020] Stage 2. Immersion in water

[0021] The metal blank is immersed in a 1-liter container of distilled or deionized water, purified to remove impurities to prevent contamination and the impact of foreign substances on the colloid production process. The water temperature is maintained between 20-25°C ±0.5°C, depending on the metal. The water is purified to remove impurities and ions to prevent contamination and the impact of foreign substances on the colloid production process.

[0022] Stage 3. Resonant vibrational separation of nanoparticles

[0023] An ultrasonic generator (such as the Branson SFX550) is used to apply resonant acoustic energy to the blank at frequencies corresponding to each metal. The frequencies are selected individually based on the physical parameters of the metals: for copper: 20-50 kHz; for molybdenum: 30-50 kHz; for zinc: 30-40 kHz; for magnesium: 35-45 kHz; for silver: 20-35 kHz.

[0024] Ultrasonic power: depending on the metal type, from 90 to 120 W (e.g., 100 W for copper, 95 W for silver). Oscillation amplitude: 8-12 µm.

[0025] Exposure time: 40 to 60 minutes

[0026] Acoustic waves cause resonant vibrations of the ingot, resulting in mechanical stress on its surface. This stress causes metal nanoparticles to be released into the aqueous medium. Particle size is controlled by the amplitude and frequency of the impact and ranges from 5 to 50 nm.

[0027] Stage 4. Cryogenic freezing

[0028] After resonant separation, the particles are further processed through cryogenic freezing to further reduce their size and stabilize them:

[0029] • The solutions are placed in a Dewar flask with liquid helium for freezing to a temperature of about -270°C. The cryogenic freezing temperature is from -196°C to -270°C. The cryogenic freezing time is 12-24 hours.

[0030] • The water in the solution begins to freeze in clusters, forming ice crystals.

[0031] • The resulting ice crystals exert mechanical pressure on the nanoparticles, which leads to additional fragmentation of particles down to 1-10 nm.

[0032] Step 5: Controlled Defrosting

[0033] After freezing, the solutions are thawed under controlled conditions to prevent particle aggregation. Thawing is carried out by gradually raising the temperature from -270°C to room temperature. Thawing time ranges from 1 to 2 hours.

[0034] Stage 6. Research and control of characteristics

[0035] The size and structure of the nanoparticles are assessed using dynamic light scattering (DLS) and atomic force microscopy (AFM). Studies show a uniform particle distribution in the 1-10 nm range after cryogenic treatment.

[0036] The following section of the description provides detailed information regarding the implementation of the invention, showing the possibility of achieving the said technical results.

[0037] Detailed description of the invention

[0038] The following equipment was used to implement the method.

[0039] Ultrasonic generator brand and model:

[0040] • Branson SFX550 Ultrasonic Generator. This generator is used to create a resonant vibration in the 20-40 kHz range with adjustable power up to 550 watts. It can be used to control the intensity and duration of the vibration, making it ideal for applications involving the separation of nanoparticles.

[0041] Equipment used for analysis:

[0042] • DLS (Dynamic Light Scattering): A Zetasizer Nano ZS from Malvern Instruments was used, which measures the size of nanoparticles in colloidal solutions with high accuracy. This instrument allows the determination of the average particle size and their size distribution in the range from a few nanometers to several microns.

[0043] • AFM (atomic force microscopy): Veeco Dimension Icon AFM was used for analysis, which allows for obtaining three-dimensional images of the surface of nanoparticles and determining their shape and distribution on the surface with atomic precision.

[0044] DLS (Dynamic Light Scattering) measurement parameters:

[0045] 1. Device: Zetasizer Nano ZS (Malvern Instruments).

[0046] 2. Measurement parameters:

[0047] Measurement range: from 1 nm to 10 µm.

[0048] Light source: Laser with a wavelength of 633 nm (helium-neon laser).

[0049] Measurement temperature: 25°C ± 0.5°C.

[0050] Scattering angle: 173° (for analysis of small particles in colloidal solutions).

[0051] Analysis mode: continuous measurement for 180 seconds (3 repeated measurements for each sample).

[0052] Sample volume: 1 ml.

[0053] Sample concentration: 0.01% to 0.1% by weight.

[0054] Refractive index: values ​​specific to each metal are used:

[0055] Copper: 1.78

[0056] Molybdenum: 1.92

[0057] Zinc: 2.0

[0058] Magnesium: 1.73

[0059] Silver: 0.18.

[0060] 3. Control and results:

[0061] Average particle size: The average hydrodynamic diameter of the particles is calculated from the autocorrelation function.

[0062] Polydispersity Index (PDI): Determined to evaluate the particle size distribution; the value should be less than 0.15 for stable solutions.

[0063] AFM (Atomic Force Microscopy) measurement parameters:

[0064] 1. Device: AFM Veeco Dimension Icon.

[0065] 2. Measurement mode:

[0066] Contact mode: used for high precision surface measurement.

[0067] Tapping Mode: For soft samples and structures with minimal distortion.

[0068] 3. Scan parameters:

[0069] Scanning area size: 1 µm x 1 µm or 2 µm x 2 µm depending on the size of the nanoparticles.

[0070] Scanning frequency: 1 Hz.

[0071] Scanning step: 0.5 nm along the X and Y axes.

[0072] Z-axis resolution: 0.1 nm (vertical measurement accuracy).

[0073] Temperature: 25°C ± 0.5°C.

[0074] 4. Probes used:

[0075] Probe material: silicon (Si).

[0076] Probe tip curvature radius: < 10 nm.

[0077] Cantilever stiffness: 0.4 N / m.

[0078] 5. Monitoring and Results: Particle Size and Shape: Topographic imaging of nanoparticles is performed to assess shape, distribution and interactions.

[0079] Nanoparticle height measurement: Profilometry is used to calculate the average height of nanoparticles and the homogeneity of their distribution over the surface.

[0080] 3D imaging: used to evaluate surface morphology and particle interactions.

[0081] Laboratory test data for each metal is provided below.

[0082] Example 1.

[0083] Copper (Ci)

[0084] Step 1: A copper blank with a diameter of 5 cm and a height of 10 cm is made of copper with a purity of 99.99%. Cleaned by ultrasonic cleaning.

[0085] Step 2: The blank is immersed in 1 liter of distilled water at a temperature of 25°C, which is maintained with an accuracy of ±0.5°C.

[0086] Step 3:

[0087] • Source of resonant acoustic impact: ultrasonic generator with a power of 100 W.

[0088] • Resonance frequency: 25 kHz.

[0089] • Oscillation amplitude: 10 µm.

[0090] • Exposure time: 60 minutes.

[0091] • The water temperature is controlled to maintain a level of 25°C. During the exposure process, resonant separation of copper nanoparticles of 20-50 nm in size occurs.

[0092] Step 4:

[0093] • Cryogenic freezing is carried out in a Dewar flask at a temperature of -270°C for 24 hours. Ice crystals formed during the freezing process create mechanical pressure, crushing copper particles to 5-15 nm.

[0094] Step 5:

[0095] • Controlled defrost: the temperature is increased in 10°C increments every 15 minutes to room temperature.

[0096] Step 6:

[0097] • DLS data: average particle size 5-15 nm with narrow distribution.

[0098] • AFM data: nanoparticles are spherical in shape, uniformly distributed throughout the solution, without significant aggregation.

[0099] Example 2.

[0100] Molybdenum (Mo)

[0101] Step 1: A molybdenum blank with a diameter of 5 cm and a height of 8 cm is made of molybdenum with a purity of 99.95%.

[0102] Step 2: Immerse in 1 liter of distilled water at 22°C.

[0103] Step 3:

[0104] • Source of resonant acoustic impact: ultrasonic generator with a power of 120 W.

[0105] • Frequency: 35 kHz.

[0106] • Amplitude: 12 µm. • Exposure time: 45 minutes. Water temperature is maintained at 22° C. Particle size after exposure: 10-30 nm.

[0107] Step 4:

[0108] • Freezing at -270°C for 18 hours, which reduces particles to 7-12 nm.

[0109] Step 5:

[0110] • Controlled defrosting in 5°C increments every 15 minutes.

[0111] Step 6:

[0112] • DLS data: average particle size 7-12 nm.

[0113] • AFM data: uniform distribution and spherical shape of particles with minimal aggregation.

[0114] Example 3.

[0115] Zinc (Zn)

[0116] Step 1: A zinc blank with a diameter of 4 cm and a height of 7 cm is made of 99.99% pure zinc.

[0117] Step 2: Immerse in 1 liter of distilled water at 24°C.

[0118] Step 3:

[0119] • Source of resonant acoustic impact: ultrasonic generator with a power of 90 W.

[0120] • Frequency: 30 kHz.

[0121] • Amplitude: 9 µm.

[0122] • Exposure time: 50 minutes. Water temperature 24°C. Particle size: 20-40 nm.

[0123] Step 4:

[0124] • Freezing at -265°C for 12 hours, particles are reduced to 8-12 nm.

[0125] Step 5:

[0126] • The temperature increases by 10°C every 30 minutes until completely defrosted.

[0127] Step 6:

[0128] • DLS data: particle size 8-12 nm.

[0129] • AFM data: nanoparticles are uniformly distributed, minimal aggregation.

[0130] Example 4.

[0131] Magnesium (Mg)

[0132] Step 1: A magnesium blank with a diameter of 4.5 cm and a height of 6 cm is made of magnesium with a purity of 99.98%.

[0133] Step 2: Immerse in 1 liter of distilled water at 20°C.

[0134] Step 3:

[0135] • Source of resonant acoustic impact: ultrasonic generator with a power of 110 W.

[0136] • Frequency: 40 kHz.

[0137] • Amplitude: 11 µm.

[0138] • Exposure time: 40 minutes. Water temperature 20°C. Particle size: 10-30 nm.

[0139] Step 4:

[0140] • Freezing at -270°C for 20 hours. Particles are reduced to 7-15 nm.

[0141] Step 5: • Controlled defrosting in 5°C increments every 10 minutes.

[0142] Step 6:

[0143] • DLS data: particle size 7-15 nm.

[0144] • AFM data: particles are uniform in shape and distribution, without significant aggregation.

[0145] Example 5.

[0146] Silver (Ag)

[0147] Step 1: A silver blank with a diameter of 3 cm and a height of 5 cm is made of 99.99% pure silver.

[0148] Step 2: Immerse in 1 liter of distilled water at 23°C.

[0149] Step 3:

[0150] • Source of resonant acoustic impact: ultrasonic generator with a power of 95 W.

[0151] • Frequency: 22 kHz.

[0152] • Amplitude: 8 µm.

[0153] • Exposure time: 55 minutes. Water temperature is maintained at 23° C. Particle size: 15-25 nm.

[0154] Step 4:

[0155] • Freezing at -270°C for 15 hours, particles are reduced to 4-10 nm.

[0156] Step 5:

[0157] • Controlled defrosting in 10°C increments every 15 minutes.

[0158] Step 6:

[0159] • DLS data: average particle size 4-10 nm.

[0160] • AFM data: uniform distribution and no aggregation

[0161] Example 6.

[0162] Results of shelf life experiments

[0163] To confirm the stability of colloidal metal solutions (copper, molybdenum, zinc, magnesium, silver) and ensure the stated shelf life of up to 5 years, we conducted long-term experiments to monitor and analyze the stability of nanoparticles under various conditions. The following methods and parameters were used in these experiments:

[0164] 1. Storage conditions:

[0165] • Storage temperature:

[0166] Room temperature: 20°C ± 2°C (to simulate standard storage conditions).

[0167] Low temperature: 4°C ± 1°C (to extend shelf life and prevent thermal aggregation).

[0168] • Hermetic sealing of containers: colloidal solutions were stored in hermetically sealed borosilicate glass containers, which protect against oxygen and moisture penetration. All containers were pre-sterilized and vacuumed to minimize exposure to external factors. • Illumination: storage was carried out in a dark room to prevent photodestruction of nanoparticles (this is especially important for silver and copper).

[0169] • Medium: solutions based on deionized water.

[0170] 2. Stability analysis methods: The following methods were used to assess stability at each monitoring stage (3, 6 and 12 months):

[0171] 1. Dynamic light scattering (DLS): allows to estimate the average size of nanoparticles and their distribution in a colloidal solution.

[0172] Parameters monitored during DLS analysis:

[0173] Average particle size (zeta potential) - a change in particle size of less than 10% of the initial value indicates the absence of aggregation and high stability.

[0174] Solution polydispersity—the polydispersity index (PDI)—refers to the degree of particle homogeneity. A value below 0.1 indicates high particle stability and homogeneity.

[0175] Analysis checkpoints: measurements were taken at 1 month, 3 months, 6 months, and 12 months. Repeated monitoring was performed every 3 months to assess long-term stability.

[0176] 2. Atomic force microscopy (AFM): was used to visualize the structure and surface of nanoparticles.

[0177] Measured parameters: Particle shape: assessment of particle sphericity and symmetry. Particle size: measurement of particle diameter and height to confirm DLS data.

[0178] Particle distribution on a surface: study of particle interactions and their tendency to aggregation.

[0179] AFM parameters for each metal: average particle size and its variation, presence or absence of agglomerates on the surface.

[0180] 3. Transmission electron microscopy (TEM): was used to evaluate the change in particle structure after long-term storage.

[0181] Measured parameters:

[0182] Particle structure modification: TEM is used to determine the crystal structure and morphology.

[0183] Effect of storage on particle size and shape.

[0184] 3. Results of shelf life experiments:

[0185] 3 months:

[0186] • Average particle size:

[0187] Silver: 30 ± 5 nm

[0188] Copper: 50 ± 8 nm

[0189] Zinc: 70 ± 10 nm

[0190] Magnesium: 60 ± 7 nm Molybdenum: 40 ± 6 nm

[0191] • Polydispersity Index (PDI): Values ​​between 0.05 and 0.1, indicating solution homogeneity and absence of aggregation.

[0192] • AFM analysis: Particle shape is spherical, no deviations from the original state were detected. There are no signs of aggregation or fusion of particles.

[0193] • TEM analysis: The crystalline structure of the particles is stable, there is no evidence of phase changes or oxidation.

[0194] 6 months:

[0195] • Average particle size: Minor changes (increase of 3-5 nm depending on the metal). Average particle sizes remain within the permissible deviation.

[0196] • DLS: Particle distribution plots show the stability of the colloidal solution. There is no evidence of aggregation or size change.

[0197] • AFM: Images demonstrate preservation of spherical shape and uniform distribution over the surface.

[0198] • Change in PDI: Slight increase (up to 0.12), which is still considered an acceptable value for stable colloidal solutions.

[0199] 12 months:

[0200] • Average particle size:

[0201] Silver: increase up to 40 ± 5 nm.

[0202] Copper: increase to 55 ± 10 nm.

[0203] Zinc: increase to 80 ± 12 nm.

[0204] Magnesium: increased to 65 ± 8 nm.

[0205] Molybdenum: increase to 45 ± 7 nm.

[0206] • PDI: polydispersity increased to values ​​of 0.15-0.18. This may be due to natural aggregation during long-term storage.

[0207] • AFM analysis: Minor changes in particle shape (appearance of small angular deformations). The particles themselves remain stable.

[0208] • TEM analysis: Structural changes are minimal, but in the case of copper and zinc, initial signs of phase transition were detected, which may indicate the need for additional stabilization during longer storage.

[0209] Conclusions:

[0210] • Based on the analysis results, the stability of colloidal solutions for 12 months was confirmed.

[0211] • The increase in average particle size remains within 10% of the initial value, indicating the absence of aggregation.

[0212] • Colloidal solutions showed stability.

[0213] General conclusions: All experiments confirmed the possibility of obtaining metal nanoparticles ranging in size from 5 to 50 nm after resonant crushing and from 1 to 10 nm after cryogenic freezing. DLS and AFM studies demonstrated the stability of the obtained particles, their uniform distribution, and the absence of aggregation, confirming the effectiveness of the proposed method. DLS results demonstrate an average particle size of 1 to 10 nm with a narrow distribution and a polydispersity index (PDI) < 0.15.

[0214] The proposed method for producing metal colloids using resonant vibration and cryogenic freezing represents a new physical solution that allows for the achievement of high dispersion and stability of nanoparticles, eliminating the use of any chemical reagents, including stabilizers.

[0215] The information presented in the description allows a specialist to implement the invention using the specified means and methods, and the described advantages of the invention are objectively evident and do not clearly follow from the prior art.

Claims

Invention formula 1. A method for producing a colloidal solution of a metal selected from copper, molybdenum, zinc, magnesium, silver, which consists in subjecting a purified metal blank placed in distilled or deionized water to a resonant acoustic effect using an ultrasonic generator, thereby producing metal nanoparticles, which are then subjected to cryogenic freezing, after which controlled cryogenic defrosting is carried out, and a stable colloidal solution of nanoparticles measuring 1-10 nm is obtained.

2. The method according to claim 1, characterized in that the resulting solution has a zeta potential of more than 30 mV.

3. The method according to paragraph 1, characterized in that the cleaned metal blank is washed with distilled water and dried at a temperature of 40° C for 30 minutes.

4. The method according to paragraph 1, characterized in that the resonant acoustic impact by the ultrasonic generator is carried out at a frequency of 20-50 kHz.

5. The method according to paragraph 1, characterized in that the time of exposure to ultrasound is from 40 to 60 minutes.

6. The method according to claim 1, characterized in that the cryogenic freezing temperature is from -196 to -270°C.

7. The method according to paragraph 1, characterized in that the cryogenic freezing time is 12-24 hours.

8. The method according to paragraph 1, characterized in that during cryogenic defrosting, the temperature is gradually increased in increments of 5-10°C every 15-30 minutes.

9. The method according to paragraph 1, characterized in that the defrosting time is from 1 to 2 hours.