Method for producing a colloidal solution of nanoscale carbon

Abstract

The technical result of the present method is simplicity, low cost and the possibility of producing nanoparticles of different types. This result is achieved in that the method for producing a colloidal solution of nanoscale carbon is carried out as follows: an organic fluid is fed into a chamber that contains electrodes, an inert gas is injected into the inter-electrode space, a high temperature plasma channel is formed in gas bubbles, thus atomizing ethanol molecules, followed by rapid cooling.

Claims

1. A method for producing a stable colloidal solution of nanoscale carbon, that the method comprising: feeding an organic liquid into a chamber containing a multi-electrode discharge device having an inter-electrode space, the organic liquid fully covering the multi-electrode discharge device; injecting an inert gas into the inter-electrode space of the multi-electrode discharge device; forming a high temperature plasma channel that atomizes molecules of the organic liquid by applying a high voltage pulse to the multi-electrode device; and rapidly cooling the atomized molecules, wherein the high voltage pulse has a predefined pulse repetition frequency which is less than or equal to 100 Hz.

2. The method of claim 1, wherein the stable colloidal solution is formed when a specific energy deposition in the liquid exceeds a threshold value.

3. The method of claim 2, wherein the organic liquid is ethanol.

4. The method of claim 1, wherein the organic liquid is ethanol.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The drawing shows a device for obtaining the colloidal solution.

EMBODIMENTS OF THE INVENTION

(2) The present method for producing the stable colloidal solution of nanoscale carbon is based on implementing the pulsed high voltage discharge in the bubbles of the inert gas injected into the organic liquid (ethanol). As noted above, the feature of the pulsed discharges in ethanol is ethanol molecules atomization in the high temperature channel followed by rapid cooling. Use of a high voltage multielectrode discharge device with gas injection into the inter-electrode space by virtue of a special formation of the plasma channel and its cooling opens up new possibilities for the production of nanostructures, carbon nanofluids.

(3) They use the dielectric chamber 1, the multi-electrode discharge device 2 wherein the gas is injected in the inter-electrode space being inside the chamber placed in ethanol 3 which partially fills the chamber. The chamber 1 is provided with a device for gas injection, system for filling and flushing the organic liquid (ethanol). The discharge device is connected to the high-voltage pulse generator 4. The device includes the pulse generator 4, the Rogowski coil 5, the voltage divider 6, the spectrograph 7, the optical waveguide 8, the pipes for flushing liquid 9, the gas vent pipe 10.

(4) The device operates as follows.

(5) The inert gas is injected into the discharge device 2 through the pipe 11. The pipe 10 is used to remove it from the reactor. After that reactor 1 is partially filled with the liquid to cover the discharge device 2 fully. A high voltage with the set value (U20 kV) and the pulse repetition frequency (f100 Hz) is supplied to the end electrodes of the discharge device. If the reactor is operated in a continuous mode, then the pipes 9 provide the necessary liquid flow rate. The pulsed discharge appears in the gas bubbles 12 filled with the alcohol vapor. The high-temperature plasma channel is formed in each of the inter-electrode spaces, it lasts for a few microseconds and has the following parameters: the temperature of heavy particles is T=4,000-5,000 K, the electron temperature is Te=1-1.5 eV, the concentration of charged particles n=(2-3).Math.10.sup.17 cm.sup.3, the diameter of the plasma channel is hundreds of microns. The single pulse energy deposition is 1.6 J.

(6) Atomization of ethanol molecules occurs in the plasma channel. As a result of subsequent rapid cooling (quenching), nonequilibrium carbon nanostructures are formed, thereby the characteristics, properties of the colloidal solution are determined. The typical time of the discharge channel cooling is few microseconds, tens of microseconds. The dynamics of heating and cooling of the plasma channel significantly affects the parameters of the nanoparticles.

(7) The specific energy deposition in the processed liquid is essential for producing the colloidal solution. In the absence of the continuous flow mode, the specific energy deposition is determined as follows:

(8) $=\frac{W.Math.f.Math.t}{V},$

(9) W is the single pulse energy deposition, f is the repetition frequency of the pulse, V is the liquid volume, t is the time of the liquid processing.

(10) In the case of a continuous flow mode:

(11) $=\frac{W.Math.f}{U},$

(12) U is the flow rate per time unit (cm.sup.3/s). As the time of the liquid processing (the specific energy deposition) increases, the liquid darkens as a result of formation of the carbon nanoparticles, and when the certain threshold value of the specific energy deposition is exceeded, the stable colloidal solution is formed (it does not precipitate for more than one year). At lower values of the specific energy deposition carbon precipitates at the bottom of the vessel in 1-2 days, the liquid becomes clarified.

(13) The parameters of the nanoparticles were studied by different methods: RS (Raman scattering), DLS (dynamic light scattering), X-ray diffraction, electron microscopy, elemental formulation, etc.

(14) We note that when the colloidal solution is heated to a temperature close to the boiling point and then cooled, the solution remains stable. The threshold of the specific energy deposition depends on the electrode material.

(15) The elemental formulation of the nanoparticle powder obtained by evaporation of the colloidal solution is as follows: C 79.05%; O 19.57%, other detected elements are Si; K; Ti; Cr; Fe. The oxygen appears as result of its absorption from the air.

INDUSTRIAL APPLICABILITY

(16) The results can be used for different applications, in particular, to produce a carbon film to coat a metal in order to reduce the coefficient of secondary electron emission, in the technology of growing diamond films and glasses, in production of elements absorbing solar radiation, etc.