RU2546156C2 - Method and apparatus for stabilisation of emulsions and colloids - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the chemical processes, in particular, to petrochemistry, and can be used for stabilisation of various emulsions and colloids, e.g. colloidal and polymer dispersions, petroleum oils, lubricants, process fluids, fuels, paints and varnishes, etc., in the process aimed at stabilising emulsions and colloids. The stabiliser for emulsions and colloids comprising tanks with an initial emulsion or colloid, treatment space for treating emulsions and colloids, and an instrument for optical inspection of the droplet size. The novelty lies in the treatment space, which is a grounded conductive pipe, comprising a central high voltage bare electrode producing a constant electric field, which acts upon the passing colloid or emulsion.

EFFECT: efficient eco-friendly process of producing stable emulsions and colloids.

2 cl, 2 dwg

Description

The invention relates to technological chemical processes, in particular to petrochemistry, and can be used to stabilize various emulsions and colloidal solutions, for example, in the production of colloidal and polymer dispersions, petroleum oils, lubricants, industrial fluids, fuels, varnishes, paints, etc. item, that is, in processes aimed at obtaining stable emulsions and colloidal solutions.

To date, widely used chemical methods of stabilization of emulsions, based on additives of emulsifiers, for example [1].

However, adding to the existing emulsion of additional substances is not always permissible, for example, in the manufacture of food products or lubricating oils with additives. The proposed method allows to stabilize the emulsion without introducing additional chemicals into the existing composition and without spending expensive special emulsifiers. Field methods for stabilizing emulsions are currently unknown.

Moreover, there is a known attempt to separate a water-oil emulsion using a low-frequency electric field [2, 3] by ABB VICTA. An internal electrostatic coagulator of this company, acting on the emulsion with a low-frequency electric field, was installed on the Norwegian oil platform Troll C. However, to date, this electrostatic coagulator has disappeared from the ABB website, like other electrostatic coagulators. The reason for this disappearance may be the effect of a reduction in the size of the droplets of the emulsion under certain conditions under the influence of a constant field (i.e., stabilization of the emulsion) instead of its separation, which we observed and formed the basis of the present invention.

The closest in technical essence is the method of preparing colloidal solutions and a device for its implementation / 4 /. This method consists in mixing the starting components and exposing them to electromagnetic microwave radiation, while controlling the quality of colloidal solutions (resistance to delamination - colloidal stability, specific amount of colloidal formations in mixed solutions and their average radius) during mixing and in prepared colloidal solutions by scattered light correlation spectroscopy, while determining the average radius, and based on the data obtained, make changes to the processing mode of the initial oh mixture. In this case, the influence of microwave radiation on the mixed components is carried out during the continuous flow of the mixed components through a tube placed in the microwave cavity with the speed necessary for the formation of stable colloidal solutions. However, this method does not make it possible to stabilize an existing emulsion.

The objective of the invention is the creation of an effective environmentally friendly technology for the preparation of stable emulsions and colloidal solutions.

The problem is solved as follows. A method for stabilizing emulsions and colloidal solutions is proposed, which consists in reducing the size of the droplets of the emulsion or colloidal formations of solutions under the influence of a high-voltage constant electric field on the emulsion or solution, and the processing result is controlled by spectral methods, and based on the data obtained, changes are made to the processing process.

It is proposed to control the size of droplets of an emulsion or colloidal formation of solutions by determining their average radius by the method of correlation spectroscopy of scattered light.

An electric field acts on an emulsion or colloidal solution when they continuously flow through a conductive tube with a central non-insulated high voltage electrode at a speed necessary to reduce the size of the droplets of the emulsion or colloidal formations, sufficient to stabilize them. The effect takes place only in the presence of electrophoretic motion of drops or colloidal formations.

Also proposed is a device for stabilizing emulsions and colloidal solutions (Figure 1), containing reservoirs with the original emulsion or colloidal solution (1, 2; 2 - an alternative way to supply emulsion from a canister); control valves (3); optical control elements (4); the working volume of the processing of the emulsion or colloidal solution in the form of grounded metal tubes (5); grounding (6); internal high-voltage electrode of the working volume tubes (7); insulators (8); high voltage source (9); receiving tank (10).

The processing process takes place in a grounded conductive tube of the working volume containing a central non-insulated high voltage electrode that creates a constant electric field acting on the flowing colloidal solution or emulsion in the presence of electrophoretic movement of drops or colloidal formations.

In addition, it was proposed to use a photon correlation spectrometer as a device for monitoring the reduction in droplet size and colloidal formations.

Thus, in the process of processing emulsions and solutions by the field, the finished product is evaluated by the method of scattered light correlation spectroscopy. This method allows you to determine the size of drops and colloidal formations and the stability of the finished emulsions or colloidal solutions against delamination.

Based on the data obtained, changes are made to the processing technology by changing the voltage at the central electrode and the flow rate of the emulsion or solution through the tubes of the working volume.

Using the correlator, the coherence time of the intensity correlation function Te is determined [5], which is associated with the diffusion coefficient D:

1 / τ _s = 2G = 2Dq ² ,

where q is the scattering wave vector:

, $$q=\frac{\mathrm{four}\pi n}{\lambda }\sin \left(\frac{\theta }{2}\right)$$

,

n is the refractive index of the medium, λ is the wavelength of the incident light, θ is the scattering angle,

Using the diffusion coefficient, the average particle radius r _p can be calculated. For example, for spherical particles, you can use the Stokes-Einstein formula:

, $$D=\frac{{\mathrm{<figure-callout\; id="6"\; label="k\; B\; T"\; filenames="00000004.png"\; state="\{\{state\}\}">k\; </figure-callout>}}_{B}T}{6\pi \eta r_p}$$

,

where k _B is the Boltzmann constant, T is the absolute temperature, η is the shear viscosity of the medium in which particles of radius r _p are suspended.

In the case when the suspension or emulsion includes particles of several sizes, the temporal correlation function is the sum of several exponentials. In our case, the DynaLS program [http://www.photocor.com/download/Alango/dynals-white-paper.htm], based on the histogram method with regularization, was used to decompose the obtained function into exhibitors.

Figure 2 presents the results of processing the DynaLS program of the correlation functions of light scattered by the Cinderella detergent emulsion in I20A oil (1.5% Cinderella in oil), i.e. the size distribution of the droplets of the emulsion, before (a) and after (b) the treatment in a constant electric field for 4 minutes in a flow mode in the device proposed in this patent. Dilution to ~ 0.015%, traditional dynamic light scattering scheme, θ = 45 °. In FIG. 2 in the upper part there is a window with a graph of the particle size distribution in nanometers, and in the lower part the peak analysis by the regularization method and the cumulant method. In the first method, we select the approximation range from 50 to 220 channels, the number of intervals is 200, and the boundaries for displaying sizes from 0.5 to 1e + 5 nm (on a logarithmic scale), as well as the background level 0. The data in the table refer to the graph in the upper half of figure 2. The first column indicates the peak number, the second indicates the relative area of the peak, the third indicates the average size of the peak, the fourth column indicates the position of the maximum value, and the fifth indicates the standard deviation. The result of processing by the cumulant method is presented in the lower left corner. The first line shows the average size, the second shows the standard deviation, the third shows polydispersity (standard deviation divided by the average size squared), the fourth shows the background, and the fifth shows the square of the relative residual error. It is seen that immediately after processing, the main peak of the particle size distribution shifts to the left by more than 2 times, i.e. the average radius of the emulsion droplets decreased during the exposure to the field by more than 2 times and thus the sedimentation stability of the emulsion increases by 2 ⁵ times, i.e. the emulsion is stabilized.

From the above results it is seen that the proposed method for stabilizing emulsions and colloidal solutions and a device for its implementation are technically feasible.

Information sources

1. S. Magnin, J. - B. Prudumm, F. Schulz. A method of preparing emulsified fuel and a device for its implementation. RF patent RU 2227155 C2 dated 08.12.1999.

2. G. Sande, W. Piasecki, P.G. Nilsen. A coalescing device.// NO patent NO-316109, 2001.

3. V. Pyasetskiy, M. Florkovsky, M. Fulchik and others. The internal case electrostatic coagulator // ABB Review, 2004, No. 4, p. 67.

4. K.V. Kovalenko, S.V. Krivokhizh, G.V. Rakaeva, L.L. Seagulls "A method of preparing colloidal solutions and a device for its implementation." RF patent RU 2306970, priority dated December 21, 2005, publ. 09/27/2007. (Prototype).

5. G. Cummins, E. Pike. Optical mixing spectroscopy and photon correlation. "World", Moscow, 1978.

Claims (2)

1. A device for stabilizing emulsions and colloidal solutions, containing reservoirs with the original emulsion or colloidal solution, the working volume of processing the emulsion or colloidal solution, and an element for optical control of droplet sizes, characterized in that the working volume of processing the emulsion or colloidal solution is a grounded conductive tube containing a central non-insulated high voltage electrode that creates a constant electric field acting on the flowing colloidal solution or em ulsia. 2. The method of stabilization of emulsions and colloidal solutions by reducing the size of the droplets of the emulsion or colloidal formations, carried out using the device according to p. 1.

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