SU972379A1 - Method of and device for measuring suspension particle electrokinetic parameters - Google Patents

Description

(54) METHOD OF MEASUREMENT OF ELECTROKINETIC PARAMETERS PART OF SUSPENSIONS AND A DEVICE FOR ITS IMPLEMENTATION

one

The invention relates to the physicochemical analysis of disperse systems, in particular, to the measurement of the electrophoretic mobility of particles, and can be used in the study of water, soil, in medicine and in the enrichment of minerals.

There is a known method for determining the electrophoretic mobility of suspension particles by fixing on the micrograph the amplitude and frequency of their pronounced oscillations in an alternating electric field 1.

This method is characterized by insufficient accuracy and duration of measurement due to the indirect (from the photograph) finding the parameter to be determined.

Closest to the present invention is a method for measuring the electrokinetic parameters of particles of suspensions, including the effect on an illuminated particle, a constant electric field and the detection of a light pulse emanating from the particle, while the latter is in the field of view of the detector.

A device comprising an electrophoretic cell with electrodes connected to a constant voltage source, an illuminator, a microscope, a focused electrophoretic cell, a photoelectric detector connected through an amplifier to a recording device 2 is used.

ten

The disadvantage of the method and the device used is that they can be used for measurements in dispersed systems with a very low concentration of particles. Otherwise there will be

15, simultaneous exposure to the photoelectric detector of several particles occurs.

The purpose of the invention is to expand the range of use of the method in the field of

20 high concentrations of suspensions.

This goal is achieved by the fact that, according to the method of measuring the electrokinetics parameters of suspension particles, including the effect on the illuminated particle of a constant electric field and the recording of a light pulse emanating from the particle, when the latter is in the field of view of the detector, the polarity of the applied voltage changes the time the particle is in the field of view of the detector and the switching frequency for a certain period of time is judged on the desired parameter.

In a device for measuring the electrokinetic parameters of suspension particles, containing an electrophoretic cell with electrodes connected to a voltage source, an illuminator, a microscope focused inside the electrophoretic cell, a photoelectric detector connected through an amplifier to a recording device, the photoelectric detector is optically aligned with the microcopy through the slit diaphragm and the device is additionally equipped with a timer and an inverter, while the timer input is connected to the amplifier output The first output of the timer is connected directly to the constant voltage source, and the second output is connected to it via the inverter.

The essence of the method consists in creating the conditions for the oscillation of a particle that is in a dispersion medium near the entrance face of the slit of the diaphragm, the frequency of which determines the mobility of the particle and its discharge. Replacing the linear-translational motion of a particle in the field of view of the detector used in the prototype method, allows for eliminating or significantly reducing the likelihood of interference with measurements from other particles present in the suspension. The drawing shows schematically a device for measuring the electrokinetic parameters of suspension particles. The device contains an electrophoretic cell 1 with electrodes 2 connected to a constant voltage source 3, an illuminator 4, a microscope 5 focused inside the electrophoretic cell 1, a photoelectric detector 6 optically aligned through a slit of the diaphragm 7 with a microscope 5 directly or with a television device screen ( not shown), the amplifier form 8, the input of which is connected to the photoelectric detector 6, and the output to the recording device 9, and the timer 1O. One of the outputs of the timer 10 is connected to a constant voltage source 3 directly, the second through an inverter 11.

The device works as follows.

Electrodes 2 of electrophoretic cell 1 filled with a sample of the suspension are connected to a constant voltage source 3. Particles suspended in the sample illuminated by illuminator 4 begin to shift under the effect of the applied voltage. Microscope 5, focused inside the electrophoretic cell 1, projects the image of the particle onto the photoelectric detector b through the slit of the diaphragm 7 directly or from the screen of the television device. The electrical impulse arising in this case is amplified by amplifier 8 and fed through timer 10 to inverter 11. The latter gives a signal to block 3, which changes the polarity of the voltage on electrodes 2. This changes the direction of movement of the particles in the cell by 180. The image of the particle leaves the slot the diaphragm 7, the photoelectric current pulse is stopped, the polarity on the electrodes, 2 and the direction of movement of the particles in the cell are restored.

Claims (2)

The cycle repeats, oscillatory motion of particles occurs. A pulsed current B of the photoelectric detector circuit 6 and an alternating current in the circuit of the electrophoretic cell 1 are formed synchronously with it, the frequency of which is proportional to the electrophoretic velocity and the electrokinetic potential of the particle. The impulse current is fed to the input of the recording device 9. The latter may consist, for example, of a digital indicator and a digitizer to display and record the magnitude of the electrokinetic potential or electrophoretic mobility of the particles. Timer 10 sets the time interval for measuring particle oscillations. It can also be used to turn off the power supply of the photoelectric detector 6 for the time interval necessary for the image of the particle to exit the field of the photoelectric detector 6 and to release it for alignment with the image of the next particle. The proposed method for measuring the electrokinetic parameters of suspension particles and a device for its implementation allow increasing the range of particle concentrations in the sample due to the low probability of exposure of the photoelectric image detector of several particles simultaneously, which expands their field of use. Claim 1. A method for measuring the electrokinetic parameters of suspension particles, including exposing an illuminated particle to a constant electric field and registering a light pulse emanating from the particle, while in the latter in the field of view of the detector, is different in that it is used to extend the range of use. method in the field of high concentrations of suspensions, change the polarity of the applied voltage for the time the particle is in the field of view of the detector and the switching frequency for a certain segment time judge about the desired parameter. 2. A device for measuring .electronic parameters of suspension particles. containing an electrophoretic cell with electrodes connected to a constant voltage source and successively located along the optical axis an illuminator, a microscope and a photoelectric detector, an amplifier connected to a recording device, characterized in that the photoelectric detector is optically combined with a microscope through the aperture diaphragm and the device is equipped with a timer and an inverter, with the timer input connected to the amplifier output, the first timer output directly connected to the source voltage, and the second output is connected to it through the inverter. Sources of information taken into account in the examination 1. Mikhailov A. Yu. Measurement of electrophoretic mobility of particles. Proceedings of MEI, 1974, no. 174, p. nineteen. 2. US Patent No. 3793180, cl. G 01N 27/26, 1974 (prototype).