FI109239B - Method for establishing the flow potential of an aqueous solution and arrangement for application of the method - Google Patents

Description

109239

METHOD FOR DETERMINING THE FLOW POTENTIAL OF AQUEOUS SOLUTION AND THE APPLICATION OF THE METHOD

The invention relates to a method for determining the flow potential 5 of an aqueous solution. The invention further relates to a device for applying the method.

Determining the surface charge caused by dissolved and colloidal substances in the aqueous suspension is important to understand the properties of the aqueous solution. The currently used methods for determining the charge state of aqueous solutions 10 are based either on the change in color of the polyelectrolyte and indicator dyes or on the determination of the flow potential in the narrow gap between the piston and cylinder of an electrically insulated cylinder / piston assembly.

The disadvantage of these methods is that the interfering substances are sensitive to the color change reaction, making accurate determination difficult and determination dependent on the analyzer. Cylinder / host combination solution • ·. ' 'The mixing is incomplete and therefore the determination time is long. As a matter of fact. ; -t is also that these assays are not suitable for solutions containing particles of size '20 fiber size or larger, but solutions are ##. 'to be filtered before analysis.

The flow potential of aqueous solutions is determined in various industries, and in particular in the paper industry, where the determination of the properties of paper pulp solutions is

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,; 25 important to observe the properties of the paper. In addition, it is important to get '·. information on the configuration as soon as possible.

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It is an object of the invention to provide a method for overcoming the drawbacks of the present methods. In particular, it is an object of the invention to provide; 30 discloses a method by which an accurate determination can be made from the determiner. '! regardless of automatically in a relatively short time for all kinds of solutions.

It is a further object of the invention to provide a device for applying method 2 109239 which is simple in design, easy to use and inexpensive.

The object of the invention is achieved by a method and a device characterized by what is stated in the claims.

In the method of the invention, the aqueous solution to be examined is transferred under pressure from a reservoir via a tube through a flow choke to a second reservoir at a pressure lower than the first reservoir, and the potential difference between the flowable solution and the non-flowable solution is measured. The voltage difference caused by the current is measured with a voltage meter connected to the electrodes. The method quickly and simply determines the flow potential of the aqueous solution. The method substantially speeds up the determination of the flow potential of the aqueous solution in comparison with previously known methods, and at the same time provides more reliable results. This provides a faster and more accurate determination of the concentration of the aqueous solution when stretched than before. The method is suitable for use as an automated assay. This saves labor costs.

J 2o> ;. The method can be used to automatically determine the flow potential of various aqueous solutions. The method is particularly suitable for use in the paper industry when determining the properties of aqueous solutions. Configurations can be made. · · Directly from the solution on site for immediate assay results.

In a preferred embodiment of the invention, the potential difference is measured between the electrode disposed in the first container and the electrode disposed in the gap of the flow choke. Such a solution is simple and inexpensive to implement.

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In another preferred embodiment of the invention, the aqueous solution to be examined is discharged from the reservoir by a pressurized gas such as compressed air or other pressurized gas 3 109239. The use of compressed air is advantageous and suitable for this purpose. Other pressurized gases such as nitrogen or other suitable gas may also be used in other applications.

In a third preferred embodiment of the invention, the aqueous solution to be examined is discharged from the container by means of a vacuum. Even under vacuum, the necessary flow is achieved reliably and accurately.

In a further preferred embodiment of the invention, the aqueous solution to be examined is discharged from 10 containers by means of a piston. Such a structure also provides a reliable and efficient flow.

The device according to the invention includes tanks, tubing connecting the tanks, a flow restrictor I between the tubes through which the aqueous solution is arranged to be transferred from one tank to another, electrodes measuring the flow potential of the solution, and a voltage gauge. Such a device is simple in structure, advantageously manufactured and reliable.

In a further embodiment of the invention, the first electrode is disposed in a first 20-vessel container and the second electrode is disposed in a flow choke. The first electrode measures the aqueous solution in the reservoir and the second electrode at the flow restrictor measures the potential of the filing solution. These electrodes initiate which potentials reliably provide a potential difference.

The invention will now be explained in more detail with reference to the accompanying drawing, which is a side elevational view of a device according to the invention.

The device shown in the figure includes two tanks 7, 8, pipes 9, 30 10 therebetween, a flow choke 1,5, an electrode 6 disposed in the tank 7 and a second electrode 2 positioned in the flow choke 1,575 and a voltage gauge 16 for measuring the voltage between these electrodes. The voltage meter 16 is wired to the electrodes. The flow 4109239 cross is formed of two pieces; a portion 1 having a duct and a portion 1 movable closure member 5 connected to a cylinder 4 which moves it, i.e. the distance between the closure portion 5 and portion 1 is adjusted by means of the cylinder. Connected to the container 7 is a channel 5 for introducing an aqueous solution into the channel. In addition, the device includes an overpressure valve 12 connected to a pump or similar air hose 13 and air hoses 14 and 15 to tanks 7 and 8. The tanks 7, 8 are cylindrical in this embodiment, but may vary in shape in different applications. The parts of the device are made of non-conductive material except for measuring electrodes. The measuring electrodes are made of metal that does not corrode in solution. The device is positioned on a precision balance, allowing the solutions to be dispensed to be accurately determined by weighing the resulting weight gain. In addition, the device includes or is connected to pneumatic devices known per se, electronics and measuring signal processing devices, and a computer.

15 These are not described in further detail.

The flow potential of the aqueous solution is determined using the method and apparatus of the invention as follows: The aqueous solution to be determined is introduced into the container 7 via a channel 17. The tanks 7 and 8 are then in normal • · «. * '20 at atmospheric pressure. When the desired amount of sample has been dispensed into the container 7, overpressure is achieved in the container 7 by supplying compressed air to the container via the overpressure valve 12 and the conduit 14. In the relief valve, the compressed air is controlled via line A, B. Reply - ;;; correspondingly, line C, D of the overpressure valve is open through channel 15 to the container 8. Thus, there is a pressure difference between the containers. This pressure difference transfers the 25 aqueous solutions in the tank 7 through the tube 9 into the gap in the flow choke and further along the tube 10 into the tank 8. The gap in the flow choke is narrow and adjustable. by adjusting the distance of the part 5 from the surface of the part 1 by means of the cylinder 4. The flow causes a voltage difference between the electrode 6 placed in the tank and the placement of the flow choke - '..! between electrode 2. The water potential in the tank 7 is used as the zero potential measurement for the flow potential. The potential difference measured by the electrodes 2 and 6 of the flowing solution and the non-flowing solution is measured by a voltage gauge 16.

'*' The voltage meter transmits the data to the computer and reports the results to 5,109,239 as desired. The measurement is done automatically.

When the aqueous solution has been sufficiently displaced to measure the flow potential from the reservoir 7 to the reservoir 8, the flow direction of the solution is reversed.

Then, the air pressure controlled via the overpressure valve 12 is directed through line A, C and the air hose 15 to the tank 8 and the tank 7 is open to normal air pressure through the air hose 14 and line B, D of the overpressure valve 12. Once the solution flow potential has been determined, the tanks and the measurement gap are flushed. The cylinder 4 has an opening for the flow choke. The wash solution is directed through a channel 17 10 to a tank 7. During rinsing, the wash solution is transferred through an open slot between the tanks 7, 8 by means of a differential pressure created by compressed air. Rinse repeatedly so that the desired level of purity is achieved with the uncharged calibration solution. Between rinses, the device is emptied by opening valve 11 in conduit 10. Rinsing of tanks and solution lines and rinsing are automatically performed according to a preselected program.

The invention is not limited to the preferred embodiment shown, but may vary within the scope of the inventive idea of the claims.

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Claims (8)

Method for determining the flow potential of an aqueous solution, characterized in that the aqueous solution to be examined is moved under pressure from a container (7) via a pipe (9) through a flow restriction (1, 5) and via another pipe (10). another container (8), where the rescue pressure is lower than in the first container (7), and that the potential difference of the flowing solution and the non-flowing solution is measured by electrodes (2, 6). Method according to claim 1, characterized in that the potential difference is measured between the electrode (6) located in the container (7) and the electrode (2) located in the flow restriction slot. 3. A method according to claim 1 or 2, characterized in that the aqueous solution to be examined is guided from the container (7) with the aid of pressurized gas, such as compressed air or some other pressurized gas: ** or suppression. '· · 4. A method according to claim 1 or 2, characterized in that the aqueous solution to be examined is led from the container (7) by means of vacuum. Process according to Claim 1 or 2, characterized in that the aqueous solution to be examined is | Is led from the container (7) by means of a piston. Apparatus for determining the flow potential of an aqueous solution, characterized in that the apparatus hears containers (7, 8), the containers connecting tubes (9, 10), a flow restriction (1, 5) located between the tubes, through which the aqueous solution is arranged to move from one container (7) to the other container (8), the electrodes (2, 6) of the solution potential of the solution measuring during movement, and a voltage meter (16) measuring the voltage difference between the electrodes (2, 6). Apparatus according to claim 6, characterized in that one electrode (2) is placed in the flow restriction (1, 5) and the other electrode (6) is placed in the container (7). 8. Apparatus according to claim 6, characterized in that the apparatus is located on a precision path. • · · »tr I M *» »» · Ml * · · • · »* ·