JPH07198655A - Flow potential measuring device - Google Patents

Abstract

PURPOSE:To eliminate difference in measurement among measuring persons by storing fluidized liquid in a pressure proof type gas-tight structure container with a space being left therein, by introducing high pressure gas into the space through manipulation of a shut-off valve so as to hold a pressure in the container, and by allowing the liquid to be fluidized by a pressure differential while by discharging the liquid so as to lower the fluid pressure. CONSTITUTION:A predetermined volume of fluidized liquid 8 is stored in a pressure- proof type gas-tight structure container 9 with a space 9a being left therein, and a shut-off valve 18 in a gas passage 13 is opened to feed N2 gas having a pressure higher than the atmospheric pressure from a pressure source into the space 9. Accordingly, the pressure in the space 9a and the passage 13 rises up to a predetermined pressure, and the pressurized condition is held by closing the valve 18. When a cock 10 in a liquid supply passage 7 is opened, brake liquid 8 flows through a passage 7 and a charge layer 62 in an E measuring cell 6 so as to generate a flow potential between electrodes 63. This flow potential is delivered to a Y-axis coordinate side of a recorder 5 through an impedance converter 41, and simultaneously, a pressure in the space is measured by a pressure detector 16, and is delivered to the X-axial coordinate side of the recorder 5 through an amplifier 42, and a graph therebetween is recorded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a streaming potential measuring device used in the streaming potential method, which is one of the methods for determining the zeta potential indicating the charge state of a solid-liquid interface.

[0002]

2. Description of the Related Art The streaming potential method is a method in which a solid sample is packed between a pair of streaming potential measuring electrodes and the potential difference, that is, the streaming potential, generated between the electrodes when a flowing liquid is passed through the packed bed is measured. This is a method for obtaining the zeta potential, which is based on the following principle.

Now, consider the case where the liquid is pushed into the inside of one capillary tube. At this time, the radius of the capillary tube is r and the length is l
And Further, if there is an electric double layer on the tube wall, and this is considered to be the molecular weight, and its thickness is δ and the potential difference is ζ, the electric charge q per unit area is given by the following equation (1).

Q = εζ / 4πδ (1) where ε: a pressure difference P is applied to both ends of the liquid permittivity tube,
In this case, the moving speed of the liquid is u (the moving speed is 0 on the tube wall and u at the distance δ). At this time, the frictional force F on the inner surface per unit axial length is given by the equation (2).

F = 2πrηu / δ (2) However, η: Viscosity coefficient of liquid In a steady state, F balances with the applied pressure, so 2πrηu / δ = Pπr ² / l (3 ) When δ is deleted from the equations (1) and (3) and transformed, 2πruq = Pεr ² ζ / 4ηl (4) The left side of the equation (4) becomes a current accompanying the movement of the liquid. Therefore,
If the induced voltage is E, the current i in the capillary tube is given by equation (5).

I = (πr ² λ / l) E (5) where λ: relative permittivity of liquid Therefore, from equations (4) and (5), ζ = 4πηλE / εP (6) ) Equation (6) is called Helmholz-Smoluchowski's equation, and is used when calculating the zeta potential from the streaming potential.

In equation (6), since 4πηλ / ε is constant with respect to the measurement sample, the zeta potential (ζ) is related to the ratio of streaming potential (E) and pressure (P), and E and P are linear. It turns out to be a relationship.

There is a streaming potential measuring device for measuring the streaming potential in order to obtain the zeta potential based on the above principle. This is a streaming potential measurement cell in which a packed bed of a solid sample is sandwiched by a pair of electrodes, a fluid liquid container containing a fluid to be supplied to the packed bed, and a gas for liquid flow supplied from a pressure source. Has a gas passage for introducing into the fluid container and has a predetermined direction in the packed bed (direction crossing the electrodes).
The flow potential generated between the electrodes when a flowing liquid is flown into the electrode can be measured.

By the way, since the zeta potential is theoretically proportional to the streaming potential E and inversely proportional to the liquid flowing pressure P as described above, in order to obtain the zeta potential from the streaming potential,
It is necessary to obtain the E / P by measuring the streaming potential at this time while forcibly changing the pressure of the flowing liquid in one direction.

Therefore, in the conventional apparatus, the pressure of the flowing liquid is forcibly changed from the pressure source side. Specifically, for example, an opening / closing valve and a pressure adjusting valve are provided on a passage between the fluid container and the pressure source, and the opening / closing valve is first opened to introduce a gas of a predetermined pressure from the pressure source into the fluid container. By doing so, a constant pressure is applied to the flowing liquid to make it flow, and then the pressure adjusting valve is gradually opened with the opening / closing valve opened to forcibly reduce the added pressure to the flowing liquid.

[0011]

However, although the E / P is theoretically constant as described above, that is, the E-P relationship is linear, as described above, the conventional streaming potential measuring device is used. However, depending on the sample, or even the same sample, depending on the filling state, a curve relationship could be obtained, which was a problem. Therefore, the measurer
In order to obtain a linear relationship with respect to -P, it is difficult to operate the pressure adjusting valve and the like while monitoring during measurement, and not only skill and know-how are required for measurement,
There is a problem in that the measurement results vary depending on the measurer.

The present invention addresses such a problem, does not require a troublesome operation during measurement, can eliminate variations among measuring persons, and has a linear relationship between streaming potential and liquid flowing pressure. An object of the present invention is to provide a streaming potential measuring device capable of obtaining the following.

[0013]

[Means for Solving the Problems] When the applied pressure to a flowing liquid is forcibly changed, the additional pressure and the flowing state and thus the streaming potential are affected by the pressure loss caused by the resistance of the packed bed in the middle of the flow path. It is considered that there is a gap between the two, and as a result, the E-P relationship appears as a curved relationship. In other words, it is considered that a gap corresponding to the pressure loss occurs between the additional pressure monitored by the monitor and the actual liquid flow pressure. Therefore, it is preferable that the method of changing the pressure is not compulsory as in the conventional method, but is performed in a form adapted to the pressure loss during flow.

From this point of view, in order to achieve the above object, the present invention contains a streaming potential measuring cell in which a packed bed of a solid sample is sandwiched between a pair of electrodes and a flowing liquid to be supplied to the packed bed. And a gas passage for introducing a gas for liquid flow supplied from a pressure source into the fluid container, and when the fluid is flowed in a predetermined direction in the packed bed, A streaming potential measuring device for measuring a streaming potential generated between a pair of electrodes is characterized by being configured as follows.

That is, while the fluid container is constructed of a pressure-tight airtight structure, an opening / closing valve for opening and closing the passage is provided in the passage, and a predetermined amount of space is left in the pressure-tight airtight structure of the fluid container. In the state of containing the flowing liquid, by introducing a gas having a pressure higher than the atmospheric pressure into the space from the pressure source and then closing the open / close valve to maintain the pressurized state, the pressure in the space and the outside The liquid is caused to flow by the pressure difference from the atmospheric pressure, and the liquid flow pressure is passively reduced as the flowing liquid flows out from the liquid container.

[0016]

According to the above construction, a predetermined amount of fluid is stored in the fluid container having a pressure-tight airtight structure, leaving a space, and a pressure higher than the atmospheric pressure is applied to the gas in the space to apply the pressurized state. When the liquid is made to flow by the pressure difference between the pressure in the same space and the outside air pressure, the liquid corresponding to the difference between the flow propulsion force and the flow resistance due to the pressure loss flows and the flow Since the pressure decreases in accordance with the change in volume of the flowing liquid or the space in the flowing liquid container caused by the above, the liquid pressure passively changes according to the pressure loss. Therefore, since there is no deviation between the flow pressure P of the liquid and the flow state and thus the flow potential E, not only when the pressure loss is small, but also in the sample state which causes a high pressure loss, the measurement result As a result, a linear E-P relationship can be obtained. As a result, the measurer does not have to perform a troublesome valve operation or the like during the measurement, and eventually, there is no variation among the measurers.

[0017]

EXAMPLES Examples of the present invention will be described below. FIG. 1 shows the overall configuration of the streaming potential measuring apparatus according to this embodiment.

As shown in FIG. 1, the streaming potential measuring device 1 basically has a main body (measurement) to which an unillustrated N ₂ gas pressure source (hereinafter referred to as a pressure source) is connected via a pressure reducer 2. Part) 3, amplifier unit 4, recorder (X in the example in the figure)
-Y recorder) 5.

The main body 3 has a streaming potential measuring cell (hereinafter referred to as E
(Referred to as a measurement cell) 6 and a fluid container 9 for containing a fluid 8 to be supplied to the E measurement cell 6 through a liquid supply passage 7.
A cock 10 that opens and closes the liquid supply passage 7, a drainage container 12 that collects the liquid discharged from the E measurement cell 6 after the measurement of the streaming potential via a drainage passage 11, and a liquid supplied from a pressure source. A gas passage 13 for introducing N ₂ gas for flowing into the fluid container 9, and a gauge valve 1 in the gas passage 13.
Pressure detector 1 connected via branch passage 15 with 4
6 and a purge valve 17 for releasing the pressure in the gas passage 13 after measuring the streaming potential.

Of these, the E measuring cell 6 is the cell case 6
1 is provided with a filling layer 62 filled with a solid sample, and the filling layer 62 is sandwiched between a pair of electrodes (platinum electrodes) 63, 63. In this case, the pair of electrodes 63, 63 are arranged so as to face each other in the direction in which the fluid 8 passes through the packed bed 62, and prevent solid sample outflow between each electrode 63 and the packed bed 62. Glass filter paper 64
Is provided. Then, when the flowing liquid 8 in the container 9 is caused to flow into the E measuring cell 6 by the pressure of the N ₂ gas supplied from the pressure source into the flowing liquid container 9 via the gas passage 13, the electrodes 63, 63 are separated from each other. It is designed to detect the streaming potential generated in the.

Further, the pressure detector 16 has a diaphragm (not shown) having a strain gauge attached thereto, and the diaphragm is provided in the gas passage 13.
When the strain is distorted by the internal pressure, the resistance change of the strain gauge accompanying it is measured so that the pressure in the gas passage 13, that is, the pressure of the N ₂ gas supplied into the fluid container 9 can be detected. It has become.

On the other hand, the amplifier unit 4 is connected to each electrode 63 of the E measuring cell 6 through an electric wire 63a and has an impedance converter 41 for recording and displaying the potential detected by the cell, and a pressure. A pressure amplifier 42 for recording and displaying the pressure detected by the detector 16 and a conductivity measuring device 43 necessary for calculating the zeta potential from the streaming potential (E) and the pressure (P) are incorporated. Has been done. Here, the streaming potential and the pressure are displayed by a meter (not shown) provided on the panel surface of the device, and are recorded as a graph of E-P by connecting the recorder 5 as shown. It has become. Further, the conductivity measuring device 43 measures the electric resistance of the flowing liquid. For the measurement, the conductivity measuring cell (λ measuring cell) 44 is connected to a connector on the front face of the amplifier (not shown), and the tip of the cell is placed in the flowing liquid. It is designed to be dipped on the side.

In addition to the above-mentioned configuration, in this streaming potential measuring device 1, as a characteristic part of the present invention, the above-mentioned flowing liquid container 9 is composed of a container having a pressure-proof airtight structure, and a gas connected thereto. An opening / closing valve 18 that opens and closes the passage 13 is provided on the passage 13. Then, as shown in the figure, the open / close valve 18 on the gas passage 13 is opened to leave the space 9a in the fluid container 9 having a pressure-tight airtight structure and leave the space 9a in the space 9a from the pressure source. N ₂ gas having a pressure higher than the external pressure is introduced into the inside, and thereby a constant pressure is applied to the flowing liquid 8 in the flowing liquid container 9, and then the opening / closing valve 18 is closed. Due to the pressure difference from the external pressure, the fluid 8 in the container 9 is moved to the E measuring cell 6
It is configured such that the pressure of the flowing liquid 8 is passively lowered as the liquid flows out of the container 9 while flowing into the filling layer 62 side.

Next, the operation of this embodiment will be described. First, in a state in which a predetermined amount of the fluid 8 is stored in the fluid container 9 having a pressure-tight airtight structure, leaving a space 9a, the opening / closing valve 18 on the gas passage 13 is opened to flow from the pressure source through the gas passage 13. When N ₂ gas having a pressure higher than the atmospheric pressure is introduced into the space 9a of the liquid container 9, the pressure in the space 9a and the gas passage 13 becomes higher than the atmospheric pressure by a predetermined pressure.

Therefore, after the constant pressure higher than the external pressure is applied to the fluid 8 in the fluid container 9 in this way, the opening / closing valve 1
When the cock 10 on the liquid supply passage 7 is opened after closing 8 and maintaining the pressurized state, the liquid liquid 8 in the liquid liquid container 9 is supplied by the pressure difference between the pressure in the space 9a and the external pressure. Flowing in the packed bed 62 in the E measuring cell 6 through the passage 7,
As a result, a streaming potential is generated between the electrodes 63 of the cell. This streaming potential is input to the recorder 5 as position data of the Y coordinate via the impedance converter 41. At the same time, the pressure in the space 9a of the fluid container 9, that is, the pressure of the fluid 8 is also detected by the pressure detector 16, which is input to the recorder 5 as position data of the X coordinate via the pressure amplifier 42. To be done. As a result, the measured values of the streaming potential and the pressure are recorded by the recorder 5 as an E-P graph showing the streaming potential (E) on the Y axis and the pressure (P) on the X axis.

By the way, in the case of obtaining such an E-P measurement result, conventionally, a pressure regulating valve is separately provided on the gas passage 13 and opened to force an additional pressure on the fluid 8. Between the added pressure measured by the pressure detector 16 and the actual liquid pressure that causes a pressure loss corresponding to the resistance when flowing in the packed bed 62, and thus between the streaming potential. There was a case where the measured streaming potential E and the pressure P had a curved relationship.

However, in the apparatus of this embodiment, as described above, the open / close valve 18 on the gas passage 13 is closed after a constant pressure higher than the atmospheric pressure is applied to the space 9a of the fluid container 9, and the state is maintained. Since the fluid 8 is made to flow by the pressure difference between the pressure in the space 9a and the outside air pressure, the fluid 8 corresponding to the flow propulsion force and the flow resistance due to the pressure loss flows. The pressure is reduced in accordance with the change in volume in the fluid container 9 that accompanies it. Therefore, the pressure of the flowing liquid 8 passively changes in accordance with the pressure loss, and a deviation does not occur between the liquid pressure P and the flowing state and thus the flowing potential E. As a result, a linear relationship is obtained as the E-P measurement result.

FIG. 2 shows an example of the measurement results of the streaming potential E and the pressure P thus measured, in comparison with the measurement results by the conventional device. (A) of the figure is based on the conventional device,
(B) is according to this embodiment. It can be seen that in the case of the conventional device (A), E-P has a curved relationship, whereas in the case of (B) according to the present embodiment, it has a linear relationship.

The measurement example shown in the graph is the pressure in the space of the fluid container, that is, the fluid (0.0 in this example).
The applied pressure to the 01M / l KCl aqueous solution) is 0.5
The measurement was performed in the range of not more than kg / cm ² . Therefore, in the case of a sample state with a large pressure loss, there is a possibility that liquid flow will not occur or measurement will take a long time, so in order to make the sample pressure loss relatively small A zeolite-based adsorbent was used as the material, and the adsorbent was roughly filled in a 2 mm E measurement cell, and the measurement was performed. In order to measure a sample with a high pressure loss and to shorten the measurement time, it is necessary to use a fluid pressure vessel having a structure that can withstand a pressure applied to the pressure drop and a pressure that is sufficiently large.

[0030]

As described above, according to the present invention, the fluid container has a pressure-tight airtight structure, and a constant pressure is applied to the fluid container in a state where the fluid is stored in the container while leaving a space. By maintaining the state, the fluid pressure of the liquid is passively changed, so that the measurement can be performed without causing a deviation between the pressure of the liquid fluid and the flow state, that is, the flow potential. Therefore, in the case of the present invention, the pressure loss is not a problem as compared with the prior art, and even if the sample state causes a high pressure loss, a linear relationship can be obtained as the E-P relationship. The hands can be released during the measurement, and there is no variation among the persons making the measurement.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an overall configuration of a streaming potential measuring device according to an embodiment of the present invention.

FIG. 2 is a graph showing an example of measurement results of streaming potential (E) and pressure (P), where (A) is obtained by a conventional device,
(B) is based on the above embodiment.

[Explanation of symbols]

 1 ... Streaming potential measuring device 6 ... Streaming potential measuring cell (E measuring cell) 8 ... Streaming liquid 9 ... Streaming liquid container 9a ... Space 13 ... Gas passage 18 ... Opening / closing Valve 62 ... Filled layer 63 ... Electrode

Claims (1)

[Claims] 1. A streaming potential measuring cell in which a packed bed of a solid sample is sandwiched between a pair of electrodes, a flowing liquid container for containing a flowing liquid to be supplied to the packed bed, and a liquid flow supplied from a pressure source. And a gas passage for introducing the gas into the fluid container, and a streaming potential measurement for measuring a streaming potential generated between the pair of electrodes when the fluid is flowed in a predetermined direction in the packed bed. In the device, the fluid container is formed of a pressure-tight airtight structure, and an opening / closing valve for opening and closing the gas passage is provided in the gas passage, and a space is provided in the pressure-tight airtight structure. In the state where a predetermined amount of flowing liquid is stored while leaving the above, the opening / closing valve is closed and a pressurized state is maintained after introducing a gas having a pressure higher than the atmospheric pressure into the space from the pressure source. The pressure in the same space and the external pressure A streaming potential measuring device, characterized in that the flowing liquid flows into the packed bed due to the pressure difference, and the flowing pressure of the flowing liquid in the flowing liquid container is passively lowered with the outflow of the flowing liquid.