JPH1038836A - Flow potential measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device that can measure flow potential easily with high accuracy from small diameter grain to large diameter grain with simple and compact constitution, without changing the flow of a fluid. SOLUTION: A fluid feeding container 11, a flow potential measuring cell 10 and a fluid receiving container 12 are communicated with one another under pressure-tight and airtight structure. The feeding container 11 is provided with a means for imparting constant high pressure, and the receiving container 12 is composed of a plurality of chambers 121, 122 that can be selectively partitioned in an airtight state by opening/closing mechanism 18. The volume of the receiving container 12 can be charged without changing a fluid passage by operation of the opening/closing mechanism 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a streaming potential, and more particularly to an apparatus suitable for obtaining a zeta potential indicating a charged state of a solid-liquid interface based on a streaming potential method.

[0002]

2. Description of the Related Art A streaming potential method is known as one of methods for obtaining a zeta potential. The streaming potential method is a method in which a solid sample is filled between a pair of electrodes, and a zeta potential is obtained by measuring a potential difference generated between the pair of electrodes when a liquid flows through the packed layer, that is, a streaming potential. .

In this streaming potential method, the flow potential of the liquid flowing through the packed bed, that is, the differential pressure P between both ends of the packed bed, is generally measured together with the streaming potential E. ) The zeta potential ζ is calculated using the Helmholtz-Smolkovski equation shown in the equation. In addition,
K in the equation (1) is a constant determined by the dielectric constant, viscosity, and conductivity of the liquid.

Ζ = k ・ E / P (1) Here, in the actual measurement, while changing the flow pressure P, the flow potential E corresponding to the flow pressure P is measured. From the combination of the measured values of the flowing pressure P and the flowing potential E, these relationships E / P are obtained, and
The zeta potential ζ is determined by the equation.

As described above, in order to flow the liquid into the packed bed while changing the flow pressure P, in a conventional measuring system of this type of measuring device, as shown in FIG. One end of a streaming potential measurement cell 30 capable of forming a packed layer 33 of a sample between 32 contains a flowing liquid, and
The other end of the cell 30 has a structure facing the inside of the fluid receiving container 35 opened to the atmosphere, while allowing the fluid to communicate with the fluid supplying container 34 capable of applying pressure to the inside using a gas. While the pressure P is measured by the pressure gauge 36 and the streaming potential E by the electrometer 37 connected between the electrodes 31 and 32, the relationship between E / P is measured while the pressure applied to the container 34 is gradually changed. It has become.

Here, in the above measuring system,
Although theoretically P and E have a linear relationship, P
May change in a curved manner with respect to the change of.
Therefore, at the time of measurement, the measurer needs to adjust the pressure applied to the container 34 while monitoring the indicated values of the pressure gauge 36 and the electrometer 37 during the measurement so that the E / P relationship becomes linear. There is a problem that considerable skill is required to obtain accurate measurement results. It is considered that the cause is that a difference occurs between the monitored value of the pressure applied to the supply container 34 and the actual flow pressure P due to the pressure loss in the system.

Therefore, the present inventor has already proposed a streaming potential measuring apparatus provided with a measuring system having a structure for solving such a problem (Japanese Patent Laid-Open No. 7-325062).
issue). In the measurement system in this proposal, a streaming potential measurement cell, a fluidized liquid supply container communicating with one end of the cell and containing a liquid to be supplied thereto, and a fluid flowing therethrough communicating with the other end of the cell. And a fluid-liquid receiving container that accommodates the fluid-liquid container and a mechanism that applies a constant pressure higher than the atmospheric pressure to the fluid-liquid supply container. I have.

According to such a measuring system, when a constant high pressure is applied to the fluid supply container, the liquid in the supply container is forced into the cell at a flow rate corresponding to the pressure difference from the receiving container. It flows into the receiving container via the packed bed and accumulates therein, and the pressure in the receiving container increases according to the amount of liquid stored in the receiving container. Therefore, when a constant pressure is continuously applied to the supply container, the pressure in the receiving container increases with time according to the amount of liquid flowing into the container, so that the pressure difference between both ends of the packed bed, that is, the flow pressure P Changes passively in response to changes in the flow velocity of the liquid flowing through the packed bed placed in the closed system, and it is necessary to change the pressure applied to the supply container as in the conventional measurement system. Therefore, the E / P relationship can be easily and accurately measured without deviating from the linear relationship.

[0009]

By the way, in a streaming potential measuring apparatus having a measuring system based on the above proposal, the volume of the receiving container depends on the factor that determines the rate of change of the flowing pressure. This is an important factor as know-how in actual measurement, and it may be better to change the volume depending on the type of sample in order to improve measurement accuracy. That is, usually, when a packed bed is formed using small particles as a sample, the flow resistance becomes large and the flow velocity of the liquid becomes slow,
In order to prevent the measurement time from becoming meaninglessly long, it is desirable that the receiving container has a small volume, and when a packed bed is formed using large particles as a sample, the flow resistance becomes small and the flow velocity of the liquid decreases. Is faster, the measurement time is too short with the same volume as the small particles, and the number of E / P data samplings is too small, resulting in a large error. In this case, it is desirable to use a large-capacity receiving container.

[0010] Here, as described above, if an apparatus having different receiving container volumes is used depending on the type of sample to be measured, the versatility of the apparatus is poor, and a plurality of receiving containers having different volumes are prepared. If the sample is selectively used according to the type of the sample, it is necessary to exchange and adjust the sample each time, which is not practical. It is also conceivable that the receiving containers having different capacities are selectively connected to the cells by switching valves or the like. However, in this case, the apparatus becomes large and the structure becomes complicated. However, this complicates the flow of liquid, which is the most important in the measurement of streaming potential, and has the effect of the problem and the necessity of providing a pressure gauge for each receiving container. Another problem is that it must be done.

[0011] The present invention has been made in view of such circumstances, and can easily convert small-sized particles to large-sized particles in a relatively simple and compact structure without changing the flow of liquid. Another object of the present invention is to provide a device capable of measuring a streaming potential with high accuracy.

[0012]

The structure for achieving the above object will be described with reference to FIG. 1 showing an embodiment. And a flowing liquid that communicates with one end of the cell 10 and contains a liquid to be flowed through the packed bed 3 in the cell 10. The supply container 11 communicates with the other end of the cell 10,
An apparatus for measuring a streaming potential generated between the electrodes 1 and 2 when a liquid flows through the packed layer 3 is provided with a fluidized liquid receiving container 12 for storing the liquid that has passed through the packed layer 3 in the cell 10. The container 11, the cell 10, and the receiving container 12 are configured to communicate with each other by a pressure-resistant airtight structure, and a gas having a pressure higher than the atmospheric pressure is introduced into the supply container so that the liquid is applied to both ends of the packed bed 3. Pressure applying means for applying a differential pressure for flowing (pressure source, gas passage 1 in the example of FIG. 1)
4a, a gas introduction valve 14b, etc.), and the receiving container 12 includes a plurality of chambers 121, 122 and an opening / closing mechanism (opening / closing valve in the example of FIG. 1) 18 for selectively and airtightly partitioning the rooms. It is characterized by having.

In the above configuration of the present invention, the opening / closing mechanism 1
By the operation 8, it is possible to substantially change the volume of the receiving container 12. That is, when the opening / closing mechanism 18 is closed, the volume of the receiving container 12 is equal to the volume of the room 121, and when the opening / closing mechanism 18 is opened, the receiving container 1 is closed.
The volume of 2 is the sum of the volumes of the rooms 121 and 122. Even if the volume of the receiving container 12 is changed by operating the opening / closing mechanism 18 in this way, since the liquid that has passed through the cell 10 always flows into the room 121 closest to the cell 10, the liquid in the receiving container 12 is changed according to the sample. Even if the volume is changed, the flow path of the liquid does not basically change, and the measurement result of the streaming potential is not affected. Also, for the same reason, the receiving container 12
It is sufficient to mount only one pressure gauge for measuring the internal pressure in the room 121 closest to the cell 10.

Since the supply container 11, the cell 10, and the receiving container 12 are connected to each other by a pressure-resistant airtight structure, a constant pressure is applied to the supply container 11 by the pressure applying means as in the above-mentioned proposal. The flow pressure P
Changes passively at a speed corresponding to the capacity of the receiving container 12, and the relationship E between the flowing pressure and the flowing potential is always accurately determined.
/ P can be measured.

[0015]

FIG. 1 is a block diagram of an embodiment of the present invention. The streaming potential measurement cell 10 which is substantially tubular as a whole and in which a pair of electrodes 1 and 2 are arranged to face each other has one end communicating with a fluid supply container 11 via a liquid supply pipe 11a. The other end communicates with the fluid receiving container 12 via the liquid receiving pipe 12a. The solid sample whose zeta potential is to be measured is filled between the electrodes 1 and 2 in the cell 10, and the filling layer 3 is formed there.

An electrometer 13 is connected to each of the electrodes 1 and 2, and the electrometer 13 measures a potential difference between the electrodes 1 and 2 due to the flow of the liquid in the packed bed 3, that is, a streaming potential E. You.

The fluid liquid supply container 11 is constituted by a container having a pressure-resistant and airtight structure, and contains therein a liquid to be flowed into the cell 10. Further, a gas passage 14a for introducing a gas (for example, N ₂ ) from a pressure source (not shown) is connected to the supply container 11, and a pressure for flowing the liquid is applied by these. Make up the mechanism. Further, the supply container 11 is provided with a pressure gauge 15a for measuring the internal pressure and a thermometer 16 for measuring the temperature of the liquid.

The gas passage 14a is provided with a gas introduction valve 14b for opening and closing the passage 14a to introduce / stop gas from a pressure source into the supply container 11. There is provided a branch path 14d provided with an atmosphere release valve 14c for bringing the pressure to atmospheric pressure. Therefore, by closing the atmosphere opening valve 14c and opening the gas introduction valve 14b, a gas higher than the atmospheric pressure from the pressure source can be introduced into the supply container 11,
Conversely, by closing the gas introduction valve 14b and opening the atmosphere release valve 14c, the pressure in the supply container 11 can be made equal to the atmospheric pressure.

The fluid receiving container 12 is, in this example,
The streaming potential measuring cell 10 is connected through the liquid receiving pipe 12a.
A first room 121 in airtight communication with the
And a second room 122 that is air-tightly connected to the communication pipe 12b through the communication pipe 12b.
An opening / closing valve 18 capable of airtightly separating the first and second chambers 121 and 122 is provided. This first
Each of the second chambers 121 and 122 is constituted by a container having a pressure-resistant and airtight structure.

The first room 121 has a pressure gauge 1
5b, and a liquid discharge valve 17a for discharging the liquid accumulated in the inside. The second chamber 122 has an atmosphere release valve 17 for reducing the internal pressure to atmospheric pressure.
b is provided. Here, the output of the pressure gauge 15b provided in the first room 121 indicates the pressure in the room 121 when the open / close valve 18 is closed and the output of the open / close valve 18
In the state where is open, it represents the pressure of the first and second chambers 121 and 122 as a whole.

The above-mentioned electrometer 13 and each pressure gauge 15
The outputs of a and 15b are digitized by the A / D converter 21 and then sampled by the computer 22 every moment.

Next, the operation of the above embodiment will be described together with the method of use. At the time of measurement, the fluid receiving container 1
The second open / close valve 18 and the atmosphere release valve 17b are once opened, and the air pressure in the first and second chambers 121 and 122 is set to the atmospheric pressure.

Next, the volume of the fluid receiving container 12 is selected. In other words, when measuring a sample such as particles having a small particle diameter, the flow resistance of which increases when the packed layer 3 is formed, the on-off valve 18 is used in a closed state. The volume of the receiving container 12 is substantially the volume of the first room 121. In the measurement of a sample such as a particle having a large particle diameter, the flow resistance of which is reduced when the packed layer 3 is formed, the sample is used with the open / close valve 18 opened. The volume of the fluid receiving container 12 is the sum of the volumes of the first and second chambers 121 and 122. When the device is used with the opening / closing valve 18 opened, the atmosphere opening valve 17b is closed at the time of actual measurement.

After the selection of the volume of the fluid receiving container 12 as described above, the actual amount of the fluid is stored in the fluid supplying container 11 in the actual measurement.
With the liquid discharge valve 17a of the fluid supply container 12 closed, the air release valve 14c of the fluid supply container 11 is closed and the gas introduction valve 14b is opened, so that a constant pressure higher than the atmospheric pressure is maintained inside the supply container 11. applying a pressure _P P. In this state, the supply container 11, the streaming potential measurement cell 1
0, and the receiving container 12 communicate with each other in an airtight state, and a state where a differential pressure P is generated at both ends of the cell 10, the liquid in the supply container 11 flows toward the cell 10, and the electrodes 1, 2
After passing through the packed layer 3 of the sample sandwiched between the
Flows into the first room 121. The flowing potential E generated in the packed bed 3 by the flow of the liquid is measured by the electrometer 13 via the electrodes 1 and 2, and the digital conversion data is taken into the computer 22.

At the same time, due to such flow of the liquid, the amount of liquid in the receiving container 12 increases at a speed corresponding to the flow velocity of the liquid. The pressure P _C in the receiving container 12 increases by the amount of the liquid in the container 12. Therefore, even if the pressure P _P in the supply container 11 is kept constant, the cell 1
The differential pressure P (= P _P -P _C ) at the two ends of the
It changes passively in accordance with the change in the flow velocity of the liquid flowing therethrough, and there is no deviation between the instantaneous differential pressure P and the streaming potential E. The pressure P _P in the supply container 11 and the pressure P _C in the receiving container 12 are taken into the computer 22 every moment, so that the computer 22 stores the instantaneous data of the flow pressure P and the flow potential E, which are not shifted from each other. Sampled and accurate E / P data is stored. If the equation for calculating the zeta potential に shown in the above equation (1) is written in the computer 22, the zeta potential ζ can be calculated immediately after the measurement is completed, and displayed on a display or the like.

In the above measuring operation, the selection of the volume of the receiving container 12 by operating the opening / closing valve 18 before the start of the measurement has the following effects. Now, for the sake of simplicity, the volumes of the first chamber 121 and the second chamber 122 are each assumed to be V _0, and the pressure P _C in the receiving container 12 is set to a pressure 2P ₀ twice the atmospheric pressure P _0. When the setting is made to end the measurement when the measurement is completed, when the open / close valve 18 is closed and the small capacity is selected, the receiving container 12 is closed at the end of the measurement
The amount of liquid contained in the chamber is V ₀ / V as shown in FIG.
When the opening / closing valve 18 is opened and a large capacity is selected, the amount of liquid stored in the receiving container 12 at the same time becomes V ₀ as shown in FIG. Therefore, when measuring the same sample, even when the P _C finishes measurement when it reaches the same pressure, the time of the selection of small capacity and a large capacity, to differentiate twice the amount of fluid flowing through a packed bed 3 be able to. This means that when the average flow rates from the start to the end of the measurement are equal to each other when each volume is selected, there is a double difference in the measurement time.

Therefore, when the flow resistance of the packed bed 3 is relatively small and the flow velocity is relatively high, such as a large-diameter sample, the volume of the receiving container 12 is increased to increase the required score. E / P data can be sampled. In addition, when the flow resistance of the packed bed 3 is relatively large and the flow velocity is relatively slow, such as small-diameter particles, the volume of the receiving container 12 may be made small so that the measurement time may be unnecessarily long. Can be prevented.

Here, it should be noted that the liquid passing through the cell 10 must be the first liquid regardless of whether the volume of the receiving container 12 is small or large.
No change in the flow path of the liquid resulting from the selection of the volume due to the flow into the room 121, whereby the measurement result of the streaming potential E is not affected regardless of which volume is selected. Also, regardless of the selection of the volume of the receiving container 12,
The pressure P _C of the vessel there is an advantage that can be measured by a single pressure gauge 15b provided in the first chamber 121.

In the above embodiment, the receiving container 1
2 is constituted by the two chambers 121 and 122, but the present invention is not limited to this, and the receiving container 12 is constituted by three or more arbitrary rooms, and the open / close valve 18 is provided between the respective rooms. May be provided.

[0030]

As described above, according to the present invention, the fluid supply container, the fluid potential measurement cell, and the fluid supply container are connected to each other by a pressure-resistant airtight structure.
The fluid-liquid receiving container has a configuration in which an opening / closing mechanism capable of airtightly partitioning between a plurality of rooms and the respective rooms is provided, so that the volume of the receiving container can be easily changed only by operating the opening / closing mechanism. It is possible to easily perform measurement under a more appropriate receiving container volume according to the type of sample without changing the flow path of the liquid, and thus without affecting the measurement result of the streaming potential, An accurate and versatile streaming potential measuring device can be obtained. Further, irrespective of the selection of the volume of the receiving container, the pressure in the container can be measured by one pressure gauge, so that there is no influence of changing the pressure gauge.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 shows the receiving container 12 operated by the opening / closing valve 18.
Of operation of volume selection

FIG. 3 is an explanatory diagram of a measuring system in a conventional streaming potential measuring device.

[Explanation of symbols]

 1, 2 electrode 3 packed bed 10 flowing potential measurement cell 11 flowing liquid supply container 12 flowing liquid receiving container 12b communication tube 121 first room 122 second room 13 electrometer 14a gas passage 14b gas introduction valve 14c 17b air release valve 15a, 15b Pressure gauge 18 Open / close valve

Claims (1)

[Claims] 1. A streaming potential measurement cell having a pair of electrodes opposed to each other so as to sandwich a packed layer of a solid sample, and communicates with one end of the cell to contain a liquid to flow through the packed layer in the cell. A fluid supply container, which communicates with the other end of the cell, and a fluid receiving container for containing the liquid that has passed through the packed bed in the cell. In the device for measuring the streaming potential generated between the electrodes, the supply container, the cell, and the receiving container are configured to communicate with each other by a pressure-resistant airtight structure, and a pressure higher than the atmospheric pressure in the supply container. In addition to providing pressure applying means for introducing a gas and applying a pressure difference for flowing the liquid to both ends of the packed bed, the receiving container selectively partitions a plurality of rooms and each of the rooms into a gas-tight state. The opening and closing mechanism for And a streaming potential measuring device.