Research Reports of Nagaoka National College of Technology, Vol.48, 2012

Paper

Relation between Streaming Potential and Streaming
Electrification Generated by Streaming of Water
through a Sandwich-type Cell
Kazunori MARUYAMA1, Mitsuru NIKAIDO2, Yoshinori HARA3 and Yoshie
TANIZAKI3

1Department of Mechanical Engineering, Nagaoka National College of Technology
2Department of Chemical Engineering, Ichinoseki National College of Technology
3Department of Chemistry, Nagaoka University of Technology

Both streaming potential and accumulated charge of water flowed out were measured simultaneously
using a sandwich-type cell. The voltages generated in divided sections along flow direction satisfied
additivity. The sign of streaming potential agreed with that of streaming electrification. The relation
between streaming potential and streaming electrification was explained from a viewpoint of electrical

double layer in glass-water interface.
Key Words: streaming potential, streaming electrification, electrical double layer

1. Introduction

water flowed out were measured simultaneously.

The generation of both streaming potential andstreaming electrification has been said to beoriginated from the friction between mobile liquidand solid wall1), 2). However, they have been often
argued independently. Streaming potential of liquid
has been investigated in relation to ȗ potential ofelectrical double layer on solid surface in scientificfield3). On the other hand, streaming electrification
has been recognized in a practical field such as
maintenance of pipeline of oils to avoid explosion bysome spark. Electrospray ionization in an electricfield draws recently much attention in theapplication to mass spectroscopy4). However, there
has been few report on the quantitative analysis ofstreaming electrification without an electric field.
Under an expectation to find some relation between
streaming potential and streaming electrification,
both streaming potential and accumulated charge of

2. Experimental
2. 1 Apparatus
The schematic apparatus used in this experimentis shown in Fig. 1. A sandwich-type cell for themeasurement of streaming potential was built up
using parallel two plates of quartz glass (opticalglass grinding grade, 13×29×6 mm3). The space
between two plates was about 2 ȝm. Both sides of
the cell were fixed by epoxy resin and the cell washeld between copper holders to avoid the distortionof the plates. The cell was also held between inlet
adapter and outlet adapter made by acryl resin. Four
platinum wires were placed as electrodes withinterval of 1 cm. Two of them were placed at theinlet and outlet adapters, other two Pt wires wereinserted through two holes bored through the quarts― 19 ―

Kazunori MARUYAMA, Mitsuru NIKAIDO, Yoshinori HARA and Yoshie TANIZAKI

glass. Super pure water (1.7±0.6×10-6 S cm-1 ofelectric resistivity, pH=5.7±0.3) stored in a waterbox made by quartz glass was forced to flow throughteflon tube, the sandwich-type cell, and then teflon
tube under a pressure of 10 kg cm-2 nitrogen gas. The
charge of droplet water flowed out from the outlet
teflon tube was collected in a Faraday-cage, which
was connected with an electrometer. They are
insulated from other equipment electrically. All ofabove equipment was set in an electrically shieldedbox maintained at 30r0.3 ͠. Streaming potential
was measured using an electrometer TAKEDA
RIKEN TR-8000, in which the negative terminal
was connected to Pt wire placed nearer to the inlet
adapter than another Pt wire.
2. 2 Method of measurements
Step 1: The charge of water stored in the quarts(a)water box before streaming experiment wasestimated by the charge of droplet water flowed out
from bi-path teflon tube without an additionalpressure. The droplet water was collected in theFaraday-cage and the accumulated charge wasfollowed by the electrometer. This charge wasestimated to be background.
Step 2: The water in the water box was forced toflow into the sandwich-type cell under a pressure of
10 kg cm-2. The streaming potential generated wasrecorded and the droplet water flowed out from theend of the teflon tube was collected in theFaraday-cage and their accumulated charge wasrecorded.
Step 3: After finishing the measurement of thestreaming potential, the charge of water remained in
the source water box was estimated by droplet water
flowed out through bi-path teflon tube without anadditional pressure. The droplet water was collectedin the Faraday-cage and their charge was followedby the electrometer.

3. Results and Discussion

(b)Figure 2 shows the variation of streaming
potential (Vs) generated between Pt wires A and B
(denoted as Vs(A-B)), B and C (Vs(B-C)), C and D(Vs(C-D)), and A and D (Vs(A-D)) as a function of time,
where the negative terminal of the electrometer wasconnected to each Pt wire placed near to the inletadapter. As soon as water flows,Vs suddenly jumps

8.0
6.0
Vs / volt

4.0
2.0
0.0

-2.0
-4.0
-6.0

020

40

60

80

100120t / minFig. 2 Streaming potential Vs as a function of flow time:٨Vs(A-D), ً Vs(C-D), ٤ Vs(B-C), ٖ Vs(A-B).
Cell material: quartz glass.

Fig. 1 Experimental apparatus: (a) sandwich-type cell,(b) assembly.

― 20 ―

Relation between Streaming Potential and Streaming Electrification Generated by Streaming of Water
through a Sandwich-type Cell

― 21 ―

10Vs / volt

to some positive voltage, and quickly falls down tonegative voltage and then it increases gradually.
The liquid layer attached to solid surface exists as
two parts called electrical double layer as shown inFig. 31), 2). An inner region is called the Stern layer,
where the ions are strongly bound to solid surface. Inan outer diffuse region, the ions are less firmlyattached. Within the diffuse layer there is a notionalboundary inside which the ions and particles form astable entity. When fluid moves, ions contained in
the boundary region do not move with it, but any
ions beyond the boundary move with water. Thisboundary is called slipping plane shown in Fig. 3.
Using glass capillary cell, protonic conductivity isreported to be the predominant of surface charge5).
This means that the Stern layer attached to glass
surface is covered with positive charge.
In the case of an electronic circuit, a decrease involtage is owing to the collision of electrons withlattice structure and they lose energy. The directionof electric current in electronic circuit is from higher
potential to lower potential. In this circuit, if anegative terminal of voltmeter is connected to higher
potential, voltge is observed to be negative. In thecase of streaming potential at this experiment, flowions do not lose their energy. They are merely
carried by the flow of water. Then the potential ofions in the flow does not decrease. On the basis of
this consideration, if negative ions flow with water,
negative charge will increase at outlet position, andcounter positive charge will be accumulated at theopposite side that is inlet position. Therefore the(a)50
1.0

Q / nC

Fig. 3 Interface structure.

electrometer indicates the generation of negative
voltage contrary to the case of electronic circuit.
Initial jumping to positive voltage in Fig. 2 may
be induced by sudden stream of water. The place ofslipping plane exists in the electrical double layer asshown in Fig. 3. Then negative ions travel with flowof water to give the generation of negative voltage.
Subsequently, all inner ions in the electrical double
layer are involved by the flow of mobile phase littleby little. At the same time, the positively charged
interface retaine the negative ions in the fresh water
flowed into the cell from the inlet adapter to givethem delay. This function is the same as thatappeared in a liquidcolumn chromatography. Thenthe voltage generated gradually increase and change
to positive and finally it shows some constantpositive voltage at the stationary state.
The longer the standing time before measurement,
the less the initial decrement in voltage. This implies
that some time is needed to construct stable andstationary double layer. The each distance ofadjacent Pt wires is 1 cm, however, the streaming
potentials of them are not same; Vs(C-D) > Vs(B-C) >Vs(A-B). The concentration of ions contained in fluid
water near to the slipping plane are accumulated andincreased according as water travels. Then thevoltage generated near to the outlet adapter, Vs(C-D),
is highest among above three potentials. In addition,
the potential Vs(A-D) is the same as the sum of Vs(A-B),
Vs(B-C), Vs(C-D), i.e. additivity is satisfied.
If positive charge moved with the flow of water,
the droplet water from the outlet is expected to be
charged positive. Figure 4 shows both streaming

(b)

0.5
0.0-0.5050

100150t / minFig. 4 Streaming potential (a) and charge accumulated in
Faraday-cage (b) as a function of flow time.
Cell material: quartz glass.

Kazunori MARUYAMA, Mitsuru NIKAIDO, Yoshinori HARA and Yoshie TANIZAKI

potential and collected charge accumulated in theFaraday-cage. Before application of the pressure, thedroplets slightly charged to be positive (2.5pC/cm3).
After applying the pressure to make water flow
through the cell, streaming potential shows positive
value and droplets are charged to be positive asexpected. In this case, the structure of electrical
double layer is not built up enough to show negativevoltage. After stopping the flow through the cell,
droplet water traveled through bi-path are charged tobe negative (-4.8 pC/cm3). This means that thenegative charge is accumulated in the source waterbox according as water travels through thesandwich-type cell.
Figure 5 shows the results using another cell,which was built up using borosilicate glass(Na2O-B2O3-SiO2). Before application of thepressure, the droplets slightly charged to be positive(2.3pC/cm3). After applying the pressure to makewater flow through the cell, streaming potential
shows negative voltage and droplets are charged tobe negative as expected. In this case, the structure ofelectrical double layer may be different from that ofquarts glass and, in addition, it was left for longer
time before the experiment. The long time standingis favorable condition to construct a stable electrical
double layer. After stopping the streaming of water
through the cell, water droplets through bi-pathshow relatively large positive charge (12.5 pC/cm3)
as expected. The charge collected in the
Faraday-cage decreases and then shows slightVs / volt



(a)


Q / nC

1.0(b)

0.0-1.0050

100

150200250300t / minFig. 5 Streaming potential (a) and charge accumulated inFaraday-cage (b) as a function of flow time.
Cell material: borosilicate glass.

increase according as negative streaming potential
turn to positive.
In order to estimate the charge of the cell after
streaming of water, another small glass cell wasconstructedusingborosilicate
glass(Na2O-B2O3-SiO2) and placed in the Faraday-cage.
Water was flowed through above small cell and thecharge of it was followed. The cell became slightly
charged to be positive gradually. But the charge was+0.1-0.2 pC after 60 min water streaming. It is low
enough to be trivial to take into considerationcompared with about -0.6 nC shown in Fig. 5.

4. Conclusions
Flow of pure water through the sandwich-type cell
gives rise to generation of both streaming potential
and streaming electrification. The voltages
generated in divided sections in the sandwich-type
cell satisfied additivity. The sign of streaming
potential agreed with that of streaming
electrification. The relation of streaming potential
and streaming electrification can be explained froma viewpoint of electrical double layer in glass-waterinterface.
References
1) Sparnaay, M.J.: The Electrical Double Layer, Pergamon,
Oxford, 1972.
2) Bockris, J.O’M., Conway, B.E. and Yeager, E. (Eds.) :Comprehensive Treatises of Electrochemistry, Vol.1, The
Double Layer, Plenum, New York, 1980.
3) Ball, B. and Fuerstenau, D.W.: A review of the measurementof streaming potentials, Minerals Science and Engineering,Vol. 5, pp. 267-277, 1973.
4) Collins, G., Federici J., Imura Y. and Catalani, L.H.: Charge
generation, charge transport, and residual charge in theelectrospinning of polymers: A review of issues andcomplications, Journal of Applied Physics, Vol. 111, pp.
04470-1 – 04470-17, 2012.
5) Jednaþak-Bišüan, J., Mikac-Dadiü V., and Pravdiü, V. andHaller, W.: Surface conductivity of glass at the solid/liquidinterface, Journal of Colloid and Interface Science, Vol. 70,
pp. 18-28, 1979.
(Received October 3, 2012)― 22 ―