SU1469431A1 - Device for controlling potential of electrode in electrochemical studies - Google Patents

Abstract

The invention relates to devices for electrochemical research and can be used in the chemical, metallurgical and other industries. The aim of the invention is to increase the accuracy and reproducibility of the results. This is achieved by automatically leveling the potential at the contacts of the switch key, and the stationary potential of the working electrode is established with high accuracy using a special block of analog memory. The polarization current pulse in the device at the moment of switching on is absent, and this leads to an improvement in the metrological characteristics. The beneficial effect is achieved by introducing into the device an amplifier with a two-wire input, a second switch and an analog memory block connected to the current source of the device and algebraic: a CMM adder. 2 ill., 1 tab. JWrai

Description

one

The invention relates to devices for electrochemical and corrosive research and can be used in the chemical, metallurgical and other industries.

The purpose of the invention is to increase the accuracy and reproducibility of the results.

FIG. 1 shows a block diagram of a device for adjusting the potential of an electrode during electrochemical studies; in fig. 2 - oscillogram of the transient process of the electrochemical cell current.

 The device (Fig. 1) contains a controlled source of polarization current 1, a switch 2 on the device, a three-electrode potentiometric cell 3 with a working electrode 4, an auxiliary electrode 5 and a comparison electrode 6, an algebraic adder 7, a setting unit 8 nalr1g, a booster 9 the second key is 10 with odIi and movable and two fixed contacts and the block 11 of analog memory. The output of the controlled source 1 through the switch-on key 2 of the device is connected to the auxiliary electrode 5 of the potentiometric cell 3. The working electrode 4 of the cell is connected to the common

,

m

bus device. Electrode 6 Comparison cells 3 is connected to the first

(non-inverting) input of the algebraic adder 7, the second (inverting) input of which is connected to

Sensor 8, voltage The third (noninverting T input of the algebraic adder 7 is connected to the movable contact unit P

key volume 10, a --- Р ™ «/ -«, Ha:; Ggova n m ™. where it installs not inverting through the block and the acaloy „„ „„ ,,, i1, ty

memory with electrode 6 compare cell 3o Output, algebraic adder 7 is connected to inverting

the potential of the working electrode 4 to the switching-on momentum with the opposite polarity sign (this way the electrode is grounded not the electrode, the comparison, but the working electrode).

Since the closure of the switch-on key 2 is carried out at equal potentials at both its contacts, and for a fault Jt $ U ".l 1JCA у - J

with a high accuracy of the stationary potential of the working electrode, the polarization current pulse at the time of the submatter 7 is connected to the inverter “.” “- :;„ ;;; there is no cell, in the rover of the controlled source 1. ASI-, 5k.- - h follow them

2 tjf jL- i J r

The lathgel 9 is made according to the scheme with two-wire symmetric switching on, its input being connected in parallel to the key 2, and the output to the first fixed contact of the key 10, the second non-.20 movable contact of which is connected to the common bus of the device. ...

The device works as follows

As a result, the accuracy of subsequent electrochemical measurements and the reproducibility of the polarization conditions

increase.

Example. The transient characteristics of switching on the unit in the mode of maintaining a stationary potential are measured experimentally. the first electrode — the length of the proposed device W —y — I-I-ohm. „- from the device and the prototype device. In the Cell Disable mode, vpsod-25 ,,, three-electrode

thirty

35

40

JJ J.% v / lV t "k 4mf

The nominal setpoint voltage 8 is set to zero. Key 2 is open. The movable contact of the switch 10 is connected to a fixed contact connected to the output of the amplifier 9. At the same time, the amplifier 9 is connected to the negative feedback circuit of the controlled source 1 of the polarization current, since the output voltage of the setpoint 8 is zero, and If the algebraic adder 7 has an input and the same potential (grounded working electrode 4) arrives at its inverting input, then the algebraic adder 7 works as a repeater of the output voltage of the 9 uspiter. In this case, a potential equal to a stationary potential is established at the output of the controlled source of polarization current 1. auxiliary electrode 5. When cell 3 is connected, the switch-on switch 2 key closes and pin 10 of this relay switches to zero potential. As a result, this controlled polarization current source 1 turns out to be closed by negative feedback through the reference electrode 6 and the algebraic adder 7, and the output device of the unit P serves in this mode as an output voltage. analog memory, where it establishes a .g voltage equal to a stationary

 ADt "

YOU were carried out in an open three-electrode glass cell without separation of the electrode spaces; reference electrode - silver chloride (saturated); auxiliary electrode - platinum; working solution - 0.1 n. HC1, 20 Co The transient characteristics of switching on the cell were studied according to the dependence of the polarization current over time.

(Fig. 2).

The table shows the measurement results for iron (S 0.39 cm and copper (S 1.00 cm) electrodes (the magnitudes of the stationary potentials of the working electrode are recalculated relative to the hydrogen electrode; -C- transient process duration; current amplitude through the cell; electrode potential. comparison).

Claims (1)

 The table shows that the time of the transient process and the amplitude value of the polarization current are significantly (almost in order of magnitude). The invention The device for adjusting the potential of the electrode in electrochemical studies, contains a controlled current source of polarization key, a three-electrode potentiometric cell, voltage generator and algebraic adder, the output of which is connected to the inverting input of the polarization current source, you50 55   is block P the potential of the working electrode 4 to the switching-on momentum with the opposite polarity sign (this way the electrode is grounded not the electrode, the comparison, but the working electrode). Since the closure of the switch-on key 2 is carried out at equal potentials at both its contacts, and in the socket:; Ггов п м ™. where it installs “„ „„ „,,, и1, тй a JAL $ U ".Ol 1JCA y - J c with a high accuracy of the stationary potential of the working electrode, then the current pulse of polarization at the moment under:; ";;; no cell is missing, in re:;" ;;; there is no cell, in the rivers. As a result, the accuracy of subsequent electrochemical measurements and the reproducibility of the polarization conditions increase. Example. The transient characteristics of switching on the unit in the mode of maintaining the stationary potential of the working electrode — for the proposed device — W — g — I-I- and the prototype device were measured experimentally. Opypomstva and device prototype. Experimental ° «™ ,, three-electrode 0 five 0  ADt " YOU were carried out in an open three-electrode glass cell without separation of the electrode spaces; reference electrode - silver chloride (saturated); auxiliary electrode - platinum; working solution - 0.1 n. HC1, 20 Co The transient characteristics of switching on the cell were studied according to the dependence of the polarization current over time. (Fig. 2). The table shows the measurement results for the iron (S 0.39 cm / and copper (S 1.00 cm) electrodes (the magnitudes of the stationary potentials of the working electrode are recalculated relative to the hydrogen electrode; -C- transient process duration; current amplitude through the cell; Ert - initial potential of the electrode. Comparison).  The table shows that the time of the transient process and the amplitude value of the polarization current are significantly (almost in order of magnitude). Claims An electrode potential adjustment device for electrochemical studies, comprising a controlled current source of polarization, a key, a three-electrode potentiometric cell, a voltage generator and an algebraic adder, the output of which is connected to the inverting current source input field settings, you 55 the stroke of which is connected via a switch to the auxiliary electrode of the three-electrode cell, the working electrode of which is connected to the common bus of the device, and the comparative electrode to the first input of the algebraic adder, to the second input of which is connected a voltage generator, in order to increase the accuracy and reproducibility of the results, an amplifier with a two-wire input is inserted into it, a second key with two fixed points one and one movable contacts and an analog memory unit, the two-wire input of the amplifier is connected in parallel to the first key, and the amplifier output is connected to the first fixed contact of the second key, the second fixed contact of which is connected to the total thickness of the device, and the moving contact to the third input of the algebraic adder, the fourth input of which An analog memory unit is connected to the comparison electrode of a three-electrode cell. Characteristics of the transition, the process of switching the working electrode into potentiostating mode. its stationary potential Thebes / G, AglgH  ffK Hf "ffwiff ush epeneuft9 SffjFy9, g