KCLcoal
Harmless
Posts: 7
Registered: 30-8-2019
Member Is Offline
|
|
Relationship between erosion amount and current waveform in platinum electrode in chlorate production
Various power sources are used for electrolysis with chlorate.
Batteries for charging are used as cheap ones. However, those waveforms often contain pulsations. Is there any adverse effect on the waveform that
deviates from this direct current?
I found such a paper on the relationship between waveforms and erosion in platinum electrodes.
https://www.jstage.jst.go.jp/article/sfj1989/42/8/42_8_788/_...
https://www.jstage.jst.go.jp/article/sfj1989/42/8/42_8_788/_...
The graph has been translated from Japanese to English.
The following is a part of the content of the paper.
--------------------
Juchniewicz reports the corrosion rate of a current waveform on an electrode in 0.1 M saline using a platinum-plated titanium electrode
(platinum-plated thickness: 2.0-2.5 μm. 23)
As shown in Fig. 6, in the experiment with a constant current density of 10 A / dm2, the corrosion rate under a DC constant current was about 10 times
that when a pulse wave was applied, and further in the instantaneous pulse electrolysis. Corrosion of platinum is accelerated up to 10 times.
Similarly, there is a report by Warne et al. 24) Regarding the durability when a platinum titanium electrode is used as an anode for plating of
precious metals and base metals that have been put into practical use.
They report that in the low frequency region, the elution of platinum increases as the ratio of the number of ripples increases, and that the elution
is promoted by repeatedly turning the power on and off.
23) R . Juchniewicz, J. Walaszkowski, W. Bohdanowicz, W.
Sokolski and A. Widuchowski ; Corros. Sci., 26, 55 (1986)
24) M. A. Warne, P.C.S. Hayfield ; Trans. Inst. Met. Finish.,
45, 83 (1967)
---------------------
According to this, the least eroded is full direct current. It increases as the number of pulsations increases and the peak value increases.
The power supply for the PC is a clean direct current, so there should be no problem. However, car chargers and inexpensive regulated DC power
supplies often contain pulsations, so I feel that erosion will increase. What do you guys think?
|
|
|
B(a)P
International Hazard
Posts: 1116
Registered: 29-9-2019
Member Is Offline
Mood: Festive
|
|
Thanks very much for sharing. I have often seen it written that an unsmoothed current will not effect electrode erosion, particularly when referring
to using a MOT as a source of current for a cell. Clearly that is not true. Do you have the full article in English?
|
|
|
fredsci93
Hazard to Self
Posts: 84
Registered: 29-12-2017
Member Is Offline
Mood: No Mood
|
|
PC power supplies provide stable DC only as long as they are under max current, in general this is true of every DC power supply, so a cheap USB power
supply will give stable DC given it is under max current. However if you are concerned about the stability of the DC then you could simply attach a
filter capacitor to the output (this works for MOT's as well) and as long as the capacitor is big enough and the power supply is running under max
current there is no possibility of the current waveform being dogshit (except in very unique circumstances like a broken charger)
[Edited on 27-10-2021 by fredsci93]
|
|
|
yobbo II
National Hazard
Posts: 710
Registered: 28-3-2016
Member Is Offline
Mood: No Mood
|
|
Platinum Metals Rev., 1998, 42, (l), 27-33, available below states that Pt will wear when the ripple in a DC power supply is 50 Hz.
100 or above is OK.
This is available online.
The NaCl conc. in the Japanese artical above is very dilute. .1M solution is about 5.8 grams per litre. Perhaps the effects will not be so bad at the
concentrataions normally met in a chlorate or Perchlorat cell.
IMO you should keep your Pt for Perk. only.
There is some information regarding wear rates of Pt in US Patent No. 3,475,301.
Yob
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
