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topic 43283

Electrodes best suited to split water


A discussion started in 2006 but continuing through 2017

2006

Q. I want to split water by electrical means. What electrodes would be best suited. The bath must remain clean at all times. Thank you,

MIKE SANTO
SANTO INDUSTRIES - MADEIRA BEACH, FLORIDA


2006

A. They are not cheap, but I would expect platinum clad titanium anodes to be quite durable.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


2006

A. From my days at school, in the dim and distant past, I have a recollection of electrolysing water using simple graphite electrodes.

Brian Terry
Aerospace - Yeovil, Somerset, UK


2006

A. The best electrodes are made from platinum, but this is expensive, especially if you need large areas, so a common cheaper answer is to use platinised titanium, which is titanium coated in a thin layer of platinum. For real cheapness, use graphite, but this will ultimately disintegrate. Most other metals will either oxidise or dissolve and become progressively more useless.

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


2007

A. The answer depends on what you want to achieve.
For simple experimental purposes, stainless steel is cheap and practical.
If you are considering a serious commercial application you will find that most commercial electrolyzers operate in alkaline conditions (KOH) and use either steel electrodes or nickel plated steel. To be commercially viable requires a low operating voltage i.e., low discharge overpotential. There is a great deal of information in Modern Aspects of electrochemistry No 15 Ed ralph White et al Published by Plenum Press.
Alternatively, you could buy one ready made from Brown Boveri, DeNora, Lurgi, Norsk Hydro, The Electrolyzer Corp., Telydyne etc

geoff smith
Geoff Smith
Hampshire, England


sidebar2 2007 -- appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi,

I am looking into making hydrogen by way of water electrolysis. I have been reading about Platinum electrodes needed to make this happen. If you could point me in the right direction to buy these parts it would be greatly appreciated. I want to start off small, maybe enough to run a generator, and then maybe large enough to run a car. I thought a mesh would give me more area touching the water. Also if you know of any good books or sites with info about this it would be appreciated.

I am an electrician by trade.

Randy Bush
Electrician - New Freedom, Pennsylvania, USA


2007

A. There are many sites on the topic of powering cars from water/hydrogen, Randy. Maybe try putting 'hydrogen from water' into your search engine? But there are as many quack sites as there are useful sites. An easy way you can tell the difference is that the quack sites will claim or imply that a conspiracy by the oil companies, car companies, and government is "preventing you from using this free energy source", whereashe valid sites will explain thermodynamic principles and that to generate hydrogen from water requires you to put more energy in than you will get out from burning the hydrogen.

May I suggest that you consider novel approaches like using solar heat plus a catalyst to convert solar energy directly to the liberation of hydrogen from water. You still can't get more energy out of burning the hydrogen than you collected from the sun, but at least you don't have to eat the transmission losses in electrical lines. Good luck!

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha



Palladium over silver for electrolysis electrodes?

December 2, 2016

Q. We're trying to plate a pair of small metal electrodes that must survive in a salt water environment with an impressed voltage between them. The outside surface needs to remain conductive without developing a non-conductive oxide or layer. We've been testing a copper electrode that has 150 microns of nickel, then 60 microns of gold, and then 20 microns of rhodium. The impressed voltage is less than a volt and is pulsed once every 15 minutes. The plating fails and we're getting corrosion of the copper core after a couple of weeks in seawater. We've been talking about trying silver for the base part and then plating palladium or platinum in order to have materials that are closer together on the electropotential table. Do you have any suggestions for materials or plating?

Alan Kirkpatrick
engineer - South Burlington, Vermont, USA


December 2016

A. Hi Alan. You might put your electrodes in salt water with the current off for a couple of weeks as a test, because I don't think galvanic corrosion is the issue, but rather de-plating caused by the impressed voltage.

If the electrodes don't have to carry heavy current you could try platinum-clad titanium because they won't de-plate under most conditions. If titanium can't carry the current, you would probably have to platinum plate copper electrodes -- but electrodeposition of platinum isn't easy.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


December 5, 2016

A. You might try platinum clad niobium for this application.

Lyle Kirman
Consultant - Cleveland Heights


December 5, 2016

Q. I think of cladding as being heavier than plating? How is the cladding applied?
I like the idea of testing without power applied and I'll give that a try. The power is low and is only used to determine the electrical conductivity of the seawater, but testing without power will eliminate a variable.
We have another requirement that I failed to mention in my initial question. The material must have a fairly high thermal conductivity, and that's why we've used copper and we're looking at silver for the core part. That currently eliminates titanium and stainless from consideration. Niobium (54 W/mK) may work, but a higher Tc would be better.
Thanks for the help.

alan kirkpatrick [returning]
- shelburne, Vermont, usa


December 2016

A. Hi Alan. It doesn't take much voltage to de-plate a metal, so I think the experiment will prove informative.

"Cladding" requires a thick enough covering that it be completely non-porous and pinhole-free even after allowing for some erosion and corrosion. Some types of cladding are done by autoclaving a skin of one material onto another material, and then rolling them down to thinner gauges.

Years ago I was tangentially involved in the installation of an electroplating line at a manufacturer of Dimensionally Stable Anodes, so I know that clad anodes can be manufactured by electroplating. I am not familiar with the chemistry that they employed but obviously couldn't reveal it if I was :-(

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha



April 26, 2019 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi, I am using SS 202 as a pair of electrodes, in an electric steam inhaler application. The electrodes are separated by a couple of millimeters and suspended in water. The passage of electric current creates sparks, and heats up the water. But the material erodes and become brown, and also makes the water in the container dirty brown. I tried 304 and 316 too. But all these grades become brown (looks like corrosion). Which grade of steel should I use for this application?
Thanks in advance.

Kishor Chavan
medtechlife pvt ltd(RD) - Mumbai, Maharashtra, India


April 29, 2019

A. Comment Try carbon electrodes. Just an Idea.

Joe Pelleja
- Bobcageon Ontario Canada


May 18, 2019  silly :-) 

A. Hi Kishor,

Any kind of current induced in water will produce the brown water. It depends on the quality of water and its mineral content.

Ion foot detox uses this fundamental as a neat trick to sell this foot detox thingy.

43283-1

One gets a big thrill watching the water turn brown and assuming that one has been detoxified (Including yours truly).

Sorry I can't suggest any remedy; try selling foot detox as an alternative business product?

Khozem Vahaanwala
Khozem Vahaanwala
Saify Ind
supporting advertiser 
Bengaluru, India
Saify Ind


May 20, 2019

Q. Hi Khozem,
Thank you for your answer. However I am not talking about detox. I am talking about the corrosive effect of the salt water on the steel rods, when current passed through it. It kind of produces sparks and causes corrosion. Even 316 rods, which has higher corrosion resistance, do corrode. This how the water turns brown. I am trying to solve this problem.

Kishor Chavan
- Mumbai, Maharashta, India


May 2019

A. Hi Kishor. I think Khozeem was trying to good-naturedly inform you that the water turning brown is an inherent part of your premise of electrolizing salty water with dissolved minerals in it, especially using iron-based electrodes. When you apply electricity to salty water, iron based positive electrodes (even 316SS) dissolve iron into the water, making rusty water. You might try Joe's suggestion of carbon electrodes; platinum clad titanium electrodes should work too but are very expensive, and probably not affordable for steam inhaler. But even still, Khozeem's warning might apply because, as the water is distilled away, any contaminants in the water become more concentrated and discolor it.

I'm unfamiliar with other areas of the world, but we used steam inhalers in the USA when I was a child more than 60 years ago (and probably before that), so there are dozens of expired patents you can read on the subject at uspto.gov which will offer food for thought. Good luck!

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha

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