crashboy581 - 9-2-2012 at 14:25
Hello,
I am doing a side project trying to create a water purification device. I am ussing a Ru02 coated titanium anode with a ss 304 steel cathode to
produce chlorine and disinfect e.coli in a water bucket.
I have had some problems with my Ru02 layer breaking down and I have only run it at 12 volts for a day. Does anyone know what voltage would be the
best to run these MMO anodes at or any suggestions?
Thanks!
plante1999 - 9-2-2012 at 17:20
3.33V
dann2 - 9-2-2012 at 20:29
Think in terms of Current density on the Anode (current going into the Anode divided by the surface area of the Anode in the water) and STOP rattling
on about the 'best Voltage'.
http://www.oxidizing.110mb.com/chlorate/leaddiox/dsa.html
See the link to a .pdf at the bottom of the link above.
Dann2
crashboy581 - 10-2-2012 at 13:38
I was not able to find where it talked about the ideal current density. I know ultimately what were going for is current density because it is what
faradays law uses. However I put it in terms of voltage because our cells resistance is constant and our amperage will change as the salt is being
used up.
Do you know how to determine the ideal current density?
Thanks for everything guys!
dann2 - 10-2-2012 at 14:00
The links below may be useful. The first you have seen.
http://www.platinummetalsreview.com/article/52/3/177-185/
http://www.springerlink.com/content/g5t5206760461m16/
http://www.sciencedirect.com/science/article/pii/S0167701204...
http://www.springerlink.com/content/f5426667g368t378/
The last three links were taken from the first link btw.
I am not answering you question because I don't know the answer. There is no simple answer to the question. The 'best' current density will depend on
salt concentration, how much hypo you want/need to generate per hour. How much abuse you are going to give the anode (lifetime of device). Temperature
of water. Type of Anode material, etc etc etc.
Having decided the 'best' current density (which will vary as things change) the Voltage needed to get that current denstiy will also change.
The kind (very kind) dudes over in refs. will get you papers if you ask them nicely. (no politics !!!!!!!!!!)
If in doubt make the device bigger ---> lower current density----->> will last longer. But then the expense of making the device goes up. It
will also be less discreet.
Having read your first post saying that you put 12 volts to an Anode! Thats way too much. What current started to flow? What was the surface area of
the Anode?
How much salt was dissolved? Ozone production might be anoter way to go? You would need Platinum though.
Most of these devices in pools etc have both the Cathode and Anode made from MMO so that the current can be reversed every now and then and that
cleanes the Anode/Cathode. Cathodes can bet encrused with all sorts of stuff. This may not apply to you.
MMO does not like Fluoride.
Read this link:
http://www.qixinti.com/enProducts_List.asp?id=8
The warrenty they give is longer, depending on the appliation.
Note too that if potential is mentioned it is usually referenced to a third electrode in the measureing system (not included in the actual device!).
This potenital (for Chlorine evolution or Oxygen evolution has damm all got to do with the potential (voltage) that you must apply accross the
terminals of the device to get the current density (the current flow) that you desire.
Dann2
[Edited on 10-2-2012 by dann2]
Attachment: White_paper[1].pdf (1.6MB)
This file has been downloaded 859 times
crashboy581 - 10-2-2012 at 14:13
hey our working surface area is roughly 3x11 inches it is RuO2 coated titanium. it is submerged in a five gallone bucked with 2 anodes and 3
stainless steel cathodes. It goes cathode-anode-cathode-anode-cathode. We add 5 grams of salt into the 5 gallon bucket.
When we were running it at 12 volts we were getting the following.
Time 5 10 15 20
volts 12 12 12 12
Chlorine (mg/l) 1.13 2.2 5.9 8.6
current 2.41 2.41 2.41 2.41
Thanks.
dann2 - 10-2-2012 at 14:32
You have four anode surfaces which when all added together give a total Anode surface area of 3 X 11 inches = 213 centimeters squared?
I think the Ir02 based Anodes are more suited to low salt invironments but then they are not as good at evolving Chlorine.
Is your salt concentration not too low?
Dann2
crashboy581 - 11-2-2012 at 10:41
Yes but 5 grams is the maximum amount of salt we can give it with the conditions we are working.
crashboy581 - 11-2-2012 at 11:37
I should also note that we are trying to purify the water at the same time as creating the chlorine so the created chlorine will kill e.coli directly
in the bucket it was created.