Chloride to perchlorate without errosion.

Quote: Originally posted by clearly_not_atara

Chloride might actually be reducing PbO2: 4 Cl- + PbO2 >> PbCl2 + 2 ClO- + 2 e-

Quote: Originally posted by mysteriusbhoice

According to prior papers I have read, this is the reaction that causes PbO2 to errode in pH controlled cells and also it seems late stage chlorate cells also somehow have this issue once chloride levels plummet below 30g/l it seems errosion occurs again. Then it stops once chloride levels are at zero or very low then suddenly once chlorate levels get low and the cell is mostly perchlorate the errosion happens again but less severe. There seems to be 3 times when PbO2 can erode in a chloride>perchlorate cell. 1. at the start when saltwater is used as starter instead of bleach/preran with MMO. 2. when chloride levels get low and the cell transitions to making perchlorate. 3. when chlorate levels are low and dangerous levels of ozone are generated at the anode.

Quote: Originally posted by Waffles SS

Quote: Originally posted by mysteriusbhoice   According to prior papers I have read, this is the reaction that causes PbO2 to errode in pH controlled cells and also it seems late stage chlorate cells also somehow have this issue once chloride levels plummet below 30g/l it seems errosion occurs again. Then it stops once chloride levels are at zero or very low then suddenly once chlorate levels get low and the cell is mostly perchlorate the errosion happens again but less severe. There seems to be 3 times when PbO2 can erode in a chloride>perchlorate cell. 1. at the start when saltwater is used as starter instead of bleach/preran with MMO. 2. when chloride levels get low and the cell transitions to making perchlorate. 3. when chlorate levels are low and dangerous levels of ozone are generated at the anode. I have same problem on my PbO2 anode and i am trying to solve it. I think we have to use GSDL anode(PbO2 on graphite). Most of industrial plant use this anode and also it mentioned on articles and patents. It seems PbO2 on Titanium get trouble in this cell. [Edited on 9-12-2022 by Waffles SS]

Quote: Originally posted by mysteriusbhoice

GSLD has severe issues due to CO2 formation at the PbO2-C interface caused by hydroxy radical penetration at 200ma/cm^2 and PbO2 on Ti-ATO substrate is pretty much the best. Just run the cell at O2 evolution to prevent Cl2 mediated errosion.

Quote: Originally posted by Waffles SS

Can you explain more?you mean run cell with NaClO solution at begining? How you run cell at O2 evolution? [Edited on 12-12-2022 by Waffles SS]

Quote: Originally posted by mysteriusbhoice

] When pH is high the cell evolves oxygen instead of chlorine and hypochlorite is oxidized at the anode which is what generates your chlorate just as chlorate oxidizes to perchlorate at the anode. O2 evolution is when the primary product at the anode is oxygen instead of chlorine or other gases. PbO2 gets reduced by Cl2 into PbCl2 releasing O2 and because of this it forms errosion as Pb2+ leaches then gets oxidized forming brown crud. Running bleach instead of salt ensures chlorine evolution is kept at a minimal or lower rate though it still happens.

Quote: Originally posted by Waffles SS

Thanks for your great answer. I just wonder why this problem is not mentioned in the articles and patents? (even not mentioned in www.chlorates.exrockets.com/chlorate.html) Did you tried to get Perchlorate directly from Hypochlorite? [Edited on 16-12-2022 by Waffles SS]