Dear Syed Shabbar Hassan Shah ,

Opposit problem - removing oxygen is purging by Ar for 20-30 min. Flow is "not much boiling". Water surface is mostly calm. Get rid of oxygen is much more difficult than saturating by oxygen. Thus, I think saturating is about 5 min - 10 min.

ThankYou Roman Fiala .

Syed Shabbar,

Looks like you want to anodize Titanium surface while having saturated oxygen environment in the bath. If this is so then you asked about "optimum purging rate". So first of all be cleared that there is no such thing 'optimum purging rate' for such a system. Its not like a solid based material you are going to dissolve to get utmost saturation. Remember, water already has dissolved oxygen in it and If you will purge further, it will keep only a fraction of it and the rest it will evaporate back to the atmosphere under open system. Also once you will start applying the potential, oxygen reduction mechanism will also get faster and hence concentration of O2 will continuously keep decreasing in the system. So if you really want saturated O2 environment (as per your requirement) then my recommendations based on experience are;

1-Purge O2 for initial 10 minutes (boiling state) if you have air-locked system. PDP experiment duration depends on the scan scan rate mainly. If scan rate is low then it will take about 30 minutes. So, purge oxygen again after 15 minutes for 2-3 minutes durin experiment.

2-If you have entirely open system (no air-locked) then, after purging of initial 10 minutes at boiling state, keep purging the air continuously at a very low rate (such a way that you could see only few bubbles coming out).

Good Luck!!