I have this strange behaviour when performing electrochemical N2 reduction. I often encounter NH4+ dissolved in aqueous, alkaline electrolyte (pH=13). How can this be possible? I did some control experiments as well:
- NH4Cl standard is dissolved in the cathode chamber (75ml) at concentrations between 250-1000ppb
- N2 is bubbled through the chamber at 15ml/min for 4h and bubbled through 3 acid traps (HCl, 0.01M)
- Electrolyte is stirred with magnetic stirring bar
- System is completely sealed
- Samples are taken from the acid traps and cathode chamber over 4h
- NH4+ concentration is measured by ion chromatography
- both acid, electrolyte and feed gas are very pure (+- 10ppb NH4+ background)
After 4h of bubbling I can trap about 50-60% of the NH4+ in the acid, the rest remains in the electrolyte (as NH4+, not NH3). Concentration in the acid traps increases more or less linearly with time.
How can this be possible? Is it because the amount of NH4+ is so low? I would expect like 99.99..% of the NH4+ to be converted to NH3 immediately and be evacuated from the solution.
Please look at the following below attached papers which may help you in your analysis.
Thanks
Isam Eldin Hussein Elgailani Thank you for this quick response! However, I think the articles are all talking about quaternary ammonium salts, not NH4+?
Albrecht Leis Thank you for your answer! Is it then so hard to remove the dissolved NH3 from the solution (eg bubbling N2 through it and stirring)? ps: I like the simulation but I'm not familiar with the syntax, could you give a bit more info on what each line means? Would be great!
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