Aeration-Oxidation Procedure and Chemical Questions

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MT_Keg

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I am going to dive in and assemble my own A/O apparatus to test SO2; during my research I found conflicting information and am hoping for some clarification on chemicals and methods.
  1. When it comes to the Hydrogen Peroxide Concentration I have read journal articles and instruction guides that conflict with each other. In some instances the procedure calls for 0.3% Hydrogen Peroxide and in other instances 3% hydrogen peroxide. How does the concentration of the H2O2 impact the SO2 absorption or accuracy? What is the appropriate concentration?
  2. When it comes to the NaOH i understand we have to use 0.01N, the local science store sells 0.0100N NaOH in Methanol. Is this what I am looking for? Or should I be looking for the Aqueous Solution?
  3. Various sources indicate that the air flow rate should be 1-2 lpm. Some sources identify "steady stream of bubbles". I understand that if the air flow rate is too low then we may not get all the SO2 out of the test liquid which will cause inaccuracies. If the flow is too fast then there will be insufficient contact time in the H2O2. What is the standard practice here?
Thanks for your help!

MT
 
Last edited:
1) the h2o2 concentration always should be in excess. Standard store peroxide is 3% nominally. It is supposed to react with the SO2 to form H2SO4, aka sulfuric acid, which is not volatile and you can titrate
2) haven't seen 0.01N NaOH come in a methanol solution. Wouldn't think it should make a difference though.
3) the flow rate just needs to be sufficient to volatilize the SO2. There is a time-flowrate window to get it all. The bubbles should be small enough in the peroxide soln to react.

The AO method is more accurate than the ripper method,but it's more of a pain in the rear
 
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