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Author: Subject: Formaldehyde Solution, Analysis / Purification
meohmix
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[*] posted on 5-1-2018 at 18:50
Formaldehyde Solution, Analysis / Purification


Hi all,

Having performed a catalytic oxidation of methanol vapor with air over copper, I now have a solution of formaldehyde in methanol and water with the possibility of some formic acid due to possible over oxidation.

To estimate the formaldehyde concentration of the solution produced I performed a variation of the Sodium Sulfite Method described in the 3rd ed. of Walker's text (See my post for a pdf of the given method from his text):

http://www.sciencemadness.org/talk/viewthread.php?tid=65275#...

The variation:

The ph of a known concentration of Na2SO3 was determined and a known mass of formaldehyde solution was added (raising the pH). The solution was titrated with a known concentration of H2SO4 back down to the original Na2SO3 pH. The volume of acid needed to neutralize the NaOH formed via the reaction of formaldehyde with Na2SO3 approximate the concentration of formaldehyde.

My titrations / calculations suggest that I have a solution of formaldehyde in the neighborhood of 33-36%.

(First off, if my variation on the Na2SO3 method is flawed then please, lets start with that).

Be it by chemical or physical means, my ultimate goal is a generic formalin solution (37% formaldehyde with a % of methanol, free from any possible formic acid). A solution with high methanol content is acceptable, production via paraformaldehyde is an acceptable route.

It's been a long time since chem class.

Members suggestions and thoughts are very much appreciated.

Meomix








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nux vomica
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[*] posted on 5-1-2018 at 22:08


You tube is your friend.
https://youtu.be/NqNZ3W5Hki8




My YouTube channel Nux's channel
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[*] posted on 6-1-2018 at 08:44


YT might be your friend, but I'm not sure I'd trust a video from someone who can't tell sulphide from sulphite.


If you have a solution that titrates as about 35% then you are pretty near your goal.
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