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Author: Subject: Can you only dry 3A Molecular Sieves in the Microwave? (OTC)
LuckyWinner
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[*] posted on 5-9-2020 at 06:39
Can you only dry 3A Molecular Sieves in the Microwave? (OTC)


Ive been trying to find a clear answer but could not.

quote from article:
https://chemtips.wordpress.com/2014/12/01/how-to-activate-mo...

'Unfortunately, sieves are shipped saturated with water and must be dried before use. Sieves actually absorb water at 120 degC, so a conventional drying oven is not up to the task.

Conventional wisdom is that heating to 300 degC or greater at atmospheric pressure will dry sieves, and this temperature can be reduced somewhat under vacuum [3]. Experimentally I had some success heating to ~200 degC overnight in a vacuum oven, but was never quite sure that the sieves were fully active [4].'




this means your mol sieves can not be dried in a cheap pizza oven from the supermarket that goes up to 220C max?

or is this article false.

all videos usually recommend to nuke your 3A mol sieves in a microwave for 3x5 min with frequent vents to avoid superheated water exploding your microwave.

then immediately put in vacuum desiccator till its at room temperture and seal airtight after.


no way to dry it in a regular pizza 220C oven?
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monolithic
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[*] posted on 5-9-2020 at 07:13


Yes, you can dry in a conventional oven -- this is how I always do it. Spread sieves in a thin layer on a baking sheet, heat at 200 - 250 C for several hours while mixing the sieves around every now and then. Obviously don't put sieves in an oven if they smell like solvent or you could have an explosion. I rinse them several times with tap water and let them air dry, until they no longer smell like solvent, before placing them in an oven.

You test if the sieves are activated by placing a few in your palm and then dropping 1-2 drops of water on them. You should feel them heat up quickly, almost painfully hot.

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RogueRose
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[*] posted on 5-9-2020 at 14:22


Be careful when heating things in the microwave when there isn't something like food/water in it. I think there needs to be a place for the energy to go and some materials do not absorb microwaves very well, IDK if the sieves do or not. I destroyed a magnatron and transformer when a glass beaker of water boiled away and then when there was no more water, the whole thing ended up cooking itself.
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karlos³
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[*] posted on 5-9-2020 at 15:20


You can always put a beaker(or plain drinking glass) filled with water in one of the edges, not on the rotating plate, this will absorb excessive heat.
Even better, two of them.
This is some key knowledge how to avoid your microwave exploding from solvent vapours and in consequence banging the door into your watching face with force :D

I wish I had done this when I heated that cherry stone pillow for my back in it that one time... for too long... but in my food microwave, keep that in mind!!!
Not the good ol chemistry microwave, which always has some chemical odour.
Now I can't get the smell of burnt cherry stones out of it :(
Pfui!
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stoichiometric_steve
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[*] posted on 15-9-2020 at 13:16


Quote: Originally posted by karlos³  
Y
Now I can't get the smell of burnt cherry stones out of it :(
Pfui!


As with many things, getting stuff a little bit wet before the action is the key to an enjoyable outcome :D

Seriously, wet the cherry pits from time to time. That's what carries the heat after all!
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Syn the Sizer
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[*] posted on 15-9-2020 at 14:05


Quote: Originally posted by RogueRose  
Be careful when heating things in the microwave when there isn't something like food/water in it. I think there needs to be a place for the energy to go and some materials do not absorb microwaves very well, IDK if the sieves do or not. I destroyed a magnatron and transformer when a glass beaker of water boiled away and then when there was no more water, the whole thing ended up cooking itself.


I believe the sieves will take the heat protecting the microwave. Clay is a poor insulator even if it is filled with air pockets so it should have no issues taking the in the energy, though that is a very good thing to point out.

Ultimately I would just use an oven, get a cheap toaster oven and use it as your lab oven, also that way if a person is careless one day and blows up their oven, it was a cheap counter top toaster lol.

I just think microwaves don't heat even enough and don't maintain a set temperature like an oven.
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