Re: ORGLIST:Regenerating molecular sieve 4A

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From: Jacob Zabicky (zabicky$##$bgumail.bgu.ac.il)
Date: Sun Jul 14 2002 - 09:27:04 EDT


Hello Andrea,

Yours is a very interesting question. It's worth trying a small amount of
the stuff, say 0.5 g, and see how dry does it get (wt. loss), and whether
its morphology changes. A possible scenario is this: Water effectively
absorbs the microwaves. so a very hot local spot may be produced. Say that
happens in a small spot inside the molecular sieve, rising the temperature
to several hundred deg. C, over the critical temperature of water. The
highly compressed gaseous water may break the crystalline structure and the
stuff may literally pop out. But it may be a very placid process too. Just
try it!

All the best,

Jacob

At 1:39 13/07/2002, Andrea Giordano wrote:
>hello all,
>
>this may sound curious, or maybe a nonsense, but anyway...
>
>I suppose many of you had the chance to use molecular sieves (the one with
>blue indicator for istance) to dry/store liquids.
>Well, when I had to regenerate them, I simply used a common oven for
>glassware, 'cause it's the only one we have in the lab.
>Usually temp. is set to 140 C, or something, and we just leave it that way;
>that value seems to be enough for regenerating the sieves, at least I always
>observed the apparence of the blue color of the indicator (after having left
>in the oven for 2/3 days).
>Anyway, it's written that temp. should be higher for regenerating...
>
>Just wondering.....could you use a microwave oven (after having purged the
>sieves with water, of course...) to regenerate them??
>
>thanks!
>A. Giordano
>IMC-CNR
>Rome.
>
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Prof. Jacob Zabicky
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