Sciencemadness Discussion Board

Acquisition and use of non-lab molecular sieves for solvent drying

bahamuth - 20-2-2021 at 02:23

I have been for looking for a reasonable source of molecular sieves 3A for solvent drying.
Professional lab grade products are pricey...
So i was forced to look elsewhere and I have found several high quality products but they are not specifically made for solvent drying, as their primary use is for insulated glass manufacture.

So my question is, have anyone tried using such products for drying solvents?

Brands found are Glasmol, Fenzi and such.

I ask because i had a mishap with using ebay sieves that turned into friggin clay in my solvent (ethanol).

Panache - 20-2-2021 at 03:16

I cannot speak or vouch for those products......

However i can vouch for the


Available at all good refrigeration supply outlets world wide.
You will need a hammer.

Sulaiman - 20-2-2021 at 03:33

I bought cheap '3A' molecular sieves via eBay
for drying ethanol,
first use I got a lot of dust suspended in my ethanol
AND the sieves absorbed quite a lot of my ethanol.

After washing and drying and using the filtered dusty ethanol/water
there was very little 'dust' but they still absorbed quie a lot of ethanol,
and the final product was about 98.8% ABV
So overall not very good.

I believe thst the '3A' sieves that I received are 3A to 4A, maybe more,
they are probably what you would get if you ordered sieves for windows as 4A still absorb water.

If (like most of us) you are financially constrained,
you could investigate dry rice, wheat bran etc.
I have read that there are quite a few options for drying ethanol but I've not tried alternatives yet so I can't help much.

Fyndium - 20-2-2021 at 03:43

Apparently MgSO4 will make EtOH quite dry and final drying can be done with CaO.

bahamuth - 20-2-2021 at 10:02

I know there are many ways of drying EtOH but this thread is about molecular sieves, specifically ones that are not lab grade.

The reason I mentioned EtOH was that it was the first of many solvents I wanted to purify and dry.

I have liters of dirty/wet solvents that I plan to distill and dry, conveniently.

And to have something I can reuse for drying many many times is worth a lot to me.

The cost for molecular sieves that are for insulated window use, is about 25x cheaper than lab grade stuff.

Fyndium - 20-2-2021 at 10:55

Absolutely, just wanted to note that single use MgSO4 and CaO can be very cheap, from 0.5€/kg so reusing is much more costly than discarding, because it's not for dedicated mass production use. Trans-contamination between different solvents and explosion hazard of evaporating vapor residues are to be concerned.

Non-lab grade sieves also bring costs from trial and error and degradation, etc so relative costs can quickly justify using lab grade instead of cheap-off grade.

[Edited on 20-2-2021 by Fyndium]

Fyndium - 6-4-2021 at 04:15

MgSO4 mixed with CaSO4 about 10% w/w stirred overnight did not produce difference in azeotropic ethanol after distillation. Either something I did wrong, or it does not work.

NurdRage clearly demonstrates that cheap sieves absorb none to some of the water, but also other molecules, because they are not exactly 3A.

Do the lab grade sieves warrant the high price? The off-brand 3A cost between 15-40e/kg, and the lab grade seems to go around 150e/kg.

WGTR - 6-4-2021 at 06:47

I realize that none of you are in the United States. Have you considered a place like Delta Adsorbents? I have purchased from them before. Bulk prices are very reasonable. I purchased 10 lbs from them and sold off about 5 lbs to someone else here. This split the cost between us for a far cheaper price that one could achieve by buying 5 lbs directly, about $30 each plus shipping costs. I have plenty of my own now, but if you can find one or two other people nearby who would like to split a purchase then this can be very economical.

paulll - 6-4-2021 at 09:30

Have you considered a place like Delta Adsorbents?

25USD for 1lb of 3A ... but 50USD shipping. Oof. Plus the shipping's UPS so probably another 100USD in, "brokerage fees," and then the frustration of paying all that money for the item to disappear into oblivion.
Nice thought while it lasted lol