Electronics > Projects, Designs, and Technical Stuff
Drying IPA with silica gel ? Will this work ?
Ian.M:
Unless you can set up to distil it, there's really no good options. Even if you can distil it, distillation with a good fractionating column will only get you as far as its azeotrope with water, 87.7 % IPA by weight. Refining above that concentration is a multi-step process. One possible approach would be to start by salting out the bulk of the water in the original solution with ordinary salt, then decant and chemically dry the solvent fraction with anhydrous calcium oxide (quicklime) followed by filtering and distillation into a sealed receiving vessel with a drying tube (desiccant) protecting its vent, to remove suspended calcium hydroxide nanoparticles.
However distilling 20 litres of IPA would be a significant fire and explosion hazard, and quicklime is extremely caustic and its reaction with water is significantly exothermic so you'd better have good apparatus and PPE and enough organic chemistry experience (or caustics and moonshining experience) to do it reasonably safely.
Mechatrommer:
dont waste your time on this. this is purity phobic. how much purity reduced after couple of opening the cap? -10%? -20% i have several chemical here.. thinner, spirit, ipa acetone chloroform FeCl etc that laying around for months/years. they dont seem to get any diluted a bit, the thinner can still scorch my skin the same when i bought it year ago. same as spirit and ipa etc. my only concern will be getting a good supplier that supplies pure ingredient in the first place. and as a tip, we usually buy chemical in big bottle, keep that a bit far away where its safe, sealed and seldomly opened, prepare one or few small glass bottle and fill the chemical in it for daily use good for few weeks or month of usage, so our purity phobic will be greatly reduced.
--- Quote from: BravoV on July 02, 2019, 05:00:59 am ---I can afford to buy new batch of 30 liters of IPA, its just don't like the idea to dispose that +20 liters, and have been thinking if there is an "easy & cheap" way to improve it's dryness, thats all.
--- End quote ---
right tldr earlier. so dont do that. only buy what you need in couple of years. buy 1 or 2 litre bottle. if you can get 30 litres at cheaper than 1 or 2 litre, then you already make great saving, trying to purify it may cost extra if not a lot of money and time and safety hazard, let the factory do the job. and i will doubt the purity of cheaper 30 litres compared to more decent priced 1 or 2 litre chemicals.
Shock:
I'd sell it, that way it can get repurposed. If you have problems, fill it up 30% distilled water and sell it as 30L of disinfectant/technical grade and offer free local delivery or meet up with them. Just don't sell it out of the house to avoid attracting the drug lab type of undesirables. Problem sol-vented.
helius:
While IPA/water mixtures are superior solvents (they are able to dissolve some salts, which alcohol is not very good at), they are definitely not preferred for cleaning sensitive devices like optics or magnetic tape heads. That is why 99.9% IPA is produced. IPA is hygroscopic, so when sitting in an open container it will both evaporate and pull moisture from the air, becoming a lower percent solution over time.
Silica gel can't be used to remove water from alcohols as it has affinity for both (both are polar molecules).
rikkitikkitavi:
BravoF, if your IPA doesnt leave any residue but slowly evaporating water then it should not be a problem.
High purity , i e low water content IPA is best used for non polar polutants, and follow up by a rinse with demineralised water will clean up your PCBs nicely.
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