Hi, I have read somewhere that following drying the drying agent should only be removed by gravity filtration and not by vacuum. Can someone confirm if this is really so? What is the explanation?
Hi, I have read somewhere that following drying the drying agent should only be removed by gravity filtration and not by vacuum. Can someone confirm if this is really so? What is the explanation?
Acetone and IPA, 3a molecular sieve is the best choice in my strong opinion. It can dry chemicals down to 10s of ppm over a period of days, is recyclable and doesn't need filtered off. It's cheap and inert. It has it's limitations, anything smaller than water it won't dry
Acetone and IPA, 3a molecular sieve is the best choice in my strong opinion. It can dry chemicals down to 10s of ppm over a period of days, is recyclable and doesn't need filtered off. It's cheap and inert. It has it's limitations, anything smaller than water it won't dry
Given the diameter of water (just below 2A) and acetone (just above 3A) mo
lecules, it seems like 3A molecular sieves should be ideal for acetone drying.
Can someone help me understand why I occasionally see 4A molecular sieves as the recommended drying agent, as in Coetzee & Siao. Inorg Chem 14(2). 1987.
H2O is reported to be 2.6A. The main differeence, as it apoplies to H2O dessication is 4A is A LOT cheaper. 3A and 5A are made from 4A , so tey require an extra step to manufacture. Going beyond that, 4A absorbs ammonia and a few other things that if you anted them removed would make 4 A the better choice. If you are drying ammonia gas, obviously 4a is not the best choice. Acetone is about 6a, depending on temperature and barometric pressuer it could vary by about 1. 4A absorbs carbon dioxide, hydrogen sulfide sulfer dioxide, dihydrogen. So it's useful for desulfanation and decarbonation. 4A is approved for use in food service also.
When you say 3A and 5A are "made from 4A," are you referring to the fact that 4A molecular sieves represent the basic "Class A" type of sieve (containing Na atoms) and that 3A and 5A are variations on that theme (K+ and Ca++ substitutions for Na in Class A aluminosilicate sieves, respectively)
When you say 3A and 5A are "made from 4A," are you referring to the fact that 4A molecular sieves represent the basic "Class A" type of sieve (containing Na atoms) and that 3A and 5A are variations on that theme (K+ and Ca++ substitutions for Na in Class A aluminosilicate sieves, respectively)
That is what I read they do an ion exchan on 4a to swap the sodium (some of it aparently) which is what maked the change. everything I wrote there, I learned just them. I only use 3a personally and I've never tried any other I got those measurememnts from a reputale scholastic source( te size of the molecules
