I was purifying sulfur with xylene and while vacuum filtering it through my glass sintered filter it crystallized and clogged it up. I am having a
very hard time cleaning it and unclogging it now , any suggestions on how to do this?UC235 - 6-5-2017 at 18:01
Hot xylene.macckone - 6-5-2017 at 19:50
toluene is going to dissolve it better than xylene.
pirhana solution will convert it to sulfuric acid.j_sum1 - 6-5-2017 at 19:54
My experience is that sulfur is twice as soluble in xylene compared to toluene. But either will work. Do use it hot though. The solubility decreases
significantly at cooler temperatures.
And I would be inclined to try the solvent before piranha.LD5050 - 6-5-2017 at 20:05
I used piranha solution first only because I was lazy and I was also in a hurry to clean it and didn't want to take the time and heat up xylene. The
piranha solution worked some what but I ended up having to boil up some xylene to get it really clean. I'm VERY anal about getting my vacuum filters
absolutely spotless to the point where they look brand new. Sodium bisulfite works really well for cleaning the glass sinter and making it spotless. macckone - 6-5-2017 at 20:09
Data says carbon disulfide, chlorobenzene, benzene, toluene then xylene.
Not that there is much difference between the last four.
Carbon Disulfide is the way to go but guessing that is
the OP doesn't have that or he would have been using
that instead. Toluene is more readily available.
Also a bad idea to filter hard to dissolve substances with
a fritted filter. Use a paper filter and a regular buchner funnel.j_sum1 - 6-5-2017 at 20:24
Not that there is much difference between the last four.
That data is at 25C. I believe the situation is a bit different at elevated temperatures but I don't have hard data on the solubility curves readily
at hand. Except to say that the solubility greatly increases with temperature. Do get it hot.
And I agree: If you can avoid clogging up your frit in the first place, that is preferable. Filter paper is not to be scoffed at.LD5050 - 6-5-2017 at 20:30
I was using paper filters originally but there was a very fine brown contaminate in the sulfur that was getting through the paper filter that is why I
switched to the glass vacuum filter. JJay - 6-5-2017 at 20:44
I was thinking hot xylene, but I'd consider trying hot mineral oil (~200C). That should be sufficient to melt the sulfur and let a vacuum pump pull it
through the frit.macckone - 7-5-2017 at 07:59
+1 for melting the sulphur using a high boiling point liquid.
Since you are using a frit.
Xylene does get hotter than toluene before boiling and
that may increase the perceived solubility.
