TheBlindGenius (Hive Bee)
07-25-02 00:41
No 336706
      Ways of filtering precipitates  Bookmark   

swim was looking through a catalog at his cousin's university library and came upon funnels that instead of pinholes have sintered glass at the bottom.  they have buchner, gooch, and hirsh that have this type of filters, and offer different porosities all the way down to like 3 microns.  swim was thinking that maybe these are better than regular cheap ceramic buchner funnels because product is not caught on filter paper and you don't have to change the filter paper.  swim likes the gooch one cuz it looks easy to clean since there is no long stem.  any thoughts?
(Chief Bee)
07-25-02 02:43
No 336734
      They are great, as long as something insoluble ...  Bookmark   

They are great, as long as something insoluble doesn't get stuck into the sintered glass, like precipitated noble metals and/or activated carbon. After that they look ugly.
(Old P2P Cook)
07-25-02 04:38
No 336782
      Fritted glass funnels.  Bookmark   

came upon funnels that instead of pinholes have sintered glass at the bottom.  they have buchner, gooch, and hirsh that have this type of filters, and offer different porosities all the way down to like 3 microns.
If they are Hirsch funnels or Gooch crucibles then they do not have fritted glass filter plates.

A Hirsch funnel is a variant of the Buchner funnel, the only difference between a Hirsch and a Buchner is that the Hirsch funnel has sloping sides and a smaller plate area than a Buchner.

A Gooch crucible again, like the Buchner and Hirsch funnels, has small holes in a ceramic disk. To use a Gooch crucible you put down a layer of asbestos fibers to act as the filter medium.

  swim was thinking that maybe these are better than regular cheap ceramic buchner funnels because product is not caught on filter paper and you don't have to change the filter paper.
It is much easier to get product out of a Buchner funnel than a fritted glass funnel. With a Buchner funnel you run a thin stainless steel spatula around the inside periphery of the funnel to loosen the product from the walls, turn the funnel upside down over the polyethylene sheet on your bench and tap the funnel on the bench; the cylinder of product and the filter paper will drop out of the Buchner onto the poly sheet. The ceramic (or plastic) Buchner is much stronger than the glass fritted funnel and can be rapped against the (polyethylene sheet on the) bench like this where the glass funnel would likely break.
07-25-02 20:45
No 336999
      easy to ruin  Bookmark   

I had one of these and once tried to filter some vegetable matter through it. Some of the fine particles of insoluble matter went into the sinter and turned it brown.

I will not use one again unless there is a good reason.
(Chief Bee)
07-25-02 20:54
No 337005
      Cleaning fritted glass funnels?  Bookmark   

How do you clean such fritted glass? Chromic acid might oxidize all organics to CO2, but what about inorganics? I know I have a #3 filter that is heavily contaminated with Pd/C.
(Hive Addict)
07-25-02 21:34
No 337030
      Fritted Glass / Pd/C  Bookmark   

Some info in this thread on cleaning fritted, sintered glass and glassware in general. Swim has ruined some nice glass funnels, hopelessly stopped up. Thinks he will leave them to the professionals, from now on and stay with ceramic.

 Post 50449 (mds: "Fixing Broken Glassware?", Newbee Forum)

 A centrifuge is the best way to recover Pd/C and is usefull for other things. Once someone tries it, they will never try to filter Pd/C again.
 Universities, hospitals, etc send them to surplus, when they get old and dirty. Should be availible to anyone who looks, from small to large sizes and cheap too !!
Try it, You'll like it :-)

 Post 177671 (GED: "Easy Catalyst Recovery", Chemistry Discourse)
(Hive Bee)
07-26-02 01:32
No 337105
      application  Bookmark   

swim was thinking more for using these type of funnels to filter mda.hcl, mdma.hcl, 2,5 dimethoxynitrostyrene, 2ch.hcl, or 2cb.hcl, not for pd/c, etc.  would pdcl2 and cucl2 be filterable through these type of funnels?  dissolved pdcl2 seems to stain swims regular buchner on the inside of the stem.  pain in the ass to remove.

swim knows there are regular gooch and hirsch funnels, but they do make them with sintered glass, check any chem equipment supplier.
(Stoni's sexual toy)
07-26-02 11:10
No 337339
      We used to clean them by mixing THF and red ...  Bookmark   

We used to clean them by mixing THF and red fuming HNO3 and sucking that mixture slowly through as soon as the violent exothermic reaction took off. Strong H2O2/H2SO4 works wonders on organic contaminates too.
But if that thing failed to clean immediately and remained blocked due to inorganic precipitates or really ugly tar contamination then they were discarded without a second thought, these things aren't that expensive and they are considered expendable items in professional surroundings anyway.

I'm not fat just horizontally disproportionate.
(Distinctive Doe)
08-10-02 18:05
No 344050
      Piranha Solution  Bookmark   

Here is why, as Os said, you just discard those fritted funnels.  H2O2 and H2SO4 is EXTREMELY DANGEROUS!!! crazycrazycrazy

From: (Professor Robert Toreki)
Newsgroups: sci.chem
Subject: Re: Piranha Solution
Date: 9 Apr 1997 14:00:06 GMT

In article <>
"Rebecca M. Chamberlin" <> writes:


> However, using it in an R&D lab is asking for trouble.  A classic lab
> accident with piranha solution occurred at Cornell in 1986 or so.  The
> grad students in one lab used to rotate responsibility for cleaning all
> of their glass frits by running piranha solution thru them (using "house
> vacuum") into a filter flask.  One student made the mistake of leaving a
> trace of acetone in the flask.  When the piranha solution hit the
> acetone, it went BLAMMO and a million pieces of glass embedded
> themselves into her face.  Thank heavens she was wearing her safety
> glasses or she would most likely be blind now:  the lenses in her safety
> glasses were shattered but still intact in the frames.  The chemistry
> department took a photo of the glasses and used it in their "Are you
> wearing your safety glasses?" poster for years afterward.  Not
> surprisingly, the student decided to leave chemistry after her
> hospitalization. 

As it appears that Becky, I and others have not quite gotten the point
across, let me drive it home one more time.  While you can usually tell
a conversation among chemists has gotten lame when they start swapping
lab accident stories, it is important that you **understand** that the
risk of using this solution is nowhere near the reward.

What Becky is writing about is 100% true.  I saw it.  It happened.  It
could just as easily happen to you.  Read this and then ask whether a
clean frit is worth this.

I was the first one to get to scene of the above incident.  We heard a
sound like an M-80 (about a quarter stick of dynamite) from two labs
away.  We got there within about 5 seconds to find her on the floor
halfway across the room surrounded by a large pool of blood.  The
filter flask that she was using turned to dust; we never found a
fragment larger than about 2 mm even though it had been wrapped in
heavy black electrical tape.  The metal 3 prong clamp that held the
flask sheared off at the point where it was clamped to the latticework
in the hood.  A row of glass cabinets along one wall were peppered with
holes from the shrapnel.  The lab had one of those 100 mm diameter
glass drainpipes running vertically on the wall opposite the hood
(about 8-10 m away) -- the pipe cracked in the middle ...we believe
that it wasn't from shrapnel, but from the compression wave of the

The student was wearing rubber gloves, a thick sweater, a lab coat, an
apron and safety glasses at the time of the explosion.  The hood was
down part way and saved her from catching most of it in the face.  The
arm holding the frit caught most of the damage -- the glove was
completely flayed and her arm had several hundred small bits of glass
in it as well as several fairly large lacerations.  She had a wound
about 20 mm in diameter just next to her jugular vein.  At least one
piece of glass went through her cheek. She (and everything else) was
also covered with hydrogen peroxide and sulfuric acid; something that
we didn't realize until much later because we had no way of knowing
what had happened.  I think the bleeding stopped more because she went
into shock than from the pressure were were applying in two different

She spent the next six hours having tiny bits of glass picked out of
her arm, neck and face.  I'm told that you continue to have those work
their way out of your skin for the next several weeks after such an
incident -- that you sweep your good hand across the arm and cut
yourself on the glass sticking out of your own skin.  This student had
some nerve/tendon damage and lost a bit of the motion in one or two of
her fingers; I can't recall if she had any hearing loss or not.  All
things considered, she got off pretty lucky.  And yes, she did leave
the program a short time after.

Now consider this:  10 minutes later and the rest of my research group
would have left for dinner.  She was working ALONE in her laboratory,
"just cleaning up".  Maybe she could have gotten to the phone on her
own...when I got there she was trying to get up, but not very
successfully.  Ever try to stand up in a pool of your own blood and
sulfuric acid on a linoleum floor while dazed and injured?  Me neither,
but it certainly didn't look very easy.  Think about that the next time
you are working a late night alone.

The odd thing here is that if she hadn't been working alone there would
have been many other injuries in that laboratory.  We found one large
chunk of glass imbedded in a bookcase over someone's desk.  If the
owner of the desk had been there he would have caught this fragment
with the back of his neck.  I can not stress enough how **stupid** it
is to put a desk or glovebox opposite a fume hood (or having a desk in
a lab, but that's not always avoidable).  Look around your lab and see
if you have that's scary.  And the next time you see
someone without their safety glasses on, help them find a pair or make
them leave.  It is one thing to be an innocent bystander, it is another
to be a stupid bystander.

BTW, the shattered safety glasses Becky is referring to were from a
separate accident at Cornell involving a vacuum line explosion, but
that's another story and I only know it secondhand.  Part of their
rather effective campaign to make you think about safety.

Let me just end with the question I posed at the beginning:  Were a
batch of clean frits really worth all this?


piranha solution, cleaning

More Cleaning Solution
(Stoni's sexual toy)
08-10-02 22:07
No 344107
      For such an explosion to occur there must have ...  Bookmark   

For such an explosion to occur there must have been quite a bit of acetone in the filtration flask.

Anyone ever heard about an explosion of tetranitromethane/toluene mixture in a lab? I've heard some rumors, but would like to know what really happened.

I'm not fat just horizontally disproportionate.
08-11-02 03:23
No 344203
      Explosives  Bookmark   

No. I have not heard. However, let it be known that nitromethane mixed with ANY of a number of VERY common solutions that SENSITIZE nitromethane from its precursor state back to the actual level of HIGH EXPLOSIVE that it really is can cause an explosion that makes the above example (horror story) from Foxy look like a walk in the park.

Yes. 500 ml of nitromethane (sensitized) would be more than enough to kill everyone in the room.

If you want a private message on the sensitizing agents for nitromethane so you will know what NOT to do, let me know.

God Bless

08-11-02 03:28
No 344207
      P.S.  Bookmark   

P.S. Sensitizes Nitromethane is Approximately 25% more powerful than military grade T.N.T.

God Bless
(Hive Prodigy)
08-11-02 03:37
No 344214
      P.S.?  Bookmark   

P.S. = ?

(Hive Bee)
08-11-02 03:41
No 344218
      Haha LoL primo P.S. you gotta be kidding, ...  Bookmark   

Haha LoL primo

you gotta be kidding, right?!? ~~

P.S. i think he means P.S. sensitized nitromethane is 25% more powerful that TNT.

(Hive Prodigy)
08-11-02 03:51
No 344219
      Ok  Bookmark   

I was confused to hell. I thought he meant nitromethane that was sensitized with P.S. is 25% stronger than TNT, so I was like wtf is P.S.?? That's some strong shit, that P.S. ya know. laugh

Alright, sorry, no more intrusions from me.
(Distinctive Doe)
08-11-02 04:48
No 344234
      No its nitromethane all by itself, almost.  Bookmark   

No its nitromethane all by itself, almost.
Yes 25% stronger

Those who give up essential liberties for temporary safety deserve neither liberty nor safety
08-11-02 06:41
No 344271
      P.S. Means "Post Script" - Only.... this time  Bookmark   

I checked out the above link and the information looked accurate. Nitromethane is actually hard to get lit. But when it does lite...look out. Alkaline compounds, particularly those that can contribute nitrogen are effective in a ratio of approx. 20 parts to 1.

If you want an example of how DE-sensitized nitromethane works when it DOES get lit, look at the 1/4 mile dragsters at the race track that exceed 300 miles an hour in a 1/4 mile or less. They all burn...

You guessed it....nitromethane.

God Bless


P.S. I love Explosives!!!  
(Stoni's sexual toy)
08-11-02 11:21
No 344304
      I was talking about TETRAnitromethane.  Bookmark   

I was talking about TETRAnitromethane. I know everything there is to know about regular nitromethane.

I'm not fat just horizontally disproportionate.
(Hive Bee)
10-07-02 07:49
No 365350
      Filtering PdCl2  Bookmark   

Using a centrifuge to get the PdCl2 back from am O2 Wacker would probably be difficult because of the large volume of liquid (especially since swim doesn't even have a centrifuge).  Would a fritted glass filter crucible work well to get palladium chloride out of the end solution?  Or would the particles clog the filter?  Swim has one that is 15M which means 15 mL, porosity medium.  Using his huge (and only) Buchner is no good because the amount of palladium chloride is so small compared to the size of the filter paper that it all gets stuck on the paper.  He would try it himself but he only has one and could not afford another one if this one was to become clogged.  Also, if he did it this way and it worked he could put the crucible in the oven and get back dry PdCl2!