MineMan
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Quick Filtration
Hello all,
How do you filter out your precipitates from the acid bath. This is the longest and most frustrating process for me. I dump the etn/acid bath into
cold water then wait... and wait for the acid water to filter out. The I add sodium bicarb with water and wait more... and more. I use coffee
filters. Is there a fine plastic mesh product that would go much faster. I don't want to spend the money on vacuum filtration.
What method do you use? I am only talking about 20gram batches here. it takes for ever.
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byko3y
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My vacuum filtration setup cost me 20$ for everything including 12 square meters of paper. Although a source of water with good pressure is a main
requirement.
Viscousity of sulfuric acid is really high, I don't think there's much you can do without vacuum. Do you use NaNO3+H2SO4 or HNO3+H2SO4?
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Turner
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Filtration was always the biggest pain in the ass for me, messy, time consuming, worrying about the loss of product etc. the more material you have,
the worse. Coffee filters are fine, sometimes I used a paper towel with a funnel and this went a bit faster. If you are only talking about 20 grams of
anything, one coffee filter is fine, not too much trouble.
[Edited on 8-6-2015 by Turner]
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kecskesajt
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Same problem here.I filter a 20 gramm batch with coffe filter and I pour it in,wait,wash with water,wait,bicarb wash,wait,water wash wait.When I
waiting I do something else like watch TV or play computer games,go outside for a 200m running or so.Also, there are filter for chemisty use wich are
faster,having a smaller loss,and stronger.
[Edited on 8-6-2015 by kecskesajt]
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Bot0nist
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A water aspirator and the needed accessories are pretty cheap. Even a hand pump vacuum filtration setup would save lots of time, (and bulk up your
fore arm) compared to gravity filtration. If your filtering viscous fluids or fine percipitates enough for it to annoy, then perhaps vacuum filtration
of one sort or another is worth a look.
[Edited on 8-6-2015 by Bot0nist]
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
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greenlight
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I agree with botonist, the best way for quick filtration would be vacuum filtering.
I used to use coffee filters and they just take too long as well as the fact that stronger basic or acidic solutions sometimes can make them break
through by eating through them as they are only made for coffee and hot water.
Definitely invest in one if you are going to be doing a lot of filtering.
[Edited on 8-6-2015 by greenlight]
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nitro-genes
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For most purposes, I use viscose fabric towels, available at the supermarket for a couple of cents, they resist cold dilute acids and bases reasonably
well and can be used multiple times. Filtering properties are very good (it filters out most stuff a coffee filter can't) and are environmentally
friendly as well. 
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Scientwisted
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I believe that in this matter there is no "short cut" to filtration problems. You can use the more cost efficient gravitational method. In this you
are going to wait a while for all the filtrate to pass or you can increase the filter pore size and sacrifice a small amount of the total yield. Or
you can up you lab gear and get into some more advance filtration techniques.
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aga
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Vac filtration is a whole lot quicker.
It is definitely worth the investment in a vac pump
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roXefeller
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The previous answers are right, you have to pay the price of admission. Only one thing comes to mind that is situation specific. If you are able to
grow the crystals out of solution, they come out much larger than water crash precipitate, and easier to filter. Specifically, after the first
filtration step, dissolve the crude etn in a solvent, like acetone, then add bicarb to neutralize. Then setup the single phase mixture to slowly add
water with stirring. Over the course of time, crystals nucleate, grow, and then settle out of the flow from their own weight. These are much easier
to filter, but it still requires time to grow them.
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PHILOU Zrealone
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Tips for filtration or alternatives:
1°)after crashing, first do a cold decantation step and do not filter the all mixed acid+ crash water batches; this will spare you a lot of time.
If you use a separatory funnel, the lower part will contain the fine crystals that you can let flow in a filter or in a second wash bath. All the
supernatant could be extracted with a few 10 ml of ether and the tiny extract evaporated for recollection of crystals. The two crops of primary
crystals could then be set to recrystalization in one step.
If you don't have a separatory funnel simply allow the clear supernatant to flow in another recipient with a laminar flow in a way not to perturbate
too much the lower part of the initial recipient that holds the tiny crystals. Then filtrate only the inferior part or do a second wash in the same
recipient.
2°) You may work with centrifugal force, centrifuge device...this accelarates the decantation step.
3°) Better use fiber glass filter , this is to be found in most brico shops as big rolls by the square meter for walls with cracks and irregularities
that have to be painted. This is resistant to acids...the acid mix tend to somehow desaggregate the filter paper that tends to be less effective...the
fibers of the filter paper becomes thicker and viscous and obstruates the pores of the filter yielding lower passthrough flow and thus filtration
takes much more time.
4°) You may extract the all batch with ether (or another unsoluble solvent), neutralise, evaporate and recrystallize the crystals from an appropriate
solvent.
[Edited on 10-6-2015 by PHILOU Zrealone]
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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kecskesajt
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Quote: Originally posted by PHILOU Zrealone  | Tips for filtration or alternatives:
1°)after crashing, first do a cold decantation step and do not filter the all mixed acid+ crash water batches; this will spare you a lot of time.
If you use a separatory funnel, the lower part will contain the fine crystals that you can let flow in a filter or in a second wash bath. All the
supernatant could be extracted with a few 10 ml of ether and the tiny extract evaporated for recollection of crystals. The
two crops of primary crystals could then be set to recrystalization in one step.
If you don't have a separatory funnel simply allow the clear supernatant to flow in another recipient with a laminar flow in a way not to perturbate
too much the lower part of the initial recipient that holds the tiny crystals. Then filtrate only the inferior part or do a second wash in the same
recipient.
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Bad at ETN.After crushing into water it makes a foam and not all the ETN settle to the bottom.
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PHILOU Zrealone
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Add a little ethanol, it is a foam killer and it will decrease density of the fluid vs the crystals...
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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kecskesajt
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Doesn't I must worry about EtNO3 formation?
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PHILOU Zrealone
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If ever it does form, it is very volatile and liquid so during crystalization of ETN from warm ethanol, it will simply remain in the mother liquor...
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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kecskesajt
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Thanks man,I might use this method.
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