Chemical Forums
Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: curiouscat on February 16, 2013, 02:34:56 AM
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I was looking for a flocullating agent that'd be stable at high pH (~11). Normally, I'd use Alums, Ferric / Ferrous Chlorides or Sulfates but all of those seem to work best at neutral or slightly alkaline pH (pH 7-8.5 mostly reported).
Any ideas which other agents might be good to try? The stream to be treated is Oil + CaCl2 + H2O composition but with ~10% of suspended inorganic solids in it mostly CaCO3.
The particle sizes are fairly large; 50 microns and larger. The solids separate out easily in a lab centrifuge at modest g / rpm values.
I've seen Polyacrylamides reported as flocculating agents but not sure what their basic medium stability is.
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From a ceramics source
The most common flocculants potters use are epsom salts (magnesium sulfate) and calcium chloride, though acids (such as muriatic acid) can also be used
I assume this does not apply in your case.
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From a ceramics source
The most common flocculants potters use are epsom salts (magnesium sulfate) and calcium chloride, though acids (such as muriatic acid) can also be used
I assume this does not apply in your case.
I could try magnesium sulfate. CaCl2 I already have oodles of right in there.
HCl's a no go. Cannot go to acidic pH. The oily phase needs to remain alkaline for stability reasons.
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Is it typically true, that a base environment is deflocculating and going towards neutral is flocculating?
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Is it typically true, that a base environment is deflocculating and going towards neutral is flocculating?
Never heard of that. But its a complex field and I'm no expert.
I doubt the trends are monotonic. From what I read a lot of water treatment flocs form best between pH 7-8.5.
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I tried adding potash alum (KAl(SO4)2.12 H2O) and there seems a gelatinous ppt that forms. Wonder if this might be AlCl3?
Al2(SO4)3 + 3 CaCl2 :rarrow: 2 AlCl3 + 3 CaSO4
Is this reaction to be expected?
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Gelatinous in the context of presence of Al makes me think about Al(OH)3.
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Gelatinous in the context of presence of Al makes me think about Al(OH)3.
You must be right. AlCl3 has a high solubility in H2O. Al(OH)3 does not.
I wonder what'd be a good flocculating agent in this situation. I suppose Fe-chlorides and Fe-sulfates will form hydroxide ppts too. :-\
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http://www.flocculants.info/polymer-definitions.html
This page suggests
calcium salts at pH between 4 and 14
iron salts at pH between 4 and 13
aluminum salts at pH between 4.5 and 10
If you use
Polyethylene-imines
Polyamides-amines
Polyamines
Polyethylene-oxide
are we then talking organic chemistry?
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http://www.flocculants.info/polymer-definitions.html
Thanks @bill! That looks like a great site.
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Potters flocculate alot ;)
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Try Ammonium iron(III) sulfate, NH4Fe(SO4)2ยท12 H2O, also known as ferric ammonium sulfate (FAS) or iron alum. Highly soluble and less acidic than Aluminum sulfate.
Now in the presence of CaCl2. I think we get NH4Cl, CaSO4 and Fe(OH)3. Also, I like the idea of an ammonium salt with oil (also presence).