watson.fawkes
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Commercial ion exchange resin
I recently acquired a bag of Purolite C100E strong acid cation resin at the local surplus house. It came in a 1 cu.ft. bag. This particular variety is for potable water, but
it's the same as a their C100 product (for industrial use) with an extra processing step for potable use. It doesn't say explicitly, but I'm guessing
they're extracting some low-level toxics from the manufacturing process. The ordinary use for this resin is to replace Ca(2+) and Mg(2+) ions with
Na(+) for water softener use.
I'm writing because I want to recommend the engineering data on this site. There's very good information on regeneration techniques, both co-flow and
counter-flow, bed packing, pressure drops, etc. There are regeneration regimes for brine, for Na(+) replacement, and for sulphuric acid and for
hydrochloric acid, for H(+) replacement. This resin family is able to displace cations with H(+) with the right regeneration regime, acidifying the
effluent stream in the process. The one I have is shipped with Na(+), but evidently that's changeable. There are specific warnings about running free
chlorine, hypochlorite, and strong oxidizers through the resin, so it's no good for, say, perchloric acid manufacture.
[Edit] Copy editing.
[Edited on 15-11-2010 by watson.fawkes]
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smaerd
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Thanks 
This was actually something that I wanted to learn more about.
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aonomus
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What do you plan on doing with the resin? Ion exchange chromatography? DI water system?
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watson.fawkes
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I didn't have the
most specific plans for it when I got it, but since it cost less than a dime on the dollar, I figured it was good for educational value, if nothing
else. Now that I know exactly what it is (as opposed to the kind of thing it was), I'll likely use it to charge a water softener or DI system. We have
very high Ca(2+) content where I live, and it would be useful to have a better source, even if it's not fully DI.
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arsphenamine
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Sounds like you can also sequestre metal cations as well (Pb, As, etc.).
Leftover organics such as pesticides, hormones, and psychotropics
are usually handled by activated carbon, although I would opt for
something aggressive like UV-initiated ozonolysis stirred with ultrasound.
Sonochemistry: it's not just for theatrical fog.
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watson.fawkes
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I did notice number of specialty
resins they've got, like this one: | Quote: | | FerrIX™ A33E is a proprietary hybrid ion exchange resin specifically designed for selective removal of arsenic from water, certified to NSF/ANSI 61
Standard. |
and this one: | Quote: | | Purolite® PFA460/4783 is a gel-type strong base anion exchange resin tailored for extraction of uranyl sulfate and carbonate complexes from the
leachates originated from ISL, batch or heap leaching processes. |
and my favorite one, at which I will admit
that I was agape upon first reading: | Quote: | | Purolite A530E is a special macroporous strong base anion resin crosslinked with divinylbenzene that is specially selective for hydrophobic anions. It
shows good mechanical strength and an excellent resistance to osmotic and thermal shock. The macroporous matrix and special ion exchange group
functionality imparts an especially high selectivity of Purolite A530E for perchlorate and pertechnetate. The selective removal of these oxy-anions is
possible in the presence of higher concentrations of other anions that can compete with these oxy-anions for the selective sites. The nature of the
pertechnetate is such that it would be difficult to handle the regeneration effluent. Thus it is recommended that the used resin be disposed off in a
controlled fashion rather than regenerated. |
There are more in this vein. They've got hundreds of products; I
don't claim to have even skimmed them all.
One of the consistent pieces of top-level information about these resins is their functional group. The C100E I've got lists sulfonic acid as its
group. I've seen carboxylic acid, secondary and tertiary amines, quaternary ammonium. There are probably others. It seems that they have a single
underlying resin that they process chemically to attach functional groups after the resin beads are formed.
But as to your specific question, I'm guessing that the sequestration activity for these is related to the solubility of the corresponding cation
sulfate salt. Lead sulfate, poorly soluble, should be captured. Arsenic I'm not so sure about with this product, largely because I'm not familiar with
the solubility of arsenic sulfate (and cursory web searching yielded nothing).
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