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[Killietalk] peat pellets 2
Charles Harrisonwrote:
I wonder how you are determining the Calcium in the water. Calcium referring
to the Hardness? If you
are using AA or ICP, the Calcium should still be there in the water, Brown
water that is.
Using local tap water (250 ppm Ca) filtered through peat Moss, I have
determined Calcium concentrations in the
brown water you observe and found an EDTA titration indicates a major drop in
measurable Calcium. I have then
filtered the dark Water through Activated Charcoal to remove the color
completely and found the calcium to
return to the same level by EDTA titration. The dark compounds like the
Charcoal better than they do the metal
ions. Now we should start talking about affinity coefficients, pKa's and a
relationship between the various
components, pH and the Peat. That sounds like a David Koran question. I
believe he did his Ph D on something
about Peat Mosses - Yes?
anyway
You didn't say what the pH of the water pre Peat treatment was - ? could it be
acidic or near neutral?
In response:
I use EDTA titration to measure Ca as hardness. I'm not sure if your
observations concern peat moss or peat
pellets. In ordinary peat filtration, I also observed that hardness rose
somewhat when I used activated carbon
to remove the brown color---I couldn't decide if this was due to a reversal of
the original "softening" or if it was
calcium added by the carbon (I remember the days of "bone charcoal.").
Apparently, your observations indicate
that the removal of hardness is related to the soluble brown material
(presumably lignins, etc.). I didn't consider
that idea in my own thinking, attributing the removal to the nonsoluble
components of the peat moss. I am
assuming that you removed the peat moss before you used carbon filtration. If
your observations are general, I
think we are really on the road to saying that soluble components in the peat
moss---probably the brown
pigments--bind to the Calcium, somehow making it unavailable to EDTA titration
(and perhaps rendering it
biologically inactive as well). That would be extremely interesting. I can't
think of a soluble agent in the peat
moss that could outcompete EDTA itself in binding calcium. Are there
components of lignin that are chelators
like EDTA?
My well water has a pH of 8.2 - 8.4, 340 - 390 ppm of hardness by EDTA
titration and 14 - 16 KH by the
Aquarium Pharmaceuticals colorimetric test kit. The aquifer is in the karst
which forms most of the bedrock of
this region.
"For the strength of the Wolf is the Pack, and the strength of the Pack is the Wolf..." Rudyard Kipling
"Not all who wander are lost..." J.R. Tolkien
"Truth, she lives in a distant land, of snow, and ice... and burning sand..." Stephen Crane
"Life is short, dance naked and wiggle your ass!" Big Daddy Catfish
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