[Gasification] Active charcoal
GFWHELL at aol.com
GFWHELL at aol.com
Tue Feb 21 09:06:46 CST 2012
Regarding the activation of charcoal, I read somewhere that charcoal could
be reactivated in a micro wave oven, If this is the case any water trapped
within it would turn to superheated steam and push out impurities after
which it would simply evaporate. leaving the charcoal extremely hot??
GF
In a message dated 2/21/2012 7:00:10 A.M. Eastern Standard Time,
english at kingston.net writes:
Darius,
TLUD char is said to have good surface area and sorption properties. Using
the TLUD camp stove you may be able to enhance this by simply increasing
underfire air briefly at the end of the burn cycle. You will loose a bit of
yield but you will also spike the temperature and flush the newly formed
hot char with CO and CO2 which can have an activating effect.
Page 34 of
_http://www.biochar-international.org/sites/default/files/All-Biochars--Version2--Oct2009.pdf_
(http://www.biochar-international.org/sites/default/files/All-Biochars--Version2--Oct2009.pdf)
describes a simple test that we have used to test our char. It seems to
have some value but more public data points would be useful. Although our
char had only one fifth the weight gain of a high quality AC they performed
more equally in a field trial to adsorb a toxin. Although our char is not
made in a TLUD it does experience a brief CO-CO2 flush at approximately 800C .
Thanks to all for contributions to this thread.
Alex English
On 20/02/2012 11:06 PM, Bruno M. wrote:
Hi Anand,
i think you made a bunch of good ( & cheap) suggestions to Darius,
Calcium Chloride is probably one of the cheapest ( cheaper and easier to
get the K2CO3),
since it is common used as a deicing salt on roads ( up to -20°C) and also
in household humidity absorbers ( & odor eliminator) like eg:
_http://www.damprid.com/faq#_ (http://www.damprid.com/faq#) )
but its very hygroscopic, need to be stored dry and in closed containers,
so i guess you can't soak your biomass in a 25% solution and then hoping
it to dry in the sun
( in an humid climate ), but 5% may do fine.
_http://en.wikipedia.org/wiki/Calcium_chloride_
(http://en.wikipedia.org/wiki/Calcium_chloride)
Safety: Calcium chloride can get very hot when mixed ( concentrated) in
water, and the dust is an irritant.
But there are many sources of material to make charcoal from and
even so many ways to active those carbons.
My guess is too, that for good activated carbon you need to start from
good char,
that means char made at higher temperatures ( higher temp then normally
needed for bio-char )
800-900 °C. & you like to have low ash content.
Maybe Darius this may also be of interest to you:
_www.vcharkarn.com/uploads/78/79040.pdf_
(http://www.vcharkarn.com/uploads/78/79040.pdf)
_http://revroum.getion.ro/wp-content/uploads/2010/RRCh_6_2010/Art%2002.pdf_
(http://revroum.getion.ro/wp-content/uploads/2010/RRCh_6_2010/Art%2002.pdf)
Ones you've done the activation step on your AC,
you will not know HOW active your char is, compared to
commercial AC, & that also depends on your purpose for this AC,
so you'll need some testing of the AC.
Here an example of a big lab specific known for his AC testing service,
with price indication, just you know which kind of test could be done on
it.
_http://pacslabs.com/activatedcarbon/actesting.php_
(http://pacslabs.com/activatedcarbon/actesting.php)
An example of analyzing different AC made from bagasse:
_www.waset.org/journals/waset/v34/v34-36.pdf_
(http://www.waset.org/journals/waset/v34/v34-36.pdf)
A rather simple but much used test, is the 'iodine number' or 'iodine
capacity number',
if you do this on a before and after the activation sample you get a good
impression
of how much more active area has become available.
I guess this can be done on a small budget, and without complex apparatus.
Here is the ASTM Designation: D4607-94
_www.czsochem.com.cn/download/ASTM%20Iodine%20test.doc_
(http://www.czsochem.com.cn/download/ASTM%20Iodine%20test.doc)
you may need more tests.
When we know more of the purpose of your AC, and the scale
of your operation we may be able to give more precise advice & tips, i
guess.
Grts
Bruno M.
( chemist)
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