[Terrapreta] volatile matter and char

[Edward Someus]

 SEAN

Technical response on VM: 

RE VM has an insecticidal effect 
YES, TARS ARE TOXIC FOR LIFE 

RE Low VM% is obtained at high temperatures, basically
NOT ONLY, NO MATTER IF YOU HAVE HIGH TEMP AND LONG RESIDENCE TIME IF THE
TECHNOLOGY HEAT TRANSFER EFFICIENCY IS LOW. == ORGANICS ARE LOW HEAT
CONDUCTORS. 

RE Higher temperatures produce a more "activated" charcoal too ("activated"
charcoal has a high adsorption surface area)
NO, ACTIVATION IS AN DIFFERENT PROCESS, BY HIGHT TEMP ONLY YOU CAN NOT REACH
HIGH SPECS SURFACE AREA

RE Now, charring biomass on a forest floor or in the soil will not likely
allow such high temperatures (~1000C) to be achieved, so one wonders how the
original Terra Preta soil was made with low temp char and does not suffer
from toxicity. RE Perhaps any toxicity in fresh low temperature charcoal is
lost over time once it is in the soil. 
TP IS NOT CHAR ONLY, IT IS A BLEND.  YES, TOXICITY IS CHANGING BY TIME, AND
SOONER OR LATER ADAPTED MICROBIOLOGICAL COLONIZATION MIGHT OCCUR.  BUT THIS
PROCESS IS HIGHLY DEPENDING ON SOIL TYPE + CLIMATE CONDITIONS AS WELL. TP
ORIGINAL WAS IN TROPICAL CLIMATE WHERE ORGANIC DEGRADATION IS ALWAYS FAR
MORE RAPID THAN IN CONTINENTAL CLIMATE. TP MODEN AGE DOES NOT HAVE DECADES
OF TIME TO WAIT FOR ALL THIS. 


Sincerely yours: Edward Someus (environmental engineer)
Terra Humana Clean Tech Ltd. (ISO 9001/ISO 14001)
3R Environmental Technologies Ltd. 
ADDRESS: H-1222 Budapest, Szechenyi 59, Hungary
TEL handy:  +(36-20) 201 7557
TEL / FAX:   +(36-1) 424 0224
TEL SKYPE phone via computer:  Edward Someus
3R TERRACARBON:   http://www.terrenum.net 
3R CLEANCOAL ENERGY: http://www.nvirocleantech.com 
 
-------Original Message-------
 
From: Sean K. Barry
Date: 2007.12.21. 5:43:40
To: Terrapreta Preta;  Gerald Van Koeverden
Subject: Re: [Terrapreta] volatile matter and char
 
Hi Gerrit,
 
What is the source/cause of high volatile matter in char?  Does this VM
(since it is 'volatile') decrease/volatize by itself over a short time?  


According to the article "VM" content is "a measure of the susceptibility of
charcoal to further decompose and form carbon when heated."


Translation, please?? 
 
We've asked Dr. Michael J. Antal this very question, when he was subscribed
to the list.  He was vague about what VM actually is then, too.  It is
measurable as the percent weight (VM%) of a charcoal sample (this is done
using a "proximate analysis" test), but its chemical analysis is a mystery. 
Some others have recently mentioned VM has an insecticidal effect (Dr.
Reddy).  Edward Someus also says high VM% content on charcoal is a problem
in soil.  People working with Eprida, Danny Day, Dr. Christoph Steiner, etc.
 were wondering if the VM% was a benefit as "food for microbes".
 
From what I have read about pyrolysis reactions, the VM% content is be
dictated primarily by maximum internal particle temperature in the char bits
(this can be somewhat related to residence time in the reactor).  Low VM% is
obtained at high temperatures, basically.  Higher temperatures produce a
more "activated" charcoal too ("activated" charcoal has a high adsorption
surface area).  Now, charring biomass on a forest floor or in the soil will
not likely allow such high temperatures (~1000C) to be achieved, so one
wonders how the original Terra Preta soil was made with low temp char and
does not suffer from toxicity.  Perhaps any toxicity in fresh low
temperature charcoal is lost over time once it is in the soil.
 
As you suggest, VM is "volatile", so I imagine it does dissipate somewhat
off the surface of the charcoal, through reduction by oxygen from the air,
or water.  This has been recognized as a "storage" problem for fresh
charcoal.  Fresh charcoal can spontaneously ignite!  THis occurs when the VM
reacts and creates heat).  Another question I had was,  ... What about
charcoal from natural forest fires that are quenched out by rain, for
instance?.  Wouldn't these be low temperature and leave toxins in the soil? 
But, as has been observed, soils on which forest fires have run across do
not stop plant growth.  In fact, there is a "bloom" of new growth.  So, what
s up? (with this "toxicity of of high VM% on low temperature charcoal"
scare).
 
I think this premise needs testing.  I think no none who has provided any 
field results of using charcoal in soil" here yet, has known that the
charcoal they used was low VM% or even what temperature the char was made at
(no data on this presented).  I can make charcoal with my reactor and
control the max temperature inside the reactor core.  I can do a "proximate
analysis" test on any charcoal produced and make measurements of VM%.  I
cannot discover any ways yet to characterize the chemical analysis of the VM
in any way.  Dr. Antal got short with me when I asked him about doing this. 
He told me, like in the paper, Volatile Matter is only quantifiable, not
characterize-able.  (Who gets to say, "That's bunk!" to a PhD?).
 
It may be that the processes required to produce low VM% charcoal are more
expensive than otherwise, so these producers are trying to play up the value
of their product.  I think the premise needs testing.  I think most testing
occurring now is NOT seeing this detriment in their plant growth results.
 
Carry on.
 
Regards,
 
SKB
----- Original Message ----- 
From: Gerald Van Koeverden 
To: Terrapreta Preta 
Sent: Thursday, December 20, 2007 7:53 PM
Subject: [Terrapreta] volatile matter and char


G.


The article is at the following link:


http://www.ctahr.hawaii.edu/DeenikJ/Downloads/Tai_Charcoal_CTAHR_Sym_2007
pdf
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