Greetings Everyone.
I am reading several articles about biochars and notice several use N2 atmosphere inside the muffle furnace. can you produce biochars without this N2 atmosphere or other inert gas?
If it is possible, What will be the main changes between using or not that type of atmosphere? the type of functional groups the biochar will present?
Denis Rodrigues It is very important to produce biochar under limited supply of oxygen. There are couple of reasons to that. a) to reduce flue gas production, especially CO2. b) the quality of biochar in presence of oxygen-rich environment may result in high ash content of the material and low carbon surface. c) Carbon substrate in combination with O2 molecule will react at high temperature to produce CO2 which will reduce the adsorbent property and also the active sites ratio over the biochar surface.
Now coming back to your question, "if you can use muffle furnace without N2 atmosphere?". I am presuming here that you do not have the nitrogen-based muffle furnace in your laboratory. However, you can still get the inert atmosphere. Just cover the raw material (for example wood chips) placed in a ceramic container with an aluminum sheet and then place activated charcoal over that (just to cover the surface, 5 mm thick). Again place a layer of aluminum sheet and then again put activated carbon powder over it (again, just to cover the surface). Then finally cover the set-up using aluminum cover (yes, again). This way you will create an oxygen-deficient atmosphere that will prevent the molecular oxygen to pass to the material. Don`t worry, aluminum and activated carbon is almost inert until 700 degree celcius. For more information you can go through this paper: Article Physical and biological removal of Microcystin-LR and other ...
and you can inbox me for any updates. Good luck!
The biochar is mainly produced via pyrolysis process ( where the biomass undergoes through initial decomposition. At this stage, thermally stable char is formed). After that, a secondary decomposition takes place (where unstable volatile compounds are converted into gaseous products).
During the pyrolysis, the aeration conditions vary between oxygen-limited to oxygen-free ( check this review article : Article Biochar: Production, Properties and Emerging role as a Suppo...
)That is why inert gases such as nitrogen are used during the production.
Denis Rodrigues It is very important to produce biochar under limited supply of oxygen. There are couple of reasons to that. a) to reduce flue gas production, especially CO2. b) the quality of biochar in presence of oxygen-rich environment may result in high ash content of the material and low carbon surface. c) Carbon substrate in combination with O2 molecule will react at high temperature to produce CO2 which will reduce the adsorbent property and also the active sites ratio over the biochar surface.
Now coming back to your question, "if you can use muffle furnace without N2 atmosphere?". I am presuming here that you do not have the nitrogen-based muffle furnace in your laboratory. However, you can still get the inert atmosphere. Just cover the raw material (for example wood chips) placed in a ceramic container with an aluminum sheet and then place activated charcoal over that (just to cover the surface, 5 mm thick). Again place a layer of aluminum sheet and then again put activated carbon powder over it (again, just to cover the surface). Then finally cover the set-up using aluminum cover (yes, again). This way you will create an oxygen-deficient atmosphere that will prevent the molecular oxygen to pass to the material. Don`t worry, aluminum and activated carbon is almost inert until 700 degree celcius. For more information you can go through this paper: Article Physical and biological removal of Microcystin-LR and other ...
and you can inbox me for any updates. Good luck!
Hi, Dennis! It is important to use a supply of N2 to produce a biochar. In the absence of N2, organic matter tends to decompose into ash. However, you can produce a biochar in these conditions if you use a low carbonization temperature (T < 400 ºC), short carbonization time (< 2 h), and limit the circulation of oxygen in your system. I recommend that you put your raw material in a container where you can cover it (with a alumin sheet for example), preventing oxygen from entering it.
If oxygen circulation is successfully limited, you will obtain a carbon with characteristics similar to those obtained with the supply of N2. Perhaps you get a material with less oxygenated groups on the surface and more ash.
If you don't want to produce an activated carbon, you can try the hydrothermal carbonization method.
So that was what I was thinking. The lab where I was Working which had a proper furnace and apparatus is strongly limited at the moment so I was trying to understand if I could use one furnace in another lab that is way less prepared generally regarding adsorption experimetns. And from all the answers is highly doubtful I will be able to use that one, I will check better if any of the suggestions is possible. Thank you all Renan Nunes Pratik Kumar Sarah Zayan
The use of nitrogen atmosphere is absolutely necessary. All colleague comments are underlining why. It is a big issue in pyrolysis process.
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