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Mass yield of water-quenched chars

Posted by jhofmeyr on 29 May 2016 at 17:14 GMT

I noted the procedure "Dry mass of biochar was analyzed by drying at 110°C until mass equilibrium".
QUESTION: Is it possible that the mass yield of the water-quenched chars may have been over-reported? I ask because of my understanding that this temperature is adequate for drying non-porous solids but that moisture which is adsorbed on the internal surfaces of the pores of biochar is only desorbed in the range 150 to 200 degC.

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RE: Mass yield of water-quenched chars

hschmidt replied to jhofmeyr on 29 May 2016 at 18:32 GMT

yes, we agree that the C yield is certainly overstated as not all water can evaporate at 110°C, even at 200°C there will always be some chemical and physical bound water in the biochar porous system. The reported yields are only an "orientation" about the yields and no absolute carbon yields which needs more profound investigations with e.g. TGA. We should have stated this in the paper but were not aware during redaction of the importance of this fact. Thanks for bringing it in.

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