Electrical conductivity of wood biochar monoliths and its dependence on pyrolysis temperature  

作　　者：Randeep Gabhi Luca Basile Donald W.Kirk Mauro Giorcelli Alberto Tagliaferro Charles Q.Jia 

机构地区：[1]Department of Chemical Engineering and Applied Chemistry,University of Toronto,200 College Street,Toronto,ON M5S 3E5,Canada [2]Department of Applied Science and Technologies,Politecnico di Torino,C.so Duca Degli Abruzzi,Turin 10129,Italy

出　　处：《Biochar》2020年第3期369-378,共10页生物炭（英文）

摘　　要：Biochar is traditionally used as solid fuel and for soil amendment where its electrical conductivity is largely irrelevant and unexplored.However,electrical conductivity is critical to biochar’s performance in new applications such as supercapacitor energy storage and capacitive deionization of water.In this study,sugar maple and white pine were carbonized via a slow pyrolysis process at 600,800 and 1000°C and conductivities of monolithic biochar samples along the radial direction were measured using the 4-probe method.Biochars were characterized using an elemental analyzer,scanning electron microscopy,X-ray diffraction and Raman spectroscopy.The solid carbon in biochar samples was found to consist primarily of disordered carbon atoms with small graphitic nanocrystallites that grow with increasing temperature.The bulk conductivity of biochar was found to increase with pyrolysis temperature-1 to~1000 S/m for maple and 1 to~350 S/m for pine,which was accompanied by an increase in carbon content-91 to 97 wt%and 90 to 96 wt%for maple and pine,respectively.The skeletal conductivity of biochar samples carbonized at 1000°C is about 3300 S/m and 2300 S/m for maple and pine,respectively(assuming solid carbon is amorphous);both values are above that of amorphous carbon(1250-2000 S/m).This work demonstrated the importance of carbonization and graphitization to electrical conductivity and suggested electron hopping as a likely mechanism for electric conduction in biochar-an amorphous carbon matrix embedded with graphitic nanocrystallites.

关 键 词：BIOCHAR Electrical conductivity Pyrolysis temperature GRAPHITIZATION 

分 类 号：S14[农业科学—肥料学]