Comparison between Properties of Biochar Produced by Traditional and Controlled Pyrolysis

Eman H. El-Gamal, Maher Saleh, Ibrahim Elsokkary, Mohamed Rashad, Mona M. Abd El-Latif

Biochar is usually produced from crop residues (feedstock) by pyrolysis process under controlled conditions in specialized reactors. The characterization of biochar properties produced under field condition is limited. The objective of this study was to compare the physicochemical properties of biochar produced from two feedstocks; sugarcane bagasse feedstock (SCBF) and rice husk feedstock (RHF), under traditional field conditions (primitive) and controlled conditions. The temperature of traditional pyrolysis process was kept around 500 °C. However pyrolysis temperature under controlled conditions was repeated at 450 °C and 550 °C. In general, the results showed that increasing pyrolysis temperature decreased biochar yield and increased volatile matter, total surface area and total pore volume which were higher in RHBs than in SCBBs, the pHs of both biochars were to the alkaline range, ash and Si percentages of RHBs were higher than that of SCBBs. Furthermore, the C percentage which was higher in SCBB than in RHB. The FR-IR spectral showed that the presence of free OH group and CH stretch in both feedstocks disappeared in produced biochars under different pyrolysis conditions. The SEM images showed the presence of longitudinal pores in SCBF while SCBB (550 °C) contained longitudinal structure and fewer micropores, while the images of the RHF showed disturbed order of elongated pores which have been changed to developed pores in RHB (550 °C and traditional). The data of XRD analysis of SCBF indicated the presence of cellulose and disappeared in its three biochars while, XRD data of RHF and RHBs indicate the presence of amorphous silica and quartz. Both biochars produced in the field using traditional pyrolysis unit showed approximately biochar properties as those produced under controlled condition (550 °C). Key words: Feedstock, Sugarcane bagasse, Rice husk, Pyrolysis, Biochar.