Influence of high carbonization temperatures on key performance indicators of Arundo donax derived biochars

Abstract

Biochar can be used as a solid fuel for space heating and as soil amendment to improve agricultural production. Availability of biomass feedstock and carbonization temperature are determinant factors influencing the production and applications of biochar. Arundo donax is a promising C₃ perennial crop with high biomass yield and adaptation to poor soil conditions, making it a suitable, low-cost and sustainable feedstock source for biochar production. Therefore, the aim of this study is to investigate the influence of high carbonization temperatures on key performance indicators of Arundo donax derived biochar in its heating and soil amendment applications. Biochars were produced at carbonization temperature of 500, 700 and 900 °C. Key performance indicators including proximate composition, thermal recalcitrance, combustion and energy characteristics, pH and electrical conductivity were analyzed. Increase in carbonization temperature resulted in increased fixed carbon (77.08–81.43%) and ash content (8.04–10.67%) while volatile content (7.90–14.87%) decreased. Ignition (382–535 °C), peak (460–620 °C) and burnout (530–670 °C) temperatures of biochars increased correspondingly with the carbonization temperature. Calorific value slightly increased from 29.51 to 29.94 MJ/kg. pH values (7.31–9.67) showed that the biochars are slightly alkaline. Recalcitrance index increased from 0.49 to 0.68 as the carbonization temperature increased. Microstructures of the biochars showed an improved porous structure as the carbonization temperature increased. Improvement in the key performance indicators of the biochars showed that high carbonization temperature can significantly enhance the satisfactory performance of Arundo donax derived biochars in its heating and soil amendment applications.

Keywords:

• Biochar
• carbonization
• pH
• combustion
• thermal recalcitrance
• heating

Acknowledgement

The authors wish to acknowledge the financial supports from USDA National Institute of Food and Agriculture, McIntire Stennis project WVA00118, 1007044 towards this research work. The authors wish to also acknowledge the West Virginia University Shared Research Facilities for the opportunity to use the equipment in their facilities for characterization of the biochars.

Conflict of interest

The authors declare no conflict of interest including financial, personal, or other relationships with anybody or organizations.