Slow Pyrolysis as a Promising Approach for Producing Biochar from Sunflower Straw

Abstract

Slow pyrolysis opened new channels for the highly efficient utilization of sunflower straw in salt-affected regions and obtained not only 28% to 40% biochar, but also 29% to 44% syngas and 29% to 31% bio-oil. Biochar yield decreased with increasing temperature, whereas syngas increased and bio-oil changed minimally. Both syngas and bio-oil had potential value as fuel. The biochar produced at 700 ºC had the highest pH, ash content, and water-soluble K+ of 11.9, 212 g/kg, and 23.9 g/kg, respectively, and the lowest atomic ratios for H/C and O/C of 0.19 and 0.10, respectively. However, C, other minerals, surface area, and cation exchange capacity (CEC) of biochar reached a stable level at 500 ºC. Therefore, the differential characteristics of the biochar derived from sunflower straw might show potential value in removing pollutants and improving soil fertility at 500 ºC.