Optimization of biochar preparation process and carbon sequestration effect of pruned wolfberry branches

Abstract

Abstract Pruned wolfberry branches are abundant and ideal raw material for biomass carbonization. It would provide valuable guidance for optimizing the preparation conditions of biochar of pruned wolfberry branches for carbon sequestration and emission reduction. This study adopted a single-factor experiment and response surface method (RSM) using reaction temperature and holding time as factors, and systematically investigated the effects of carbonization conditions on yield and fixed carbon content. Based on the results, the effects of temperature on yield and fixed carbon content were greater than those of holding time. Both temperature and holding time had extremely significant effects on yield, and the interaction had significant effects. Temperature had an extremely significant effect on fixed carbon content, while holding time and the interaction had no significant effect. Through the RSM, the optimized pyrolysis temperature was 530°C and the holding time was 2 h. The potential for carbon sequestration of biochar generated by wolfberry branches and returned to the soil was evaluated. Biochar was believed to contribute to carbon sequestration and emission reduction in Qinghai province; 68.56 × 103 t of carbon emissions could be reduced annually from combustion in the atmosphere and 34.42 × 103 t of carbon could be fixed if all biochar were applied to soil.