Figure 1. Van Krevelen plot of elemental ratios for rice straw (▪) and sawdust (□) derived biochars prepared at various charring temperatures.

Thick line represents the direction for dehydration reactions and grey shadings highlight approximate elemental ratios of unaltered biomacromolecules (cellulose and lignin) and black carbon materials (char and soot) following Hammes et al. [16].