Table 1.
Yields, elemental composition, atomic ratios, pH and EC of rice straw and rice bran derived biochars prepared at various charring temperatures.a
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].
Figure 2.
Solid-state 13C NMR spectra of rice straw (A) and rice bran (B) derived biochars prepared at various charring temperatures.
Figure 3.
Synchronous and asynchronous 2D 13C NMR maps of rice straw and rice bran derived biochars over charring temperatures (100∼600°C).
Red represents positive correlation, and blue represents negative correlation; a higher color intensity indicates a stronger positive or negative correlation.
Figure 4.
Asynchronous 2D 13C NMR maps of rice straw and rice bran derived biochars over charring temperatures (100∼600°C) in a shorten range of bands.
Red represents positive correlation, and blue represents negative correlation; a higher color intensity indicates a stronger positive or negative correlation.
Table 2.
Pearson correlation coefficiency (R) between properties (pH, EC) and functional groups derived from solid state 13C NMR spectroscopy.a