## 3 Results and Discussion
However, cassava stems contained the highest amount of N (1.27%) and the lowest in corncobs (0.74%). The cassava rhizomes had the highest level of O (55.37%), while corncobs contained the lowest levels of O (50.76%). The results of analysis following transformation of the feedstocks into biochar (shown in Table 2) revealed that corncob biochar contained the highest levels of C and H (81.35% and 2.42%, respectively) while the amount of C and H was similar for the other two biochar types: 64.25% and 2.73% for cassava rhizomes and 62.95% and 2.24% for cassava stems, respectively. Cassava stem biochar contained the highest O content (33.44%) while corncobs contained the lowest (15.23%). Comparing the chemical composition of each type of feedstock with its biochar product, the analyses of all three samples confirmed an increase in the proportion of C in biochar compared with the original biomass. The amount of C in corncobs increased by the highest percentage (39.69%), \begin{table}
\begin{tabular}{c c c c} \hline  & **Corncob** & **Cassava Rhizome** & **Cassava Stem** \\ \hline C (wt\%) & 41.66 \({}^{\mathrm{a}}\)\(\pm\) 1.12 & 37.60 \({}^{\mathrm{a}}\)\(\pm\) 2.22 & 41.55 \({}^{\mathrm{a}}\)\(\pm\) 0.92 \\ H (wt\%) & 6.84 \({}^{\mathrm{a}}\)\(\pm\) 0.36 & 6.15 \({}^{\mathrm{a}}\)\(\pm\) 0.58 & 6.04 \({}^{\mathrm{a}}\)\(\pm\) 0.13 \\ N (wt\%) & 0.74 \({}^{\mathrm{b}}\)\(\pm\) 0.02 & 0.88 \({}^{\mathrm{b}}\)\(\pm\) 0.04 & 1.27 \({}^{\mathrm{a}}\)\(\pm\) 0.14 \\ O (wt\%) & 50.76 \({}^{\mathrm{a}}\)\(\pm\) 0.89 & 55.37 \({}^{\mathrm{a}}\)\(\pm\) 1.64 & 51.14 \({}^{\mathrm{a}}\)\(\pm\) 1.18 \\ H/C ratio & 1.97 \({}^{\mathrm{a}}\)\(\pm\) 0.17 & 1.96 \({}^{\mathrm{a}}\)\(\pm\) 0.27 & 1.74 \({}^{\mathrm{a}}\)\(\pm\) 0.06 \\ O/C ratio & 0.91 \({}^{\mathrm{a}}\)\(\pm\) 0.05 & 1.10 \({}^{\mathrm{a}}\)\(\pm\) 0.09 & 0.92 \({}^{\mathrm{a}}\)\(\pm\) 0.05 \\ C/N ratio & 65.63 \({}^{\mathrm{a}}\)\(\pm\) 1.89 & 50.16 \({}^{\mathrm{b}}\)\(\pm\) 3.86 & 39.30 \({}^{\mathrm{b}}\)\(\pm\) 3.53 \\ Molecular formula & CH\({}_{1.97}\)O\({}_{0.91}\) & CH\({}_{1.96}\)O\({}_{1.10}\) & CH\({}_{1.74}\)O\({}_{0.92}\) \\ Surface area (m\({}^{2}\)/g) & 2.54 \({}^{\mathrm{b}}\)\(\pm\) 0.41 & 2.78 \(\pm\) 0.23 & 2.51 \(\pm\) 0.03 \\ Total pore volume (cm\({}^{3}\)/g) & 0.0034 \({}^{\mathrm{b}}\)\(\pm\) 0.0007 & 0.0043 \({}^{\mathrm{b}}\)\(\pm\) 0.0004 & 0.0058 \({}^{\mathrm{a}}\)\(\pm\) 0.0006 \\ Average pore diameter (Å) & 31.05 \({}^{\mathrm{c}}\)\(\pm\) 0.75 & 69.57 \({}^{\mathrm{b}}\)\(\pm\) 5.58 & 83.34 \({}^{\mathrm{a}}\)\(\pm\) 1.79 \\ \hline \end{tabular} Note: Data are shown as the Mean \(\pm\) SE. \({}^{\mathrm{a}}\), \({}^{\mathrm{b}}\), \({}^{\mathrm{c}}\), Means followed by a different letter are significantly different at the 0.05 level (\(p<0.05\)).  
\end{table} 
Table 1: Properties of biomass feedstocks. followed by cassava rhizomes (26.65%) and cassava stems (21.40%). For H and O the opposite trend was observed. The distinct chemical composition of biochar resulted from a slow pyrolytic conversion of the biomass feedstock. Biomass is made up of three main components: hemicellulose, cellulose and lignin. In general, these components are represented at levels of 20-40%, 40-60% and 10-25%, respectively, as lignin wt% of the lignocellulosic biomass [55; 56]. The slow pyrolysis process dissociates bonds between C and functional groups on the surface area of the biomass, including -OH, aliphatic C-O and aliphatic C-H groups [57; 58; 59]. The high temperature drives off volatile compounds and gases including CO\({}_{2}\), CO, H\({}_{2}\)O, and volatile hydrocarbons [31; 59; 60; 61]. Higher temperatures lead to increased amount of volatile matter which in turn boost the content of aromatic structures, especially when the temperature exceeded 400 \({}^{\circ}\)C [58; 62; 63]. Elevated levels of aromatic compounds contribute to enhanced stability of the biochar structure. The H/C molar ratio indicated formation of aromatic compounds.