# High Cellulose Purity by Acid Hydrolysis Pretreatment on Kenaf Outer Bast
## 3 Result and Discussion
### Optimum Conditions of Kenaf Outer Bast  
The focus was on raising the high purity of cellulose content. Table 4 shows the optimum condition in this experiment. Regarding the high content of cellulose, the optimum condition has been divided into two potentials. A concentration of 0.25 N has a high yield of solid content, and a low concentration weakly removes hemicellulose content compared with high concentrations [48; 49]. Meanwhile, a 1.00 N concentration of sulfuric acid powerfully removes hemicellulose. Unfortunately, the cellulose was followed by a hydrolyze with high acid concentration [6; 24; 25]. Hence, this suggests the lower acid concentration obtained a high yield of biomass, and hydrolyzed hemicellulose with high acid concentration improved the purity cellulose of kenaf outer bast content. The synergistic effect of the acid concentration of sulfuric acid as catalysis with a temperature on acid hydrolysis reaction to hydrolyze hemicellulose was significant [42; 44]. Obtaining pure cellulose in this study requires 130 C as the high temperature for each acid concentration. Furthermore, the effect of high temperature was a loss of yield content [41]. Otherwise, the low temperature obtained a small amount of hemicellulose with high yield content. The ideal reaction time for hydrolysis should completely hydrolyze hemicellulose into monosaccharides without high degradation of the cellulose. An increased reaction time of acid hydrolysis led to more degradation of produced glucose [24]. Therefore, the most appropriate way to remove hemicellulose and obtain high purity of cellulose is a high-temperature reaction with higher acid concentration and short reaction time. This project aims to contribute to the scientific and industrial communities to produce biorefinery high-purity cellulose by selectively removing hemicellulose. From a biomass source, treatment, and chiefly the optimum treatment condition, is investigated to obtain \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Optimal for**} & \multirow{2}{*}{\
\begin{tabular}{c} **Acid Con \({}^{\text{a}}\)** \\ **(N)** \\ \end{tabular} } & \multirow{2}{*}{**Temp \({}^{\text{b}}\) (\({}^{\text{c}}\)C)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Time** \\ **(min)** \\ \end{tabular} } & \multirow{2}{*}{**Yield (\%)**} & \multicolumn{3}{c}{**Chemical Composition**} \\ \cline{5-8}  & & & & & **Cellulose** & **Hemicellulose** & **L Lignin** \\  & & & & & **(\%)** & **(\%)** & **(\%)** \\ \hline Higher yield & 0.25 & 130 & 60 & 54.4 \(\pm\) 0.1 & 51.4 \(\pm\) 0.1 & 2.5 \(\pm\) 0.1 & 0.6 \(\pm\) 0.1 \\ \hline Pure cellulose & 1.00 & 130 & 120 & 49.6 \(\pm\) 0.1 & 47.9 \(\pm\) 0.1 & 0.8 \(\pm\) 0.2 & 0.8 \(\pm\) 0.1 \\ \hline \hline \end{tabular}  
* Acid concentration; \({}^{\text{b}}\) Temperature.  
\end{table} 
Table 4: The optimal condition of dilute acid hydrolysis on kenaf outer bast. Figure 4: Chemical composition of kenaf outer bast with different reaction times of acid hydrolysis with 0.5 N sulfuric acid at 110 C.  
high purity of cellulose. Several studies have analyzed the effectivity of acid hydrolysis hydrolyzed carbohydrates with different aims. On the other hand, 4% of sulfuric acid hydrolyzed kenaf bast fiber in 60 min at 140 \({}^{\circ}\)C contained 56.8% of cellulose [50]. In equilbalance with that result, this study on 1.00 N of sulfuric acid at 130 \({}^{\circ}\)C 60 min collected 90.1% of cellulose. Furthermore, considering a high yield content of the optimum condition acid hydrolysis kenaf outer bast, we found 96.6% purity of cellulose from the total yield. Meanwhile, cellulose purification from other kenaf fibers using the alkaline treatment and bleaching only contains 89.5% purity of cellulose [51]. This research identified acid hydrolysis, up to now, as worthy of a bioreinery step production purity of cellulose.