The Crystallinity of Arenga pinnata “Ijuk” Fiber Cellulose through KMnO₄ Addition on NaClO Bleaching Process

Arenga pinnata “ijuk” fiber is one of the lignocellulosic sources that is abundant in Indonesia. At present, this fiber is only for brush, shiever, mat, and rope. Delignified “ijuk” fiber is a potential source of cheap crystalline cellulose, a material that can be used for composite. This paper presents chemical treatment of A. pinnata “ijuk” fiber to get cellulose with high crystallinity. The fiber is treated by alkalization with 2% sodium hydroxide (NaOH) for 1 h, 0.01 n KMnO₄ as NaClO activator for 10 min and bleaching with 5% NaClO at varying time of treatment 3, 5, 7 h, respectively. For comparison, the fiber is treated with 2% sodium hydroxide (NaOH) for 1 h and then with 5% NaClO without KMnO₄ for 3 h (N3). Addition of KMnO₄ as NaClO activator will control ClO gas released and then the bleaching process becomes more effective because the ClO gas will bleach the fiber, not releasing fast to the air. Furthermore, NaClO leads an oxidative fragmentation from the remaining lignin and then the lignin dissolves out from the fiber. The result shows that the highest crystallinity of the cellulose is the fiber which is treated by alkalization with 2% sodium hydroxide (NaOH) for 1 h, 0.01 n KMnO₄ for 10 min, and oxidation with 5% NaClO for 5 h (KN5). Fourier transform infrared confirms the removal of some lignocellulosic components such as lignin, wax, and hemicelluloses; X-ray diffraction reveals an increase of crystalline parts in the fiber via cellulose through crystallinity index value. Field emission scanning electron microscopy displays dimension and surface morphology of fiber. So the treatment can remove some amorphous part of the lignocellulose namely, lignin and hemicellulose to obtain cellulose with high crystallinity.