The raw material presented a compact, rigid and smooth surface, with low porosity. The external wall was characteristic of lignin structure and exhibited silica bodies (phytolis) embedded in OPEFB structure, these are the most common minerals found on the surface of woody plants, as also reported by Baharuddin et al.(2013). The OPEFB fiber from acid pretreatment showed partial
internal disruption of cell wall, preserving external walls without silica bodies, the absence of this was important to enhance microbial attack or enzymatic saccharification of OPEFB fibers
(Baharuddin et al., 2013).
The increment in NaOH removed the external walls of OPEFB fibers, attributed to lignin solubilization. The OPEFB fibers obtained had more porosity, homogeneity, uniformity and highest surface area. The holes present in OPEFB fibers were assumed to be effective in the swelling of the OPEFB structures, attracting the microbes and enzymatic reactions for the subsequent bioconversion as reported by Shamsudin et al. (2012). The lignin L2 obtained is a polyhedral rigid structure with smooth surface.