Chemical and thermal properties of pure lignin are depending on the plant origin, extraction method and type of
lignocellulosic. In this study, lignin from oil palm empty fruit bunch (EFB) and kenaf core were recovered from soda black
liquor by two steps of acid precipitation with hydrochloric acid and followed by soxhlet with n-hexane. The XRD analysis
of purified EFB lignin (EAL) and purified kenaf core lignin (KAL) exhibited amorphous properties, similar to the standard
alkali lignin (SAL). The FTIR and Raman spectra showed that all samples consist of HGS unit. In FTIR, the syringyl unit is
assigned at (1125 cm-1), (1327 and 1121 cm-1) and (1326and 1117 cm-1) meanwhile the guaicyl unit is assigned at (1263,
1212 and 1028 cm-1), (1271, 1217 and 1028 cm-1) and (1270, 1211 and 1030 cm-1) for SAL, EAL and KAL, respectively.
The peak around 1160 cm-1 represents C-O stretching of conjugated ester group present in HGS lignin. As for Raman, the
HGS unit exists in the range of 1100-1400 cm-1. Among the purified samples, the TGA result showed that KAL has a better
thermal stability with the residue of 36.49% and higher Tg value which is 152.69°C.
The factors responsible for the low solubility percentage of oil palm empty fruit bunch (OPEFB) cellulose pulp compared
to kenaf when dissolved in aqueous NaOH/urea solvent system was reported. Physical and chemical properties of both
cellulose pulp were studied and compared in terms of the lignin content, viscosity average molecular weight (Mη),
crystallinity index (CrI), cellulose pulp structure and their zero span tensile strength. The structure of both OPEFB and
kenaf cellulose pulp were characterized using high powered microscope and field emission scanning electron microscopy
(FESEM) assisted by ImageJ® software. The results show that the most significant factor that affected the OPEFB and
kenaf cellulose dissolution in NaOH/-urea solvent was the Mη with OPEFB having a higher Mη of 1.68×105 compared to
5.53 × 104 for kenaf. Overall, kenaf cellulose appeared to be produced in higher quantities presumably due to its lower
molecular weight with superior tensile strength and permeability in comparison to OPEFB.