Title: Utilisation of superheated steam in oil palm biomass pretreatment process for reduced chemical use and enhanced cellulose nanofibre production

Authors: Mohd Nor Faiz Norrrahim; Hidayah Ariffin; Mohd Ali Hassan; Nor Azowa Ibrahim; Wan Md Zin Wan Yunus; Haruo Nishida

Addresses: Faculty of Biotechnology and Biomolecular Sciences, Department of Bioprocess Technology, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia; Research Center for Chemical Defence (CHEMDEF), Universiti Pertahanan Nasional Malaysia, Kem Perdana Sungai Besi, 57000 Kuala Lumpur, Malaysia ' Faculty of Biotechnology and Biomolecular Sciences, Department of Bioprocess Technology, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia; Institute of Tropical Forestry and Forest Products (INTROP), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia ' Faculty of Biotechnology and Biomolecular Sciences, Department of Bioprocess Technology, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia ' Faculty of Science, Department of Chemistry, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia ' Department of Chemistry, Centre for Defence Foundation Studies, Universiti Pertahanan Nasional Malaysia, Kem Perdana Sungai Besi, 57000 Kuala Lumpur, Malaysia ' Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka 808-0196, Japan

Abstract: In this study, superheated steam (SHS) pretreatment was used as a green approach to partially remove hemicellulose from oil palm mesocarp fibre (OPMF). OPMF was treated with SHS at 260°C for 30 min prior to delignification by NaClO₂ to obtain mainly cellulose fibre. Hemicellulose removal by KOH was conducted as a control experiment. Both SHS- and KOH-treated OPMF were later nanofibrillated using a wet disk mill (WDM). The characteristics of CNF produced were analysed in terms of morphological, crystallinity and thermal properties. Based on the chemical compositional analysis, SHS-treated OPMF had residual hemicellulose content of 11% (w/w), and there was no hemicellulose residue in KOH-treated OPMF. The presence of hemicellulose in SHS-treated OPMF was later found to enhance CNF formation during WDM process, whereby it was shown that nanofibrillation of SHS-pretreated OPMF occurred as early as 6^th cycle, compared to KOH-pretreated OPMF (8th cycle). This observation could be explained by the presence of hemicellulose which prevented hornification of the cellulose microfibrils during milling process. This finding is significant as not only can the use of chemicals be reduced during pretreatment step, but the use of SHS pretreatment contributed greatly to the productivity of the CNF.

Keywords: OPMF; oil palm mesocarp fibre; cellulose nanofibre; SHS; superheated steam; nanofibrillation; wet disk milling.

DOI: 10.1504/IJNT.2019.107360

International Journal of Nanotechnology, 2019 Vol.16 No.11/12, pp.668 - 679

Published online: 18 May 2020 *

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