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ABSTRACT: Oil palm frond (OPF) waste is one of the sustainable raw materials obtained after pruning of the OPFs. The objective of this study is to produce cellulose nanocrystals (CNC) from OPFs by chemo-mechanical treatment. The multi-step process started with removal of extractives, wax and pectins by soxhlet extraction, followed by removal of lignin using sodium chlorite and 10% (v/v) acetic acid. The bleached samples were then soaked in potassium hydroxide to remove the hemicellulose and finally underwent acid hydrolysis with 64% (v/v) sulphuric acid hydrolysis for 1 h. The CNC obtained were characterised using transmission electron microscopy (TEM), X-ray diffractions (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analyser (TGA). The TEM images showed that the fibres were well dispersed and the treatment had reduced the size of fibres with average dimensions of 9.88 nm in diameter and 504.12 nm in length. The XRD results showed that the crystallinity index of the extracted cellulose fibres was 52.3% in comparison with the raw OPF, 35%. The results from FTIR analysis showed some differences in the peaks and some were shifted due to removal of some components in the fibres. The TGA confirmed that the CNC had improved its thermal property by having an onset temperature of258.34°C in comparison with the raw OPF, 197.48°C. This isolated CNC has great properties and can be used in many applications such as in biomedical field, food industry, cosmetics and wood products.
Keywords: Oil palm frond, cellulose nanocrystals, chemo-mechanical, OPF waste, isolated CNC
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1. INTRODUCTION
Lignocellulosic materials are derived from agricultural waste and in Malaysia, a major contributor of biomass waste is from the oil palm (Elaeis guineensis) plantation. Malaysia has the second largest oil palm plantation area in the world which was reported to be 5.4 million hectares as of 2014.1 Oil palm plantation has generated a huge quantity of lignocellulosic resources consistently throughout the year in the form of oil palm trunk (OPT), empty fruit bunches (EFB), oil palm frond (OPF) and leaves. The OPF was reported to be the largest biomass which is 47% out of the total oil palm waste.2 Despite being a waste, OPF is abundant, readily available and inexpensive which makes it suitable to be used as...