Effect of Microwave-Alkali Techniques on the Morphology and Physical Changes of Treated Oil Palm Empty Fruit Bunches Fiber

Abstract

Empty fruit bunches fibre (EFB) consisting of 44 % cellulose, 16 % lignin and 35 % hemicelluloses component was treated using microwave-alkali (Mw-A) agitated pre-treatment so as to disrupt the recalcitrant structures in the fibre. Morphology and chemical changes of treated EFB were used as indicators to the effectiveness of Mw-A treatment. The results obtained were compared with conventional pre-treatment process. The morphology of the treated fiber was observed using scanning electron microscope. The reduction in the EFB composition during Mw-A treatment was justified by measuring the total extract cellulose; remaining lignin and hemicellulose, and ash content after the process was performed. Results revealed that Mw-A pre-treatment technique exhibited a more effective removal of lignin and hemicelluloses as compared to the conventional or chemical treatment.

Novel Pre-treatment for Lignocellulosic Biomass Delignification Using Alkaline-Assisted Ohmic Heating

“…Another 8% was comprised of extractives and other removal components in the sample. The results obtained were in the ranges found in the literature, which were 15%-30% lignin, 20%-45% hemicellulose, and 20%-65% cellulose (Hamzah et al, 2020;Krishnan et al, 2017;Mohammad et al, 2020;Wadchasit et al, 2020). The holocellulosic component in the EFB was the highest by combining the portion of hemicellulose and cellulose (68%).…”

“…Then, the sample mixture was transferred into the ohmic cell and ohmic heated for 5 minutes at 80°C at a fixed solid-to-liquid ratio of 1:100. The determination of chemical composition for native, size reduced, and ohmic heated EFB was carried out using the Technical Association of the Pulp and Paper Industry (TAPPI) method to see if there was any significant potential for ohmic heating pre-treatment (Hamzah et al, 2020;Mohammad et al, 2020). From the result, further optimization of AA-OH parameters on EFB was done accordingly to one factor at a time (OFAT) for three different variables such as reaction time (5-25 mins), temperature (80-120°C), and concentration of NaOH (1-5% w/v).…”

“…Pores formed when pre-treatment using sodium hydroxide (NaOH) formed silica holes (Hamzah et al, 2020), as most of the silica components were removed with extractives on the EFB surface. Removing silica is crucial (Głazowska et al, 2018) because it may create precipitation of insoluble compounds, contributing to biomass recalcitrance.…”

“…Removing silica is crucial (Głazowska et al, 2018) because it may create precipitation of insoluble compounds, contributing to biomass recalcitrance. As the silica is deposited in the cell wall, it will protect the plant from enzymatic hydrolysis and microbial attack, acting as one of the physical barriers for fiber, which can cause problems during biomass utilization for bioenergy production (Hamzah et al, 2020;Le et al, 2015). Furthermore, after removing the lignin surfaces of the fiber, circular silica bodies were revealed to be deposited on the surfaces (Palamae et al, 2017).…”

“…The most favored methods in trend for EFB pre-treatment are acid/alkaline-assisted microwave heating which combines the physical (microwave heating) and chemical pretreatments, where chemical solvents used such as sodium hydroxide, NaOH (Hamzah et al, 2020;Nomanbhay et al, 2013;Yaser et al, 2017), sulphuric acid, H2SO4 (Akhtar et al, 2015;Fatriasari et al, 2017) and ferric (III) chloride, FeCl3 (Hassan et al, 2021). Electrochemical (EC) pre-treatment is also categorized as one option for 'greener' alternative technologies for delignification (Tamburini et al, 2011) and has started to venture into the reduction in the recalcitrance of LCB (Panigrahi et al, 2021).…”