Production Process and Optimization of Solid Bioethanol from Empty Fruit Bunches of Palm Oil Using Response Surface Methodology

Abstract

This study aimed to observe the potential of solid bioethanol as an alternative fuel with high caloric value. The solid bioethanol was produced from liquid bioethanol, which was obtained from the synthesis of oil palm empty fruit bunches (PEFBs) through the delignification process by using organosolv pretreatment and enzymatic hydrolysis. Enzymatic hydrolysis was conducted using enzyme (60 FPUg−1 of cellulose) at a variety of temperatures (35 °C, 70 °C, and 90 °C) and reaction times (2, 6, 12, 18, and 24 h) in order to obtain a high sugar yield. The highest sugars were yielded at the temperature of 90 °C for 48 h (152.51 mg/L). Furthermore, fermentation was conducted using Saccharomyces cerevisiae. The bioethanol yield after fermentation was 62.29 mg/L. Bioethanol was extracted by distillation process to obtain solid bioethanol. The solid bioethanol was produced by using stearic acid as the additive. In order to get high-quality solid bioethanol, the calorific value was optimized using the response surface methodology (RSM) model. This model provided the factor variables of bioethanol concentration (vol %), stearic acid (g), and bioethanol (mL) with a minus result error. The highest calorific value was obtained with 7 g stearic acid and 5 mL bioethanol (43.17 MJ/kg). Burning time was tested to observe the quality of the solid bioethanol. The highest calorific value resulted in the longest burning time. The solid bioethanol has a potential as solid fuel due to the significantly higher calorific value compared to the liquid bioethanol.

Improved bioethanol production from oil palm empty fruit bunch using different fermentation strategies

“…During the last decade, one of the critical threats to the world has been the depletion of fossil resources in combination with an increase in energy consumption, which has resulted in a dilemma between the essential need for fuel and food while searching for sustainable non-edible feedstock for biofuel production (Derman et al, 2018). Therefore, secondgeneration feedstock as non-edible biomass for bioethanol production is being generally replaced by agricultural or lignocellulosic biomass (Nurfahmi et al, 2019;Kirdponpattara et al, 2022). Hence, studies have investigated the production of lignocellulosic bioethanol from cheap renewable, lowcost sources (Khomlaem et al, 2023) such as wheat straw (Qiu et al, 2018), sweet potato peel (Mithra et al, 2018), rice straw (Todhanakasem et al, 2019;Singh et al, 2020;), waste bamboo (Song et al, 2020), corn cob (David et al, 2020), sugarcane bagasse (Saha et al, 2019) and sweet sorghum bagasse (Thanapimmetha et al, 2019).…”