Biochemical Conversion of Lignocellulosic Biomass from Date Palm of <i>Phoenix dactylifera</i> L. into Ethanol Production

• Main Authors: Yousra Antit, Inmaculada Olivares, Moktar Hamdi, Sebastián Sánchez
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Energies
• Subjects: enzymatic hydrolysis; ethanol; fermentation; cellulosic fibers from date palm; <i>P. tannophilus</i>; pretreatment
• Online Access: https://www.mdpi.com/1996-1073/14/7/1887

Cellulosic fibers from date palm are among the most promising lignocellulose feedstock for biorefinery purposes. The world production is between 1.9 and 2.4 million t/year. Initially, a pretreatment with dilute-sulphuric acid of these fibers was performed using a response surface methodology, with temperature and process time as factors. The aim is to produce bioethanol from young and old fibers from date palm, <i>Phoenix dactylifera</i> L. Optimal thermochemical pretreatment conditions for both fibers palms were 220 °C in hydrothermal conditions (without acid); in these conditions pretreated young fibers presented a maximum content in holocelluloses of 45.18% and old fibers 61.97%. Subsequently, during the enzymatic hydrolysis a maximum yield of total reducing sugars (<i>TRS</i>) was reached, 46.32 g/100 g for pretreated dry young fibers and 48.54 g/100 g for pretreated dry old fibers. After enzymatic saccharification, hydrolysates were fermented by <i>Pachysolen tannophilus</i> (ATCC 32691) to ethanol, reaching yields (<i>Y</i>_E/TRS) of 37.94 g ethanol/100 g of <i>TRS</i> for young fibers and 35.84 g ethanol/100 g of <i>TRS</i> for old fibers. Globally, considering the full process, in the fermentation of the hydrolysates, a yield (<i>Y</i>_E) of 10.64 g ethanol/100 g of dry young fibers and 10.88 g ethanol/100 g of dry old fibers was reached.