Organosolv delignification of agricultural residues (date palm fronds, Phoenix dactylifera L.) of the United Arab Emirates

Date palm fronds (primary agricultural residue of the United Arab Emirates) were used as a feedstock in an ethanol–water organosolv delignification process to generate organosolv lignin (OSL) and enzymatically digestible cellulose-rich pulp. Conditions of the treatment (temperature, catalyst concentration and amount of ethanol in the digesting solvent mixture) were screened and preliminarily optimized for OSL recovery and digestibility of the cellulose-rich pulp as primary and secondary response variables, respectively. OSL recovery was positively influenced only by temperature (140–200 °C), while the digestibility of the cellulose pulp was positively influenced by temperature and negatively influenced by ethanol content in the digesting solvent. Maximum production of 12.93 g lignin/100 g RM (raw material) and 21.38 g glucose/100 g RM was achieved. Xylan losses reached up to 70%, increasing with temperature. Addition of the catalyst (sulfuric acid) was found to have no significant influence on any of the responses investigated.