Lignin extraction from oil palm empty fruit bunch fiber (OPEFBF) via different alkaline treatments

Abstract

This study was conducted to investigate the efficiency of lignin extraction from oil palm empty fruit bunch fiber (OPEFBF) by using aqueous sodium hydroxide and aqueous ammonia solutions. In this study, the aqueous ammonia treatment was conducted via three different modes, namely low temperature-long time soaked treatment (LTLt-NH3), high temperature-short time soaked treatment (HTSt-NH3), and low temperature-long time replenished treatment (LTLt-Rep-NH3). Low- and high-temperature treatments were conducted at 50 and 100 °C, respectively. The efficiency of lignin extraction upon aq. NaOH treatment at 120 °C and solid content of 1:17 (OPEFBF-to-liquid) for 180 min was not significantly different with the LTLt-Rep-NH3 treatment at 50 °C and solid content of 1:7 (OPEFBF-to-ammonia) for 4 days. Among the tested methods, LTLt-Rep-NH3 treatment was proved to be the best lignin extraction method. Under the optimum conditions, approximately 64% of Klason lignin had been removed from the OPEFBF and about 33.0 ± 2.2% of lignin was successfully recovered, with minimal lignin structural deconstruction.