Process intensification of delignification and enzymatic hydrolysis of delignified cellulosic biomass using various process intensification techniques including cavitation
Abstract
Different methods of pretreatment including alkali treatment, treatment with ultrasound, biological treatment using laccase enzyme and combined treatment like ultrasound-laccase for Napier grass have been tried. With alkali pretreatment optimized conditions obtained were sodium hydroxide 0.3% w/v giving 86% delignification at temperature of 80 °C, treatment time of 2 h. In physical methods of treatment ultrasound, at a temperature of 45 °C, treatment time of 2 h, operating at frequency 24 kHz and power of 100 W gave 18% delignification. For laccase pretreatment, optimized conditions obtained were 300 rpm impeller speed, enzyme concentration 10 U/gm of Napier grass gave 50% delignification with cellulose. The optimized conditions for delignification by using combination treatment of ultrasound & enzymatic were obtained at 24 kHz frequency, 100 W giving 75% of delignification in 6 h. An enhancement in lignin degradation by 25% and reduction in the treatment time from 12 to 6 h is achieved as compared to only laccase treatment.