Kraft lignin recovery from de-oiled Jatropha curcas seed by potassium hydroxide pretreatment and optimization using response surface methodology

The present study explores resource recovery from the de -oiled Jatropha curcas seed (DJS) using alkaline pretreatment. Potassium hydroxide (KOH) was utilized for the alkaline hydrolysis at a solid loading rate of 10 % w/v for the kraft lignin (KL) recovery. The process variables optimized were reaction time (6.36 - 73.63 min), temperature (85.68 - 156.3 degrees C), and KOH concentration (0.61 - 12.38 % w/w). Response surface methodology was used to optimize the process parameters. The maximum amount of KL recovered under optimal conditions was observed to be 89.6 %. The functional group changes in treated and untreated DJS were explored through Fourier transform infrared spectroscopy (FTIR) analysis. 1 H NMR and FTIR techniques were employed to characterize recovered lignin. Nitrobenzene oxidation of the lignin was performed to understand the lignin monomer profile. The recovered lignin has an S/G ratio of 0.36. The pretreated DJS biomass can be subjected to enzymatic hydrolysis for enhanced sugar yield.