Optimization of a novel sequential alkalic and metal salt pretreatment for enhanced delignification and enzymatic saccharification of corn cobs

Abstract

This study presents a sequential sodium phosphate dodecahydrate (Na3PO4·12H2O) and zinc chloride (ZnCl2) pretreatment to enhance delignification and enzymatic saccharification of corn cobs. The effects of process parameters of Na3PO4·12H2O concentration (5–15%), ZnCl2 concentration (1–5%) and solid to liquid ratio (5–15%) on reducing sugar yield from corn cobs were investigated. The sequential pretreatment model was developed and optimized with a high coefficient of determination value (0.94). Maximum reducing sugar yield of 1.10±0.01g/g was obtained with 14.02% Na3PO4·12H2O, 3.65% ZnCl2 and 5% solid to liquid ratio. Scanning electron microscopy (SEM) and Fourier Transform Infrared analysis (FTIR) showed major lignocellulosic structural changes after the optimized sequential pretreatment with 63.61% delignification. In addition, a 10-fold increase in the sugar yield was observed compared to previous reports on the same substrate. This sequential pretreatment strategy was efficient for enhancing enzymatic saccharification of corn cobs.