Investigation of Reaction Mechanism and the Effects of Process Parameters on Ionic Liquid-Based Delignification of Sugarcane Straw

The delignification of sugarcane straw (SCS) was investigated using 1-ethyl-3-methylimidazolium acetate, [Emim][OAc], varying three process parameters such as temperature, residence time, and stirring rate. The maximum degree of delignification was around 63.9% at 90 degrees C for a stirring rate of 1400 rpm and a residence time of 5 h. The 2(3) full factorial statistical model was well-fitted with the experimental results. Among the 26 solid-liquid reaction mechanisms studied in this study, Zhuravlev, Lesokhin, and Templeman diffusion (i.e., shrinking core/product layer) model was found to be the most suitable model for describing the delignification mechanism of SCS using [Emim][OAc]. When compared with other process parameters, higher temperatures produced low crystalline and low thermally stable recovered cellulose-rich material with high porosity and BET surface area due to higher degree of crystalline cellulose I to amorphous cellulose II transformation. The recovered lignin was of low molecular structure with high content of phenolic OH- groups and syringyl units. The recovery of [Emim][OAc] was > 85% with no structural changes. Graphical