As a green and efficient component separation technology, organic acid pretreatment has been widely studied in biomass refining. In particular, the efficient separation of lignin by p-toluenesulfonic acid (p-TsOH) pretreatment has been achieved. In this study, the mechanism of the atmospheric separation of bagasse lignin with p-TsOH was investigated. The separation kinetics of lignin was analyzed. A non-simple linear relationship was found between the separation yield of lignin and the concentration of p-TsOH, the temperature and the stirring speed. The shrinking nucleus model for the separation of lignin was established based on the introduction of mass transfer and diffusion factors. A general model of the total delignification rate was obtained. The results showed that the process of lignin separation occurred into two phases, i.e., a fast stage and a slow stage. The results provide a theoretical basis for the efficient separation of lignin by p-TsOH pretreatment.
Keywords: kinetics; lignin; mechanism; p-toluenesulfonic; shrinking nucleus model.