Simultaneous preparation of lignin-containing cellulose nanocrystals and lignin nanoparticles from wood sawdust by mixed organic acid hydrolysis

In the global search for sustainable and environmentally friendly materials, the efficient utilization of biomass resources has become a hot research topic. Due to the high specific surface area, nanocellulose crystals (CNCs) have attracted considerable attention. However, CNC preparation often requires the separation of lignin and hemicellulose, which wastes resources. In this study, lignin-containing cellulose nanocrystals (LCNCs) and lignin nanoparticles (LNPs) were prepared from p-toluenesulfonic acid (p-TsOH)/formic acid (FA) pretreated poplar wood in one-step. The process was performed in a mixed acid system with a mass ratio of p-TsOH, FA, and deionized water (DI) of 3:5:2, and mechanical stirring at 80 ºC for 3 h. Under these conditions, the lignin removal rate was about 70 %, and the LCNCs yield was more than 40 %. The p-TsOH is regained by vacuum distillation and recrystallization, and the recovery rate can reach 60 %. The prepared LCNCs were then carbonized and used as an electrode for electrochemical testing. The electrode obtained by carbonizing LCNC exhibits an areal capacitance of 156.4 F g−1 (0.5 A g−1). The study provided a new prospect for the efficient utilization of lignocellulosic nanomaterials. •The preparation of lignin-containing cellulose nanocrystals reduces the waste of lignin and improves the overall performance.•Lignin-containing cellulose nanocrystals are prepared by mixed organic acid hydrolysis.•Lignin-containing cellulose nanocrystals are prepared into electrodes for use as supercapacitors.