Green production of lignocellulose nanofibrils by FeCl3-catalyzed ethanol treatment

The traditional strategy for isolating cellulose nanomaterials requires various chemicals and a high energy input, while achieving a low product yield owing to lignin removal during pulping and bleaching. Here, we propose a green ethanol pretreatment process with a synergistic effect using ultrasound and FeCl3 to produce lignocellulose nanofibrils (LCNF) with a high yield (over 67 %) from thermomechanical pulp. Notably, a high-aspect-ratio LCNF with uniformly distributed lignin nanoparticles, a high lignin content, and excellent thermostability (Tmax > 330 °C) with a typical cellulose I crystalline structure were successfully obtained. In addition, reduced distillation can easily retrieve the FeCl3 solution and ethanol, reducing reagent waste. In general, FeCl3-catalyzed ethanol pretreatment can serve as a sustainable and environmentally friendly approach for converting sustainable lignocelluloses into high value-added nanomaterials. Moreover, the obtained LCNF can be applied in diverse fields.