Efficient extraction of lignin-rich nanofibers from rambutan peel using a two-step delignification process

Abstract

Fibrillated cellulose obtained from waste streams is highly valued because it converts a residual byproduct into a high-performance, and sustainable material. However, its use is often limited by preparation methods that are both complicated and time-consuming. In this study, we introduce a straightforward approach for production of lignin-containing carbohydrate nanofibers (LCNFs) through a two-step partial delignification process. Our approach is based on a peracetic acid (PAA) treatment followed by an alkaline sodium hydroxide (NaOH, 2 wt% and 5 wt%) step. We examined the produced LCNFs with regard to chemical composition, zeta potential, morphology, colloidal stability, thermal stability, and particle size. Rambutan peel served as the biomass source, yielding LCNFs with lignin contents between 14 and 22 wt% and cellulose contents of 50–73 wt%, at an overall yield exceeding 43 wt%. High-pressure homogenization of the fibers treated with the two-step partial delignification produced LCNFs with an average diameter of less than 9.8 nm. The colloidal stability of the LCNFs was studied after six months of storage at 4 °C, demonstrating stable suspensions and unchanged chemical composition. Thermal analysis revealed significant improvements in thermal stability for the NaOH-treated LCNFs, with onset temperature (T_onset), of 287 °C (PAA-2N) and 305 °C (PAA-5N), and T_max at 340 °C and 343 °C, respectively. This eco-friendly process for producing LCNFs offers a scalable pathway for developing high-performance nanofibers with broad industrial application.

Graphical abstract