Potential aspect of rice husk biomass in Australia for nanocrystalline cellulose production

Abstract

Abstract Nanocrystalline cellulose (NCC) was produced from rice husk biomass (Oryza sativa) by a chemical extraction process to explore the potential aspect of agro-waste biomass in Australia. In this work, the delignified rice husk pulp (D-RHP) was produced by alkaline delignification of raw rice husk biomass (R-RHB) using 4 mol·L− 1 alkali solutions (NaOH) in a jacketed glass reactor under specific experimental conditions. D-RHP was bleached using 15% sodium hypochlorite, and the bleached rice husk pulp was coded as B-RHP. Finally, raw suspension of NCC was produced by the acid hydrolysis of B-RHP using 4 mol·L− 1 sulphuric acid. The raw suspension of NCC was neutralized by a buffer solution and analyzed by TAPPI, FT-IR, XRD, SEM, AFM, and TEM. FT-IR spectra of NCC are different to R-RHB but similar with B-RHP and D-RHP. From XRD results, the crystallinity of NCC was found to be approximately 65%. In AFM analysis particle thicknesses have been confirmed to be in the range of (25 ± 15.14) nm or (27 ± 15.14) nm which is almost the same. From TEM analysis particle dimensions have been confirmed to be in the range of (50 ± 29.38) nm width and (550 ± 302.75) nm length with the aspect ratio ~ 11:1 (length/diameter) at a 500 nm scale bar. On the other hand, at a 200 nm scale bar the particle dimensions have been confirmed to be in the range of (35 ± 17) nm width and (275 ± 151.38) nm length with the aspect ratio ~ 8:1. The aspect ratio of individual crystalline domain was determined in TEM analysis which is 10:1 (100/10). Therefore the aspect ratios and dimensions of nanoparticles in NCC suspension are almost the same and in nano-meter scale, as confirmed from both AFM and TEM results. The yield of NCC from B-RHP was found to be approximately 95%, and the recovery of cellulose from R-RHB is about 90%.