Novel Chemo-Mechanical Production of Nanocellulose from Coconut Pith

Abstract

Nanocellulose has been receiving tremendous attention due to its unique properties such as high strength, flexibility low density, biocompatibility, and natural hydrophilicity with numerous hydroxyl groups effortlessly modified for different purposes. Lignocellulosic biomass, especially coconut residues like coconut shells, coconut fibers, coconut husks, etc., has been effectively utilized for cellulose production in various sizes and morphologies such as microcrystalline cellulose, nanocellulose crystals, nanocellulose fibrils. In this study, novel chemo-mechanical production of nanocellulose from coconut pith (CP) is developed by implementing two-stage alkaline pretreatment, ball milling, acid hydrolysis, centrifugation, and dialysis. Nanocellulose obtained from CP is evaluated for its particle size distribution, zeta potential, chemical composition, crystalline and chemical structure. All parameters of ball-milling time, solid-to-liquid ratio, and hydrolysis duration greatly affect the formation of cellulose nanoparticles from CP as well as the stability of the particle system. Based on the experimental results, the cumulative intensity of particle size below 300 nm and in the range of 300 – 600 nm is respectively 40.93% and 59.08%, indicating the evident effectiveness of the developed chemo-mechanical approach in nanocellulose synthesis from cellulose-rich CP with an initial high holocellulose content of 49.07%. Remarkably, the crystallinity index of our nanocellulose from CP is as high as 72.08% compared to that from coconut husks. The present work demonstrates the potency of combining ball milling and acid hydrolysis in stable nanocellulose synthesis from CP and lays the foundation for further investigation to apply the formulated technique in industrial production.