Investigation of the Effect of Process Parameters on Fabrication of Nanocrystalline Cellulose from Crotalaria Juncea

Abstract

Crotalaria juncea bast fibers a novel cellulose rich material is valorized by producing cellulose nanocrystals (CNCs) which gained much attention due to its unique properties. CNCs obtained during this study consisted of two steps: pretreatment of C. juncea fibers to obtain chemically purified cellulose followed by sulfuric acid hydrolysis. Efficacy of two different pretreatment methods chlor-alkali method (pre-treatment-I) and ultra sound assisted chlorine free alkaline peroxide (pre-treatment-II) methods was examined for CNC preparation. Pre-treatment-I was found to be more effective yielding higher crystallinity and higher surface sulfate ester groups containing CNCs compared to CNCs obtained using pre-treatment-II. Moreover the cellulose structure was altered with more pure cellulose-I structure obtained from pre-treatment-I. The process conditions of pre-treatment – I was optimized for CNC preparation. The acid concentration of 80%(w/v) was found to be optimized to produce CNCs with~43% yield, 80.9% crystallinity index having a rod-like structure (Length −120 ± 26 nm and diameter − 25 ± 5.5 nm). The surface charge density of the optimized CNC was found to be 0.34 meqv/g and a zeta potential −27.7 mV was recorded emphasizing stable dispersion.

Keywords

• nanocrystalline cellulose
• crotalaria juncea
• pretreatment
• crystallinity index
• degree of sulfation
• thermal stability