Production of Cellulose Nanocrystals Suspension with High Yields from Water Hyacinth

Abstract

ABSTRACT Acid hydrolysis is commonly used to extract cellulose nanocrystals (CNC) from natural fibers. This research thus investigates the effect of hydrolysis temperatures and time on the yields of CNC from water hyacinth. The aim is to determine the optimal acid hydrolysis condition for water hyacinth fiber that effectively enhances the CNC yield. The acid hydrolysis temperatures were varied between 50 and 60°C and the hydrolysis time between 15, 30, 60, and 120 min. Prior to the hydrolysis, raw water hyacinth fiber was treated with alkaline and bleached by hydrogen peroxide. The results showed that the optimal hydrolysis condition was 60°C and 30 min, with the crystallinity index of 80%, the crystalline size of 3.91 nm, and the CNC yield of 71.5%. The transmission electron microscopy morphology of CNC from water hyacinth was of whisker shape, with the diameter and length of 10 nm and 200–500 nm. The results also indicated that, unlike the hydrolysis time, the hydrolysis temperature had a negligible effect on the crystallinity index. Besides, under the optimal hydrolysis condition, CNC was of stable aqueous suspension with a zeta potential of −43.21 mV, indicating high physical colloidal stability.