Cauliflower Waste Derived Lignin-Containing Cellulose Film: Synthesis, Characterization and Study of Thermal and Electrical Conductivity Properties

Abstract

Cauliflower has the highest ratio of non-edible to edible portion and hence generates a huge amount of waste biomass which may comprise of proximately 17.32% cellulose, 9.12% hemicellulose, and 5.94% lignin. This study focused on the successful synthesis of lignin- containing cellulose nanocrystals (LCCN) from the non-edible portion of cauliflower using a combination of alkali treatment and mild acid hydrolysis. The highly dispersed nanophase of the synthesized nanocellulose in LCCN was confirmed by X-ray diffraction (XRD) and had a crystallite size of 7.26 nm and a crystallinity index of 53.5%. The chemical, mechanical and conductive properties of LCCN were examined by standard methods such as Fourier- transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and four-probe instrument. Uniform and flexible thin films of the synthesized LCCN using 40% acid fraction were found to be suitable and were successfully prepared on a glass plate at ambient temperature by solvent casting method. The thickness of this 40% fraction LCCN film was measured to be 55μm by the interference method and it also showed the lowest thermal expansion and highest thermal stability. Conductivity studies indicated the lowest resistivity of 0.755 Ohm. cm in 40% LCCN. Therefore the synthesized LCCN film can be a useful low-cost, environment-friendly biopolymer material for a number of next-generation composite preparations, conductive substances, and packaging applications.