Optimization and Characterization of Cellulose Nanocrystal Production from Aseptic Tetra Pak Food Packaging Waste

Abstract

Cellulose fibers were extracted from the recycled Tetra Pak aseptic food package wastes, and high value-added cellulose nanocrystals (CNC) were produced by the acidic hydrolysis. At the optimum H2SO4 concentration of 25% w, the whiteness index of CNC obtained at 30 °C for 30 min CNC was 84.42%, while it was 56.00% for 50 °C for 60 min CNC. The effects of temperature and time on the hydrolysis yield were optimized by the Central Composite Design and the maximum yield was determined at the condition where the temperature was high and the time was the lowest. The physical and structural properties of different CNCs were investigated using several characterization techniques. The FTIR and TGA analyses of the CNCs obtained at different temperatures and times showed similar spectra and degradation temperatures with each other, respectively. The crystallinity index of alkaline-treated cellulose calculated from the XRD patterns was much lower than those of all of the CNCs. According to AFM measurements and SEM micrographs, it was confirmed that as the temperature and time increased, the diameters of the CNCs were reduced. The lowest diameter value was measured as 175 nm at 50 °C for 60 min CNC, whereas, on the other hand, the highest diameter value was measured as 403 nm at 30 °C for 30 min CNC.