Valorization of pea by-products for the isolation of cellulosic microfibers: extraction and physico-chemical characterization

Abstract

Tremendous by-products are generated from food processes, which cause environmental and economic issues. The valorization of these low-priced wastes will, not only reduce these drawbacks, but also provide attractive raw materials for alternative sustainable technologies. The aim of this study was to explore the utilization of agro-industrial wastes, the pea pods, as renewable bio-sources for the isolation of cellulosic microfibers (CMFs). The CMFs were extracted applying a multi-step process (dewaxing, hot water, alkaline and chlorine-free bleaching treatments). The analysis of the raw material indicated that it contains 27.3 ± 0.700% wt α−cellulose, 17.3 ± 1.201% wt hemicelluloses and 14.94 ± 0.028% wt lignin, amongst other components. The yield, α-cellulose content and average thickness of the extracted CMFs were 26.1 ± 1.430%, 84.38 ± 0.37 % and 11 ± 0.905 µm, respectively. The discard of the majority of lignin and hemicelluloses from the surface of the fibers was checked by color study, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and thermogravimetry (ATG). The peaks exhibited by the isolated CMFs in X-ray diffraction patterns refer to the presence of type I cellulose with a crystallinity of 63.61%. Additionally, thermogravimetric analysis demonstrated the thermal stability of CMFs compared to the raw material. Data are promising for getting benefits from these vegetable wastes for cellulose isolation and its potential application in bio-based materials leading to an efficacious waste control.