Physicochemical characterization of microcrystalline cellulose derived from underutilized orange peel waste as a sustainable resource under biorefinery concept

In this work, orange (Citrus sinensis) peel has been explored as sustainable resource for the production of microcrystalline cellulose (MCC). Herein, two strategies, i.e. (route 1) traditional acidified sodium chlorite and (route 2) ecofriendly total chlorine free (TCF) methods were compared for their efficiency in removing non-cellulosic constituents. Afterwards, ultrastructure, composition, crystallinity and thermal properties of the resulting MCCs were investigated. As compared to MCC-1, MCC-2 presented smooth surface with no non-fibrous components. From XRD diffractograms, highest CrI value obtained for MCC-2 (85 %) as compared to MCC-1 (69 %) which pointed towards superior purification efficiency of TCF approach corroborated with the outcome of FTIR and SEM analysis. TGA-DTG analysis showed that Tmax value shifted to ∼330 °C for MCCs, compared to native OP (313 °C). The observed WHC of MCCs was higher than their precursors due to more exposed surface area available for hydrophilic interactions that improved its water retention ability.