Individualization of nanofibrillated cellulose from Sri Lankan rice straw: structural characteristics and thermal properties

Abstract

Rice straw is the agricultural production residue which is considered as an agricultural waste. Though it is utilized in various ways, there is a greater possibility for value addition by disintegrating nanofibrillated cellulose from this commercially underutilized waste material. In this study, nanofibrillated cellulose (NFC) was individualized from locally available rice straw variety Murunkan via chemo-mechanical treatments. Firstly, cellulose fibers were extracted from rice straw via a set of chemical processes. Then using high intensity ultrasonication (HIUS) treatment acquired cellulose fibers were individualized into nanofibrillated cellulose. Structural, morphological and thermal behavior of NFC throughout the chemo-mechanical processes were studied. FTIR analysis confirmed that the chemical composition of nanofibrillated cellulose was mainly cellulose where amorphous natured hemicellulose and lignin were effectively removed during chemical processes. From the set of chemical processes, Murunkan variety yielded around 34 per cent cellulose fibers. Out of these cellulose fibers around 17 per cent NFC was individualized via the HIUS treatment. Microscopy study showed that the diameters of the extracted NFC ranged between 100 to 200 nm. Findings of this study will not only add value to the rice straw but also embrace sustainable transition to a bioeconomy in the country.