Cellulose nanofibers based materials have emerged to be promising green and sustainable materials, due to their exceptional properties like biodegradability, abundance, high strength, good mechanical and thermal properties. These bio-based materials have gained importance because of their diverse applications in nanofiber-reinforced composites, separation membranes, cosmetics, flame-resistant materials, gas film barriers and biomedical applications. However, the defibrillation of cellulose into nanocellulose requires intense use of chemicals and mechanical energy. Also, the properties of nanofibers including chemical, mechanical and morphological vary with the process of pretreatment and defibrillation. Therefore, extracting high grade nanofibers from cellulose by applying considerably less mechanical energy and chemical consumption is a technological challenge.<br/>Here in this work, three different defibrillating approaches: TEMPO-mediated oxidation, nitric acid/ sodium nitrite oxidation and high pressure homogenization were applied, in order to achieve inexpensive and more sustainable defibrillating process for high hemicellulose content grass. Different characterization techniques like electrical conductivity titrations, transmission electron microscopy(TEM), fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), 13C CP-MAS NMR and Thermogravimetry(TGA) were performed to study charge density, structure and morphology of cellulose nanofibers obtained.<br/><br/>A comparative study of mentioned three processes on spinifex grass indicate that the quality of nanofibers, in terms of aspect ratio is best from TEMPO-oxidation. The chemical consumption during the process of preparation of charged nanofibers is extensively decreased for nitric acid/sodium nitrite process in comparison to TEMPO oxidation because raw biomass was used directly without any chemical pretreatment and mechanical assistance. Although, the chemicals used during the process of homogenized and nitric acid/sodium nitrite process are comparatively same, but the product obtained from homogenized process is more aggregated and have the impurities of microfibers. Carboxycellulose fibers from nitric acid approach are being investigated as adsorbents for heavy metal ion remediation from waste-water while TEMPO-oxidized nanofibers will be best suited in membrane technology for water purification.

Extraction of nanocellulose from a unique grass - spinifex via different methods and its application in water purification

256th National Meeting (2018)

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