Isolation of Cellulose Nanofibres: Elucidation of a Novel Approach Utilizing Fungal Pretreatment

In plant cell wall, cellulose chains are organized into perfect stereoregular configuration called microfibrils through a regular network of inter and intramolecular hydrogen bonds. The cellulose microfibril along with hemicellulose chains that tether to the cellulose microfibrils and other polysaccharides through hydrogen bonding forms the cell wall structural framework. Isolation and application of cellulose nanofibres is expanding rapidly due to their environmental benefits and specific strength properties, especially in nano-biocomposite area. Currently, cellulose nanofibres are isolated from natural fibres through a combination of high energy refining and high pressure homogenization or through a combination of biological and mechanical process that involves fibre treatment with hydrolytic enzymes followed by high pressure homogenization and all of these processes are very energy intensive. In this research, a fungal pre-treatment for wood fibres is investigated which can bring about internal defibrillation in the fibres through reduction of hydrogen bonds and cleavage of hemicellulose chains tethering the cellulose microfibrils together. The pre-treatment of wood fibres with Ophiostoma Ulmi, a causative agent of Dutch elm disease in Elm trees, has found to reduce the energy requirement to isolate cellulose nanofibres. The treatment has found to bring about internal defibrillation in the fibres by disrupting the hydrogen bonding that holds the hemicellulose - cellulose microfibril network and the cellulose chain in the cellulose microfibrils together. The effect of bio-treatment on hydrogen bonding density and their nature in the fibre cell wall was investigated using FT-IR and 13C NMR and its effect on cellulose structure using FT-IR and X-ray crystallography. The treated fibres showed a decrease in the intra-molecular hydrogen bonding density and crystallinity and also a decrease in the hemicellulose content. The net energy required to isolate cellulose nanofibres from bio-treated fibres was estimated at 2,000 kWh/T compared to 16,000 kWh/T required for isolating nanofibres from untreated fibres. The isolation of cellulose nanofibres from treated and untreated fibres by refining in disk refiner tends to obey the Rittinger’s law. These observations confirm the fact that Ophiostoma ulmi treatment of fibres can significantly reduce the energy required to isolate cellulose nanofibres from wood pulp fibres.

Department dc:contributor.department

Chemical Engineering and Applied Chemistry

Year dc:date.issued

2012

Author dc:creator

• Janardhnan, Sreekumar

Advisor dc:contributor.advisor

• Sain, Mohini

• Cellulose
• Nanofibres
• Ophiostoma Ulmi
• Internal defibrillation
• Hydrogen bond
• FTIR spectroscopy
• NMR spectroscopy
• Cellulose nanofibre isolation

Language dc:language.iso

en_ca

Handle dc:identifier.uri

http://hdl.handle.net/1807/67279

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/67279