Ionic Liquid-assisted Fabrication of Nanocellulose from Cotton Linter by High Pressure Homogenization

Nanocellulose (NC) was prepared from cotton linter using ionic liquid (IL) 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4) as both swelling agent and catalyst followed by high-pressure homogenization. Evidence suggested that the IL played a significant role with respect to hydrolysis of the linter cellulose. The effects of various reaction conditions on the NC preparation were investigated in this study. The successful conversion of the cotton to NC was analyzed, which showed that the prepared NC had a uniform rod-like shape that was 50 nm to 100 nm in diameter and 500 nm to 800 nm in length. The characterization of the NC by X-ray diffraction and thermogravimetric analysis revealed that the crystalline cellulose I structure was retained in the NC and it showed stable thermal properties. The recycled ionic liquid exhibited a slightly decreased cellulose hydrolysis ability. The application of [Bmim]HSO4 as both a catalyst and swelling agent introduced an effective and environmentally friendly method for NC production.