The delignification and bleaching of non-wood fibres with peroxymonosulphate. Part 4. Jute

The effect of peroxymonosulphate (Oxone) as an activating agent for the delignification of jute has been studied. Activation conditions were varied in the following ranges: Oxone0-200 gL-1 and temperature 30-100°. Delignification was followed by extraction with 1 M NaOH. The residues were analysed for lignin and residual neutral sugar composition both before and after alkali extraction. Diffuse reflectance Fourier-transform infrared spectra of the residues after alkali extraction were analysed. Treatment of jute with acid alone showed that the constituent NCPs were relatively resistant to acidolysis even at 100°, although there was evidence of acidolysis of lignin-carbohydrate linkages in the corresponding DRIFT spectra. Treatment with acidic Oxone reduced residual levels of both lignin and non-cellulosic polysaccharides. Subsequent extraction of the residues with 1 M NaOH produced greater reductions. Delignification exhibited a direct relationship with both temperature and Oxone concentration, resulting in a maximum level of lignin removal of 97%. There was evidence that some of the constituent pectic polysaccharides and glucomannan were linked to lignin, Oxoneproved to be an effective bleaching agent and produced increased levels of brightness with increasing temperature and Oxone concentration. In some cases, equivalent levels of brightness were achieved by concurrently increasing the temperature and decreasing the Oxone concentration.