Spectral analysis and kinetic studies of enzymatic delignification of kraft wood pulp by xylanase

Abstract

The traditional bleaching methods used chlorine as bleaching agent which produced large amount of chlorinated organic compounds including dioxins which are persistent environmental pollutants. The alternate methods using peroxides and enzymes were developed to achieve total chlorine free bleaching. The xylanase enzyme was used as bleaching agent in this study. The delignification study was performed to evaluate the optimum conditions required for obtaining minimum kappa number of the pulp to remove maximum lignin from the wood fibres. The interactions of various factors such as pulp consistency, enzyme dosage and temperature were studied. The best conditions for enzymatic bleaching obtained were 10% consistency, 50 IU of enzyme dosage and 52oC in the range studied. The predicative mathematical models were developed for enzymatic bleaching. The activation energy for xylanase delignification of paper pulp was 13.989kJ/mol. The significant functional groups in bleached pulp samples were analysed using Fourier transform infrared spectroscopy and the surface morphology of pulp fibres was studied using Scanning electron microscopy images.