Efficient removal of residual lignin from eucalyptus pulp via high-concentration chlorine dioxide treatment and its effect on the properties of residual solids

In fact, effectively removing lignin from pulp fibers facilitates the conversion and utilization of cellulose. In this study, the residual lignin in eucalyptus pulp was separated using a high concentration of chlorine dioxide. The effects of chlorine dioxide dosage, temperature, and time on lignin removal were investigated. The optimal conditions are chlorine dioxide dosage 5.0%, reaction temperature 40 °C, and reaction time 30 min. The lignin removal yield is 88.21%. The removal yields of cellulose and hemicellulose are 2.28 and 17.00%, respectively. The treated eucalyptus pulp has higher fiber crystallinity and thermal stability. The carbon content on the fiber surface is significantly reduced. The results show that lignin is removed by efficient oxidation, and the degradation of carbohydrates is inhibited using high concentrations of chlorine dioxide at low temperatures and short reaction times. This provides theoretical support for high value conversion of cellulose.