Extraction of hemicellulose by hot water to reduce adsorbable organic halogen formation in chlorine dioxide bleaching of bagasse pulp

To study the influence of the content of hemicellulose on the absorbable organic halogen (AOX) formation in chlorine dioxide bleaching, a pH pre-corrected hot water pretreatment was developed. The influence of lignin on AOX formation was eliminated by the control of hot water extraction time, AOX formation was decreased by 33.27% under optimal hot water extraction conditions. The chemical composition of bleaching effluent was analyzed by GC-MS, and the formation of chlorobenzene and chlorophenol was inhibited by removal of hemicellulose, the ring structures of which were degraded into chain macromolecules and small molecules. The hemicellulose structure of raw material and bleached pulp was characterized by ATR-FTIR and NMR. This finding revealed differences in the structures of the bagasse hemicelluloses and the solid residual hemicelluloses. AOX formation was affected by the structure of hemicellulose. A new process combining biorefinery and clean pulp and paper was developed through these experiments.