Pulp-bound organochlorine in fully-bleached chemical pulp

The spatial distribution of pulp-bound organochlorine in bleached chemical pulp fibres has been studied with state-of-the art microanalysis techniques with very low instrumental detection limit and, simultaneously, high spatial resolution. Many techniques were explored for use on pulp fibres. Most satisfactory results have been achieved through secondary ion mass spectrometry, which successfully reveals the distribution pattern of pulp-bound organochlorine in the fibre wall. It is found that chlorine distribution is relatively uniform along the fibre outer surface, but is occasionally more concentrated in some small areas. In the fibre cross-section, however, chlorine is enriched in the middle of the fibre wall. The heterogeneous distribution of pulp-bound organochlorine in bleached fibres has implications for fibre chemistry and ultrastructure.;This research addresses, for the first time, the question: can cellulose or hemicellulose contribute to the generation of organochlorine, especially pulp-bound organochlorine? It was discovered that organochlorine is indeed formed from the chlorination of cellulose and other carbohydrate materials which have been modified during cooking. The occurrence of carbohydrate-derived organochlorine broadens current perspectives in the chemistry of pulp bleaching.;The chemical bonding state of carbon-chlorine bonds was investigated with X-ray photoelectron spectroscopy. Moreover, the stability of pulp-bound organochlorine to various chemical treatments has been tested. Based on these studies, it has been established that pulp-bound organochlorine is covalently bound to the pulp, at least 100 ppm being bonded to cellulose. It is also rationalized in this thesis that the non-uniform distribution of pulp-bound organochlorine in fully-bleached fibres may be caused by the non-uniform distribution of hemicellulose and hence hemicellulose-linked organochlorine. Removal of this hemicellulose-linked organochlorine, e.g., through xylanase treatment, resulted in uniform chlorine distribution across the fibre wall.