Oxygen-delignified kraft pulps from mature and young eucalypt woods were bleached with sequences involving chlorine (C), chlorine dioxide (D) and alkali-oxygen (EO). The bleaching filtrates were analysed for chlorinated organic compounds by gas chromatography with the use of a mass selective detector. Chlorinated compounds found included a range of chlorinated phenols, neutral compounds, aliphatic acids and phenolic acids. A total of 41 chlorinated phenols were identified, mostly in the filtrates following chlorination {(EO)[C]} and only few in the (EO)[D] filtrates. 2-Chlorosyringaldehyde was the only significant chlorinated phenol obtained after D-prebleaching. There was no indication of differences in the types of chlorinated phenols obtained from the mature and young eucalypt samples, although there were higher levels of phenols in filtrates from the younger wood sample. The dominant chlorinated neutral compounds found in the filtrates were chloroform, chloroacetones and chlorodimethylsulfones. Most chloroform and chloroacetones were found in the C-stage filtrates, while chlorodimethylsulfones were found in both C and D-stage filtrates to the same extent. An abundant compound with probable molecular formula C5H3ClO3 was also in the neutral fraction. The chloroacetic acids were the only aliphatic acids detected and were found in all filtrates examined. A method for the analysis of chlorinated phenolic acids involving sequential acetylation and methylation of the extracts was devised. Three chlorinated phenolic acids were identified in the filtrates as their methyl ester acetates. The total amount of chlorinated compounds analysed was consistently higher in the young eucalypt sample than in the mature sample, and correlated well with the generic parameters AOX and EOX. High molar mass (HMM) solids prepared from the C(EO) bleaching filtrates by ultrafiltration had higher chlorine contents than those from the D(EO) bleaching filtrates. Apparent molecular mass distributions of the HMM solids determined by high performance size exclusion chromatography were dependent on the method of detection.

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