Summary Bench filtrates from three-stage conventional bleaching sequences (CEoD) with substitution degrees of chlorine by chlorine dioxide in the first stage equals to zero, 25%, 75% and 100% have been analysed for their content of chlorinated phenolic compounds (CPCs). Alternatively, CPCs filtrates content of an AZEoPD sequence were also determined. A cellulose pulp obtained from a mixture of 85% Eucalyptus saligna (young trees) and 15% Acacia mearnsii delignified with oxygen (kappa number 10.0) was employed in all bleaching tests. Levels of CPCs were determined by using an in situ acetylation method followed by GC/ECD technique. GC/MS of bleaching filtrates was employed in qualitative analyses. CPCs content in filtrates and the Kovacs' equivalent toxicity for the total filtrates of the studied bleaching sequences are presented. The lowest content of CPCs was found in AZEoPD filtrates, as expected due to the utilised bleaching agents. CPCs were not detected in the filtrates of stage D from the AZEoPD sequence probably due to the low lignin content of the pulp. Mixed filtrates of the sequence DEoD, showed the lowest CPCs content among conventional bleachings. Results are in accordance with those found in the literature for hardwood and softwood pulp. The equivalent toxicity in the sequences Dc(75/25), DEoD and AZEoPD was found to be lower than the limit given by Kovacs to characterise chronical toxicity.
Abstract.Two methods for analysis of chlorinated organic compounds found in pulp bleaching effluents have been compared in order to determine their efficiencies. Method A uses a solid phase extraction followed by derivatization with acetic anhydride. Method B consists in an in situ derivatization followed by liquid-liquid extraction of the acetic esters. Both methods have proved to be efficient for analyzing chlorinated organic compounds and, with the exception of 3,4,5-trichlorosyringol which appeared in a very low concentration when method A was employed, all compounds present in the standard mixture as well as in a pulp bleaching effluent sample have been detected. A detection limit of 0.4 ppb has been established. Quantitative determinations are being carried out and will be presented in a future article. 0 1995 John Wiley 9: Sona, Inc.
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