Chlorinated fluorenes and alkylfluorenes in bleached kraft pulp and pulp mill discharges

The occurrence and levels of polychlorinated fluorenes (PCFLs), methylfluorenes (C₁-PCFLs) and dimethylfluorenes (C₂-PCFLs) were studied by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) in hardwood and softwood pulp, effluent and biosludge from a bleached kraft mill. Semiquantitative concentrations of these compounds were estimated using selected ion monitoring and a mass spectral resolution of 10,000. The identification of PCFLs and C₁-PCFLs was confirmed by the chlorination mixtures of fluorene and 2-methylfluorene.

Several congeners were found for each compound groups studied and isomer patterns were similar in bleached pulp and biosludge. The approximated sum levels of di- and trichloro isomers of PCFLs, C₁-PCFLs and C₂-PCFLs in the biosludge were about 2, 5 and 4 ng/g dry weight (dw), respectively. The levels of the corresponding compounds in the softwood pulp were 0.5, 0.8 and 0.2 ng/g dw, respectively. Of the studied compounds, only C₁-diCFLs (0.01 ng/g dw) were detected in the hardwood pulp. In the effluent, PCFLs were non-detectable, but traces of C₁-diCFLs (0.5 ng/L) and C₂-pentaCFLs (0.06 ng/L) were found. These were observed mainly as dissolved in the filtrate and not as particle-bound.