Application of pyrolysis-gas chromatography-mass spectrometry to the analysis of pitch deposits and synthetic polymers in pulp and pulp mills

Abstract

Different pitch deposits and impurities, including synthetic polymers occurring in pulps and pulp-mills, have been studied by pyrolysis-GC/MS. Among the samples analyzed, two organic deposits taken from a pulp mill before and after elementary chlorine free (ECF) bleaching, a series of rubber pieces collected from a centri-cleaner unit, and a series of specks occasionally occurring in a total chlorine free (TCF) bleached pulp were selected for this study. Pyrolysis in the presence of a methylating agent, tetramethylammonium hydroxide (TMAH) was required to identify deposits formed by salts of ellagic and fatty acids since these moieties decarboxylate upon conventional pyrolysis. Pyrolysis of the selected rubber pieces allowed the identification of polyisoprene, polystyrene, poly-α-methylstyrene and other synthetic polymers not completely characterized, arising from machine breakage. Likewise, the specks occurring in a TCF pulp were constituted by small fragments of trans-poly(isoprene) rubber. The characteristic pyrograms could be used as fingerprints to trace their source.