Pyrolysis products as markers in the chemical characterization of paperboards from waste paper and wheat straw pulps

Analytical pyrolysis was used to characterize paperboard prepared with wheat straw subjected either to semichemical or biomechanical pulping (the latter including solid-state fermentation with the ligninolytic fungi Pleurotus ostreatus and P. floridanus) and variable proportions of waste paper. Pyrolysis products were also quantified and selected in attempt to match the industrial and laboratory parameters used in the assessment of pulp quality. Although the pyrolytic compounds from straw pulp and from waste paper pulp (mainly derived from wood fibres) were essentially the same, significant quantitative differences were found. The yields of up to 14 pyrolytic compounds were related to the percentage of waste paper in the pulps: typical cinnamyl- and syringyl-phenolics being the most diagnostic for straw, whereas the methoxyphenols with an oxidized n-chain (aldehyde-ketone) were diagnostic for waste paper. Only the yields of six pyrolysis products (mainly anhydrosugar molecules) were significantly different as regards the pulping method, suggesting different hemicellulose removal patterns.