Organic composition of a pulp and paper mill sludge determined by FTIR, C-13 CP MAS NMR, and chemical extraction techniques

The organic composition of a primary pulp and paper mill sludge (PMS) was determined by carbon-13 cross polarization nuclear magnetic resonance spectroscopy with magic angle spinning (C-13 CP MAS NMR), Fourier-transformed infrared spectroscopy (FTIR), and chemical extraction methods. Spectroscopic studies showed that the PMS consisted of cellulose type I, which is present in ordinary pulp, with a minor uronic acid and lignin contribution. Minor to large structural changes occurred during extraction of lignin, holocellulose, and cellulose. The standard chemical techniques used to extract these components resulted in sample degradation as well as changes in functionality and structural organization. Chemical extraction techniques were therefore unsuitable to accurately quantitate the organic composition of PMS, and the spectroscopic techniques used provided a more reliable, semiquantitative assessment of actual organic composition.