PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 1, Number 1, 2015
Figure 3. The 13C-NMR spectra of raw RPMS.
The presence of N alkyl C may also contributed to this resonance region. The large doublet between 72 and 75ppm was due to the C-2, C-3 and C-5 carbons of cellulose and the peak at 63 and 65ppm was due to the cellulose C-6 carbon. The signal at 89ppm and highly shielded shoulder at 83ppm were due to presence of cellulose carbon C-4. Usually the peaks at 72 and 106ppm are thought to correspond to resonance of carbons in polysaccharides rings and to anomeric carbons in polysaccharides [42]. Furthermore, Schmidt et al . [43] observed the signal at 72 and 106ppm together with a shoulder around 65 to 90ppm, most likely due to polysaccharides. The peak at 103ppm was due to hemicellulose. The high resonance at 174ppm may arise from phenolate, carboxylic and amide groups [44]. The 13C NMR obtained in this study suggested that the RPMS consisted of chemically isolated cellulose and contains little lignin plus hemicellulose-like material. The high cellulose content in the paper mill sludge may be accounted for in part by mechanical and chemical degradation occurring during paper manufacture and bleaching. The lack and comparatively low level of lignin was due to the bleaching process. The mechanical degradation of polysaccharides during paper manufacturing may thus be responsible for the production of paper mill sludge with a high cellulose and low lignin content. 3.6. FTIR Spectra of Paper Mill Sludge The FTIR spectrum complemented the structural information obtained in the 13C-NMR spectrum. Infrared spectroscopy is a technique used to identify various functional groups in unknown substances via the identification of bond vibrations at designated wavelengths. The FTIR spectrum for the raw RPMS of Paper Mill 2 (PM2) (Figure 4) showed a broad band around 3389cm − 1 corresponding to OH stretching of phenolic OH groups. The band attributed to the hydroxyl group and water at 3700 – 4000cm − 1 was also detected in the raw and RPMS compost. The moisture of raw and RPMS compost was found to be higher than the mineral soil. However, the intensity was too weak and considered insignificant. A distinct peak at 2924cm − 1 corresponding to C-H stretching of the CH2 groups, indicates
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Article 2 – Environment (sludge)
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