Photoacoustic Fourier transform infrared spectroscopic study of hydrogen peroxide bleached de-inked pulps

The single-stage hydrogen peroxide bleaching of recycled de-inked pulps from old newsprint in the laboratory is investigated using Fourier transform infrared photoacoustic spectroscopy (FT-IR-PAS). Intensities relative to three internal standard peaks (3400, 1507, 1060 cm−1) were used to observe significant changes in the 1800–1300 cm−1 region due to chemical changes in the pulps resulting from the peroxide bleaching treatments. The bleaching and alkali treatments caused changes in absorption bands in the 1800–1300 cm−1 region. Variations in the band intensity have been related to changes in pulp brightness and to oxidation of the pulps.