Improvement of Peroxide Bleaching Yield and Efficiency of TMP Using Glyoxal Crosslink Agents

Today, peroxide bleaching is the dominant bleaching process for thermomechanical pulp (TMP). The yield loss in peroxide bleaching mainly contributes to the dissolution and depolymerization of cellulose and hemicelluloses under alkaline conditions. In this research, a method that could partially crosslink cellulose and hemicelluloses to avoid the dissolution and depolymerization of carbohydrates, to increase pulp yield during the peroxide bleaching of TMP, was proposed. It was surprising that not only the bleaching yield was increased, but also the peroxide bleaching efficiency was remarkably improved. It was also determined that the proposed approach had no effect on most of the physical properties of the bleaching pulp. Effective components analysis indicated that glyoxal and modified glyoxal resins could improve the peroxide bleaching yield and efficiency of TMP. The possible mechanisms of the crosslinking agents to improve peroxide bleaching efficiency and yield were studied by ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectra analysis.