Hydrogen peroxide bleaching of CMP pulp using magnesium hydroxide

Abstract

Conventional bleaching of hardwood CMP pulp with magnesium hydroxide (Mg(OH)2) show significant benefits over bleaching with sodium hydroxide (NaOH) under various conditions. Magnesium hydroxide bleaching generate higher optical properties, higher pulp yield and lower effluent COD at the same chemical charge, but the physical properties were found to be similar for both processes. The initial freeness of the bleached pulps and refining value to reach a target freeness (about 350 ml. CSF) were more for the Mg(OH)2-based process. The residual peroxide of filtrate from the Mg(OH)2-based process was very high as compared to conventional bleaching.