A series of experiments was performed to evaluate the effect of substituting sodium carbonate for the sodium hydroxide used in peroxide bleaching of spruce CTMP. Three peroxide levels were tested: I , 2, and 4% HzOz, and two levels of causticsubstitution; SO% and 80%. At both the 2% and 4% peroxide levels, substituting 50% of the caustic charge with sodium carbonate decreased the initial bright...
