PURPOSE: To suppress the formation of nitrified substance in delignifying and bleaching process by reacting lignocellulosic pulp with a sufficient liquid nitrosating agent in an acidic and oxygen atmosphere under powerful agitating condition before alkaline oxidative stages.
CONSTITUTION: Lignocellulosic pulp, especially chemically cooked lignocellulosic pulp, is reacted with sufficient liquid nitrosating agent and at least a stoichiometric amount of oxygen in the acidic and oxygen atmosphere under powerful agitating condition at a pH of 1.7-4, before alkaline oxidative stages in the bleaching sequence. The consistency of the pulp in water is set at least 5 wt.%, and setting the amount of the nitrosating agent as sufficient to give about 0.1-1.2 wt.%, of the active nitrosonium ion based on the pulp dried in the furnace.
RUPAATO DOUSOUZA
JIEFURII SHIYAOCHIENGU SHII
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