| 摘要 |
<p>PURPOSE: To decolor and bleach colored waste paper without deteriorating properties of cellulose fiber by treating the colored waste paper with an oxidizing reactant consisting of an peroxide such as monoperoxysulfuric acid (or its salt), or its mixture, and an aqueous solution of a halogen ion. CONSTITUTION: Colored waste paper for xerography or the like is treated to make pulp by a pulp-making machine or the like beforehand, the formed pulp is washed, and after the addition of an oxidizing reactant consisting of at least one kind selected from peroxides (e.g. potassium monoperoxysulfate) such as monoperoxysulfuric acid and mixtures of one or more kinds of its salts, and an aqueous solution (e.g. hydrochloric acid) of a halogen ion selected from bromine, chlorine and iodine ions, and their mixtures, the washed pulp is treated under acidic condition of pH 2.7 at the start and then pH of no larger than 3.5, at a concentration of 12% in terms of dry pulp at 60 deg.C for 60 min. Thus, colored waste paper is decolored and bleached without deteriorating the properties of cellulose pulp.</p> |
