過酸化水素漂白 過酸化水素漂白反応機構の基礎理論

Abstract

Since the worldwide pulp bleaching technologies have been changing rapidly from chlorine to non-chlorine, the role of hydrogen peroxide in pulp bleaching is getting more and more important recently. Hydrogen peroxide is a rather unstable bleaching reagent especially under the presence of metalic ions. Yet, the decomposition mechanisms are not well understood. Decomposition of hydrogen peroxide leads to the formation of acitive oxygen species which take part in the reaction with chemical components of pulp and it makes the chemistry of hydrogen peroxide bleaching even more complicated.Hydrogen perxiode itself is a nucleophylic reagent. It is often used in alkaline media to form an even stronger nucleophile which is a hydroperoxy anion. It can be used as an electrophile through activation by various methods. The active oxygen species formed from hydrogen peroxide may also react with pulp constituents as bleaching reagents. Thus, there are many kinds of reactions possible in hydrogen peroxide bleaching. However, the selevities of the reactions, which are to decompose lignin without docomposing cellulose, have got to be always taken into consideration.In view of above mentioned points, discussed here are several bleaching processes such as stabilized hydrogen peroxide bleaching, high temperature hydrogen peroxide bleaching, acidic hydrogen peroxide bleaching, dioxirane bleaching and peracid bleaching.