Study of the Influence of Bleaching Process Time on the Brightness of the De-Inked Waste Paper Pulp Using Hydrogen Peroxide as a Bleaching Agent

Abstract

This research aims to study bleaching time influence on the brightness level of the de-inked waste paper pulp using hydrogen peroxide as a bleaching agent, and that will be through evaluating how pulp brightness changes within a range of process times. In addition, the kinetics of the bleaching reaction is studied and analyzed.The experiments were conducted using a laboratory pulper designed to simulate the industrial pulpers, but also modified to meet the goals and conditions of the research.The results show that brightness increases with bleaching time, and the optimum time for bleaching process at research conditions was determined at 70 min. It is also found that applying longer times would contribute with only minimum additions on brightness and that do not justify the costs of operating with extended periods. On the other hand, lowering process time below 70 min may result in a considerable decrease in the brightness of the recycled pulp. Here, kinetics shows a significant remaining amount of peroxide after the process ends, which leads to lower brightness and efficiency.

Keywords: Bleaching, Time, Brightness, Hydrogen peroxide.