Hydrogen Peroxide Bleaching of Agro-Based Fibers Bleachability and Improvement

摘要

A method of bleaching agro-based fiber materials including wheat straw, flax and hemp comprises two steps: pretreatment of the fibers with an aqueous acidic solution (e.g. pH 2 - 3) followed by conventional hydrogen peroxide bleaching. This process offers a multiple-fold increase in bleaching efficiency as compared to conventional bleaching. While low pH promotes removal of transition metals, other mechanisms may also contribute to the brightening enhancement resulting from the pretreatment. This process can eliminate the need of adding sodium silicate and magnesium sulfate as peroxide stabilizers. Between the fiber materials, flax and hemp have far better bleachability than wheat straw.