ECF bleaching technology of wheat straw pulp with high silicon content

The study of ECF bleaching for wheat straw with high silica content was carried out. The effects of the high silica content on the bleaching performance were also analyzed. The research was mainly focused on the bleaching effects of the pulp in D stage through various dosage of chlorine dioxide and different bleaching temperature, as well as P stage of different dosage of hydrogen peroxide. Results show that the process with the addition of 0.8% chlorine dioxide in D stage, the temperature 70℃, and 2.5% hydrogen peroxide in P stage, the pulps can be bleached to 84.73%ISO brightness by DEQP sequences. The viscosity is 576 ml/g, ash content is 6.13% and silica content is 3.11% in the bleached pulps. Compared with the pulp properties and the state of the silica cells observed by using optical microscope with the brown pulp, the silica exists in the forms of compounds in the pulp and has no effect on wheat straw pulp bleaching performance.