Refining, dewatering, and paper properties of soda-anthraquinone (soda/AQ) pulp from rice straw

Abstract

The dynamic drainage, zeta potential, cationic demand, fiber morphology, ash content, and silica content of rice straw soda-anthraquinone (soda/AQ) pulps were measured to study the effects of a mechanical treatment on the drainage performance. The physical properties of handsheets prepared from each beaten sample were also analyzed. It was indicated that pulp fibers played an important role in increasing the beating degree in comparison with non-fibrous cells during refining. The dynamic drainage curve could be divided into three different stages in terms of the drainage rate, and the difference between the pulps screened-out non-fibrous cells (Pnof), and unremoved non-fibrous cells (Pf) decreased with refining. Due to the absence of a large quantity of non-fibrous cells, as the beating proceeded, the straw pulp presented an ever-increasing tendency in terms of kink index and curl index. Also, cationic demands of pulps increased linearly and the zeta potential of the fibers decreased gradually with beating. Rice straw was found to be favorable for papermaking, helping to compensate for an acute shortage of wood in China.