Feasibility of rice straw as a raw material for the production of soda cellulose pulp

The main objective of this work is to evaluate the suitability of rice straw and soda anthraquinone (soda-AQ) pulping process to produce pulp and paper. To reach this aim, it was used a central composite factorial design to study the influence of operational variables (temperature (155-185 degrees C), cooking time (30-90 min), soda concentration (10-20%), anthraquinone concentration (0-1%) and liquid/solid ratio (6-8)), in soda anthraquinone cooking of rice straw on pulps and paper sheets properties obtained. Based on the yield values obtained, nearly one half of the raw material can be efficiently converted into cellulose pulp and paper sheets. Also, the Kappa number/viscosity ratio of the pulp facilitates its efficient bleaching. Finally, based on the values for above-described physical properties, the pulp can be used to obtain paper or board and recycled paper (as % virgin fibre). In Spain are produced annually 757,000 t of rice straw. If we considered an average yield process of 45%, it would be possible to obtain 340,000 tons of pulp. These tons would be absorbed by the market taking into account the necessities in cellulosic pulp consumption. (C) 2010 Elsevier Ltd. All rights reserved.