The Survey of Chemical Paper Pulp Properties Produced from Rice Straw Based on Formaldehyde Sulfide Method.

The aim of this study was to evaluate the effect of formaldehyde addition to Sodium Sulfide cooking liquor for chemical Pulp Production from rice straw. Rice straw (oryza sativa) was collected from the rice field of Salmanshahr and was carried to the laboratory of wood and paper in Gorgan University. Digestion conditions of pulp included cooking temperature of 160 °C، digestion times of 30، 60 and 90 min and useing chemical (16، 18 and، 20% Sodium sulfite and 4 and 6% formaldehyde) based on oven dry dosages weight of raw material. Four different treatments، at a Kappa number ranges of 12 - 14 were selected from each pulp In order to evaluate the effect of formaldehyde added based on Kappa number and pulp yield relations. Hand sheets with grammage of 60 g/m2 were prepared from each of pulp samples and their properties were measured using the related Tappi standard. The results indicated that the addetion of formaldehyde in sulfite liquor increased the pulp yield at the same Kappa number، accelerated delignification rate and improved delignification selectiving as well as improving the mechanical properties of paper