CELLULOSE

1. CELLULOSE CHEMIS1RY AND lECHNOLOGY ~ . TOTALLY CHLORINE FREE (TCF) BLEACHING OF WHEAT STRAW SODA -ANTHRAQUINONE PULP A. JAHAN LATffiARI, S. HEDJAZI,* R. PATI,** o. KORDSACHIA*** and U. TSCHIRNER**** AzadIslamic Uriiversity, Karat], Iran *Faculty cfNatural Resources, University cfTehran, Karat], Iran **Zentrum Holzwirtschcft (lHW), University cfHamburg, Germany ***Federal Research Center for Forest and Forest Product, Institute for Wood Chemistry and Chemical Technology cfWood, Hamburg, Germany ****Faculty cfNatural Resources, University cf Minnesota, 204 Katfert Laboratory, USA Received July 19,2005 Totally cWorine free (TCF) bleaching of wheat straw soda -anthraquinone (AQ) pulp was investigated. Previous pulping experiments,perfonned \U1der different conditions had revealed that soda -AQ pUlpulg with 16% active alkali for 90 minutes, at 160 °C, yields pulp suitable for bleaching experiments. TCF bleachingwas perfonned in an 0 Q (OP) or 0 Q (OP)P sequence.Oxygen delignification with an alkali chargeof 2.5 % NaOH at 90 °C and 90 min resulted in a delignification rate over 50 %. In the subsequent (OP) stage,drastic conditions (4% HzOz, 2.75% NaOH, 90 min at 98 °C) were required to exceed an 80% ISO brightness. With a final P stage,brightness could be improved to 84-85% ISO. Bleaching led to only small losses in tensile and burst strength for \U1changed strength. Shortbeating in a Jokro mill was sufficient to tear attain a breaking length well above 7 kill. The results of tJ:J.e study indicate that TCF bleaching can be successfullyapplied to wheat straw soda -AQ pulps to produce pulp for writing and printing paper \;ithout detrimentally affecting the environment. KEywords: wf,eat straw, soda -AQ pulping, TCF bleaching INTRODUCTION Iran, located in an arid region, is mainly a the paper industry. Bagasse has been utilized land of deserts and mountains, and only a on a large scale in pulp production for the last very small part of its area is covered with 40 years and its utilization is now forests. These forests are mainly well-established. non-productive. Some wood lands scattered The annual production of almost 10 in the mountains ought to provide wood for a million tonnes of straw in Iran represents a demanding society with growing population. promising potential of fiber supply for the Therefore, Iran is facing a severe shortage of pulp and paper industry, as well as for board wood supply, which is increasing annually. production, yet the utilization of straw for Consequently, Iran, like most of the Asian such ends has not been considered as countries, has been searching for different seriously as it deserves. Various factors have sources of cellulosic fibers to fulfill its impeded large-scale utilization of straw for requirements for pulp production. fiber supply. Anlong them, cattle feed Fibers from non-wood agricultural I utilization and deficiencies in the appropriate residues such as wheat and rice straw, as well technology for straw storage and handling are as bagasse from sugar cane plantations, the "YO most important ones. Straw is be.ing present promising fiber supply sources for used as cattle fodder, although its nutrition Cellulose Chern. Technol., 40 (t), 413-420 (200(;) i