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s. Hedjazi*1, A. Jahan Latibari2, R. Patt3, O. Kordsachia4, D. ParsapajouhS and U. Tschirner6

s. Hedjazi*1, A. Jahan Latibari2, R. Patt3, O. Kordsachia4, D. ParsapajouhS and U. Tschirner6. 1Ph.D. Student, Faculty of Natural Resources,University of Tehran, I.R. Iran. 2 Assistant professor, Islamic Azad University, Karadj, I.R.lran.

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s. Hedjazi*1, A. Jahan Latibari2, R. Patt3, O. Kordsachia4, D. ParsapajouhS and U. Tschirner6

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  1. s. Hedjazi*1, A. Jahan Latibari2, R. Patt3, O. Kordsachia4, D. ParsapajouhS and U. Tschirner6 1Ph.D. Student, Faculty of Natural Resources,University of Tehran, I.R. Iran 2 Assistant professor, Islamic Azad University, Karadj, I.R.lran. 3Professor, Zentrum Holzwirtschaft (ZHW), Hamburg University, Germany 4 Senior Researcher,Federal ResearchCenter for Forestand Forest Products, Institute~ofWood Chemistry, Hamburg, Germany 5Professor, Faculty of Natural Resources,University of Tehran, I.R. Iran 6 Associate Professor, Faculty of Natural Resources,Minnesota University (Received 9 March 2005, Accepted 6 August 2005) Abstract Pulp and paper production from non-wood fiber especially from agricultural residues, is accompanied by serious global challenges. Utilization of CEH bleaching sequenceon non-wood chemical pulps not only causes serious environmental concerns, but also reduces the possibility of closed mill water circulation. Therefore the application of TCF bleaching (O/Q/OP sequence)on wheat straw soda pulp was investigated. Two application periods (90 and 150 minutes), sodium hydroxide variation of between 1-4.5% and consistencyof 8, 10, 12, 14 and 16% were investigated in oxygen delignification stage. Bleaching with H202/O2 was studied in two stages.In stage 1, the influence of H202 variation (1-4%) and in stage 2, the application ofDTPMPA, MgS04, Na2Si203along with two time periods of 90 and 120 minutes were studied at a constantcharge of 4% H202. Statistical analysis revealed that the effect of NaOH, tempera~e and consistency in oxygen delignification on kappa number, viscosity and brightness was significant at 1% level, and an application of one percent NaOH for 90 minutes caused43% reduction in lignin content. The effect of H2O2charge, temperature and various additives ~n.OP staj?,e statistically significant. The results of this stage indicate that if sodium silicate is is applied, brightness can reach values higher than 80 %ISO while the use up of H202 being significantly reduced. The application of this compound must be at a minimum level of 2%. Strength properties of unbleached and TCF bleached pulps indicate that TCF bleaching was conducted selectively and the strength of TCF bleached pulp is superior to CEH bleached one. Finally the results indicate that the brightness and strength properties of O/Q/OP bleached wheat straw soda pulp are superior to CEH while the AOX of bleaching effluent is also kept at zero level. Keywords: Wheat straw', Soda pulp, TCF bleaching, Oxygen delignification, Hydrogen peroxide bleaching

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