IMPROVING THE BLEACHING PROCESS IN CMP PULP FROM MAZANDARAN WOOD & PAPER COMPANY
In first phase, the effect of different rate of NaOH to H2O2 values on bleaching of chemi-mechanical pulp (CMP) was investigated (sodium hydroxide in three levels 1.5％, 2％ and 3％ and also peroxide consumption in three levels 2％, 3％, 4％). The unbleached CMP pulp had been obtained from Mazandaran Wood & Paper Company and this pulps specifications were the following: 5.25 pH value; 37.5 initial brightness; 745 mL initial freeness. Bleaching process included two stages: (1) Chelation stage (2) Alkali peroxide bleaching stage. Results of this phase have indicated that brightness increased by the growing in the level of peroxide, but the increasing in caustic sodas percentage had inhomogeneous effects on pulp brightness. As data have shown, the best brightness values were found in 0.75 NaOH/H2O2 ratios. The increasing of caustic soda to peroxide ratio made a noticeable upward trend in the yellowness of pulp and so a decrease in brightness values. Also, NaOH/H2O2 ratios below 0.75 resulted lower brightness. The yield of bleaching process was reduced by raising the rate of caustic soda to peroxide. Finally, the rate of 0.75 was selected as the best NaOH/H2O2 ratio. In second phase, the effects in replacement of caustic soda by magnesium hydroxide were examined. The rate of Mg(OH)2/H2O2 was measured by titration based on the best rate of NaOH/H2O2 (0.75) and it was measured 0.6. The results have shown that, this replacement caused to improve optical properties and pulp yield. But the physical properties of bleached pulps were similar in both processes.
Bleaching Hydrogen peroxide Caustic soda Yield Brightness
Farhad Zeinaly Jalal Shakhes Alireza Shakeri Nooshin Zeinaly
1Islamic Azad University, Gorgan Branch,Young Researchers Club,Gorgan,Iran Department of Wood & Paper Science Faculty of Faculty of Forest and Wood Technology,Gorgan Universit Department of Chemistry,Faculty of sciences,Golestan University,Gorgan, Iran Department of Chemistry, Islamic Azad University,Gorgan Branch, Gorgan, Iran
国际会议
International Mechanical Pulping Conference 2011(2011国际机械浆学术会议)
西安
英文
267-270
2011-06-26（万方平台首次上网日期，不代表论文的发表时间）