提高芦苇KP末端H2O2漂白效率的研究

Improvement of Hydrogen Peroxide Bleaching Efficiency of Reed Kraft Pulp

对原漂白工艺与改进的H_2O_2漂白工艺进行了实验室对比,结果表明,后者的漂白效果要远优于前者。但调整后的H_2O_2漂白工艺对工厂未充分洗涤的次氯酸盐(H段)漂白浆没有漂白效果。添加乙二胺四乙酸二钠盐(EDTANa_2)的螯合效果与乙二胺四乙酸四钠盐(EDTANa_4)的相当,但它们都优于DTPA。当EDTANa_2(用量0.1%)与三聚磷酸钠(用量0.1%)复配物作为H_2O_2漂白的螯合剂时,H_2O_2对未充分洗涤H段漂浆的漂白效果明显,添加少量的尿素与双氰胺,H_2O_2漂白效果不提高。浆料筛分结果表明,芦苇浆末端H_2O_2漂白前的细小组分来自于原浆,H_2O_2漂白前浆料中细小组分(过200目)的含量对H_2O_2漂白效率影响较大,当细小组分含量大于5%时,H_2O_2漂白后未洗浆的白度较低。对原浆中的细小组分进行显微镜观察可知,细小组分中大部分是非纤维细胞,其中有80%左右(面积)的是尘埃,20%左右是杂细胞或细小纤维。

Original and modified hydrogen peroxide bleaching conditions of reed kraft pulp were compared in this paper. The results showed that the bleaching result of the latter was better than that of the former. However, the effect of modified hydrogen peroxide bleaching conditions on the pulp which was bleached with H sequence and not washed thoroughly was little. On the other hand, the chelating effect of EDTANa2 or EDTANa4 during the hydrogen peroxide bleaching process was similar and better than that of DTPA. The addition of 0. 1% EDTANa2 and 0.1% trimeric sodium phosphate obtained a good bleaching result. In addition, the unsatisfied bleaching result was obtained when a small amount of urea or dicyandiamide was added during the hydrogen peroxide bleaching process. The result of fractionation of the pulp showed that the amounts of the fine fraction （ -200 mesh） of the unbleached pulp and the pulp bleached with H sequence were similar. Furthermore, the brightness value obtained by the hydrogen peroxide bleaching process was lower when the amount of the fine fraction （ -200 mesh） of H bleachend pulp was more than 5%. Microscope observation showed that about 80% （area） and 20% of the fine fraction of the pulp are dust and parenchyma cell or fine fiber respectively.