USE OF TAED AS ACTIVATOR TO INCREASE PEROXIDE BLEACHING - LIGNIN MODEL COMPOUND AND OPTIMIZED CONDITIONS
The first part of our study is about the kinetic of a lignin model compound, acetovanillone, in TAED/H2O2 and peroxide-alone systems (TAED stands for tetraacetyl-ethylenediamine). Our results show that the oxidation of acetovanillone follows a first-order kinetic in both systems studied. TAED/H2O2 system is about one hundred times more reactive than peroxidealone system in term of the oxidation of acetovanillone. The results of this study explain why, while using TAED/H2O2 system to bleach TMP softwood pulp, the initial pH should be around 11 for increased production of peroxyacetic acid, and the final pH should be around 7 to minimize decomposition and increase bleaching efficiency and reactivity. The second part focuses on the TAED/H2O2 bleaching system at low consistency on spruce-balsam thermomechanical pulp. Our experiments show that the TAED/H2O2 system improves significantly (6％ ISO) the brightness of softwood TMP pulp, compared with the peroxide-alone system. For each fixed molar ratio of TAED/H2O2, there is an optimum range for addition of alkali to achieve a maximum brightness gain of TMP pulp, a well-defined linear correlation was found between the molar ratio of TAED/H2O2 and the optimal alkali charge. An optimal TAED/H2O2 ratio is obtained at 0.7, slightly higher that the theoretical value of 0.5, due to the saponification reaction of TAED. TAED/H2O2 results in pulps slightly more susceptible to light-induced yellowing in the UV and visible region of the spectrum at very long irradiation times. The short term light-induced yellowing is about the same for both kinds of pulps.
bleaching peroxide activator TAED yellowing thermomechanical pulp
Q. Hu C. Daneault S. Robert
D(e)partement de chimie-biologie, Centre de recherche en p(a)tes et papiers, Universit(e) du Qu(e)be D(e)partement de chimie-biologie, Centre de recherche en p(a)tes et papiers, Universit(e) du Qu(e)be
国际会议
16th International Symposium on Wood,Fiber and Pulping Chemistry(第十六届木材、纤维及制浆化学国际会议)
天津
英文
559-565
2011-06-08（万方平台首次上网日期，不代表论文的发表时间）