CONTROLLING DARKENING REACTIONS DURING MECHANICAL PULPING WITH ADDITIVES-A POSSIBLE APPROACH TO IMPROVING BRIGHTNESS AND BLEACHABILITY

The first part of this paper summarizes relevant literature information, which rationalizes our selection of chemicals. The second part reports some preliminary screening results. We have investigated a wide range of reagents, chosen for their different chemistries and divided into seven classes: (1) reducing agents, (2) reduced sulfur compounds, (3) hydrogen donors, (4) antioxidants and radical scavengers, (5) nucleophiles, (6) chelating agents, and (7) oxidizing bleaching agents. It is noted that some chemical reagents fall into more than one class. The obtained results will be discussed with respect to the effectiveness of each class.

GPC-ELSD法评价脱墨生产过程胶黏物含量的变化

本文介绍了一种新的胶黏物含量测定方法——凝胶渗透色谱—蒸发光散射检测器联用(GPC-ELSD),并采用该方法考察脱墨浆生产过程中主要工段的浆料、纤维组分和细小纤维组分中的胶黏物的含量变化,评价胶黏物的去除效果。结果表明:脱墨浆生产线中主要工段的浆料、纤维组分和细小纤维组分的THF抽出物组成中胶黏物相对含量最小,木材抽出物次之,其他未知组分相对含量最大;细小纤维组分比纤维组分上含有更多的胶黏物;浮选工序有利于去除细小纤维组分上的胶黏物,但是其他后续工段对细小纤维组分上的胶黏物的除去较难;微细胶黏物的去除、细小纤维组分上胶黏物的去除以及减少白水循环过程中胶黏物的积累可能是解决胶黏物障碍问题的关键。