In this study, three kinds of rough-wrought hemicelluloses (RHCs) were obtained via alkali extraction on different raw materials. One was untreated Phyllostachys edulis powder; the second was obtained via benzyl alcohol extraction of Phyllostachys edulis powder; and the third was holocellulose of Phyllostachys edulis powder. Carboxymethyl hemicelluloses (CMXs) were prepared by the alkalization and etherification of RHCs and were used to enhance the tensile strength of household paper. The results demonstrated a synergistic effect between CMX and polyamide epichlorohydrin resin (PAE), and the addition of small amount of CMX (0.35 kg/t pulp) can significantly improve the dry and wet tensile indices of paper. Study results of CMX strengthening mechanism revealed that the addition of CMX can improve the retention of PAE, especially the fine fiber, due to the adsorption of charges. The use of CMX in paper not only saves production costs but also reduces the proportion of long fiber, which is beneficial to the closed circulation and treatment of white water.

Deinking is an important process in waste paper recycling process, and this study mainly focuses on the properties of the deinking agent and process optimization. DIA-30 prepared in our laboratory, and FS and LD, were the three representative deinking agents studied herein. Brightness, effective residual ink concentration (ERIC), dirt, macro-stickies, fiber loss during repulping, flotation, and washing processes were measured to evaluate the performance of the deinking agents and optimize process conditions. Each of the deinking agents exhibited different advantages: DIA-30 was optimal for deinking efficiency, brightness enhancement, as well as dirt and macro-stickies removal, whereas LD was optimal for ink removal during flotation process but performed poorly in terms of brightness enhancement. FS showed a relatively balanced performance compared to those of DIA-30 and LD in the deinking process, but DIA-30 is the best option for deinking due to its outstanding comprehensive properties. The optimal repulping conditions for the deinking of 100% old magzines (OMG) using DIA-30 are as follows: repulping temperature, 60℃; pulp consistency, 13 wt%; repulping time, 20 min; H₂O₂ dosage, 0.5 wt% (oven-dried pulp); NaOH dosage, 1.2 wt% (oven-dried pulp); Na₂SiO₃ dosage, 0.3 wt% (oven-dried pulp); and optimum DIA-30 dosage, 0.1 wt%.

This paper summarizes the possible application of lignin extraction from black liquor and the development of lignin extraction technology. Lignin extraction from black liquor is an important, economical method to resolve the bottleneck associated with the recovery boiler and achieve the targeted capacity expansion in pulp mills. A few of key issues must be taken into cosideration when lignin extraction technology is adopted on the industrial scale.