Abstract

Reactivity of dissolving pulp is one of the main parameters to determine its availability to be transformed into viscose. It is related to the use of carbon disulphide (CS₂). An industrial sequential totally chlorine free bleaching process is used as case study. It is carried out in two stages: (1) Alkaline extraction (EOP) and (2) peroxide bleaching (PO). In order to assess how to decrease the use of carbon disulphide, several experiments were performed at laboratory scale for the two stages mentioned before by modifying the operating conditions: NaOH and H₂O₂ dosages, time and temperature. Reactivity using a modified Fock’s method and pentosan content was analysed along with quality pulp parameters: α-cellulose, viscosity and lignin content (kappa number). Results showed that reactivity increases through the bleaching process and varies with the chemical dosage in both stages. Pulp obtained at the best conditions had the following characteristics: reactivity, 95.3%; α-cellulose 91.17%; intrinsic viscosity, 448 mL/g; kappa number, 1.81 and pentosan content 2.86%, and as a result, CS₂ usage was reduced by 11.88%. At the best conditions obtained in this work, NaOH dosage in PO stage was reduced to zero and temperature was slightly lower, when compared with industrial operating conditions.

中文翻译：

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纤维生产用溶解浆漂白程序的技术和环境改进

摘要

溶解纸浆的反应性是确定其转化为粘胶纤维有效性的主要参数之一。它与二硫化碳（CS ₂）的使用有关。以工业顺序全无氯漂白工艺为例。它分两个阶段进行：（1）碱萃取（EOP）和（2）过氧化物漂白（PO）。为了评估如何减少二硫化碳的使用，通过更改操作条件（NaOH和H ₂ O _2），在实验室规模下针对上述两个阶段进行了几次实验剂量，时间和温度。使用改进的Fock方法和戊聚糖含量以及纸浆质量参数（α-纤维素，粘度和木质素含量（kappa值））分析了反应性。结果表明，在整个漂白过程中，反应性均增加，并且在两个阶段中均随化学剂量的变化而变化。在最佳条件下获得的纸浆具有以下特征：反应性，95.3％; α-纤维素91.17％; 特性粘度，448 mL / g；卡伯值，1.81和戊聚糖含量为2.86％，因此，CS _2的使用量减少了11.88％。与工业操作条件相比，在这项工作中获得的最佳条件下，PO阶段的NaOH用量减少到了零，温度略低。