In this study, the manners in which temperature (45–77 °C) and the addition of xylan (5 g/95 g lignin) influence the onset of precipitation and evolution of the particle size distribution during acid precipitation of softwood kraft lignin were investigated in situ. No systematic trend between the onset pH of precipitation and the temperature or the addition of xylan could be observed at these conditions: the average onset pH was found to be 9.3. However, the size of the agglomerates increased as the temperature was increased, but added xylan rendered a decrease in agglomerate size. A higher onset pH was measured at increased Na ion concentration. The results indicate that the ionization degree of the phenolic groups influences the precipitation at 1 M Na ions but it is also probable that the degree of ionization of the carboxylic groups (on kraft lignin and xylan) influences precipitation (particle numbers and sizes).

中文翻译：

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从水溶液中酸沉淀硫酸盐木质素：pH、温度和木聚糖的影响

在本研究中，研究了温度（45-77 °C）和木聚糖（5 g/95 g 木质素）的添加对针叶木硫酸盐木质素酸沉淀过程中沉淀开始和粒度分布演变的影响方式。原地。在这些条件下，没有观察到沉淀起始 pH 值与温度或木聚糖添加量之间的系统趋势：发现平均起始 pH 值为 9.3。然而，附聚物的尺寸随着温度的升高而增加，但添加的木聚糖使附聚物的尺寸减小。在增加的 Na 离子浓度下测量到更高的起始 pH 值。