物理化学学报 >> 2015, Vol. 31 >> Issue (6): 1118-1128.doi: 10.3866/PKU.WHXB201503271

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温度对碱木质素在溶液中微结构及物理化学性质的影响

李浩, 邓永红, 张晓鸿, 邱学青   

  1. 华南理工大学化学与化工学院, 制浆造纸工程国家重点实验室, 广州510640
  • 收稿日期:2015-03-02 修回日期:2015-03-26 发布日期:2015-06-05
  • 通讯作者: 邓永红, 邱学青 E-mail:yhdeng08@163.com;xueqingqiu66@163.com
  • 基金资助:

    国家重点基础研究发展规划项目(973) (2012CB215302)和国家自然科学基金(21436004, 21374032)资助

Influence of Temperature on Microstructure and Physicochemical Properties of Alkali Lignin in Aqueous Solution

LI Hao, DENG Yong-Hong, ZHANG Xiao-Hong, QIU Xue-Qing   

  1. State Key Laboratory of Pulp and Paper Engineering, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, P. R. China
  • Received:2015-03-02 Revised:2015-03-26 Published:2015-06-05
  • Contact: DENG Yong-Hong, QIU Xue-Qing E-mail:yhdeng08@163.com;xueqingqiu66@163.com
  • Supported by:

    The project was supported by the National Key Basic Research Program of China (973) (2012CB215302) and National Natural Science Foundation of China, (21436004, 21374032).

摘要:

研究了温度对碱木质素(AL)的微结构及物理化学性质的影响. 在20-60 ℃范围内, 采用表面电荷仪、动态光散射、zeta 电位仪、粘度计、表面张力仪、石英晶体微天平、紫外和荧光等仪器, 研究了AL在碱性溶液中的分子聚集形态、表面带电情况、亲疏水特性、溶液特性粘度以及AL在气液和液固界面上的吸附等性质. 结果表明, AL溶液的特性粘度、表面张力以及分子的表面电荷密度都会随温度上升明显降低, 而分子内和分子间聚集作用、分子的疏水性以及在液固界面上的吸附量会随温度上升逐渐增大, zeta 电位绝对值则呈现出先降低后上升然后再降低的趋势. 分析认为, 温度上升会同时降低AL中弱酸性基团的电离程度和AL与水分子间的氢键作用, 这两个因素的变化直接导致了AL微结构和物理化学性质的改变. 温度升高时, 水由AL的良溶剂逐渐变为不良溶剂, 尽管AL通常被视为阴离子表面活性剂, 但其受温度影响时所呈现出的变化规律却更类似于非离子表面活性剂.

关键词: 碱木质素, 温度, 微结构, 聚集, 物理化学性质

Abstract:

The effects of temperature on the microstructure and physicochemical properties of alkali lignin (AL) in alkaline aqueous solutions were studied at 20-60 ℃. The relationships between temperature and the physicochemical properties of AL, such as the aggregation morphology, molecular surface charge and hydrophobicity, intrinsic viscosity, adsorption characteristics on gas-liquid and liquid- solid interfaces were investigated experimentally using particle charge detection, dynamic light scattering, zeta plus measurements, viscometry, surface tension and dynamic contact angle measurements, quartz crystal microbalance, ultravioletvisible and fluorescence spectroscopies. As the temperature increases, the molecular surface charge density, the intrinsic viscosity, and surface tension of the AL solution decrease significantly. In contrast, the molecular hydrophobicity, intermolecular and intramolecular aggregations, and the amount of AL adsorbed onto liquid-solid interface increase. The AL molecular state changes from extended to compact with increasing temperature. Furthermore, when the temperature increases, the absolute value of the zeta potential first decreases, then increases, and then decreases again. Analysis suggests that the increase in temperature not only reduces the ionization degree of the weak acidic groups in AL, but also weakens the hydrogen bonds between ALmolecules and water molecules. These two factors lead directly to changes in the AL microstructure and physicochemical properties. Based on the results of this study, a mechanism for the microstructural changes in AL with changing temperature was proposed. It was concluded that water would transform from a good solvent to a poor solvent with decreasing temperature. Although AL is often viewed as an anionic surfactant, the regular changes in its physicochemical properties with temperature are more like those of a nonionic surfactant.

Key words: Alkali lignin, Temperature, Microstructure, Aggregation, Physicochemical property

MSC2000: 

  • O647