Thermal diffusion of oligosaccharide solutions: the role of chain length and structure.
Thermal diffusion of oligosaccharide solutions: the role of chain length and structure.
复制标题
低聚糖溶液的热扩散：链长和结构的作用。
DOI：
10.1021/jp104534m
复制
发表时间：
2010
影响因子：
3.3
通讯作者：
S. Wiegand
中科院分区：
文献类型：
--
作者：
P. Blanco;H. Kriegs;B. Arlt;S. Wiegand
采用红外热扩散强迫瑞利散射（IR-TDFRS）技术研究了低聚糖热扩散行为的链长依赖性。研究了三种双糖，蔗糖、纤维素糖和麦芽糖，两种三糖，麦芽糖和棉子糖，以及一种四糖，水苏糖。我们确定了热扩散（D(T)）、质量扩散(D)和Soret （S(T)）系数作为温度和浓度的函数。在所研究的温度（20-50℃）和浓度（0.2-0.6667 wt）范围内，水中单糖在冷侧积累，而低聚糖则随着温度的降低或糖浓度的增加而在暖侧富集。此外，我们还测定了混合物的运动粘度（nu）、密度（rho）和热膨胀系数（alpha），以检验D(T)和比值（alpha /nu）之间的线性相关性，该比值最近在单糖水溶液和烷烃混合物中被发现。最后，我们发现在整个研究温度范围内，D(T)和D随低聚糖链长的增加而衰减，这与非极性混合物的实验结果和理论预测相矛盾。
We investigated the chain length dependence of the thermodiffusion behavior of oligosaccharides by the infrared thermal diffusion forced Rayleigh scattering (IR-TDFRS) technique. Three disaccharides, sucrose, cellobiose and maltose, two trisaccharides, melezitose and raffinose, and a tetrasaccharide, stachyose, have been studied. We determined the thermal diffusion (D(T)), mass diffusion (D), and Soret (S(T)) coefficient as a function of temperature and concentration. While monosaccharides in water accumulate at the cold side in the investigated temperature (20-50 degrees C) and concentration (0.2-0.6667 wt) range, oligosaccharides enrich on the warm side with decreasing temperature or increasing sugar concentration. Additionally, we determined the kinematic viscosity (nu), the density (rho), and the thermal expansion coefficient (alpha) of the mixtures in order to check the linear correlation between D(T) and the ratio alpha/nu, which has been recently found for aqueous solutions of monosaccharides and for alkane mixtures. Finally, we found that D(T) and D decay with increasing chain length of the oligosaccharides in the whole studied range of temperatures, in contradiction with experimental results for nonpolar mixtures and theoretical predictions.