Microgeometry-independent equation for measuring infinite dilution activity coefficients using gas-liquid chromatography with static-wall-coated open-tubular columns
Microgeometry-independent equation for measuring infinite dilution activity coefficients using gas-liquid chromatography with static-wall-coated open-tubular columns
复制标题
使用静态壁涂层开管柱气液色谱法测量无限稀释活度系数的微观几何独立方程
DOI：
10.1016/j.chroma.2020.461264
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发表时间：
2020
影响因子：
4.1
通讯作者：
Ren Qilong
中科院分区：
文献类型：
--
作者：
Xu Qianqian;Su Baogen;Bao Zongbi;Yang Yiwen;Yang Qiwei;Ren Qilong
气液色谱法是测定无限稀释活度系数（γ∞）的有效方法。涂壁开管色谱柱（WCOT）与填料色谱柱相比具有许多优点，应作为一种较好的色谱柱，但WCOT色谱柱载气流量和固定相用量小，限制了其在γ∞测定中的应用。在静态涂壁开管柱（SWCOT）测定γ∞时，数学策略在避免定量问题方面取得了一定进展。然而，以前报道的策略是基于假设SWCOT柱是一个几何上理想的空心圆柱，这确实偏离了现实。在本研究中，我们在不作上述假设的情况下，利用滞留体积（VM）与固定相体积（VL）之间的关系，推导出一个新的与微观几何无关的方程，并利用该方程测定了不同有机溶质在离子液体（1-丁基-3-甲基咪唑二氰胺和1，3-二丁腈-咪唑双）中的γ∞（（三氟甲基）磺酰基）酰亚胺，两者均在阴离子或阳离子中含有双氰基。采用相负荷法消除了界面吸附对分配的影响。由实验得到的γ∞值直接计算了两种离子液体的无限稀释偏摩尔过量焓、选择性和容量，并采用线性溶剂化能关系（LSER）模型对两种离子液体的特性进行了表征。该方程的建立将促进SWCOT柱在热力学测量中的应用，并有利于化学分离过程中新型溶剂的快速筛选。
Gas-liquid chromatography is an effective method to determine infinite dilution activity coefficients (γ∞). Wall-coated open-tubular (WCOT) column which offers more advantages over packed column should be a preferable column type; however, the small carrier gas flow rate and stationary phase amount in WCOT columns limit its application in the determination ofγ∞. Mathematical strategy made some progress to avoid the quantification problem in the determination ofγ∞by static-wall-coated open-tubular (SWCOT) columns. However, the previously reported strategy was based on the assumption that SWCOT column was geometrically an ideal hollow cylinder, which indeed deviates from the reality. In this study, without that assumption, we derived a new microgeometry-independent equation by using the relationship between the hold-up volume (VM) and the volume of stationary phase (VL), and used it to measure theγ∞of various organic solutes in two ionic liquids (ILs) 1‑butyl‑3-methylimidazolium dicyanamide and 1,3-dibutyronitrile-imidazolium bis((trifluoromethyl)sulfonyl)imide, both of which contain double cyano groups in the anion or cation. Phase loading study was adopted to eliminate the influence of interfacial adsorption to partition. The infinite dilution partial molar excess enthalpy, selectivity and capacity were directly calculated from the experimentalγ∞values, and the linear solvation energy relationship (LSER) model was used to characterize the specific properties of both ILs. This new established equation will promote the application of SWCOT columns in thermodynamic measurement and benefit the fast screening of novel solvents for chemical separation processes.