Climate change due to substantial increases of greenhouse gases, such as carbon dioxide and methane, is a major environmental challenge today. Recently, the use of molecules, such as tetra-n-butylammonium halides (TBAX), have been shown to form semi-clathrate structures in water that are able to entrap/sequester, transport and store small molecules at moderate temperatures at atmospheric pressure. However, there is some concern that during such an industrial application, the water used to form these semi-clathrates will have other solutes, such as alkali metal halides, which may have an effect on the stability of the semi-clathrate structures. This work uses Differential Scanning Calorimetry (DSC) to measure the latent heats of fusion, and the freezing and melting temperatures of binary Tetra-n-butylammonium chloride (TBAC)/water semi-clathrate complexes formed from solutions that are 0 to 8 molal TBAC. DSC analysis will be used to measure the stability of any semi-clathrate complexes formed in the presence of various amounts of either added KCl or LiCl. Phase diagrams of complexes formed from the ternary solutions of TBAC-LiCl-H2O or TBAC-KCl-H2O will be compared to that formed from the binary TBAC-H2O solutions. It is hypothesized that lithium ion, with its large charge-to-surface density and its tendency to become heavily hydrated, will likely disrupt the ability of TBAC to form stable semi-clathrate structures. However, the much larger potassium ion, with its much smaller charge-to-surface density and its much weaker tendency to become hydrated, is less likely to disrupt these semi-clathrate structures due to hydration. Further, at low concentrations of KCL, the enhanced concentration of chloride ion, which plays a role in the formation of the semi-clathrate structure, may act to enhance the semi-clathrate structures compared to those formed from the binary TBAC-H2O solutions.

Effect of adding lithium chloride or potassium chloride on the tetra-n-butylammonium chloride/water semi-clathrte system using differential scanning calorimetry

254th National Meeting (2017)

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