Dual Promotional Effect of <scp>l</scp>-Tryptophan and 1,3-Dioxane on CO<sub>2</sub> Hydrate Kinetics in Seawater under Static/Unstatic Conditions for Carbon Capture and Storage Application
Vikas Dhamu, M. Fahed Qureshi, Nithila Selvaraj, Lauren Ji Yuanmin, Iva Tianhui Guo, Praveen Linga
Abstract
CO 2 hydrates hold promising applications, including as a medium for carbon storage in oceanic sediments, as a result of their high storage capacity. However, the presence of high salinity in sediments is likely to affect the CO 2 hydrate kinetics. To counter this challenge, the CO 2 hydrate formation, dissociation, and deep morphology have been investigated in seawater (SW) under static and non-static conditions. Moreover, the effect of a kinetic promoter [1000 ppm of l -tryptophan ( l -tryp)] and a thermodynamic promoter (5 wt % 1,3-dioxane) and dual promotional effects of kinetic and thermodynamic promoters (1000 ppm of l -tryp + 5 wt % 1,3-dioxane) have also been studied. In situ Raman spectroscopy was used to probe the real-time CO 2 dissolution in seawater in the presence of 1,3-dioxane. The CO 2 uptake in seawater for the static system was estimated to be in the following order (20 h): CO 2 (30.5 ± 5.0 mmol/mol) > CO 2 + 1000 ppm of l -tryp (30 ± 1.20 mmol/mol) > CO 2 + 1,3-dioxane + 1000 ppm of l -tryp (26.2 ± 7.1 mmol/mol) > CO 2 + 1,3-dioxane (21.1 ± 6.1 mmol/mol). In comparison, for the non-static system, the CO 2 uptake in seawater was estimated to be in the following order (20 h): CO 2 + 1000 ppm of l -tryp (67.8 ± 2.20 mmol/mol) > CO 2 + 5 wt % 1,3-dioxane (49.3 ± 7.0 mmol/mol) > CO 2 + 5 wt % 1,3-dioxane + 1000 ppm of l -tryp (42.9 ± 4.8 mmol/mol) > CO 2 (39.5 ± 4.1 mmol/mol).