Understanding the effect of moderate concentration SDS on CO2 hydrates growth in the presence of THF

Xinrui Cai; Joshua Worley; Anh Phan; Matteo Salvalaglio; Carolyn Koh; Alberto Striolo

doi:10.1016/j.jcis.2023.11.136

Understanding the effect of moderate concentration SDS on CO₂ hydrates growth in the presence of THF

J Colloid Interface Sci. 2024 Mar 15:658:1-11. doi: 10.1016/j.jcis.2023.11.136. Epub 2023 Nov 27.

Authors

Xinrui Cai¹, Joshua Worley², Anh Phan³, Matteo Salvalaglio¹, Carolyn Koh², Alberto Striolo⁴

Affiliations

¹ Thomas Young Centre and Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, United Kingdom.
² Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, United States.
³ School of Chemistry and Chemical Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom.
⁴ Thomas Young Centre and Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, United Kingdom; School of Sustainable Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, OK 73019, United States. Electronic address: astriolo@ou.edu.

PMID: 38091793
DOI: 10.1016/j.jcis.2023.11.136

Abstract

Hypothesis Additives like Tetrahydrofuran (THF) and Sodium Dodecylsulfate (SDS) improve Carbon Dioxide (CO₂) hydrates thermal stability and growth rate when used separately. It has been hypothesised that combining them could improve the kinetics of growth and the thermodynamic stability of CO₂ hydrates. Simulations and Experiments We exploit atomistic molecular dynamics simulations to investigate the combined impact of THF and SDS under different temperatures and concentrations. The simulation insights are verified experimentally using pendant drop tensiometry conducted at ambient pressures and high-pressure differential scanning calorimetry. Findings Our simulations revealed that the combination of both additives is synergistic at low temperatures but antagonistic at temperatures above 274.1 K due to the aggregation of SDS molecules induced by THF molecules. These aggregates effectively remove THF and CO₂ from the hydrate-liquid interface, thereby reducing the driving force for hydrates growth. Experiments revealed that the critical micelle concentration of SDS in water decreases by 20% upon the addition of THF. Further experiments in the presence of THF showed that only small amounts of SDS are sufficient to increase the CO₂ storage efficiency by over 40% compared to results obtained without promoters. Overall, our results provide microscopic insights into the mechanisms of THF and SDS promoters on CO₂ hydrates, useful for determining the optimal conditions for hydrate growth.

Keywords: CO(2); Hydrates; Promoters; SDS; THF.