Experimental Measurements of Diffusion Coefficients of the CO₂–SF₆ Tracer System under Oceanic Sequestration Conditions

In the context of global climate change, ocean sequestration has attracted much attention as an important means of reducing CO2 emissions, and an accurate determination of the diffusion coefficients of CO2 tracer systems in the oceans is crucial for assessing the efficiency of carbon sequestration. In this study, Raman spectroscopy was used to investigate the variation rule of the diffusion coefficients of pure SF6, pure CO2, and different ratios of CO2–SF6 gas mixtures under different temperatures, pressures, and salinities, using the NaCl solution prepared in the laboratory as the experimental medium. Not only is the diffusion behavior of SF6 under low-temperature and high-pressure ocean storage conditions studied in detail but also the influence of SF6 on CO2 diffusion coefficients in mixed gases is analyzed, which fills the gap of SF6 diffusion coefficients under ocean storage conditions and provides important basic data and theoretical support for the development of ocean carbon storage technology.