Effect of Green Nanomaterials on CO2 Diffusion Coefficient and Interfacial Tension in Nanofluids: Implication for CO2 Sequestrations

This research explores nanomaterials' potential in CO2 capture and storage, emphasizing their role in CO2 diffusion and interfacial tension. We aimed to develop eco-friendly nanomaterials and evaluate their impact on CO2 sequestration, considering factors like pressure, temperature, salinity, and nanoparticle concentration. The research involved experimental measurements of CO2 diffusion in brine solutions and brine-based nanofluids containing green silica NPs and SiO2/Xanthan nanocomposites. CO2 diffusion coefficients were determined through practical pressure decay measurements using the Sheikha method. These measurements were conducted within a Fluid EVAL (PVT) cell, allowing CO2 interaction with each solution. The results of the study revealed significant improvements in the carbon dioxide (CO2) diffusion coefficients and reductions in interfacial tension when utilizing water/silica nanofluids containing 0.5 wt.% and 0.1 wt.% concentrations, in comparison with a brine solution without nanoparticles (NPs) and with a high salt concentration (20 wt.% NaCl). The CO2 diffusion coefficient increased from 2.15E-09 to 4.01E-09 m(2)/s. An even more significant enhancement was observed with 0.1 wt.% SiO2 NPs, where the CO2 diffusion coefficient reached 4.87E-09 m(2)/s. In addition, CO2 interfacial tension reduced from 44.3517 to 1.0388 mN/m and 0.9098 mN/m, respectively. The general trend of the measured carbon dioxide diffusion coefficient aligned with increased pressure and temperature. Additionally, when considering the transition to a supercritical state, the findings highlighted consistent behavior, independent of variations in pressure and temperature. Conversely, the interfacial tension between CO2 and nanofluids decreased in response to heightened pressure and temperature. Moreover, an increase in salinity led to a rise in interfacial tension. In conclusion, heightened CO2 diffusion and reduced interfacial tension improve CO2 sequestration, enhancing CO2 transport, absorption, and storage efficiency for successful long-term CO2 storage.