CO₂ Absorption Performance and Thermophysical Characterization of Si-ZIF-8/Ethylene Glycol/Amine Non-aqueous Nanofluids

The development of advanced solvent systems capable of simultaneously enhancing carbon dioxide (CO₂) absorption and both thermal (such as thermal conductivity) and non-thermal transport properties (such as viscosity) is vital for improving the efficiency of post-combustion carbon capture processes. Here, nonaqueous nanofluids based on surface-improved ZIF-8 (SI-ZIF-8) nanoparticles dispersed in ethylene glycol (EG)/2-(2-aminoethylamino) ethanol (AEEA) media, were investigated. The nanoparticles were dispersed by ultrasonication at concentration of 0.05 and 0.1 wt%. This hybrid system integrates chemical absorption via reactive amines with physical adsorption and transport properties enhancement provided by porous nanostructures. The influence of the presence of SI-ZIF-8 on CO₂ absorption capacity and transport properties was systematically evaluated. The results indicate that the addition of nanoparticles increases CO₂ absorption and viscosity as well as that it improves thermal conductivity compared to the base solutions EG/AEEA, while having marginal effect on the density of the system. The enhancement is attributed to synergistic mechanisms including additional adsorption sites, improved interfacial mass transfer, micro convection effects, and augmented heat dissipation during the exothermic absorption process. To our knowledge, this is the first systematic study of the thermophysical properties, transport phenomena, and CO 2 absorption of nanofluids based on the non-aqueous EG/AEEA/SI-ZIFF-8 mixture.