Surface modified single-step nanofluid for improved CO2 absorption and storage Prospects at pore-scale in micromodels: CO2 utilization for saline porous media.

The utilization (absorption and areal sweep) of injected carbon dioxide (CO 2) can be enhanced if a viscous and agglomeration free nanofluid is used as most of the nanoparticles (NPs) prefer to stay in bulk phase rather than adsorbing on CO 2 surface. NP adsorption can be improved if non-participating NPs are surface modified with a suitable surface modifying agent e.g. , triethoxy (vinyl)silane (TVS). Thus, in this study, single-step approach was used to synthesize agglomeration free TiO 2 nanofluid whose surface modification was carried out in varying proportion of TVS (1–5% v/v) followed by the discussion on comparative CO 2 absorption and storage performance by different tools such as DLS, IFT, Rheology, Contact-angle, and Micromodel flow. The basic nanofluid (T o) showed greater CO 2 absorption after surface modification as demonstrated by molality results. However, surface modification also decreased dispersion stability of surface modified nanofluids (T 1 , T 2 , and T 3) and T 2 was regarded as the most stable nanofluid with −64.4 mV (ζ-potential) and 153 nm (NP size). After surface modification, increase in NP size and settlement was higher for surface modified nanofluids than T o , which exhibited dispersion stability of 84 d with −53.4 mV and 15 nm. Contact angle results also showed that surface modified nanofluids possess greater affinity for CO 2 absorption than basic nanofluid (T o). Rheological analysis was also consistent with other tests where viscosity was found dependent on both storage period and temperature, and NP settlement was found to be the most influential parameter on flow properties of nanofluid. Finally, pore scale analysis was performed to understand areal sweep of injected CO 2 in micromodel with and without nanofluid, where nanofluid imparted greater CO 2 storage by diverting it in un-swept pore networks of micromodel which were untapped by CO 2 without nanofluid. • Surface modified single-step TiO 2 nanofluid was used for CO 2 absorption and storage. • The size and dispersion stability of nanofluid was dependent on surface modifying agent. • Rheological property of nanofluids was investigated as a function of time and temperature. • Nanofluids showed least wetting on rock surface after surface modification. • Micromodels were used to envisage CO 2 storage with/without nanofluid at pore scale. [ABSTRACT FROM AUTHOR]