Investigating dispersion regimes for effective mass transfer in single-step silica nanofluids for improved CO utilization
Department of Petroleum Engineering, Rajiv Gandhi Institute of Petroleum Technology Amethi, 229304, Jais, UP, India
Accepted: 2 February 2021
Published online: 25 May 2021
Nanofluids are novel colloidal dispersions of particles (size nm) dispersed in base fluids which have widespread industrial applications. However, the suspended particles in the nanofluids are highly prone to agglomeration and sedimentation. Thus, it becomes highly essential to understand the “dispersion regime” inside the nanofluid to ascertain its viability for desired applications. The dispersion regime is the state of particle suspension inside the base fluid and it has not been widely explored in past literature. Hence, in this work, the dispersion regimes inside silica nanofluids synthesized via single-step method have been explored by the simultaneous UV–Vis, CO absorption, electrical conductivity, and viscosity measurements. Unlike past studies, a comprehensive comparative study (with respect to the base fluid) was carried out to denote NP agglomeration and dispersion regimes. The parameters varied were pH (2–12) and salinity (0–4 wt%), and the optimum conditions in which silica nanofluids exhibited a well-dispersed dispersion regime (i.e. negligible NP agglomeration) have been identified. Increasing salinity beyond wt% induced agglomeration in the silica nanofluid (evident by the change in dispersion regime). Scanning electron microscope (SEM) images were used to verify the presence of anticipated dispersion regime inside the fluid. Based on these observations, single-step silica nanofluids showed improved heat/mass transfer capacity in the pH range of 7.6–9.4 and salinity wt% NaCl. At higher salinity ( wt%) and at low pH conditions (denoting an acidic environment), NP agglomeration was severe and use of nanofluid is not recommended.
© The Author(s), under exclusive licence to EDP Sciences, Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2021