Experimental Study of CO₂ Absorption Capacity Enhancement of Fe₂O₃ and SiO₂ Nanofluids and their Stability Studies

The major focus of this research work is the use of DI water-based Fe2O3 and SiO2 nanofluids for CO2 absorption using a specially made absorption cell, and stability of nanofluids by using UV- spectroscopy and Zeta potential. Nanofluids concentrations considered are 0.03, 0.06, 0.09 and 0.12 wt%. The experiments are conducted for initial pressures of 5, 7.5 and 10 bar inside the absorption cell. The absorption cell is made of stainless steel so that it can withstand high pressures. The temperature is kept constant at 300 K throughout. The effect of types of nanoparticles, initial pressure and concentration of nanofluid on CO2 absorption capacity has been discussed. The stability tests were conducted right after the preparation of the nanofluid and 4 weeks after preparation. From the experimental studies, it was found that there is a CO2 absorption capacity enhancement of 21.03%, 22.95% and 20.59% at 5, 7.5 and 10 bar, respectively, at 0.06 wt% of Fe2O3 nanofluid as compared to the base fluid. For SiO2 nanofluid, the CO2 absorption capacity was enhanced by 10.34%, 18.67% and 13.61% at 5,7.5 and 10 bar, respectively, at 0.09 wt% as compared to the base fluid. 0.06 wt% and 0.09 wt% are the optimum concentrations for Fe2O3 and SiO2 nanofluids, and zeta potential studies have shown that these nanofluids are highly stable at the optimum concentration. It was observed that at equilibrium, the adsorption of CO2 gas at the nanoparticle surface resulted higher absorption capacity of nanofluids. Major Findings: The CO2 absorption was higher at higher pressure. The increase in concentration of nanofluids increased the CO2 absorption capacity of both nanofluids. The stabilities of the nanofluids were superior even after 4 weeks of preparation.