Experimental study and analysis of CO₂ and SO₂ absorption in various water-based nanofluids by response surface...

The absorption of acidic gases in the oil and gas industries is important due to their toxicity and corrosive effects. Recently, the application of nanofluids based on aqueous or organic solvents as absorbents has been examined by a variety of researchers. In this study, a single bubble column was exploited to study the effect of water-based nanofluids on the absorption processes of SO₂ and CO₂ using response surface methodology (RSM) based on Box-Behnken three-level experiment design. With this in mind, CO₂ and SO₂ are separately injected at the bottom of a bubble column filled with one of the nanofluids: Al₂O₃-water, SiO₂-water, or ZnO-water for each experiment. Then, the rate of SO₂ or CO₂ absorption in the nanofluids has been elucidated. The effect of important parameters including the weight fraction of the nanoparticles (NPs) (0.01, 0.055, and 0.1 wt.%), gas-liquid contact time (150, 300, and 450 s), and the diameter of nozzle for gas injection (0.46, 0.57, and 0.68 mm) have been studied. Results revealed that the maximum molar flux of both gases was observed in the ZnO-water nanofluid, followed by the SiO₂-water nanofluid. In addition, increasing the nanoparticle mass fraction and the bubble size causes the molar flux to rise. However, increasing the gas-liquid contact time causes the molar flux of the mentioned gases to decrease. Finally, a set of the accurate equations has been proposed to predict the molar flux of SO₂ and CO₂ in the various nanofluids assessed in this work.