Enhanced CO2 absorption and reduced regeneration energy in Si-ZIF-8/Sulfinol-M nanofluid: experimental and thermodynamic evaluation with data-driven modeling

Abstract

The study investigated the CO2 absorption/desorption characteristics of a nanofluid comprising Sulfinol-M (base solvent), γ-Al2O3 nanoparticles (0.1 wt. %), super actived carbon (SAC) (0.1 wt. %), and silica-2-methylimidazole zinc salt (Si-ZIF-8; 0.02 wt. %). Experiments were conducted by a static method at T = 313.15, 323.15, 333.15, and 393.15 K and pressures up to 1.2 MPa. The results show that all three nanofluids increase absorption capacity; notably, Si‑ZIF‑8 nanoparticles exhibited average enhancement factors of approximately 40% at 323.15 K and 44% at 333.15 K. Desorption studies at 393.15 K showed poor performance for SAC and γ-Al2O3 nanoparticles, while Si-ZIF-8 nanoparticles successfully reduced CO2 loading by 22%. The ΔHabs values were determined by the Clausius–Clapeyron equation. Accordingly, the heat of CO2 absorption for Si- ZIF-8 base nanofluid exhibited 21% reductions at a loading of 1 wt.% compared to the base solvent. Furthermore, data modeling by genetic programming yeilded an average absolute relative deviation (AARD) of 10.8%, a root-mean-square error (RMSE) of 0.042, and a coefficient of determination of R2 = 0.979.