Experimental Investigation of the Influence of Nanofluids on the Wetting of Membrane Contactors in the CO2 Capture Process

Using nanofluids in gas-liquid membrane contactors has offered promising advantages over conventional solvents for CO2 adsorption. However, some critical concerns, such as membrane wetting, remain unresolved, which harms the long-term application of this technology in industrial applications. Indeed, the behavior of membranes in the interaction with nanofluids in the matter of wetting phenomena has not yet been properly investigated. In this work, an experimental investigation of the wetting phenomenon in membrane contactors used for CO2 absorption by monoethanolamine-based nanofluid is reported. The impact of dispersing nanoparticles (NPs, multi-walled carbon nanotube functionalized with COOH) on the wetting fraction, mass transfer coefficient, and absorption efficiency is evaluated in detail. The effects of nanofluid characteristics, operational conditions, and membrane pore size distribution on wetting phenomena are investigated. It was found that the breakthrough pressure, nanofluid surface tension, and viscosity increased with the NP concentration, leading to a lower wetting fraction. On the other hand, the liquid velocity, temperature, and time increase the possibility of wetting. The results showed that the critical pore diameter (d(c)) for a given transmembrane pressure increased by more than 20% by adding only 0.2 wt % NPs to the base fluid. In addition, increasing the surface tension and viscosity of the nanofluid compared to the base fluid through the addition of NPs leads to an increase in the breakthrough pressures in the range of 5-10% for the nanofluid, and as a result, the wetting fraction reduces.