Membrane Absorption Coupling Process for CO2 Capture: Application of Water-Based ZnO, TiO2, and Multi-Walled Carbon Nanotube Nanofluids

Abstract

In this work, stable water-based zinc oxide (ZnO), titania (TiO2), and multi-walled carbon nanotube (MWCNT) nanofluids are prepared and examined as CO2 absorbents in a polypropylene hollow fiber membrane contactor. Different operating variables, such as liquid flow rate, gas flow rate, and concentration of nanoparticles, and their effects on CO2 molar flux are investigated. The long-term stability of nanofluids is monitored using ultraviolet–visible spectroscopy. Also, ζ-potential measurements and sediment photography are applied to confirm the results of nanofluid stability. Dynamic light scattering is used to determine the size distribution of dispersed nanoparticles. The results show that the increase in the nanoparticle concentration to 0.15 wt % has a favorable effect on CO2 absorption efficiency as a result of the increase in Brownian motion and other related mechanisms. However, it adversely affects the CO2 absorption by lowering the nanofluid stability at higher concentrations. The obtained result...