Amino functionalized ZIF-90@GO/MDEA nanofluid: As a new class of multi-hybrid systems to enhance the performance of amine solutions in CO2 absorption

Global climate change has enforced a critical action to mitigate carbon emissions. In this study, a novel procedure was investigated by addition of amine-functionalized graphene oxide into mehyldiethanolamine (MDEA) to improve the CO2 absorption capacity. The nanocomposite EDA@ZIF-90@GO was prepared by incorporation of (3-Aminopropyl) triethoxysilane (APTES) onto the graphene oxide surface and consequently functionalization of as-prepared nanostructure with ZIF-90 as well as ethylenediamine (EDA). This reagent was utilized because of various functional groups, high surface area, and potential surface modification. The stability of nanofluid was measured by zeta potential analysis. Firstly, we studied the nanoparticle loading using MDEA based nanofluid containing different dosages of GO to reach the optimal concentration. The results revealed an absorption enhancement of 9.1% and 10.4% for dosages of 0.1 wt% and 0.2 wt%, respectively. Then, after the addition of 0.1 wt% EDA@ZIF-90@GO to amine solution, the CO2 absorption was enhanced up to 23%. Different partial pressure and temperatures were employed and the results showed that the temperature has a negative effect on the performance of the system, while increasing the CO2 partial pressure led to an increase in absorption capacity rate. Thermal gravimetric analysis (TGA) confirmed the reusability of the nanofluid due to the high temperature needed for the decomposition of functional groups. Thermal conductivity and convective heat transfer coefficient were improved after addition of the nanoparticles into the base fluid.