Thermo-Rheological Characterization of Natural Deep Eutectic Solvents (Nades) Used in Co2 Capture

Abstract

The rheological behavior of a fluid is an important property that has a distinct impact on its flow behavior, which influences viscosity dependent phenomena and applications such as pumping, mass transfer rates, and hydrodynamics. This thesis herein intended to provide a detailed rheological description of mainly Lactic acid (LA) and Malic acid (MA) based Natural deep eutectic solvents (NADES). The effect of three different hydrogen bond acceptors (HBA) of B-Alanine, Betaine, Choline Chloride nature upon its addition with a fixed hydrogen bond donor (HBD) component at a fixed molar ratio of 1:1. The changes in the rheological properties as a function of physical, thermal and mechanical parameters that provide an indication of the material’s tolerance under different field operational circumstances for their potential use as environmental green sorbents for CO2 capture were intensively investigated. The shear flow and viscoelastic behaviors of all six samples were analyzed and studied for the insurance of effective CO2 capture. The use of a rheogram was used to describe the effect of forward and backward temperature ramping on the apparent viscosity trend of the LA-based NADES systems. The density was also measured and compared to the apparent viscosity behavior under the effect of temperature. Moreover, the viscoelastic properties were also thoroughly described to best describe and investigate the disturbance in networks on the microstructure level in the NADES structure upon frequency sweep. The rheological characterization of shear flow measurements was evaluated using the Bingham model, which best implied on the apparent viscosity formulated over shear rate and the dynamic yield stress of the NADES systems.