Natural deep eutectic solvent (NADES) produced herein this work by mixing betaine and alanine with lactic acid and malic acid with 1:1 molar mixing ratios. Thermophysical properties including water content, thermal stability, density and gas solubility of CO 2 and N 2 were experimented at different isotherms for wide pressures range up to 50 bars. Moreover, detailed rheological experiments were conducted on the studied materials to obtain viscosity and deduce the dynamic flow behavior. A pressure driven physisorption mechanism was observed for the studied systems. Betaine based NADES materials showed superior carbon dioxide and nitrogen solubility when they are mixed with lactic acid. On the other hand, the rheological experimental results show shear-thinning effect in which the η is decreasing with shear rate at all temperatures. Low viscosity profiles NADES assure the less mass transfer resistance for lactic acid based NADES systems and it also confirmed that the high CO 2 and N 2 solubility for lactic acid based NADES samples.

A potential of natural deep eutectic solvent (NADES) produced with the mixture of choline chloride with lactic acid, malic acid, citric acid and fructose is studied in this work. Experimental techniques are used to collect thermophysical property data including water content, thermal strength, density and gas solubility of CO2 and N2 data at pressures up to 50 bars. Detailed rheological measurements and various models have been studied to describe the dynamic flow behavior. Moreover, a density functional theory (DFT) and classical molecular dynamics (MD) methods have been used for investigating the physicochemical properties, structuring, dynamics and interfacial behavior of the studied NADES from the nanoscopic point of view to infer its viability for extensive usage. The rheological experimental results show usual shear‐thinning effect in which the η is decreasing with shear rate at all temperatures. A trend of studied NADES viscosity profiles were found as very similar to that of common ionic liquids that were previously, where the viscosities of all studied NADES decreased with increasing temperature. DFT simulations yielded with an accurate quantification of short‐range interaction but liquid state is also characterized by middle and long‐range interaction together with volumetric effects. Molecular orientations were quantified by radial distribution functions and the developed interactions are topologically characterized.

No abstract

Particles size distribution (PSD) is introduced as a tool for analysis of bentonite aggregation and swelling kinetics. Raw Ca-bentonite was purified using a combined wet sieving and sedimentation processes, followed by thermochemical treatment with Na 2 CO 3 to increase its swelling capacity. The detailed analysis of the PSD shows a strong correlation between the PSD and the swelling process. For the chemically treated raw bentonite, PSD revealed two different peaks representing unswelled and swelled particles along with some aggregates. The swelling is shown to be a kinetically controlled process that depends on time, temperature, and bentonite chemical composition. At the beginning of the chemical treatment, the effect of aggregates was more dominant; therefore, the viscosity did not increase much with particle size. However, the combined chemical and thermal treatment has enhanced the Na-activation process and boosted bentonite swelling. The rheological measurements have shown enhancement in the viscosity and confirmed the PSD findings. The same optimal treatment conditions are obtained from both rheological measurements and PSD analysis. A model is developed based on classical reaction rate kinetics and used to describe the conversion from unswelled to swelled particles. The PSD has a strong correlation with the physical properties of the suspension such as the viscosity. The swelling rate fits a second order model with a rate constant, k, in the range 0.002 to 0.124 h À1 and an activation energy, E, of 87 kJ/mol. PSD analysis together with the developed kinetic model are powerful tools for studying the swelling kinetics of bentonites.

No abstract