الملخص الإنجليزي
Ionic liquids (IL) are non-volatile liquids that have attracted interest for a range of
applications. However, a novel group of IL analogs known as deep eutectic solvents
(DES) has lately attracted a lot of interest as a flexible and practical alternative to ILs.
Because they share many of the favorable characteristics of ILs while overcoming their
major drawbacks, these solvents can be tailored to be effective substitutes. DESs are
typically less costly, safer, more sustainable, and easier to make. The capacity to
manufacture these liquids with few preparation steps is one of the most important
features that allow them to be used on a large industrial scale.
In this work, two new eutectic solvents were prepared by combining imidazole with
monoethanolamide and menthol with PEG200. Density () and viscosity () were the
two physical properties determined for the two eutectic solvents at the studied molar
ratios (1:2, 1:3, and 1:4) within a temperature range of 25 to 65 ºC. The experimental
data was regressed as a function of temperature and molar ratio. For the two studied
systems of imidazole-MEA and menthol-PEG 200 the measured density varied within
the ranges (1.042- 0.999 g/cm3
) and (1.039– 1.04g/cm3
), respectively. While viscosity
varied within the ranges of (19.7– 3.21cP) and (40– 6.08 cP), respectively.
The CO2 solubility was investigated for the two DESs in different molar ratios under
the pressure of 10 bar and a temperature range of 30-60 ºC. The highest CO2 loading
for imidazole-MEA was 0.711 (mole CO2/mole DES) at 30 ºC, 10 bar and molar ratio
of 1:4. For the menthol-PEG 200 system, the highest CO2 loading of 0.598 (mole
CO2/mole DES) was achieved at 30 ºC, 10 bar and molar ratio of 1:2. From the results
obtained, it was observed that the solubility of CO2 in these two DESs has a strong
direct relationship with pressure while inversely proportional to temperature.
To monitor the CO2 absorption behavior and detect any possible enhancement of
chemical absorption, the prepared eutectic solvents were also combined with
water. Experimental investigations revealed that both eutectic solvents' CO2
absorption capability is influenced by pressure and water content. For the imidazole MEA eutectic mixture, the CO2 absorption capacity was almost doubled when a 50%
water content was used. Using imidazole-MEA and menthol-PEG200 mixed with 50
%v water, the optimum CO2 absorption capacity of 1.357 and 0.7468 mol CO2/mol
DES at the operating conditions of 30 ºC and 10 bar.
Solubility of CO2 was verified in terms of Henry's constant. The calculated Henry's
constant (Hx) for the imidazole-MEA system (Hx =4.35−5.02 MPa) was found to be
lower than that for the menthol-PEG200 system (Hx= 4.76- 5.11MPa). Calculated
Henry's constants at 30 ºC were compared to to other DESs and ILs indicates that the
DES systems suggested in this work portrayed better CO2 absorption capability. In
addition, the absorption enthalpy of CO2 was also calculated. Results revealed the
strong interaction between CO2 and the two DES affirmed by the negative enthalpy
value.
This fundamental study leaves the door open for more in-depth investigations
involving these two novel DES systems. Special attention can be given to applications
involving carbon dioxide capture and those involving chemical reaction and extraction
technological processes.
