PHYSICAL PROPERTIES AND SOLUBILITY OF C02 IN BIS(2- HYDROXYETHYL)AMMONIUM ACETATE ([BHEAA]), 1-BUTYL-3- METHYLIMIDAZOLIUM TETRAFLOUROBORA TE ([BMIM] [BF 4]) AND MONOETHANOLAMINE (MEA) BASED HYBRID SOLVENTS

An industrially attractive solvent to capture COz, has been developed by
incorporating the desirable properties of ionic liquids(ILs) as well as amines through
mixing of the targeted ILs with amine to form hybrid solvents for the effective capture
of COz. In the present work, ILs of two different families namely, bis(2-
hydroxyethyl)ammonium acetate ([bheaa]) and 1-butyl-3-methylimidazolium
tetraflouroborate ([bmim] [BF 4]) have been chosen to form a new binary/ ternary
solvents in combination with monoethanolamine (MEA) and water for the solubility
of C02. In order to establish the physical properties for the new binary [ (bheaa +
water); (bheaa+ MEA); (bmimBF4+water); BmimBF4+MEA) I ternary [(bheaa +
MEA + Water) (bmimBF4 + MEA + Water)] solvents, density, viscosity and
refractive index measurements have been made at T = (293.15 to 353.15) K for the
whole composition range. Based on the measured values the effects of temperature
and concentration of individual spicies have been discussed in detail and suitable
correlations have been proposed.
The excess properties, namely, the excess molar volume V', viscosity deviation t'l.iJ,
as well as the refractive index deviation t'l.no, have been deduced from the measured
density, viscosity and refractive index values respectively for all the binary and
ternary systems studied in the research. The Redlich Kister equation was used to
correlate the estimated excess properties for the binary systems while the Cibulka
equation was used to correlate the excess properties for the ternary systems.
The COz uptake capabilities of the present developed hybrid binary ([bheaa] +water;
[bheaa] +MEA; [bmimBF4] +water; [bmimBF4]+MEA) I ternary ([bheaa] +MEA+
Water, [bmimBF4] +MEA+ Water) solvents, have been made by using the SOLTEQ
High Pressure Gas Solubility Cell (Model: BP-22) and the results are presented and
the effect of concentration, pressure and temperature on the COz uptake have been discussed in detail. The present results indicated that the aqueous solution of [bheaa]
+ MEA have been found to have better C02 loading than the aqueous solution of
[bmim][BF4] + MEA. The combination of these chosen ILs with selective amine
solution have proved to have the characteristics for efficent C02 capture and seems
to be a promising alternative for the aqueous amine solution/absorbents which are
currently being used for C02 absorption.