Absorption of SO sub(2) by renewable ionic liquid/polyethylene glycol binary mixture and thermodynamic analysis

Separation and removal of SO sub(2) before atmospheric release of the flue gas is essential to combat acid rain formation. Traditional chemical absorbents and conventional ionic liquids (ILs) suffer from several shortcomings including waste, second pollution, high viscosity, poor biodegradability an...

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Bibliographic Details
Published in:RSC advances 2015-10, Vol.5 (107), p.87750-87757
Main Authors: Han, Guo-Qiang, Jiang, Yao-Tai, Deng, Dong-Shun, Ai, Ning
Format: Article
Language:English
Subjects:
Absorbents
Atmospherics
Binary mixtures
Biodegradability
Ionic liquids
Polyethylene glycol
Solubility
Thermodynamic models
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Summary:Separation and removal of SO sub(2) before atmospheric release of the flue gas is essential to combat acid rain formation. Traditional chemical absorbents and conventional ionic liquids (ILs) suffer from several shortcomings including waste, second pollution, high viscosity, poor biodegradability and low absorption capacity. In this work, two renewable ILs where both cation and anion come from biodegradable materials, 2-hydroxyethyl-trimethylammoniume levulinate ([Choline][LA]) and 2-hydroxyethyl-trimethylammoniume lactate ([Choline]L), were synthesized and mixed with polyethylene glycol 200 (PEG200) to form 40 w% ILs binary mixture as SO sub(2) absorbents. Solubilities of SO sub(2) in the above two mixtures were measured under the temperature range of 303.15-333.15 K and the pressure up to 1.2 bar, with the result of 6.97-7.24 mol kg super(-1) absorbents at 1.0 bar and 303.15 K. When the SO sub(2) pressure is reduced to 0.039 bar, the solubilities are still 1.77-1.84 mol kg super(-1) absorbents. Reaction Equilibrium Thermodynamic Model (RETM) was used to analysis the thermodynamic behavior of SO sub(2) in present ILs mixtures. The obtained absorption enthalpies are as low as -39.81 and -51.69 kJ mol super(-1) for the two binary mixtures, respectively. The two mixtures possess one or more improvements over commonly reported ILs in the aspects of biodegradability, absorption capacity, cost and energy consumption for regeneration of absorbents.
ISSN:2046-2069
DOI:10.1039/c5ra13750k