Hybrid Ionic Liquid-Chitosan Membranes for CO2 Separation: Mechanical and Thermal Behavior

Esther Santos,Enrique Rodríguez-Fernández,Ángel Irabien,Clara Casado-Coterillo

doi:10.1515/ijcre-2014-0109

Esther Santos, Enrique Rodríguez-Fernández + Show 2 more

Open Access

https://doi.org/10.1515/ijcre-2014-0109

Copy DOI

Abstract

Abstract Pure chitosan (CS) and hybrid ionic liquid-chitosan membranes loaded with 5 wt% 1-ethyl-3-methylimidazolium acetate ([emim][Ac]) ionic liquid were prepared in order to improve the thermal behavior of supported ionic liquid membranes (SILMs) for CO2 separation. Gas permeability, solubility and diffusivity were evaluated in the temperature range 298–323 K. The temperature influence was well described in terms of the Arrhenius–van’t Hoff exponential relationships. Activation energies were calculated and compared with those obtained for SILMs with the same ionic liquid. The introduction of this ionic liquid in the hybrid solid membrane decreases the permeability activation energy, leading to a lower influence of the temperature in the permeability and diffusivity. Moreover, the thermal behavior is similar to pure chitosan membranes, and the mechanical strength and flexibility were improved due to the introduction of the ionic liquid in the polymer matrix.

Highlights

The ability to efficiently separate CO2 from other light gases has received a great attention aiming at capture greenhouse gases
Where pfeed and pperm are the pressures in the feed and permeate compartments, respectively; β a geometric parameter (1,100 m−1); P the permeability through the membrane calculated under constant partial pressure
The tensile strength of the hybrid room temperature ionic liquids (RTILs)/CS membrane is lower than the pure polymer membrane, but the elongation at break is greatly improved, even higher than other data for CSbased membranes reported in the literature [18, 19]

Summary

Introduction

The ability to efficiently separate CO2 from other light gases has received a great attention aiming at capture greenhouse gases. RTILs are liquid salts at room temperature, typically composed of bulky organic cations and organic or inorganic anions showing a large variety of properties such as negligible vapor pressure, thermal stability at high temperatures or non-flammability [4] Their physicochemical properties can be tuned by the appropriate selection of the cation or anion resulting in enhanced properties such as gas solubility. In a previous work [5], the CO2/N2 separation in the temperature range 298–333 K of commercial acetate-based RTILs and ionic monomers was studied in the form of SILMs. The temperature influence on the gas permeability, solubility and diffusivity was evaluated and the activation energies were calculated but the long-term stability was not evaluated. From our knowledge, it is the first time a completely solid membrane based on hybrid

Methods

Results

Conclusion