Synthesis and application of a novel Amino-Starch derivative as a new polymeric additive for fixed facilitated transport of carbon dioxide through an asymmetric polyethersulfone (PES) membrane

In the current study, we prepared a novel water insoluble Amino-Starch (AS) derivative using Williamson ether synthesis method. The prepared AS was used as a polymeric additive for the preparation of an integrally skinned asymmetric polyethersulfone (PES) membrane. The PES/AS membranes were combined with a facilitated transport mechanism and solution-diffusion mechanism in an integrally skinned asymmetric membrane for the separation of CO2 from CH4 for the first time. The miscibility of PES and the synthesized AS was confirmed by Differential Scanning Calorimetry (DSC). The change in the membrane morphology was investigated using Scanning Electron Microscopy (SEM). The sorption isotherms were obtained to investigate the effect of the AS on the membrane gas sorption capacity. Introducing the AS into the PES membranes leads to a denser sub-layer and a higher CO2 sorption capacity of the prepared membranes. A higher CO2 permeation, a lower CH4 permeation and a higher CO2/CH4 selectivity are the most important changes in the performance of the PES membranes caused by the incorporation of a facilitated transport in CO2 permeation and a denser sub-layer of the prepared membranes. Furthermore, the glass transition temperature (Tg) as well as the non-equilibrium free volume of the PES membranes was decreased and the plasticization pressure of the PES membranes was improved by introducing the AS into the PES membranes. The incorporation of the facilitated transport mechanism in the PES/AS membranes altered the membrane behavior against the change in the feed pressure and the feed temperature.