3D structure enhancers based on functionalized MIL-53(Al) for improved dimethyl carbonate/methanol pervaporative separation

Abstract

Dimethyl carbonate (DMC) is considered an alternative, green solvent. This paper focused on enhancement in membrane performance in DMC removal by pervaporation (PV) from azeotropic mixture of DMC/methanol as a consequence of the incorporation of nanofiller into a PDMS matrix. Engineering a hydrophobized analogue of MIL-53(Al) (NHOCOCF3-MIL-53(Al)) as nanoenhancers for improved membrane materials is presented. XRD analysis confirmed the successful synthesis of MOFs and proved that modification does not influence crystalline structure of MOF, which is well retained. Properties of the membranes in PV were assessed employing separation factor (β) and thickness-normalized Pervaporation Separation Index (PSIN). Modified PDMS membranes possess better separation properties compared with pristine one. Results revealed that the incorporation of 5 wt% of NHOCOCF3-MIL-53(Al) caused an increase of β from 3.1 to 3.7, a significant value for organic-organic PV. Essential part of the work was to analyze impact of the presence of water in the feed on overall membrane effectiveness. It was observed that in the case of traces amount of water in the feed solution, water was preferentially transported from the feed to the permeate side. However, the transport of water through membranes was partially suppressed when water content in the feed was over 0.7 wt%.