Enhanced pervaporation performance of PEG membranes with synergistic effect of cross-linked PEG and porous MOF-508a

Abstract

MOF-508a with moderate 1D channels and large pore cavity size, was successfully synthesized and firstly incorporated into polyethylene glycol (PEG) to prepare mixed matrix membranes (MMMs) for desulfurization via pervaporation. Four kinds of cross-linkers were employed to cure PEG polymers, and PEG membrane cured with oxalic acid acquired much better comprehensive pervaporation performance. The uniformly dispersed MOF-508a in PEG matrix interrupted the crystalline region and decreased PEG crystallization degree. MOF-508a might act as facilitated transport carriers for thiophene molecules based on coordination interaction between Zn2+ and S, and large pore cavities provided multi-scale transport pathways for thiophene molecules. Besides, the strong interaction between MOF-508a and PEG enhanced the interfacial compatibility, which might provide more selective transport pathways for small molecules. Owing to the synergistic effect of cross-linked PEG and porous MOF-508a, the MOF-508a/PEG-5 MMMs exhibited outstanding enrichment factor of 30.4 with permeation flux of 0.485 kg/m2h, which were 98 % and 110 % higher than those of pristine PEG membrane. The enrichment factor of MOF-508a/PEG out-performed most the ever-reported membranes, which might provide some new insight in designing high-performance MMMs by rationally achieving synergy of porous fillers and polymer matrix.