Preparation and ion separation properties of sub-nanoporous PES membrane with high chemical resistance

The sub-nanochannel materials have attracted extensive attention because of the great potentials in ion separation and water filtration due to their unique ionic transport properties. However, effectively preparing the subnanoporous membranes with tunable channel size is still a challenge. In this study, a green and convenient method is introduced to prepare sub-nanoporous polyethersulfone (PES) membrane with highly aligned channels by swift heavy ion irradiation, UV sensitization, and water rinse. Through adjusting the membrane's UV sensitization time, the channel diameter of sub-nanoporous PES membrane can be facilely regulated at subnanoscale, which is essential to design the tailor-made membranes for specific applications. It is found that ionic transport in sub-nanoporous PES membrane exhibits voltage-activated features associated with the ionic dehydration at angstrom-confined space, with the corresponding I-V characteristics showing a dependence on ion species, channel size, and solution pH. Such a membrane can work as an excellent ion-exchange membrane in electrodialysis ion separation, exhibiting a separation ratio of K+:Na+:Li+:Mg2+ as high as 83:56:14:1 and K+ transport rate up to 0.82 mol h-1 m- 2 under 10 V driving force. It is proved that the sub-nanoporous PES membrane also possesses strong chemical and electrochemical tolerances, which are the prerequisites for future utilizations.

Automated summary

A study presents a green and convenient method to prepare sub-nanoporous PES membrane with highly aligned channels, which can be facilely regulated at subnanoscale by adjusting membrane's UV sensitization time for tailor-made membrane design. The membrane exhibits excellent ion-exchange performance in electrodialysis ion separation, with high separation ratio and transport rate. The strong chemical and electrochemical tolerances of the sub-nanoporous PES membrane are essential for future applications.