Novel sandwich structure of electrospun PLA calixarene nanofiber membranes for improved heavy metal ion removal performance

Water pollution, driven by the limited availability of clean water, is a critical global issue, with heavy metal ions posing significant threats to aquatic systems and human health due to their toxicity and persistence. Adsorption using electrospun fiber mats, such as biodegradable polylactic acid (PLA), offers a promising solution, particularly when combined with calixarenes, which selectively capture metal ions. However, calixarene incorporation increases hydrophobicity, affects adsorption efficiency. This study addresses this challenge by developing layered (sandwich) electrospun membranes, comprising two PLA layers enclosing a calixarene-loaded PLA layer, for nickel ion removal. Wettability tests confirmed reduced hydrophobicity, while adsorption studies demonstrated higher performance of the sandwich structure, with enhanced thermodynamic spontaneity and distinct kinetic adsorption mechanisms. This work highlights the potential of sandwich-structured membranes for water purification and provides a foundation for further research into their optimization and application.