Iron oxide/poly (vinylidene fluoride-hexafluoropropylene) membranes for lithium-ion battery separator and arsenic removal applications

The here presented experiments report on bi-functional iron oxide (Fe3O4)/poly (vinylidene fluoride-hexafluoropropylene) - PVDF-HFP porous membranes prepared through thermal-induced phase separation (TIPS) for As(III) and As(V) adsorption and posterior second life as a lithium-ion battery (LIB) separator considering a circular economy paradigm. The bi-functional membranes' physical-chemical properties, their ability to remove arsenic species from aqueous solution, and subsequent performance as a battery separator for LIB were assessed. A highly porous structure characterises the membranes, and the incorporation of nanoparticles (NPs) does not change the chemical and thermal properties of the polymeric membrane. The membrane with 10 wt% of Fe3O4 revealed the ability to remove approximately 81% and 82% of arsenite and arsenate from water, presenting equally remarkable reusability after five cycles, with an efficiency loss below 12%. The second life of this material as a battery separator revealed an ionic conductivity of 2.3 mS.cm-1 and a discharge capacity of 60 mAh.g-1 at 2 C-rate. This work proves the multifunctionality of the membranes and the possibility of a second life.