Mechanochemical Upcycling of Polyvinylidene Fluoride: Lewis Acid Induced Generation of Sodium Aluminium Fluorides
Minh Bui, Jakob Bölle, Jörg Radnik, Steffen Weidner, Luise Sander, Mike Ahrens, Kerstin Scheurell, Kannan Balasubramanian, Franziska Emmerling, Thomas BraunA sustainable mechanochemical process for the generation of sodium aluminium fluorides by conversion of polyvinylidene fluoride (PVDF) waste on using ball milling in the presence of a Lewis acid was developed. The generated fluorides can be key materials for the aluminium production process. The Lewis acid AlCl 3 initiates dehydrofluorination steps at PVDF, releasing HF for further fluorination of both NaCl and AlCl 3 to yield chiolite under ball milling conditions. Further calcination of chiolite generates cryolite with an overall yield of 62% with respect to AlCl 3 . The procedure avoids the use of solvents and minimises energy consumption. The identity and phase purity of the products was confirmed by XRD, NMR, IR, and Raman analyses. It was also demonstrated that powdered PVDF, real‐life PVDF membrane waste or PVDF extracted from Li‐ion batteries can be upcycled into industrially relevant fluoride materials. The presented method offers a sustainable approach for resource recovery and environmental remediation.