Decomposition of fluoropolymers by their mineralization in subcritical water

Abstract Fluoropolymers have many industrial applications such as not only general-purpose products (packing, tubes, sinks, valves etc.), but also ion-exchange membranes, optical fibers, resists, energy devices, etc., because of their unique properties. While applications of these polymers are being spread, waste treatment techniques for the polymers are not well established, because these polymers are thermally and chemically stable owing to the presence of strong C–F bonds, and incineration treatment generates hydrogen fluoride gas, which seriously damages incinerators. This chapter describes effective methodologies to decompose cutting-edge fluoropolymers (i.e., ion-exchange polymer membranes, poly(vinylidene fluoride) (PVDF), poly(ethylene-co-tetrafluoroethylene) copolymer (ETFE), and VDF-related copolymers) to F– ions in subcritical water by reductive or oxidative reactions, with the aim for recycling fluorine element. One pot formation of CaF2 in the presence of Ca(OH)2 is also reported for several reaction systems.