[ recycling ] infrastructure based on pyrometallurgical processes . This involves incineration of the entire MEA as a way to separate the PGMs from fluoropolymers and other MEA constituents . PFSA polymer itself is expensive to produce , and incineration not only causes the loss of the inherent value of the PFSA polymer component , but also generates severe environmental burdens as toxic hydrofluoric fumes are released in the process . A major concern is the formation of hydrogen fluoride ( HF ), a toxic compound that is both harmful to human health and highly corrosive . The application of the pyrometallurgical procedures therefore requires special protective linings for the furnaces as well as elaborate scrubbing systems to eliminate HF from the emission . 10 Despite such investments , any fluorine constituents remaining in the PGM-containing slag could hamper the subsequent separation . In addition , through incineration the valuable PFSA material is essentially destroyed and cannot be recycled . Therefore , with the rapidly increasing feed of spent MEAs , the traditional pyrometallurgical recycling method will not be feasible .
MEA recycling using classic hydrometallurgy
Internationally , many groups have expressed interest in MEA recycling , and a number of procedures for recovering PGMs from end-of-life fuel cells with high efficiencies and under the premise of avoiding HF emissions have been reported . It must be stressed , however , that none of these procedures has been implemented on an industrial scale so far . The most common technique is leaching of the individual PGMs by hydrometallurgy . However , as PGMs have very noble characteristics , their resistance to dissolution is also quite high . Consequently , strong acids in combination with strong oxidants 11 are required in the leaching process , leading to the formation of soluble PGM complexes . In addition , platinum dissolution and mineral extraction were also studied using ionic liquids and deep eutectic solvents 12 , 13 , which showed high extraction efficiency . However , their large-scale implementation is undesirable due to the corrosive or high-cost chemicals involved in the process and due to related emission issues .
Fig 4 . A representative material composition in a polymer fuel cell MEA , where the fluoropolymer includes both PFSA and PTFE
Hydrogen Tech World | Issue 7 | December 2022 31