Plastic Purification and Separation Through Solvents

For a successful circular plastic economy, production of well-purified and well-performing recycled polymers is key. Otherwise, reapplication of recycled polymers in high-demanding applications will fail and undermine the principle of circularity. In addition to classic mechanical recycling, solvents may significantly enhance the performance of separation and purification technologies as outlined in this chapter. Whereas the use of solvents is a common principle in some areas of polymer production (e.g., polyacrylonitrile (PAN)), their use in deinking, delamination, and dissolution-based recycling is currently evolving. This chapter describes principles of solvent use and focusses on dissolution processes. These benefit from highly selective solvents and enable separation of laminates and composites, including recovery of glass or carbon fibers. Specific unit operations further allow separation of inorganic fillers or organic additives, including legacy additives. The purification is further demonstrated by a detailed description of three specific case studies, comprising recycling of flexible packaging, flame-retarded insulation panels, and fiber-reinforced composites. Finally, the status of commercialization and a tool for economic process evaluation is presented.