A systematic review of methodologies and solutions for recycling polyurethane foams to safeguard the environment

Today, plastic plays a pervasive role in everyday life. Their improper disposal can create ongoing environmental challenges. Polyurethane (PU) is a polymer with elastomeric properties that exhibits significant adhesion and durability. PU has various colors and resistance to acid and alkali substances. The widespread use of PU has caused a significant presence of these compounds in landfills. Therefore, it can cause significant plastic pollution globally. This increased environmental concern has prompted researchers and innovators to explore sustainable methods for recycling PU foam. Therefore, the recycling of PU waste is recognized as an essential requirement due to its economic and environmental benefits. Although the latest reviews focused on physical, chemical, and biological methods of PU recycling, a comprehensive review of other PU recycling methods is needed. Therefore, the present study is a systematic review of recent initiatives and innovations in the field of recycling and modification of PU foam production methods to recognize and reduce environmental impacts. In the present study, major global databases such as Web of Science, PubMed, Scopus, Google Scholar, and Iranian databases (up to January 2024) were searched with relative keywords to identify studies published in authoritative journals. Data were collected from qualified articles on different PU recycling methods and innovative processes. From a total of 1088 articles found, finally, 46 studies met the objectives and inclusion criteria. Based on the results, today various methods are used to recycle PU compounds, but more attention has been paid to efficient methods such as energy production and high-consumption products such as rubber and adhesive from these compounds. In addition, it highlights some approaches, such as the production of absorbents from PU foams, which not only improve the current technology but also show promise in reducing the environmental impact of this ubiquitous material.