A review on VOCs from recycled plastics

Abstract

Plastic demand is continuously growing and, with it, the amount of plastic waste. The packaging industry is by far the largest source of single-use plastic products that, after use, end up in landfills and oceans. Mechanical recycling is the solution most widely implemented in the global industry and its effectiveness and reliability have been demonstrated for processing post-industrial plastic scrap. The recycling of post-consumer plastic waste, however, requires an upgrade in the current technology to achieve complete decontamination and removal of malodorous substances embedded in the polymer. This review explores the state-of-the-art technology currently employed in the mechanical recycling of plastic waste, focusing on the progress made for the removal of volatile organic compounds emitted from recycled materials. Followed by a review of the analytical techniques that have been applied for the identification of volatile organic compounds, including, in particular, the techniques used for the identification of odor-active substances. Finally, this review gathers from literature all the volatile organic compounds and odor-active substances identified in virgin and recycled polymers, aiming to evaluate whether there is a notable difference between them based on the chemical structure of the emitted VOCs. As a result, 437 volatiles were gathered, which show the difference between post-consumer recycled plastics and the other plastic waste sources. A larger number of volatile organic compounds, especially flavor and fragrances-based substances as well as oxygenates, appear in post-consumer plastic waste compared to virgin and post-industrial plastic scrap.