Development of New Sustainable Solvent and Antisolvent Systems for HDPE Recycling: Dissolution and Precipitation

12/07/2023

Plastic waste has been a topic of increasing interest in recent years, and the recycling technologies available are still far from reaching the required capacity. We are at a point where end-product quality will dictate the real shift to a circular plastic economy. Polyolefins are one of the most abundant plastics, but their recycling faces various difficulties. This work focused on the recycling of HDPE through dissolution-precipitation. Although a few works have been published on this topic, there is an urgent need to use greener solvents and minimize energy usage for this kind of process to become a viable alternative for the years to come. Several natural terpenes were screened based on COSMO-RS predictions for HDPE solubility, from which four were selected to carry out the experimental work: limonene, α-pinene, p-cymene, and squalane. Even though squalane showed little capacity for dissolving HDPE, the remaining solvents were suitable for the process. The dissolution and precipitation conditions were optimized based on the results for limonene, being fixed at 3wt%, 10 min at 110°C, and antisolvent/solvent ratio of (2/1). Comparing HDPE and solvent recoveries for the various solvents, the best results were obtained for α pinene as solvent and ethanol as antisolvent. The recovered samples were analyzed through various techniques, showing little modifications between the recycled and the pristine materials. The scale-up of the process and the solvent reuse were also investigated, as well as the separation of HDPE and PET, and the possibility of using the same solvent/antisolvent system for recovering PP.

Authors in the community:

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  S

  Sofia Canteiro Aparício

  ist193488

Supervisors of this institution:

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  I

  Isabel Maria Delgado Jana Marrucho Ferreira

  ist129097

chemical-engineering - Chemical engineering

por - Portuguese

Instituto Superior Técnico