A Novel Solvent-Based Recycling Technology: From Theory to Pilot Plant

Document Type

Book Chapter

Publication Date

1-26-2024

Department

Department of Mechanical Engineering-Engineering Mechanics

Abstract

We have developed a solvent-based technology for the extraction of single pure resins of food quality. The technology is called Solvent Targeted Recovery and Precipitation (STRAP). We have carried out numerous lab-scale experiments (in batches of 10-1000 g), with various plastic wastes, both post-industrial recycling and post-consumer recycling, including multi-layer flexible films. The key to the successful implementation of STRAP is the ability to pre-select solvents and temperatures to selectively dissolve a single polymer from all components in the mixture. The team has developed an extensive fundamental understanding of dissolution, enabling a successful operation. To aid in solvent selection, we developed a first-principles molecular modeling approach to rapidly predict temperature-dependent polymer solubilities. The technology is currently being scaled up to a 0.5 ton/day continuous Process Development Unit (PDU), which will be the basis for the next industrial scale. The technology requires relatively low temperatures (100-135°C) and equipment that is available in the chemical industry. We carried out extensive techno-economic and life-cycle assessments that showed (i) a STRAP system can be profitable as a stand-alone system at a 4,000 ton/y facility, with a great advantage of size, and (ii) due to the low process energy, the GHG emissions are reduced by over 90% in comparison to fossil-based polymer production. A line of the STRAP technology extracts a single polymer; to extract multiple polymers, multiple STRAP lines are required. Various methods can remove ink, pigments, or colorants, producing pure, colorless resins of food quality. The STRAP scheme depends on the source of the waste. It is to be noted that we successfully separated nine resins from arbitrarily mixed plastic wastes. Through our industrial partners, we showed that our extracted resins can be reused for their original film applications. The single most important economic factor is solvent recovery, at >99.9% of the solvent used, which is the solvent recovery system we are developing. Both lab scale and upscale results are presented and discussed.

Publication Title

Technology Innovation for the Circular Economy: Recycling, Remanufacturing, Design, System Analysis and Logistics

ISBN

[9781394214297, 9781394214266]

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