(306c) Sustainable Separation and Recycling of Organics and Plastic By Thermochemical Conversion

Mixed waste plastics are inherently difficult to recycle and reuse due to the presence of numerous contaminants, a wide range of melting temperatures, and degradation in material properties during processing. Clothing is even more difficult to recycle as it incorporates non-polymeric materials (e.g., zippers, buttons) as well as organics (e.g., cotton). While the organic fraction eventually breaks down in a landfill, the synthetic plastics (e.g., polyester, nylon, spandex) persist as environmental pollutants. There is a need for improving waste plastic separation contaminated with organics and non-plastics.

Mainstream investigated a hydrothermal process that consists of bulk material separation followed by a moderate-temperature, catalytic degradation scheme to rapidly breakdown cotton while leaving the synthetic fibers untouched and able to be recycled. In this work we will discuss the reaction kinetics and reactor design for a slurry fed hydrothermal process for decomposition of cotton into sugar-derivatives when mixed and entrained in a waste plastic waste matrix using heterogeneous or homogeneous acid or base catalysts and the specific effects from temperature, residence time, pre-treatment loading including the resulting yield and selectivity and a corresponding process design, technoeconomic analysis, and life cycle assessment to evaluate the viability and sustainability of the process.