Sustainable valorisation of waste-derived plastic rich materials into porous carbon materials for adsorption cooling applications

Abstract

The thermochemical valorisation of waste materials rich in plastics offers a sustainable approach for waste reduction and the generation of high-value products, aligning with the European Green Deal and circular economy principles. This study investigates the conversion of three solid waste streams: refuse-derived fuel (RDF) from municipal (RDF_MW) and industrial (RDF_IW) sources and tyre-derived fuel (TDF) into activated carbons for application in adsorption cooling systems. A two-step activation process, combining pyrolysis at 600 °C with subsequent steam (850 °C) or chemical (KOH at 800 °C) activation, was employed to enhance porosity and surface area. RDF_IW-derived carbon activated with KOH achieved a maximum BET surface area of 955 m$^{2}$/g, while methanol adsorption tests showed an uptake exceeding 40 %. Heavy metal analysis revealed significant Zn contamination in TDF (up to 37,415 mg/kg), while Cr, Pb, and Sn were prominent in RDF samples; chemical activation reduced Zn content by up to 70 %. Performance testing in methanol-based adsorption chillers showed that RDF_IW_H2O and RDF_IW_KOH samples achieved specific cooling powers (SCP) of 53.5 W/kg and 88.9 W/kg, and coefficients of performance (COP) of 0.631 and 0.673, respectively, comparable to commercial activated carbons (CWH-22: SCP = 95.5 W/kg, COP = 0.615). These findings demonstrate the dual benefit of valorising heterogeneous waste into functional sorbents while enabling energy-efficient, low-grade thermal cooling systems.