Waste-Derived carbon porous materials for enhanced performance in adsorption chillers: A Step toward a circular economy

In this study, a comprehensive examination of commercial activated carbons and novel porous carbon materials derived from waste was conducted to evaluate their potential as bed materials in adsorption chillers driven by waste heat. The research uniquely focuses on synthesizing and analyzing sorbents from two distinct waste sources: lignin and excavated waste, aiming to expand the sustainable application of waste-derived materials. A thorough characterisation of the sorption properties was performed using mercury intrusion porosimetry, low-temperature gas adsorption, and dynamic vapour sorption measurements with methanol. These techniques provided detailed insights into the microporous structure and surface areas of the materials, ranging from 500 to 2000 m2/g for the activated carbons. Notably, the lignin-derived magnetic biochar demonstrated an exceptionally well-developed surface area and superior sorption properties at operational conditions of 30 °C, reaching relative adsorption of 59.89 % at P/P_o of 100 %—up to 70 % higher than that of commercially available activated carbons. This material’s performance highlights its potential as a high-efficiency adsorbent in adsorption chillers, surpassing many commercially available options. However, the char obtained from excavated waste exhibited limitations due to high ash and heavy metal content (786 mg/kg Pb and 127 mg/kg Zn), suggesting challenges for its use in activated carbon synthesis. This study bridges a critical knowledge gap by exploring innovative pathways for utilizing waste-derived porous carbon materials in adsorption cooling, thus contributing to the development of sustainable, waste-based solutions for heat-driven cooling applications.