Biochar activated by potassium carbonate to load organic phase change material: Better performance and environmental friendliness

Chemically activated biochar, which is characterized by its high surface area, thermal stability, and chemical compatibility, exhibits great potential for loading phase change material (PCM) to enhance heat transfer and prevent leakage. However, conventional chemical activation processes typically involve highly corrosive and toxic chemical activators that pose environmental hazards. Biochar that is activated by K2CO3, which achieves high porosity while minimizing adverse environmental effects, has been applied in some fields. In this study, K2CO3 was employed as a chemical activator, and five waste biomass materials were utilized as precursors to produce biochar samples for the loading of paraffin (PA), stearic acid (SA), and polyethylene glycol (PEG). The results revealed that the activated biochar derived from corncob (CC) exhibited remarkable textural characteristics, and it had a specific surface area of 1053.95 m2/g and a total pore volume of 0.467 cm3/g. Additionally, owing to its larger specific surface area and richer textural characteristics, the loading capacities of CC for PA, SA, and PEG were as high as 78.79 %, 80.83 %, and 85.19 %, respectively. Furthermore, introducing PA, SA, and PEG into CC resulted in thermal conductivity enhancements of 1.460-, 1.138-, and 1.271-fold, respectively. Lastly, incorporating biochar improved the thermal stability of the composite PCMs. This study aimed to explore the performance of the biochar activated by K2CO3 in PCM loading, enhancing the environmental sustainability of waste biomass-derived activated biochar in PCM loading applications.