Influence of Pyrolysis Temperature and Time on Biochar Properties and Its Potential for Climate Change Mitigation

Abstract

The thermochemical conversion of disposable bamboo chopstick (DBC) wastes into biochar is a practical strategy for converting waste into resources. This study aimed to investigate the effects of pyrolysis temperature and holding time on the physicochemical properties of DBC biochar and its potential for climate change mitigation. Properties affecting the biochar efficiency and potential for application were analyzed: moisture content (MC), volatile matter (VM), fixed carbon (FC), ash, pH, and carbon (C), hydrogen (H), nitrogen (N), and oxygen (O) content. Six different pyrolysis conditions were studied, with temperatures of 400 °C, 450 °C, and 500 °C and holding times of 20 and 60 min, at a constant heating rate. The results demonstrated that temperature and holding time significantly affected the physicochemical properties and performance of the biochar. Increases in %C, %FC, %N, and pH and reductions in %MC, %VM, %H, and %O were found when the temperature was increased at different holding times. The aromaticity increased and the polarity decreased significantly with increasing temperature and holding time. The results showed that temperature interacts significantly with holding time, and these two factors jointly affect the contents of MC, ash, FC, C, H, N, and O (R2 of 0.997) and pH (R2 of 0.999). The DBC biochar obtained via pyrolysis at 450 °C and 500 °C for 20 and 60 min could be applied for climate change mitigation. The best DBC biochar was obtained at a pyrolysis temperature of 500 °C and a holding time of 20 min. This biochar showed good hydrophobicity, tremendous stability, the highest C (88.06%) and FC (76.49%) values, and the lowest ash (2.62%) and VM (19.23%) contents.