Aromaticity, polarity, and longevity of biochar derived from disposable bamboo chopsticks waste for environmental application

Transforming disposable bamboo chopstick (DBC) wastes into biochar is an effective way to achieve waste-to-resource conversion. This research focused on the elemental and chemical composition of biochar and revealed how these properties affect biochar performance in real-world applications, particularly with respect to climate change mitigation. This research is aimed at examining the effect of pyrolysis temperature on the aromaticity, polarity, and longevity of DBC biochar. The DBC feedstock was pyrolyzed at different temperatures of 400 °C, 450 °C, 500 °C, and 550 °C with a holding time of 20 min at a constant heating rate of 20 °C min-1. The chemical composition, including carbon (C), hydrogen (H), nitrogen (N), oxygen (O), volatile matter (VM), ash, and fixed carbon (FC) contents, were analyzed. The aromaticity, polarity, and longevity of biochar are presented by the atomic ratios of H/C, O/C, (O + N)/C, and C/N, and these ratios are used to determine the potential of biochar for use in climate change mitigation applications. The findings demonstrated that DBC biochar produced at various pyrolysis temperatures contained C contents ranging from 77.54% to 88.06%, ash contents ranging from 2.62% to 2.99%, and a half-life of over 1000 years (O/C < 0.2). Pyrolysis temperature significantly affected biochar properties, as supported by the results for the FC/ash ratio (>10); the ash, FC, C, and N contents increased with increasing temperature; in contrast, the VM, H, and O contents decreased. The results revealed that DBC wastes are the potential feedstock to produce good-quality biochar that could be applied for environmental purposes. Furthermore, the research demonstrated that the best-performing DBC biochar was produced at 500 °C, which had the highest C content, aromaticity, and longevity and the lowest polarity as represented by the values of O/C, H/C, and (O + N)/C, and this biochar could be applied for climate change mitigation purposes.