Influence of pyrolysis atmosphere, temperature, and particle size co-regulation on the physicochemical properties of bone char

Compared to other biochars, bone char can take advantage of its unique mesoporous structure and ionic polarity sites for adsorption. However, previous studies have not clarified the influence of various process parameters on the physicochemical properties of bone char. Therefore, we systematically analyzed the physicochemical properties of bone char with different pyrolysis atmospheres (CO2/N2), temperatures (300–900 °C), and particle sizes (less than 0.15 mm, 0.15–0.45 mm, and 0.45–0.90 mm) and their differences. The results showed that the pyrolysis atmosphere at 900 °C significantly affects the physicochemical properties of bone char, such as pore structure, ash content, electrical conductivity, surface functional groups, and crystal structure. The pyrolysis temperature is crucial in regulating the pore structure, ash content, acidity, and other physicochemical properties of bone char. It plays a significant role in the pyrolysis process from 300 °C to 500 °C and from 700 °C to 900 °C. The particle sizes significantly affect the electrical conductivity and basic functional group content of bone char at different pyrolysis atmospheres and temperatures. The bone char with sizes less than 0.15 mm prepared at 700 °C with N2 as the pyrolysis atmosphere has a rich mesoporous structure, a higher ash content, a higher basic functional group content, etc., and is more suitable as an adsorbent. The study results provide a theoretical basis for selecting appropriate pyrolysis process parameters to produce bone char that meets environmental treatment applications.