Comparative Study of Biochar from Different Biomass Feedstocks: Toward Sustainable Resource Utilization and Environmental Applications

This study examines the structural, chemical, and thermal properties of biochars from slow pyrolysis of hardwood (HW), corn cob (CC), and wheat straw (WS) at 400 °C and 700 °C, evaluating their potential in environmental and industrial applications. A combination of spectroscopic, crystallographic, thermal, and microscopic techniques was employed to monitor the degradation of biomass components and the development of the carbonaceous matrix. The results show that pyrolysis temperature has a significant impact on the properties of biochar. Higher temperatures (700 °C) increased the pH (up to 10.3 for WS700), the carbon content (e.g., 89.8% for HW700), the ash content (up to 24.8% for WS700), and the specific surface area (e.g., 306.87 m²/g for CC700) while decreasing polar functional groups and volatile matter (as confirmed by FTIR). SEM showed enhanced porosity at 700 °C, which was supported by BET analysis. XRD and Raman showed increased graphitization and structural order with temperature, especially for HW and CC biochars, while WS biochars retained mineral components like SiO₂ and CaCO₃. TGA analysis showed improved thermal stability at 700 °C only for biochar derived from wheat straw, while HW and CC biochars showed similar total mass loss regardless of pyrolysis temperature. These biochars exhibit high potential for soil remediation (high pH), water purification (large surface area), and carbon storage (high aromaticity), with HW700 and CC700 also suitable for high-temperature industrial applications due to their stability.