Transforming gasification tar into microporous biocarbon: Insights into structure, thermal insulation, and energy potential

Gasification tar is a hazardous liquid byproduct rich in carcinogenic polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds, posing significant disposal challenges and environmental risks. Instead of complex, chemical-intensive remediation, this study investigates a direct, activator-free pyrolysis pathway to valorize urban biomass tar into functional solid biocarbon. The tar was carbonized at 700°C, 800°C, and 900°C to evaluate the evolution of its physicochemical properties. The optimal thermochemical conversion was achieved at 900 °C, where structural analysis using TEM and Raman spectroscopy confirmed the transformation of volatile organic liquids into a stable turbostratic carbon framework characterized by developed microporosity (BET surface area of 113.2 m²/g). Crucially, the biocarbon produced under these optimal conditions exhibited an exceptionally low thermal conductivity (~0.07 W/mK), comparable to or lower than commercial biochar-based composites. This insulating behavior is attributed to phonon scattering within the disordered carbon domains and microporous network. While the specific surface area (113.2 m²/g) is moderate compared to activated carbons, it is sufficient to support the material’s stability. Additionally, elemental analysis indicated low sulfur and nitrogen content alongside a high calorific value (~7041 cal/g), suggesting a dual potential as a clean renewable fuel. These findings establish a viable circular economy strategy, converting hazardous gasification waste into a stable, high-value material with experimentally demonstrated potential for sustainable thermal insulation, alongside promising theoretical prospects for broader environmental and energy recovery applications.