Heavy metals and PAHs adsorption characteristics of bio-asphalt in road runoff.

Upcycling the solid biomass waste into bio-oil and biochar are promising solutions to mitigate environmental pollution caused by solid waste and offer value-added products with tremendous applications, simultaneously. The bio-oil and biochar could be considered as excellent alternatives to the petroleum-based asphalt, however, the application potential of bio-oil and biochar could be compromised, due to the high oxygen content of the bio-oil and presence of heavy metals in the biochar. In this study, biochar modified asphalt (BMA) and biochar modified bio-asphalt (BMBA) were successfully developed using wood waste as feedstock. 16 polycyclic aromatic hydrocarbons (PAHs) and 6 heavy metals were mainly assessed by adsorption characteristics using prepared samples. The major results demonstrates that the concentrations of Cd2+, Cr3+, Cu2+, and Ni2+ elements leached from bio-asphalt was within the acceptable levels (2 mg/L) regarding environmental pollution. And adsorption ability of bio-asphalt was selective and that the ability of BMBA in reducing heavy metals concentration was better than BMA. Major parameters including rainfall time and solar irradiation time could slightly affect the toxicity of PAHs leached from bio-asphalt in the road runoff. Biochar and bio-oil were promising additives for petroleum-based asphalt given its environmental benefits and sustainable properties. [Display omitted] • 16 PAHs and 6 heavy metals leaching toxicity of bio-asphalt are investigated. • The heavy metal adsorption ability of bio-asphalt is selective. • Rainfall time and irradiation time increase PAHs leaching toxicity of bio-asphalt. • Biochar protects asphalt from heavy metal and PAHs pollution. • There are synergistic effects of rainfall and irradiation on heavy metals and PAHs in bio-asphalt leachate. [ABSTRACT FROM AUTHOR]