Experimental and computational study of photocatalytic degradation of volatile organic compounds in bitumen using sulfur-doped phenol-rich bio-oils.

Asphalt pavements are a significant source of volatile organic compounds (VOCs) emissions under solar radiation, accelerated asphalt aging and urban air pollution. Effective mechanisms are essential to reduce the environmental and health impacts of road infrastructure. In this study, a sustainable bio-based modification strategy is presented using sulfur-doped phenol-rich bio-oils derived from wood pellets (WPn) to suppress VOCs release from asphalt. In this process, tetrameric radical sulfur ([Formula: see text]) reacts with the WPn to generate [Formula: see text]-WPn intermediates that capture VOCs molecules through a C-S cross-coupling pathway, forming stable VOCs-[Formula: see text]-WPn adducts. The mechanism was validated experimentally using GC-MS, FT-IR, and UV-Vis spectroscopy, and supported by TD-DFT computational analysis. The UV-Vis absorption spectral of [Formula: see text] has been red-shifted to nearly 400 nm which potentially enhanced the ability of these VOCs compounds to absorb light at wavelength higher than 200 nm, thereby favoring the direct photodegradation of VOCs compounds. Also, the calculated activation energy barriers for the [Formula: see text] and VOCs reaction pathways were found to range between - 5.62 and - 25.86 kcal/mol, confirming the thermodynamic feasibility and suppression potential of VOCs emissions. This work highlights a practical and environmentally friendly approach for the development of cleaner and more resilient urban infrastructure.