Green activation of tea-stalk biochar for sustainable suppression of asphalt fume emissions via multi-mechanism adsorption

Abstract

To promote sustainable road construction and reduce harmful emissions during asphalt paving, a green bio-based adsorbent was developed by activating tea-stalk-derived biochar (TB) using phytic acid, a biodegradable plant-derived organophosphate. This activation introduced a multiple adsorption mechanism that integrates physical adsorption, chemical interactions, and catalytic transformation. The results show that phytic acid significantly increased the specific surface area and micropore volume of TB, facilitated the development of graphitic structures to enhance π–π interactions with aromatic hydrocarbons, and incorporated phosphorus-containing functional groups that enabled chemical bonding and catalytic conversion. At only 0.5% dosage, the activated biochar (PTB) achieved a 64.2% reduction in VOCs and a 93.1% for H₂S, both exceeding the higher dosage of 2% TB (58.6% and 85.4%, respectively). GC-MS results confirmed that, under the influence of multiple adsorption mechanisms, PTB exhibited higher suppression efficiency across all categories of asphalt fume components, particularly for highly hazardous compounds such as benzene derivatives, alkenes, thiophenes, and ketones. This biochar-based approach offers a sustainable pathway for reducing asphalt-related air pollution during road construction, thereby supporting cleaner transport infrastructure and contributing to improved urban air quality.