Enhancing micropollutant removal efficiency using sustainable activated charcoal
Résumé
This study aims to develop a sustainable and low-cost activated carbon (AC) from wood charcoal to improve the removal of persistent micropollutants, such as pesticides, drug residues, and per-and polyfluoroalkyl substances (PFAS), from drinking water. The AC was produced through physical activation using steam in a rotary furnace, with activation temperatures ranging from 850 to 900 °C and times varying from 1 to 2.5 hours. The textural properties, adsorption kinetics, equilibrium behaviour, and potential adsorption mechanisms of the AC were thoroughly investigated. N 2 adsorption isotherms revealed a transition from microporous to mesoporous structures as both activation time and temperature increased, resulting in BET areas between 600 and 1380 m²/g. Among the produced ACs, one was selected for its outstanding performance in removing micropollutants, demonstrating rapid adsorption kinetics even at low AC doses and high pollutant concentrations. The adsorption kinetics were well described by a model suggesting fractal adsorption behaviour, while isotherms indicated multilayer adsorption for certain micropollutants, with additional models providing insights into molecular aggregation and anchoring geometry. This AC exhibited unprecedented efficiency in removing micropollutants, particularly PFAS, reaching 1977, 670 and 3135 mg/g for perfluorooctanoic acid, perfluorooctanesulfonic and perfluorohexanoic acid, respectively, and outperformed commercial ACs due to its optimized mesoporous structure.
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