Thermochemical valorization of biomass using acid mine drainage: Syngas, furfural, and biochar-based catalysis for acetaminophen removal

Abstract

Acid mine drainage (AMD) is a major environmental pollutant prevalent in areas impacted by mining activities. It poses serious risks to both human health and surrounding ecosystems due to its high acidity and the presence of toxic metals. In this study, AMD was utilized as a catalytic medium for the thermochemical conversion of sawdust (SD), aiming to valorize AMD and enhance the efficiency of the thermochemical process. AMD-treated SD was pyrolyzed under various conditions to examine product yields and their functional properties. AMD promoted the decomposition of hemicellulose and cellulose components in SD, leading to increased production of syngas (H2, CH4, and CO), and shifted the bio-oil composition toward higher yields of furfural and levoglucosenone (LGO). The biochar produced from AMD-treated sawdust exhibited a mesoporous structure and contained catalytically active species such as Fe⁰ and CaS. This biochar efficiently activated sodium persulfate for the degradation of acetaminophen (k obs = 0.04 min−1), with sulfate radicals (SO4•−) identified as the primary reactive species. The catalyst demonstrated high stability, maintaining over 91% acetaminophen removal efficiency after multiple reuse cycles. Overall, this study introduces a novel approach that integrates AMD valorization with the production of renewable fuels, platform chemicals, and functional biochar, offering a sustainable strategy for waste remediation and environmental applications.