Performance and reaction mechanism of montmorillonite/α-Fe2O3/starch bio-nanocomposite as high-efficiency photocatalytic degradation of acetaminophen: Characterization, feasibility, and pathway

The worldwide challenge of eliminating pharmaceutical contaminants requires immediate attention. Developing bio-based catalysts that are eco-friendly, reusable, and high-performance, employing starch (ST) and montmorillonite (MMT) as support, holds tremendous promise as a novel biocatalyst for pharmaceutical waste removal. In this study, a montmorillonite/α-Fe2O3/starch (MMT/α-Fe2O3/ST) bio-nanocomposite photocatalyst was successfully synthesized and used for acetaminophen (ACT) degradation under UVA-LED irradiation. The influence of operational factors, such as catalyst, ACT concentrations, and solution pH, on photocatalytic activity was examined in detail; catalyst: 0.75 g/L, pH: 7.1, leading to total ACT (10 mg/L) removal in ∼80 min. MMT/α-Fe2O3/ST showed excellent durability due to negligible Fe leaching. After four successive degradation cycles, ACT and TOC elimination efficiencies remained over 91 and 42.7 %. Compared to other anions studied, carbonate ions suppressed the most ACT degradation. Based on the radical scavenger experiments, hydroxyl and superoxide radicals and holes were involved in the MMT/α-Fe2O3/ST system. LC-MS results were used to propose ACT degradation pathways. This work illuminated the significance of biocatalysts in removing emerging pollutants from wastewater. •The MMT/α-Fe2O3/ST bio-nanocomposite degraded ACT under UVA-LED irradiation extremely effectively.•Proposed a degradation mechanism based on the identified intermediates.•Carbonate and nitrite ions inhibited ACT degradation, while chloride ions had no effect.•After four degradation cycles, ACT and TOC elimination efficiencies remained over 91 and 42.7 %.