High-capacity removal of oxytetracycline hydrochloride from wastewater via Mikania micrantha Kunth-derived biochar modified by Zn/Fe-layered double hydroxide

Antibiotic contamination in water has been an increasing global concern, and how to effectively remove antibiotics (e.g., oxytetracycline [OTC] hydrochloride) from wastewater becomes imperative. In this study, the biochar derived from an invasive plant (Mikania micrantha Kunth) was synthesized with Zn/Fe- layered double hydroxide (LDH) by co-precipitation method (ZnFe-LDH/MBC) to remove OTC from water. ZnFe-LDH/MBC posed the highest OTC removal performance of 426.61 mg/g. ZnFe-LDH/MBC exhibited stability and efficiency in OTC adsorption at different pH levels and under interfering conditions with co-existing ions, as well as outstanding regeneration capabilities during adsorption-desorption cycles. Furthermore, the removal of OTC by ZnFe-LDH/MBC was mediated by several processes including pore filling, hydrogen bonding force, electrostatic interaction, π-π interaction, as well as complexation. Consequently, ZnFe-LDH/MBC has excellent potential for the purification of OTC pollutants that is low-cost, efficient, and environmentally friendly.