Quartz sand-supported polydopamine/Co–Ni ZIF catalyst for efficient degradation of tetracycline antibiotics in water

Tetracycline hydrochloride (TCH), a widespread aquatic antibiotic contaminant, threatens environmental sustainability and human health by fostering antibiotic resistance. Here, a hierarchical quartz sand@polydopamine/Co-Ni-ZIF (QS@PDA/CoNi-ZIF) composite catalyst is developed to stimulate peroxymonosulfate (PMS) for TCH removal. In this design, the Co-Ni-ZIF component acts as a highly active PMS activator, with polydopamine (PDA) as an adhesive interface to stably immobilize ZIFs on QS. Using QS as a catalyst substrate exemplifies the concept of “functional redevelopment of traditional materials.” Component synergies enable rapid electron transfer and accelerate Co 2+ /Co 3+ and Ni 2+ /Ni 3+ redox cycling, enhancing reactive oxygen species (ROS) generation. The catalyst achieves dual radical (•SO 4 − , •O 2 − ) and non-radical ( 1 O 2 ) degradation pathways, removing 96.0% TCH within 40 min under optimized conditions. Intermediate analysis reveals three plausible degradation pathways. The composite exhibits broad environmental adaptability (>90% efficiency at pH 3.0-11.0 and in complex water matrices with competing ions) and retains >82% efficiency over four cycles, confirming robust stability and reusability. This work demonstrates QS@PDA/CoNi-ZIF as a scalable solution for treating refractory organic wastewater with high contaminant loads. • A novel QS@PDA/CoNi-ZIF catalyst was developed for efficient PMS activation. • 96% TCH degradation was achieved within 40 minutes. • The redox cycling of Co/Ni ions accelerates •SO 4 − , •O 2 − , 1 O 2 generation. • Three possible degradation pathways are revealed by LC-MS analysis.