Modulating Cu2O/CuO on attapulgite for boosting peroxymonosulfate activation

Peroxymonosulfate (PMS) activation is an economically viable and efficient advanced oxidation process used to degrade recalcitrant organic pollutants. In this study, the copper oxide/attapulgite (CuxO/ATP) catalyst was synthesized via the hydrothermal method. The catalytic degradation efficiency was assessed using ciprofloxacin (CIP) as the model pollutant. The influence of catalyst dosage and PMS concentration on CIP degradation was examined. Additionally, the capability of the catalyst to degrade CIP under varying pH conditions, temperatures, and in the presence of diverse inorganic ions was investigated. The findings revealed that CuxO/ATP exhibited superior performance compared to pure CuxO in PMS activation for CIP degradation. Microstructural analysis indicated well-dispersed CuxO nanoflowers on the attapulgite, facilitating a synergistic effect between the two components. The presence of attapulgite enhanced the dispersion of CuxO, leading to an increase in the exposed surface area. In addition, attapulgite facilitated the adsorption of pollutants onto the CuxO interface, while CuxO, in turn, activated PMS to generate active free radicals, thereby enabling the catalytic oxidation of pollutants. Through a series of free radical quenching experiments, sulfate radicals were identified as the predominant species responsible for CIP degradation, playing a pivotal role in the system. Moreover, a plausible catalytic mechanism was discussed. Furthermore, reusability tests demonstrated the catalyst's stability and recyclability. This research not only presents a novel and robust approach for CuxO catalyst synthesis but also offers deeper insights into the mechanism underlying CuxO activation of PMS.