Ultrafast degradation of Cu(II)-EDTA by peroxymonosulfate activated with polyoxometalate clusters intercalated layered double hydroxides: Simultaneous decomplexation and resourcelization

Abstract

Technologies used to handle metal pollution are often ineffective for complexed metals, which have refractory biodegradability, high solubility, and strong mobility, posing significant threats to the ecological environment. This work proposed a novel catalytic system for the proper disposal of Cu(II)-EDTA pollution. Polyoxometalate cluster intercalated CaFe layered double hydroxide (LDH-CoPW) prepared through a mild and convenience method was applied to activate peroxymonosulfate (PMS) for the degradation of Cu(II)-EDTA and the simultaneous immobilization of the released Cu(II). Compared to direct waste or complex regeneration of catalysts, the application of used LDH-CoPW in clean energy production was proposed to further reduce carbon emissions. Under the combination of 0.1 g/L of LDH CoPW and 0.1 mM of PMS, nearly 100 % of Cu(II)-EDTA was removed within 3 min of reaction time, and 49.6 % of Cu(II) was adsorbed within 60 min of reaction time. The second-order reaction kinetic constants of Co(IV) = O with various probes were confirmed by competition kinetics method. Based on this, Co(IV) = O was identified as the dominant RSs using a scientific probe-based kinetic model. Furthermore, CaFe-LDH did not directly activate PMS but ensured the reactivity of the catalytic system by promoting the redox cycle of cobalt species. Finally, due to the regulation of Cu on the electronic structure of the catalyst, the electrochemical performance of the used LDH-CoPW surpassed that of fresh LDH-CoPW and CaFe-LDH, showing great potential in clean energy production.