Insight into the selection of oxidant in persulfate activation system: The effect of the target pollutant properties.

As a rising branch of advanced oxidation processes, persulfate activation has attracted growing attention. Unlike catalysts that have been widely studied, the selection of persulfate is previously overlooked. In this study, the affecting factors of persulfates were studied. The effect of target pollutant properties on superior persulfate species (the species with a higher degradation efficiency) was investigated by multiwalled carbon nanotube (MWCNT)/persulfate catalytic systems. Innovatively, the E HOMO (or vertical ionization potential (VIP)) value of the target pollutant was proposed to be an index to judge the superior persulfate species, and the threshold is VIP= 6.397–6.674 eV, E HOMO = −8.035∼− 7.810 eV, respectively. To be specific, when the VIP of phenolic compounds is higher (or E HOMO of phenolic compounds is lower) than the threshold, the catalytic performance of peroxymonosulfate would be higher than that of peroxydisulfate. Moreover, the effects of coexisting cations on peroxydisulfate superior species were further investigated. It was illustrated that the hydrated cation radius of coexisting cations would influence the pollutant degradation efficiency under some circumstances. This study provides a new approach to improve the cost of persulfate activation systems and promotes the underlying downstream application of persulfate activation systems. [Display omitted] • The properties of target pollutant would influence the superior persulfate species. • E HOMO and VIP of pollutant can be applied to judge the superior persulfate species. • Co-existing cations of PDS showed little effect on heterogeneous catalysis. • The superior peroxydisulfate species were not affected by the target pollutants. [ABSTRACT FROM AUTHOR]