Activation of peroxymonosulfate for degrading ibuprofen via single atom Cu anchored by carbon skeleton and chlorine atom: The radical and non-radical pathways

Single atomic Cu catalysts (SACs Cu@C) anchored by carbon skeleton and chlorine atom was synthesized by hydrolyzing Cu-MOFs and then pickled by aqua-regia to remove Cu nanoparticles (NPs Cu). Comparative characterizations revealed that SACs Cu@C was a hierarchically porous nanostructure and Cu dispersed uniformly throughout the carbon skeletons. With less active components, SACs Cu@C behaved better in activating PMS over NPs Cu@C on ibuprofen removal (91.3 % versus 30.2 % in 30 min). Two Cu coordination environments were found by EXAF and DFT calculation, including four-coordinated Cu with 4C atoms and six-coordinated Cu with 4Cu and 2Cl atoms. The obvious interfacial electron delivery between PMS and SACs Cu@C was found, which was enhanced by Cl atom. Cu(I)/Cu(II) redox cycle would donate electron to peroxy bond of PMS for generating OH, SO4- and O2-. But electron transferred in opposite direction when PMS bonded to Cu atom through its terminal oxygen atom in sulfate, which formed 1O2. IBP degradation proceeded through both radical and non-radical route. IBP degradation was inhibited with the presence of TBA, methanol and furfuryl alcohol but accelerated by p-BQ, which could accelerate OH generation. Two degradation pathways were deducted. This study provided a new insight into catalysts designed for PMS activation.