The consortium of heterogeneous cobalt phthalocyanine catalyst and bicarbonate ion as a novel platform for contaminants elimination based on peroxymonosulfate activation

The design of catalytic oxidation processes with high efficiency has attracted considerable attention for a long while in environmental catalysis. In this work, a novel oxidation system, CFs-CoPc/PMS, was developed by coupling cellulosic fibers-bonded cobalt phthalocyanine (CFs-CoPc) with peroxymonosulfate (PMS). CFs-CoPc/PMS system could effectively decolorize azo dyes such as Acid Red 1 (AR1) with almost 100% decolorization efficiency in 35 min, suggesting that the CFs-CoPc/PMS system was a highly efficient oxidation process. In addition, bicarbonate ion (HCO3(-)) was further introduced to CFs-CoPc/PMS to construct a combined system, CFs-CoPc/PMS/HCO3(-). Remarkably, this system turned the negative effect of HCO3(-) observed in most reported Co/PMS systems into a positive one, which enhanced the AR1 decolorization with over 2-fold increase of the rate constant. The main factor responsible for the enhancement was high-valent cobalt-oxo intermediates (PcCo(IV)=O), which was presumably generated via the heterolytic cleavage of the PMS OO bond by CoPc-HCO3(-) complex. It is noteworthy that high-valent cobalt-oxo intermediates as the major active species is different from most reported mechanisms in Co/PMS systems, in which hydroxyl and sulfate radicals are recognized as the dominant active species. This study paves an avenue for developing highly efficient catalytic oxidation technology for wastewater remediation.