Cobalt sulfide nanofilm-assembled cube as an efficient catalyst for activating monopersulfate to degrade UV filter, 4,4 '-dihydroxybenzophenone, in water

Abstract

As hydroxylated benzophenones (HBPs) represent most typical UV filters and UV stabilizers, increasing release of HBPs into the aquatic environment has caused serious threats to the aquatic ecology. Among various HBPs, 4,4 ' Dihydroxybenzophenone (4HBP) receives growing attentions as an emerging contaminant due to its potential toxicity of endocrine disrupting effect. For establishing useful techniques to remove 4HBP from water, this study, as the first study, aims to develop cobalt sulfide as a heterogeneous catalyst to activate monopersulfate (MPS) for generating sulfate radical (SO4 center dot- ) to degrade 4HBP. Especially, a unique cubic assembly of cobalt sulfide nanofilms (CSNF) is developed through a simple sulfurization of Prussian Blue (PB) in the form of Co3[Co(CN)6]2 to transform this PB to CSNF. Such a resulting CSNF exhibits much higher catalytic activities than the pristine PB, and the reference catalyst, Co3O4, for activating MPS to degrade 4HBP in terms of degradation extents and kinetics. With very low dosages of CSNF = 50 mg/L and MPS = 100 mg/L, 5 mg/L of 4HBP could be fully eliminated in 15 min, validating that CSNF is a promising catalyst for activating MPS to 4HBP. Ea of 4HBP degradation by CSNF-activated MPS is also determined as 68 kJ/mol. The activation mechanism and degradation pathway of 4HBP degradation by CSNF-activated MPS is investigated using electro paramagnetic resonance and mass spectrometer, respectively, to further to provide insights into degradation behaviors for developing optimal sulfate-radical-based advanced oxidation processes of 4HBP degradation.