In-situ construction of Co(OH)2 nanoparticles decorated urchin-like WO3 for highly efficient degradation of sulfachloropyridazine via peroxymonosulfate activation: Intermediates and DFT calculation

Sulfachloropyridazine (SCP) was commonly used as a broad-spectrum sulfonamide antibiotic and hard to be removed through traditional sewage treatment process. In this study, we developed a simple and controllable strategy to realize in-situ construction of Co(OH)(2) nanoparticles decorated urchin-like WO3 (Co(OH)(2)/WO3), which could efficiently remove SCP through peroxymonosulfate (PMS) activation. Some tiny nanoparticles of Co (OH)(2) decorated on the spines/nanorods or surfaces of urchin-like WO3y by transmission electron microscopy (TEM) analysis. The obtained 10 wt% Co(OH)(2)/WO3 realized completely removal of SCP (degradation efficiency 100%) with a high reaction rate constant (k(1)) of 0.88 min(-1) within 3 min at optimal pH 7. That was because the urchin-like WO3 with numerous adsorption functional groups on its surface (e.g., W = O and -OH bonds) could adsorb the Co2+ easily to form CoOH+, which was perceived the rate-limiting step for PMS activation and generating radicals. Radical quenching experiments indicated that SO4 center dot- played a more significant role than HO center dot radicals. Density functional theory (DFT) calculation revealed that the atoms of SCP with high Fukui index (f-) were active sites, which preferred to be attacked by the electrophilic SO4 center dot- and HO center dot radicals. The toxicity of the intermediates by SCP degradation was evaluated by quantitative structure-activity relationship (QSAR) prediction through Toxicity Estimation Software Tool (T.E.S.T.). The possible degradation pathway and catalytic mechanism for SCP removal were proposed. Considering the good catalytic properties of Co(OH)(2)/WO3-PMS, the material will show great application potential in the removal of emerging contaminants in water.