Removal Of Refractory Organic Pollutants By The Heterogeneous Fenton-like Systems Mediated With Surface-disordered WO₃

Persistent organic pollutants such as dyes and phenolic pollutants have the characteristics of refractory degradation,high toxicity,and bioaccumulation.At present,some water treatment technologies cannot be widely used in practice because of their high cost,strict conditions and easy secondary pollution.How to effectively remove these emerging pollutants from water is main objectives of this study.Heterogeneous catalysis is promising for water treatment.Solid catalysts play governing roles.Herein,we aims to efficiently degrade organic pollutants through heterogeneous Fenton technology by transition metal oxide D-WO₃.Herein,the surface-disordered WO₃,D-WO₃,engineered with surface and sub-surface defective sites from NaBH₄reduction was proven to be an effective catalyst for H₂O₂and PMS activation.The defective degree and defects amount on WO₃were regulated by NaBH₄.More than 95%of two typical azo dyes,rhodamine B（Rh B）and Malachite Green（MG）,were selectively degraded in D-WO₃/H₂O₂system during 5.0 h,while no significant activity was observed for Methyl Orange（MO）as well as bisphenol A（BPA）,roxarsone（ROX）,phenol,4-chlorophenol（4-CP）,p-nitrophenol（PNP）,o-aminophenol（OAP）,urea,and2,4-dichlorophenol（2,4-DCP）in comparison under the identical conditions（mainly less than 20%）.Also within 5.0 hours,in the D-WO₃/PMS system,three typical phenolic pollutants,phenol,BPA,and 2,4-DCP were selectively degraded by more than 80%,while no significant activity was observed for4-chlorophenol,p-nitrophenol and roxarsone in comparison under the identical conditions.The system showes a higher ratio when treating azo dye the higher activity of D-WO₃/H₂O₂system can decolor the dye in a shorter time.The experiment also proved that the system of activating H₂O₂and PMS with D-WO₃as the catalyst can still show better activity in complex natural water bodies with weak water matrix effects than the traditional Fenton system.Both Electron spin resonance（ESR）and radical scavenging tests indicated the minor role of·OH and·SO₄^-from H₂O₂and PMS activation on D-WO₃,confirming that its catalytic mechanism is the transfer of dielectric electrons between pollutants and oxidants.The superior activity of D-WO₃could be mainly attributed to the surface and sub-surface defects with finelytailored local atomic configurations and electronic structures of central metal sites.Surface and sub-surface defective sites could serve as the reactive sites of interfacial adsorption,dissociative activation,and catalytic decomposition for both oxidant and pollutants,with high adsorption energy,strong structural activation,and superior catalytic activity.Our findings provided a new chance for nonselective radical catalysis based on transition metal oxides and a promising catalyst with high performance,low cost,and no toxicity for pollutant degradation with weak matrix effects in wastewater and surface water.