Removal Of Refractory Organic Pollutant Based On The Fenton-like System Of Transition Metal Oxide

Organic substances such as Roxarsone and bisphenol A are highly toxic and difficult to degrade,which seriously affect the earth’s ecological environment and organisms,and their safe,efficient and cost-effective treatment are actively perused.Herein,we aim to remove refractory organic pollutants with high efficiency and reduced secondary pollution through heterogeneous Fenton technology.First,a heterogeneous iron-based Fenton-like technology was designed and validated with much reduced secondary pollution,mainly attributed to the bi-functional properties of both Fenton-active and arsenic-affinitive iron oxides.This simple one-step strategy not only exhaustively degraded organoarsenicals,but also selectively adsorbed the released high-toxicity arsenic from treated water.Through the structural analysis and research on the adsorption characteristics of several typical iron oxides prepared,it is proved that the iron oxide has excellent enrichment structure and high adsorption effect.With Roxarsone as target,the FeOOH-based Fenton-like system exhibited a much superior capacitie for both Roxarsone degradation and arsenic adsorption in various water matrices,compared to typical homogeneous systems under similar conditions.More than 80%of Roxarsone was degraded after 3.0 h,and most of the released AsO₄^3-was removed simultaneously,without any additional post-treatment.The superior capacity of FeOOH might be mainly attributed to its strong redox-cycling capacity of surface central Fe atoms from their thermodynamically favorable electronic structure.Second,we confirmed,for the first time,that the fine modulation on semiconducting TiO₂ was able to improve the redox-cycling capability for heterogeneous peroxydisulfate(PDS,S₂O₈^2-)activation and radicals generation.PDS activation by defective TiO_2-x exposed by high-energy{001}polar facets was a superior Fenton-like catalytic system for rhodamine B（RhB）and bisphenol A（BPA）degradation,with good activity and selectivity under neutral pH.By fluorescence measurements with terephthalic acid and electron paramagnetic resonance（EPR）technique,only the SO₄·^-was identified to be the main reactive species from PDS activation on defective TiO_2-x for pollutants degradation.Compared to the reported TiO_2-x/H₂O₂ system,the proposed TiO_2-x/PDS system exhibited much lower water matrix effects in the presence of four typical anions,natural organic matters and real surface water for target pollutants degradation.The selective SO₄·^--mediated TiO_2-x/PDS catalytic system in natural water matrix and the no toxicity of catalytic material were of considerable interest for practical environmental applications with highly complex chemistry.