Based On The Construction Of Ag₂O Nanofiber Membranes And The Study Of As(?) Oxidation Driven By Visible Light

Dye wastewater containing heavy metal pollutants?such as arsenic,As?derived from textile industry pose serious threats to human health.Photocatalytic technology can effectively control the arsenic pollution in dye wastewater.Recently,Ag₂O has received wide attention from scholars due to its narrow band gap.This paper reviews the oxidation of arsenite[As???]and the preparation of polyacrylonitrile?PAN?nanofiber membranes,and then introduces the research progress of Ti O₂,Ag₂O and schwertmannite.The author therefore proposes the idea of constructing Ag₂O-reinforced composite materials with PAN as the substrate,and systematically investigates the performances and mechanisms for As???oxidation and removal by as-prepared composites.Ag₂O/Ti O₂composites with different Ag₂O loadings were prepared by p H-induced precipitation.XRD,TEM and XPS analyses were used to characterize the composition and microstructure of the obtained materials.Oxidation of As???was employed to evaluate the catalytic activity of Ag₂O/Ti O₂composites under visible light,and the effects of catalyst contents,p H and initial As???concentration on the catalytic performance of Ag₂O/Ti O₂were investigated in detail.The results showed that the 30%Ag₂O/Ti O₂exhibited the best activity.The oxidation and removal percentages of As???after 120 min visible light irradiation were 60.70%and 83.00%at p H 4.0,respectively.Scavenger experiments confirmed that the main active species for As???oxidation were h⁺and O₂^·-involved in the system of Ag₂O/Ti O₂.In order to improve the recyclability of powder materials,we prepared PAN@Ag-Ag₂O/Ti O₂?labeled as PAN@ATX?nanofiber membranes via electro-spinning technology and p H-induced precipitation method.The characterization results showed that the formed Ag-Ag₂O/Ti O₂heterostructure on the surface of PAN@AT nanofibers can promote the separation of electron-hole pairs.Kinetic experiments showed that the catalytic activity of PAN@ATX increased first and then decreased with the increase of Ag-Ag₂O contents,and the optimal oxidation efficiency for As???was obtained at p H=5.0 in the system of PAN@AT4?92.10%after 120 min reaction?.In addition,the PAN@AT4 nanofiber membranes can retain 81.60%of the original As???oxidation activity after repeating four cycles,which indicates good recyclability of PAN@AT4.Scavenger experiments and EPR characterization confirmed that the main active species for As???oxidation were h⁺and·OH involved in the system of PAN@AT4.Schwertmannite?Sch?exhibits high adsorption capacity to arsenic.PAN@Ag-Ag₂O/Sch?labeled PAN@ASX?nanofiber membranes were prepared by electrostatic spinning technology and p H-induced precipitation method to remove the residual total As after As???oxidation reaction.Kinetic experiments showed that the Ag-Ag₂O contents have an important effect on photocatalytic activity of PAN@ASX.PAN@AS0.10 has the best removal ratio for total As at p H 4.0,and it can reach 90.96%after 120 min reaction.In addition,scavenger experiments confirmed that the main active species for As???oxidation were h⁺and·OH involved in the system of PAN@AS0.10.PAN@AS0.10 had good recycling performances,and it can retain 87.20%of the original As???oxidation activity after repeating four cycles.It can be known that the developed PAN@ASX nanofiber membranes have broad application prospects in the fields of wastewater treatment?containing heavy metals?and environmental remediation.