Degradation Of Rhodamine B Using H₂O₂ Catalyzed By BiOI/FeOOH With Visible Light

With the rapid development of dyes industry,the dyes wastewater has become a great environmental problem.Due to the stable structure and the complex constitute of dyes,the traditional wastewater treatment technologies are difficult to purify them to satisfy with the effluent discharge standard.Fenton reaction has a broad application prospect because of its strong oxidation ability and low price.While it can cause plenty of sludge by consuming many chemical agents.The defects of Fenton reaction can be overcome by combination with light irradiation.Therefore,exploration high efficiency visible light catalyst is becoming key points of photo-Fenton reaction.In this study,BiOI and BiOI/FeOOH photocatalysts were prepared,and the structure of the catalysts was characterized by SEM and XRD.Rhodamine B?RhB?solution was used to simulate dye wastewater,BiOI and BiOI/FeOOH were used as photo catalysts to degrade Rh B in the presence of hydrogen peroxide.The photocatalytic properties of catalysts under different conditions were tested,and the catalytic mechanism was discussed.BiOI was prepared by chemical precipitation and solvothermal method and labeled as BiOI-1 and BiOI-2,respectively.SEM results showed that BiOI-1 was lamellar and BiOI-2 was spherical with a particle size of about 400 nm.In the visible light-BiOI/H₂O₂ catalytic system,H₂O₂ had obvious synergism with BiOI-1 and BiOI-2,and the rhodamine B removal rate increased from 44.54% and 6.47% to 99.18% and 99.72%,respectively.The active species in visible light-BiOI-1/H₂O₂ catalytic system are mainly ·OH,h+ and ·O₂^-,while ·OH and h⁺ play main role in the visible light-BiOI-2/H₂O₂ catalytic system.Pure BiOI still reveals poor photocatalytic performance in degrading organic pollutants of the water on account of the fast recombination rate of photo-generated electron-hole pairs.Constructing heterojunction with other semiconductors is an effective method to improve the separation of electron-hole pairs.Different proportions of BiOI/FeOOH composite catalysts were prepared by hydrothermal reflux method.Characterization showed that nanoparticles of FeOOH grew uniformly on the surface of BiOI spherical structure.Both of them have particle size of 400-500 nm.The catalytic degradation of Rh B was significantly increased and the amount of H₂O₂ was reduced in case of FeOOH/BiOI compared with pure BiOI.Under the similar reaction conditions,the H₂O₂ was reduced from 1.00 mol/L to 5.00×10^-3 mol/L,and the removal rate of Rh B reached 99.94% within 40 min.It was revealed by active species capture experiments that ·OH and h+ played important role in the visible light-BiOI/FeOOH/H₂O₂ catalytic system.As the composites of FeOOH/BiOI can catalyze H₂O₂ under visible light irradiation to enhance the Rh B removal and reduce the chemical agent consumption,it's considered to be a potential method to treat dye waste water.