Study On The Degradation Of Bisphenola By A Electro-fenton Oxidation Process Based On The Catalyst Of Immobilized Iron Ion

Advanced Oxidation Process is a highly effective method of treating organic waste water, is widely used in the field of waste water treatment. The electro-Fenton process has various advantages including quick reaction rate, simple operation and environmental friendly characteristic, so it has been gained a widespread concern.However, the traditional electro-Fenton also has several shortcomings such as a narrow suitable pH range and a mass of iron sludge, so the heterogeneous Fenton oxidation has a deeper research and application value. Bisphenol A is an organic compound possessing an estrogenic effect, and it is an important chemical raw material, widely used in the production of various kinds of daily necessities, packaging and baby supplies. It is can be disposed into the water via the production of waste and landfill leachate to be dangerous to biological health. Effective and economical method of bisphenol A degradation still needs further research currently.In this work, two catalysts were prepared and used along with the porous carbon cathode and the Ti/SnO₂-Sb₂O₅-IrO₂ anode to build heterogeneous electro-chemical oxidation systems for bisphenol A degradation. The catalytic performance and stability of the catalyst, the impact of the DC voltage, the initial concentration of bisphenol A,catalyst dosage and other factors on TOC removal rate was investigated. The following conclusions were achieved:（1） The ferrous ions was loaded onto an ion-exchange resin by ordinary immersion method to prepare ion exchange resin supported catalyst, and trivalent iron ions was supported on zeolite to prepare zeolite supported catalyst. The loading amount of Fe2+ on ion exchange resin was 256.7 mg/g, and loading of Fe3+ on zeolite was 33.6 mg/g. Both the two catalysts have a well catalytic activity.（2） The heterogeneous electro-chemical oxidation system was constructed by solid-phase catalysts, porous carbon cathode, and Ti/SnO₂-Sb₂O₅-IrO₂ anode.Bisphenol A was degraded by anodic oxidation and heterogeneous electro-Fenton oxidation, and which the latter was the main method compared with the anodic oxidation.（3） The porous carbon cathode was prepared using 15.0 mLpolytetrefluoroethylene（PTFE）, 30 g graphite addition, 1 g carbon nanotube and 15 mL ethanol. Under the conditions of pH 3.0, 3.0 V and air supply, the maximum hydrogen peroxide concentration of 162.6 mg/L was obtained by the reaction of 120 min.（4） Under the conditions of pH 3.0, 3.0 V, 25 g/L iron catalyst loaded on exchange resin, the degradation of 60 mg/L bisphenol A presented 67.3% TOC removal, while under neutral condition, 64.3% TOC removal was obtained. In addition, this catalyst was characterized by the considerable desorption during the initial use.（5） Under the conditions of pH 3.0, 3.0 V, 2.5 g/L iron catalyst loaded on zeolite,the degradation of 60 mg/L bisphenol A presented 70.8% TOC removal by the treatment of 240 min, while at pH 8.0, 50% TOC removal was obtained.（6） During the degradation of bisphenol A using the iron catalyst loaded on zeolite at pH 3.0, a small amount of iron ion fall off dissolving into the solution（1.8 mg/L after 360 min reaction）, while at pH 8.0, the desorption of iron ion almost can be neglected. From these results, it can be concluded that the degradation of organics was ascribed to the heterogeneous Fenton oxidation reaction on the surface of the solid-catalyst. Therefore, this process based on the solid-catalyst can enlarge the scope of pH application and avoid the produce of iron sludge during the subsequent treatment.