| Decontamination of persistent organic pollutants has been a key issue in the field of water and wastewater treatment. Fenton process is a well-defined advanced oxidative technology, which has increasingly gained more and more attention due to its high degradation efficiency, relatively low cost and large application potential. In recent years, many studies have been carried out to obtain higher degradation efficiency by improving reactive conditions and mechanism. Some novel or classical types of processes have become the hot issue, such as electrochemical Fenton, ultrasonic Fenton, Fenton with UV/visible light and heterogeneous Fenton method, etc. However, these methods are confined to the laboratory stage and it still needs a large number of experiments to apply the technology to industry.This work is aimed at developing new types of Fenton system by means of designing peculiar Fenton catalysts, followed by detecting their efficiency; service life; influential factors on their degradation efficiency; characterizing the morphologic structure and properties of catalysts and elucidating their catalytic mechanism. This work mainly included the following three sections:1. Designing and preparing the defective TiO2-x SCs exposed by high-energy {001} facet as the heterogeneous solid Fenton catalyst, activating hydrogen peroxide with a defect-centered Fenton-like mechanism, with the Fe3O4, pristine TiO2 as the two reference materials. We systematically analyzed the morphologic structure and properties of defective TiO2-x catalyst by SEM, TEM and XRD measurements, and estimated the degradation efficiency of photocatalysts with both simulated and practical wastewater samples; Moreover, we thoroughly explained the Fenton-like mechanism of the defective TiO2-x SCs. Through comparative analysis of the structural properties and degradation rate, it is confirmed that the catalytic activity of defective TiO2-x SCs was far more superior to that of pristine TiO2, with better stability compared with the typical Fe3O4 reference.2. The p-type semiconductor Cu2O was loaded onto three different nano-structured carbon materials to obtain composite semi-conductive photocatalyst. Three kinds of nano-structured carbon substrates were adopted:nitrogen doped graphene oxide (N-rGO), reduced graphene oxide (rGO) and carbon nanotubes (CNT). The developed hybrid catalysts could be able to thermodynamically react with O2 and H2O under visible light irradiation to in-situ produce hydrogen peroxide for Fenton reaction. After Fe2+was added into the solution, photocatalytic Fenton system driven by visible light was build up. We detected morphology structure of the three kinds of photocatalysts by SEM, XRD analysis; Analyzed ORR for catalysts; Tested efficiency of degradation of organics. Experimental results confirmed the designing was successful and feasible and it has best photocatalytic efficiency when using N-rGO as the nano-structured carbon substrate.3. Iron oxides can both be used as solid catalysts for the heterogeneous Fenton and adsorb inorganic high-toxicity arsenic in the water body effectively. Based on these characteristics of iron oxides, We consider applying the heterogeneous Fenton system of iron oxides to the treatment for waste water containing organic arsenic compounds. Three kinds of iron oxides:FeOOH, Fe3O4 and Fe2O3 were selected as heterogeneous Fenton catalysts to perform the experiments, all of them exhibited good performance for the removal of both organic and inorganic arsenic. The inorganic arsenic in the final effluent was controlled less than 40 ?g/L. Among the three Fe-based heterogeneous Fenton catalysts, the FeOOH exhibited the most performance for the Fenton degradation and arsenic adsorption in the water body. |
PDF Full Text Request