Preparation Of The Cathode Material For Electro-Fenton Technique And Its Application In Organic Pollutant Degradation

With development of chemical industy,a large number of refractory organic pollutants have been produced,resulting in serious pollution of the water environment.As one of the advanced oxidation technologies,the electro-Fenton（EF）process has been widely used in the treatment of refractory organic pollutants because of its mild reaction conditions,simple equipment and wide range of application.In this thesis,three kinds of composite cathodes,including（reduced Graphene Oxide/Cabon Fiber,rGO/CF）,α-Bi₂Mo₃O₁₂-rGO/CF andγ-Bi₂MoO₆/CF,were prepared and their morphologies,structures and properties were characterized by SEM,XRD,FTIR,EIS and CV.The catalysis towards electrochemical reduction of dissolved oxygen to hydrogen peroxide was investigated in EF system,and the degradation of organic wastewater were also studied.The electrolysis conditions for were optimized and the reactive oxygen species produced during EF treatment were determined.Moreover,the degradation mechanism of the target pollutants was discussed.In EF system with rGO/CF composite cathode,experiment results of EIS showed that rGO/CF electrode had lower electric resistance than that of CF electrode,and results of CV indicated that rGO/CF had obvious catalytic effect for the electrochemical reduction of oxygen.The bulk electrolysis with rGO/CF cathode for electro-reduction of oxygen showed that the maximum amount of H₂O₂ reached 313.13μmol·L^-1 when supplied current was 9 mA,the pH was 3.0 and the electrolysis time was 180 min.It was much higher than that in CF cathode system.Degradation for Rhodamine B（RhB）showed that removal rate of RhB reached 99.3%under the optimal conditions in the presence of iron alginate as Fenton-like reagent.The UV-vis spectra showed that during electrolysis process the large conjugated system of RhB has been destroyed to be molecule with small aromatic ring,indicating incomplete degradation of RhB.In EF system withα-Bi₂Mo₃O₁₂-rGO/CF composite cathode,experiment results of FTIR showed that there was chemical bond betweenα-Bi₂Mo₃O₁₂ and rGO.The experiment results of EIS showed thatα-Bi₂Mo₃O₁₂-rGO/CF electrode had lower electric resistance than that ofα-Bi₂Mo₃O₁₂/CF electrode.The bulk electrolysis for electro-reduction of oxygen showed that the maximum amount of H₂O₂ reached to602.25μmol·L^-1 when supplied current was 12 mA,pH was 3.0,the oxygen flow rate was 1.5 L·min^-1,and the electrolysis time was 180 min.It was much higher than that in rGO/CF andα-Bi₂Mo₃O₁₂/CF cathode system.Degradation experiment of P-nitrophenol（PNP）experiment showed that the electro-Fenton system had a better removal effect on PNP wastewater.In the presence of ferric（III）alginate microspheres,the degradation rate of PNP was 68.9%under the optimum conditions.The UV-vis spectra showed that during electrolysis process the conjugated structure,the cochromatic hydroxyl group and the nitro group of PNP were all destroyed,which resulted in degradation of PNP D to small molecules without UV absorption.In EF system withγ-Bi₂MoO₆/CF composite cathode,the effect of preparation pH on the properties of the materialγ-Bi₂MoO₆ was investigated,and the experiment results showed that when preparation pH was 9.0,the preparedγ-Bi₂MoO₆ had a regular morphology with a flake structure and had lower resistance and the strongest catalysis on the electrochemical reduction of oxygen than that prepared at other p H.The bulk electrolysis with rGO/CF cathode for electro-reduction of oxygen showed that the maximum amount of H₂O₂ reached 554.21μmol L^-1 when the loading dosage ofγ-Bi₂MoO₆ was 0.05 g,the supplied current was 9 mA and pH was 3.0.It was much higher than that in CF cathode system.Degradation for Rhodamine B（RhB）showed that removal rate of RhB reached 99.1%under the optimum conditions.The most useful oxidant for the degradation of RhB was investigated and the result showed that hydroxyl radical·OH played main role for RhB removal.The changing of UV-vis spectra during electrolysis showed that the large conjugated system of RhB was degraded to small molecule,and further mineralized.