The Study Of Pd Particle Electrodes For Bromate Electroreduction

As a common ozone disinfection by-product,BrO₃^-is carcinogenic and genetictoxic.Based on the systematic analysis for bromate removal processes,electroreduction is widely used in common wastewater treatment methods,which is easy-to-control and produces less byproducts.However,the hydrogen evolution reaction occurs,reducing the current efficiency.The three-dimensional electrode,which improves electroreduction and fills particles between the cathode and anode,can increase the specific surface area,promote the electric transmission,strengthen the generation of reducing agent [H],and enhance the removal efficiency of contaminant.Bromate was reduced to bromide on the surface of cathode.Simultaneously,bromate removal occurred on the particles with H2 which produced on the cathode as reducing agent.The conventional water treatment strategies face the challenge to remove harmful BrO₃^-from drinking water.The Pd catalyst has the capacity to store and activate hydrogen.Here,Pd/Al₂O₃ and Pd-In/Al₂O₃ particle electrodes were synthesized via an impregnation and calcination method and the electrochemical reactor was designed.The potential application of particle electrodes in the electrocatalytic reduction of BrO₃^-was studied.The structural characterizations of Pd/Al₂O₃ and Pd-In/Al₂O₃ confirmed the uniform distribution of Pd nanocrystals.The surface zeta potential of Pd-In/Al₂O₃ is +38.6mV,higher than that of Pd/Al₂O₃.The result of XRD shows the formation of In0.15Pd0.85 alloy.The XPS data shows that the binding energy of Pd 3d3/2 increases from 334.4eV to 335.77 eV with the rise of In content,indicating the regulation for the electronic state of Pd by In,which resulted in the superior catalytic efficiency and low energy consumption.The adsorption effect of Pd-In/Al₂O₃ is better than Pd/Al₂O₃.Effect experiments of Pd/Al₂O₃ show the optimal Pd loading amount is 3 %.Effect experiments of Pd-In/Al₂O₃ showthe optimal conditions for the reduction was determined to be 1:4 molar ratio of Pd to In,0.9 mA/cm2 current density and 1 g/L catalyst dosage,the removal efficiency of BrO₃^-is 96.37 %.Investigation on the influence factors indicated that both the direct and indirect reduction could be facilitated by decreasing solution pH.The reactive species and possible electrocatalytic mechanism were further investigated.The ESR spin trapping demonstrated the enhanced production of atomic [H] under the regulation for the electronic state of Pd by In,which contributed to the significantly improved electrocatalytic reduction of BrO₃^-.