Study On Ce And La Modified Anode Preparation And Its Electro-catalytic Ability For Simulated Phenolic Wastewater Oxidation

In recent years,electrochemical oxidation technology has gradually become a development area of industrial wastewater treatment owing to its following features: clean processing way,wide adaptability,high power efficiency,great automaticity,etc.In this study,ultrasonic coating � thermal decomposition method was engaged to prepare Ce and La doping Ti/SnO₂-Sb anodes.After that,the electrochemical characteristics and stability of the two type anodes were compared at the same conditions;then their wide adaptability was researched through the electro-catalytic degradation of p-cresol using Ti/SnO₂-Sb-Ce anode;finally the mechanism of phenol degradation on Ce doping anode was discussed.Firstly,Ce and La doping Ti/SnO₂-Sb anodes were prepared using ultrasonic coating � thermal decomposition method.SEM images showed that the two modified anodes presented similar surface morphology,of which Ce doping anode was more compact and plump.The experiment of phenol degradation indicated that doping of the two rare earth elements dramatically improved the performance of initial a nodes,and the optimal current density of both doping anodes is 10 mA�cm-2;the best doping rate of Ce and La into the Ti/SnO₂-Sb anode is 1% and 3% respectively.Secondly,in the experiment of electro-catalytic oxidation degradation of p-cresol using Ce doping anode,XRD image demonstrated that the doping of Ce introduced a CeO₂ into metal oxide coating,benefiting the properties of electrodes.SEM photographs showed that appropriate doping of Ce could optimize the anode's surface morphology but excessive doping should harm its characteristics and stability,which tallies with results of the above experiments.Degradation experiments at different current densities indicated that the optimal current density is 20 mA�cm-2 when Ce doping anodes prepared used in the electrochemical degradation of p-cresol.At last,the mechanism of phenol degradation on Ce modified anodes was studied.Since valence electronic configuration 4f15d16s2 of Ce atom has one more 4f1 than that of La atom,activity and stability of Ce doping anode were a little better than those of La doping anode.With comparison of initial and final SEM pictures and XRD images of the anodes used to degrade phenol,the surface of the final anode grew some white particles of vary sizes which occupied the active vacancies and the new CeO₂ in the coating disappeared so that gradually deprived the anode of electrochemical activity.HPLC analysis showed that intermediate compounds of phenol degradation on Ce doping anode included benzoquinone,maleic acid,fumaric acid,succinic acid,acrylic acid,oxalic acid,methanoic acid,etc.