| Sono-electrochemical oxidation is a clean process waste water purification technology.The introduction of sonochemistry to electrochemistry,made the continuous cleaning and activation,to achieve the regeneration of electrode to accelerate the process of mass transfer of pollutants from the main body of liquid to the surface,eliminating the concentration polarization,improving the catalytic effect of electrochemical system,existence of the advantages of high treatment efficiency,simple operation,no secondary pollution,etc.The electrode material is the core of sono-electrochemical oxidation technology.In the basis of summarized current methods of Ti/Pb02 electrode preparation,a new method that covered stannum and antimony mixed oxide compounds as bottom by thermal decomposition thchnology after coarse treatment of the titanium substrate was provided in this paper.Then a-Pb02 was electrode posited in alkaline solution as mesosphere;finally electrode posited ?-PbO2 in acidity solution was used as surface layer.In the paper,methylene blue(MB),actaminophen(APAP)is the target pollutions,uesd the method of sono-electrochemical oxidation to study.Firstly,the dergadation of methylene blue is studied under the condition of sonochemistry.the effect of various process parameters on the pollutant is investigated by the method of single-factor,also optimized the parameters.A novel lead dioxide electrodes co-doped with rare earth(La2O3)and polytetrafluoroethylene(PTFE)were prepared by the electrochemical deposition and applied as anodes for the degradation of typical dye wastewater(methylene blue)in the sono-electrochemical system.The result showed that the removal of 200mg/L methylene blue reached to 89.51%under the condition of 49.58 W·cm-2 power,50 Hz frequency,La-PbO2/Ti used as the anode,71.43 mA·cm-2current density,14.2 g·L-1 sodium sulfate after reaching 2 h.A possible degradation mechanism was discussed and the probable degradation pathway was deduced.Secondly,the dergadation of paracetamol is studied under the condition of sono-electrochemical.The result showed that the APAP removal efficiency and the mineralization efficiency reached a substantial increase,the catalytic efficiency showed a significant improvement in the use of rare-earth doped electrode.The law of process factors showed that the condition of the electrode doped with Ce2O3 under electrolyte concentration of 14.2 g·L-1,49.58 W·cm-2 power,50 Hz frequency,pH =3,71.43 mA·cm-2 current density,had the best degradation efficiency.The APAP of 500 mg·L-1 removal rate reached 92.20%and its COD and TOC value declined to 79.95%and 58.04%,the current efficiency highly got to 45.83%after degradation process for 2.0 h.Futhermore,the removal rate under the condition of zoochemistry,electrochemistry,sono-electrochemistry proved the existence of synergistic effect.By analysis the energy consumption,the result showed that the existence of zoochemistry strengthen the presence of the mass transfer of the electroactive material and its reaction products on the surface of electrode,and inspired a large number of high energy active subatance-OH and-H,promoted the efficiency of the oxidation.The intermediates formed during the degradation reaction were identified by using gas chromatography-mass spectrometry(GC-MS)and ion chromatography(IC).The results demonstrated that the pllutant primary decomposed into large molecule metabolites under the attack of-OH free radicals and other active groups.As the reaction proceed,these metabolites via ring-open,bond-broken etc.were oxidized to small molecule acids or ions,ultimately,completely mineralized to CO2 and H2O,and achieved the effective degradation of organic contaminations. |
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