Study On The Preparation Of Electrodes With Visible Light Response And Photoelectro Catalytic Degradation Of Heavy Matal Comliexes

Heavy metal pollution has paid more and more attention of public, due to its strong stability,heavy metal complexes can enhance the migration of heavy metals and cause a wider range ofheavy metals pollution. Conventional water treatment technology can not effectively treat suchcomplexes, so this paper aims to explore a method to effectively deal with heavy metalcomplexes and achieve recovery of heavy metals.In this paper, a new film was deposited onto ITO substrate from a complex solution bydip-coating method, which was used as anode to degrade Cu/Pb–EDTA and cyanide.Simultaneously, the liberated heavy metal ions were recovered by electrodeposition process atcathode. The oxidation and reduction processes were investigated.1.Cu-EDTA was selected as the target pollutants, with Bi2MoO6electrode asanode,photocatalytic oxidation, electrochemical oxidation and the photoelectric catalyticoxidation of Cu-EDTA were compared. The results showed that at the reaction time of2h, theremoval ratio of EO and PC on Cu-EDTA was only40%and0%, the recovery ratio of Cu(II) is40%and0%，respectively; the removal ratio of PEC on Cu-EDTA and the recovery ratio of Cu2+was55%and55%，respectively. These results indicate that the PEC shows good synergisticeffect between photocatalytic oxidation and electrochemical oxidation. Simultaneously, otherfactors on this process was investigated.2.The crystalline of the Co-BiVO4film was confirmed to be monoclinic crystal. At1.5V,the removal efficiencies of Pb-EDTA at photoelectrocatalytic process and electro-oxidation weredetermined to be75%and65%at120min. Nearly no loss of Pb-EDTA was observed in thephotocatalysis process. The liberated Pb2+was observed to be deposited onto the anode surface.In the case of Cu-EDTA, the removal efficiencies of Cu-EDTA at photoelectrocatalytic processand electro-oxidation were determined to be70%and50%, respectively. Correspondingly, therecovery efficiencies of Cu were measured to be70%and50%. The liberated Cu2+was depositedonto the cathode.3.In the degradation of complex state cyanide with Bi2MoO6electrode as anode, thetreatment effect is largely rises with the voltage increases. Complex state cyanide was selected asthe target pollutants, photocatalytic oxidation, electrochemical oxidation and the photoelectriccatalytic oxidation of Cu-EDTA were compared and electrochemical oxidation has been shown to be more efficient than the photoelectric catalytic oxidation. Simultaneously, the hydroxylradical quencher—CO32-is added to promote the effect of the PEC. Cu2+reduction process oncathode was analyzed with the XPS.4.The effect of PC oxidation of NaCN at Bi2MoO6electrode is weak. In the degradation ofNaCN with PEC process,when the voltage is1.5V, the reaction time is120min, the totalresidual cyanide content is10%. When the voltage is increased to2.5V, the effect become worsedue to the hydrogen and oxygen evolution.The EO oxidation of NaCN at Bi2MoO6electrode,when the voltage is2.5V, the reaction time is120min,the removal efficiencies ofNaCN is25%. NaCN was selected as the target pollutants, photocatalytic oxidation,electrochemical oxidation and the photoelectric catalytic oxidation of NaCN were compared, theresults indicate that the PEC shows good synergistic effect between photocatalytic oxidation andelectrochemical oxidation. The CO32-promoted the effect of the PEC in oxidating NaCN.