Jieqi Feng,Hao Lan,Qibin Tao,Wenqing Chen,Qizhou Dai
In this study, a novel NCNS-Ce-PbO 2 electrode was prepared by electrodeposition method using the rare earth metal Ce and synthesized nitrogen-doped carbon nanosheets (NCNSs). Various characterization and electrochemical performance tests showed that the NCNS-Ce-PbO 2 electrode possessed a denser surface and smaller grains than other NCNS-PbO 2 and Ce-PbO 2 electrodes, with more active surface sites and thus could generate more hydroxyl radicals. N , N -diethyl-m-toluamide (DEET) was selected as the model contaminant to evaluate the electrochemical performance of the novel NCNS-Ce-PbO 2 electrode. The effects of initial pollutant concentration, current density, electrolyte concentration, and initial pH on the removal rates of DEET and chemical oxygen demand (COD) were investigated. Under optimal conditions, after degradation of 150 min, the removal rate of DEET and COD reached 100% and 80.52%, respectively. GC–MS was used to identify intermediate products in the degradation process. The degradation mechanism and possible degradation pathways of DEET with NCNS-Ce-PbO 2 electrode were discussed. The good stability of the NCNS-Ce-PbO 2 anode was confirmed by accelerated lifetime experiments.
In this paper, Ti/SnO2-Sb/Ce-PbO2 anode is electrodeposited from MSA bath, and the effect of Ce3+ concentration in bath on the phase composition and morphology of lead dioxide electrode is elucidated. It is found that with the addition of 2 mM Ce3+ ion to the bath the Ce-PbO2 anode exhibits highest stability in 0.5 M H2SO4, and cerium exists as Ce (IV) in the PbO2 film. The electrocatalytic activity of lead dioxide anode for phenol removal is slightly enhanced by the inclusion of Ce. The significant improvement in electrocatalytic activity can be achieved by the addition of small amount of Bi3+ ion to the bath containing Ce3+ ion. In this study, electrocatalytic activities of various anodes follow the order: Ce,Bi-PbO2 > Ce-PbO2 > undoped PbO2 > Bi-PbO2.
Hexafluoropropylene oxide dimer acid (HFPO-DA), an emerging persistent pollutant, has been prevalently utilized as an alternative to perfluorooctanoic acid (PFOA). Analogous to PFOA, HFPO − DA presents remarkable resistance against degradation by conventional technologies. In this study, we prepared Ce doped PbO 2 anode (Ce-PbO 2 ) and paired it with cathode to form redox system for the degradation of HFPO-DA in water. The results showed that the degradation rate of HFPO-DA over Ce-PbO 2 was as high as 1.67 × 10 −2 min −1 , much higher than that of Boron-doped diamond electrode (BDD, 6.84 × 10 –3 min −1 ). The Ce-PbO 2 anode also has the theoretical lifetime as high as 82.7 years. Free radical quenching experiments indicated that both reactive oxygen species (ROS) and reductive radicals contributed to the degradation of HFPO-DA. These degradation reactions start from a direct electron transfer, followed by electroreduction and a series of free radical reactions including decarboxylation, ether bond cleavage, and the “4A” processes (generation of Alkyl radicals, Alcohols, Acyl fluorides, and Acids in sequence) until it is decomposed into small molecules. Meanwhile, new intermediates (CF 3 CF 2 CF 2 OCF 3 CH•) generated by cathodic H• are dominating the reductive reaction during the electrochemical process. This “buttering bread on both sides” redox mechanism deepens the understanding of the degradation process of HFPO-DA and provides an efficient treatment strategy.
危险品化学品经营许可证（带存储）