Anodic electrochemical behavior was studied on graphite anode at 1000 ℃ in cryolite-alumina molten salt by means of cyclic voltammetry. The high current peak in a typical cyclic voltammogram was discussed. It is cons...Anodic electrochemical behavior was studied on graphite anode at 1000 ℃ in cryolite-alumina molten salt by means of cyclic voltammetry. The high current peak in a typical cyclic voltammogram was discussed. It is considered that a type of oxyfluoroaliminate complex anions reacts with carbon to form a high-resistance CF film on the anode surface at a high potential. The passivation potential is 3.28 V in 0.5% alumina-containing electrolyte, and the passivation potential increases with alumina content increasing which indicates that the alumina content determines the anodic process in the cryolite-alumina molten salt system.展开更多
In view of the unclear cause of perfluorocarbons(PFCs)emission in the anode effect stage of aluminum electrolysis,the microscopic formation mechanism of PFCs was studied by density functional theory calculation and X-...In view of the unclear cause of perfluorocarbons(PFCs)emission in the anode effect stage of aluminum electrolysis,the microscopic formation mechanism of PFCs was studied by density functional theory calculation and X-ray photoelectron spectroscopy(XPS).It is found that the discharge of fluorine containing anions([F]−)on carbon anode first causes the substitution of C—H by C—F and further results in the saturation of aromatic C—C bonds,leading to the appearance of—CF_(3)or—C_(2)F_(5)group through six-carbon-ring opening.Elimination of—CF_(3)and—C_(2)F_(5) with F atom could be a likely mechanism of CF_(4) and C_(2)F_(6) formation.XPS results confirm that different types of—CF_(x) group can be formed on anode surface during electrolysis,and the possibility that[F]−discharges continuously at the C edge and finally forms different C—F bonds in quantum mechanical calculation was verified.展开更多
Vanadium‐based catalysts are considered the most promising materials to replace cobalt‐based catalysts for the activation of peroxymonosulfate(PMS)to degrade organic pollutants.However,these traditional vanadium spe...Vanadium‐based catalysts are considered the most promising materials to replace cobalt‐based catalysts for the activation of peroxymonosulfate(PMS)to degrade organic pollutants.However,these traditional vanadium species easily leak out metal ions that can affect the environment,even though the of vanadium is much less than that of cobalt.Compared to other vanadium‐based cata‐lysts,e.g.,V_(2)O_(3),fluorinated V_(2)AlC shows a high and constant activity and reusability regarding PMS activation.Furthermore,it features extremely low ion leakage.Active oxygen species scavenging and electron spin resonance measurements reveal that the main reactive oxygen species was 1O_(2),which was induced by a two‐dimensional confinement effect.More importantly,for the real‐life application of tetracycline(TC)degradation,the introduction of fluorine changed the adsorption mode of TC over the catalyst,thereby changing the degradation path.The intermediate products were detected by liquid‐chromatography mass spectroscopy(LC‐MS),and a possible degradation path was proposed.The environmental impact test of the decomposition products showed that the toxicity of the degradation intermediates was greatly reduced.Therefore,the investigated ultradu‐rable catalyst material provides a basis for the practical application of advanced PMS oxidation technology.展开更多
基金Projects (50804010, 51074046) supported by the National Natural Science Foundation of China
文摘Anodic electrochemical behavior was studied on graphite anode at 1000 ℃ in cryolite-alumina molten salt by means of cyclic voltammetry. The high current peak in a typical cyclic voltammogram was discussed. It is considered that a type of oxyfluoroaliminate complex anions reacts with carbon to form a high-resistance CF film on the anode surface at a high potential. The passivation potential is 3.28 V in 0.5% alumina-containing electrolyte, and the passivation potential increases with alumina content increasing which indicates that the alumina content determines the anodic process in the cryolite-alumina molten salt system.
基金the financial supports from the National Natural Science Foundation of China(Nos.51974373,51874365,62133016)the Major Scientific and Technological Innovation Projects of Shandong Province,China(No.2019JZZY020123)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2019zzts242)。
文摘In view of the unclear cause of perfluorocarbons(PFCs)emission in the anode effect stage of aluminum electrolysis,the microscopic formation mechanism of PFCs was studied by density functional theory calculation and X-ray photoelectron spectroscopy(XPS).It is found that the discharge of fluorine containing anions([F]−)on carbon anode first causes the substitution of C—H by C—F and further results in the saturation of aromatic C—C bonds,leading to the appearance of—CF_(3)or—C_(2)F_(5)group through six-carbon-ring opening.Elimination of—CF_(3)and—C_(2)F_(5) with F atom could be a likely mechanism of CF_(4) and C_(2)F_(6) formation.XPS results confirm that different types of—CF_(x) group can be formed on anode surface during electrolysis,and the possibility that[F]−discharges continuously at the C edge and finally forms different C—F bonds in quantum mechanical calculation was verified.
文摘Vanadium‐based catalysts are considered the most promising materials to replace cobalt‐based catalysts for the activation of peroxymonosulfate(PMS)to degrade organic pollutants.However,these traditional vanadium species easily leak out metal ions that can affect the environment,even though the of vanadium is much less than that of cobalt.Compared to other vanadium‐based cata‐lysts,e.g.,V_(2)O_(3),fluorinated V_(2)AlC shows a high and constant activity and reusability regarding PMS activation.Furthermore,it features extremely low ion leakage.Active oxygen species scavenging and electron spin resonance measurements reveal that the main reactive oxygen species was 1O_(2),which was induced by a two‐dimensional confinement effect.More importantly,for the real‐life application of tetracycline(TC)degradation,the introduction of fluorine changed the adsorption mode of TC over the catalyst,thereby changing the degradation path.The intermediate products were detected by liquid‐chromatography mass spectroscopy(LC‐MS),and a possible degradation path was proposed.The environmental impact test of the decomposition products showed that the toxicity of the degradation intermediates was greatly reduced.Therefore,the investigated ultradu‐rable catalyst material provides a basis for the practical application of advanced PMS oxidation technology.
