Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe（NO3）3.9H2O and Co（NO3）2.6H2O as the precursors, and its catalytic performance was investigated in ozonation of 2-（2,4-dichlorophen...Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe（NO3）3.9H2O and Co（NO3）2.6H2O as the precursors, and its catalytic performance was investigated in ozonation of 2-（2,4-dichlorophenoxy）propionic acid （2,4-DP）, nitrobenzene and oxalic acid. The experimental results indicated that Fe3O4-CoO/Al2O3 catalyst enabled an interesting improvement of ozonation efficiency during the degradation of each organic pollutant, and the Fe3O4-CoO/Al2O3 catalytic ozonation system followed a radical-type mechanism. The kinetics of ozonation alone and Fe3O4-CoO/Al2O3 catalytic ozonation of three organic pollutants in aqueous solution were discussed under the mere consideration of direct ozone reaction and OH radical reaction to well investigate its performance. In the catalytic ozonation of 2,4-DP, the apparent reaction rate constants （k） were determined to be 1.456 × 10^-2 min-1 for ozonation alone and 4.740 × 10^-2 min^-1 for O3/Fe3O4-CoO/Al2O3. And O3/Fe3O4-CoO/Al2O3 had a larger Rot （6.614 × 10^-9） calculated by the relative method than O3 did （1.800 x 10-9）, showing O3/Fe3O4-CoO/Al2O3 generated more hydroxyl radical. Similar results were also obtained in the catalytic ozonation of nitrobenzene and oxalic acid. The above results demonstrated that the catalytic performance of Fe3O4-CoO/Al2O3 in ozonation of studied organic substance was universal to a certain degree.展开更多
Co-Al-W-0.1B superalloys have been isothermally oxidized at 900℃ for 1000,5000 and 10000 h in order to investigate their oxidation behaviors.The oxide layers and morphologies were characterized by X-ray diffraction a...Co-Al-W-0.1B superalloys have been isothermally oxidized at 900℃ for 1000,5000 and 10000 h in order to investigate their oxidation behaviors.The oxide layers and morphologies were characterized by X-ray diffraction and scanning electron microscopy combined with energy-dispersive spectroscopy.After1000 h exposure,a Co3W/γ zone,an Al2O3layer,a mixture of Co,Al,W oxides layer and a CoO layer are established on the substrate alloys.After extended oxidation,a discontinuous Al2O3layer in Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys leads to an additional mixed oxide layer on the substrate instead of the Co3W/γ zone.The oxide layers that form on the Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys are much thicker than those on the Co-9Al-11W-0.1B alloy,and continuously thicken during oxidation.The higher content of W is beneficial to improving the oxidation resistance as it facilitates a faster formation of Co3Was well as Al2O3.展开更多
基金supported by the National Natural Science Foundation of China(No.50578146,20876151)the National Science Foundation of Zhejiang Province,China(No.Y5080178)
文摘Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe（NO3）3.9H2O and Co（NO3）2.6H2O as the precursors, and its catalytic performance was investigated in ozonation of 2-（2,4-dichlorophenoxy）propionic acid （2,4-DP）, nitrobenzene and oxalic acid. The experimental results indicated that Fe3O4-CoO/Al2O3 catalyst enabled an interesting improvement of ozonation efficiency during the degradation of each organic pollutant, and the Fe3O4-CoO/Al2O3 catalytic ozonation system followed a radical-type mechanism. The kinetics of ozonation alone and Fe3O4-CoO/Al2O3 catalytic ozonation of three organic pollutants in aqueous solution were discussed under the mere consideration of direct ozone reaction and OH radical reaction to well investigate its performance. In the catalytic ozonation of 2,4-DP, the apparent reaction rate constants （k） were determined to be 1.456 × 10^-2 min-1 for ozonation alone and 4.740 × 10^-2 min^-1 for O3/Fe3O4-CoO/Al2O3. And O3/Fe3O4-CoO/Al2O3 had a larger Rot （6.614 × 10^-9） calculated by the relative method than O3 did （1.800 x 10-9）, showing O3/Fe3O4-CoO/Al2O3 generated more hydroxyl radical. Similar results were also obtained in the catalytic ozonation of nitrobenzene and oxalic acid. The above results demonstrated that the catalytic performance of Fe3O4-CoO/Al2O3 in ozonation of studied organic substance was universal to a certain degree.
基金funding from the China Scholarship Council program(No.201306290056)supported by the National Natural Science Foundation of China(No.51775440)
文摘Co-Al-W-0.1B superalloys have been isothermally oxidized at 900℃ for 1000,5000 and 10000 h in order to investigate their oxidation behaviors.The oxide layers and morphologies were characterized by X-ray diffraction and scanning electron microscopy combined with energy-dispersive spectroscopy.After1000 h exposure,a Co3W/γ zone,an Al2O3layer,a mixture of Co,Al,W oxides layer and a CoO layer are established on the substrate alloys.After extended oxidation,a discontinuous Al2O3layer in Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys leads to an additional mixed oxide layer on the substrate instead of the Co3W/γ zone.The oxide layers that form on the Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys are much thicker than those on the Co-9Al-11W-0.1B alloy,and continuously thicken during oxidation.The higher content of W is beneficial to improving the oxidation resistance as it facilitates a faster formation of Co3Was well as Al2O3.
