Catalytic performance of Fe 3O 4-CoO/Al 2O 3 catalyst in ozonation of 2-(2,4-dichlorophenoxy)propionic acid, nitrobenzene and oxalic acid in water

Abstract

Fe 3O4-CoO/Al 2O3 catalyst was prepared by incipient wetness impregnation using Fe(NO 3) 3-9H 2O and Co(NO 3)2-6H 2O 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 Fe 3O 4-CoO/Al 2O 3 catalyst enabled an interesting improvement of ozonation efficiency during the degradation of each organic pollutant, and the Fe 3O 4-CoO/Al 2O 3 catalytic ozonation system followed a radical-type mechanism. The kinetics of ozonation alone and Fe 3O 4-CoO/Al 2O 3 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 x 10 −2 min- 1 for ozonation alone and 4.740 x 10 −2 min −1 for O 3/Fe 3O 4-CoO/Al 2O 3. And O 3/Fe 3O 4-CoO/Al 2O 3 had a larger R ct (6.614 x 10 −9) calculated by the relative method than O 3 did (1.800 x 10- 9), showing O 3/Fe 3O 4-CoO/Al 2O 3 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 Fe 3O 4-CoO/Al 2O 3 in ozonation of studied organic substance was universal to a certain degree.