Cobalt Oxide-Modified Titanium Dioxide Nanoparticle Photocatalyst for Degradation of 2,4-Dichlorophenoxyacetic Acid

2,4-dichlorophenoxyacetic acid (2,4-D) has been recognized as a possibly carcinogenic compound to human, therefore, 2,4-D should be treated before it is discharged to the environment. Photocatalytic degradation of 2,4-D has been proposed as one of the best methods that offer environmentally safe process. In the present research, titanium dioxide (TiO 2 ) was modified with cobalt oxide (CoO) and tested for photocatalytic degradation of 2,4-D under UV light irradiation. Different amounts of CoO (0.1, 0.5, 1 and 5 mol%) were added onto TiO 2 by an impregnation method. The photocatalytic reaction was monitored and analyzed by measurement of 2,4-D absorbance using UV spectrophotometer. After 1 h photocatalytic reaction, it was confirmed that the sample with low loading of 0.1 mol% gave the highest photocatalytic activity among the bare and modified TiO 2 photocatalysts. The photocatalytic activity was decreased with the increase of CoO loading, suggesting that the optimum amount of CoO was an important factor to improve the performance of TiO 2 . Based on fluorescence spectroscopy, such addition of CoO resulted in the reduced emission intensity, which showed the successful decrease in the electron-hole recombination.