Photocatalytic Degradation Of Azo Dye Over TiO₂ Supported On Activated Carbon

Photocatalytic has a great potential for the removal of organic pollutants from wastewater and attracted the attention of many researchers in recent years. In the present study, two photocatalysts, TiO2/AC and Ag-TiO2/AC, have been prepared by Sol-Gel-impregnation and the photocatalytic degradation of Methyl orange and Congo red on these catalysts have been studied.Several factors, such as the pH value, the pollutant primary concentration and the loading amounts of TiO2, had been investigated to obtain the optimal reaction conditions. Then, the photocatalytic degradation of Methyl orange and Congo red on the Ag-TiO2/AC had been studied under these conditions. It has been found that: the pH value was a key factor to affect the activity, and the highest decoloration rate of Methyl orange could be obtained at the pH value of 3, while it was 9 for Congo red;the higher the pollutant primary concentration, the higher decoloration rate, when the primary concentration was below 20 mg/L;the degradation performance of Methyl orange is best when the TiO2 loading amount was 29.8%, while it was 37.4% to Congo red.The dye's degradation process has been studied by the means of ultraviolet-visible spectrum and it revealed that: Chemical oxygen demand (COD) began to be removed when the dye decoloration almost finished, and acid organic product was produced in the course of Congo red degradation;synergetic effects between the TiO2 and the activated carbon were favorable for the photocatalytic degradation of azo dye;light absorption characteristic velocity( ka,A (λ)) of azo dye and total quantum yields (φa,A(λ)) of hydroxyl group were mainly factors to affect the photocatalytic degradation activity.