PHOTOCATALYTIC DEGRADATION OF ORGANIC CONTAMINANTS IN SEMICONDUCTOR SUSPENSIONS ADDED H2O2

The photocatalytic oxidation of aqueous solutions of phenol, p-nitroph enol, 4-chlorophenol, aniline, hydroquinone and pyridine have been stu died in gas recycling reactor utilizing TiO2 as photocatalyst in the p resence and in the absence of hydrogen peroxide. The rate of oxidation of organics to CO2 was measured by using natural and artificial near u.v. light. The disappearance of each solute obeys pseudo first order kinetics with respect to organic whereas the rate of mineralization is zeroth order. While the addition of small amounts of hydrogen peroxid e significantly enhanced the photomineralization rate of all organic c ompounds, high concentration of it inhibited the reaction. The optimum concentration of H2O2 ranges from 1x10(-2) to 0.5x10(-2) M for 10(-4) M organic solutions. The complete mineralization for 10(-4) M of each organic resulted in approximately 50-110 minutes whereas this period was shortened to 6-28 minutes by the addition of an optimum amount of H2O2.