The degradation of two commercially available dyestuffs (C.I. Reactive Black 5 and C.I. Disperse Orange 25) by ultraviolet radiation (UV), ultrasonic irradiation (US), UV/H2O2 and US/H2O2 processes was investigated in a laboratory-scale batch photoreactor equipped with a 55 W immersed-type low-pressure mercury vapor lamp and a sonoreactor with low frequency (42 kHz) plate type transducer at 170W of acoustic power. The toxicity was also evaluated in acute toxicity studies using Daphnia magna. Results showed that color removal efficiencies by US and US/H2O2 processes were negligible for both dyes. Almost complete disappearance of Reactive Black 5 (97.9%) in UV/H2O2 process was possible after 5 min of irradiation. The maximum color removal efficiency of Disperse Orange 25 after 10 min of irradiation, however, was only 9.2% and reached a maximum value of 41% after 120 min of irradiation. Pseudofirst order kinetics with respect to dyestuffs concentrations was found to fit all the experimental data. The results clearly
showed that both dyes examined were toxic to D. magna and resulted in quite low LC50 values.
Aleboyeh A, Aleboyeh H, Moussa Y, Dyes Pigm., 57, 67, 2003
Beltran FJ, Ozone-UV radiation-hydrogen peroxide oxidation technologies. In: Tarr MA (Ed.), Chemical Degradation Methods for Wastes and Pollutants. Environmental and Industrial Applications. Marcel Dekker, Inc., New York, USA, 2003
Catalkaya E, Bali U, Sengul F, Environ. Sci. Pollut. Res. Int., 10, 113, 2003