CuO has been synthesized in the nano-sized (10-15 nm) and 
examined as a photocatalyst for degradation of metronidazole in 
its aqueous solution. The removal studies were performed in the 
absence of light and under the effect of UV-radiation. The 
influences of various operational parameters such as catalyst dose, 
drug concentration, and time of exposure on percentage 
photodegradation of metronidazole were investigated. The 
experimental results revealed that the photodegradation of 
metronidazole increased with increasing CuO dose and exposure 
time, while decreasing with increase initial concentration of 
metronidazole. The maximum degradation efficiency (85.0%) 
occurred after about 120 min of irradiation. The degradation rate 
followed first order kinetics with a rate constant of 0.0198 min-1
.