Sonochemical treatment of Orange II using ultrasound at a range of frequencies and powers

A range of methods are reported for the treatment of Orange II in aqueous solution with a variety of ultrasonic equipment in the absence of oxidants. The frequencies studied were 20 kHz (using a probe system) and a range of baths at 40, 380, 850, 1000 and 1176 kHz using different power inputs. Using ultrasound alone the higher frequencies were more efficient for the decolorization of Orange II. The most effective decolorization of Orange II in terms of power was achieved at 850 kHz and increased from 4.1% to 49.0% with increasing ultrasonic power from 2.04 W to 22.07 W over 2 hours. This trend was in good agreement with the corresponding production of H₂O₂ during the sonication of water in the absence of Orange II. The decolorization followed first order reaction kinetics. A simple economic comparative assessment of the different types of ultrasonic equipment in terms of power consumption and effective decolorization revealed that the 850 kHz bath at a power of 22.07 W was the most cost effective system.