Removal of methyl orange from aqueous solution using a 1.6 MHz ultrasonic atomiser

Under 1.6 MHz atomisation, methyl orange (MO, 10 mg L−1) removal was mainly influenced by the calorimetric power, so that as the calorimetric power doubled, MO removal (%) increased three-fold. MO removal was favoured by low pH, low solution volume and high air flow rate. By analysing the effect of a radical scavenger on MO removal, it was found that the major MO removal mechanism was sonochemical degradation of MO in the bulk solution due to cavitation. CCl4 (100 mg L−1) increased MO removal by 22.9% from a 90 mL solution having 10 mg L−1 MO at pH 2. Atomiser design is thus an important factor to consider when implementing sonochemical remediation to ensure that the maximum possible calorimetric energy intensity is obtained within the atomiser.