Degradation of phenol by the collapse of microbubbles

This study focuses on the application of microbubble collapse technique to the wastewater treatment. We have verified that collapsing air microbubbles lead to the decomposition of phenol, a common pollutant. A reduction in phenol of similar to 60% was observed during a 2-h test period when air was used as the microbubble source. We have also studied the dependence of phenol degradation on the pH of the solution and the type of gas within the microbubbles. The pseudo-first-order kinetic constant for the degradation of phenol, k, increased linearly with the concentration of H+ in solution. The use of oxygen microbubbles gave rise to the highest k value (1.6 h(-1)) measured. It is suggested that hydroxyl radicals play an important role in the phenol decomposition process. The acquired information would be useful for the future application of microbubbles in the field of wastewater treatment. (C) 2009 Elsevier Ltd. All rights reserved.