Air or air-ozone mixtures were bubbles in the reacting suspension at a flow rate of 0.030 L min-1. Ozone was produced by feeding synthetic air to an ozonator (Microlab) able to vary the ozone production rate in the 1 to 20 mmol h-1 range. In
order to determine the concentration of ozone in the gas phase introduced to the reacting system, the absorbance of gaseous ozone was measured at 254 nm using a UV–Vis spectrophotometer (Shimadzu)