Effect of aluminium oxide contaminants on the process of ozone decomposition in water

Catalytic ozonation for the removal of organic contaminants in water on alumina

“…Some reports contradict this and suggest that aqueous ozone is not decomposed by alumina [6,11]. Other reports further suggest that molecular ozone reactions may be involved [2,11]. The results presented in this work clearly indicate that ozonation in the presence of alumina involves radical mechanisms.…”

“…Qi et al [10] also confirmed that alumina promotes the generation of hydroxyl radicals but the group claimed that surface hydroxyl groups of alumina do not interact with ozone. Some reports contradict this and suggest that aqueous ozone is not decomposed by alumina [6,11]. Other reports further suggest that molecular ozone reactions may be involved [2,11].…”

“…It has been recently reported by Nawrocki and Fiolek [11] that higher ozone decomposition in the presence of alumina as compared with ozonation alone may be due to alkaline contaminants present on the surface of alumina, which when desorbed from alumina's surface to the bulk solution can change pH of solution and these pH changes can lead to increased ozone decomposition rates [11]. Therefore, it is important to monitor pH during the ozonation and catalytic ozonation process.…”

“…4 indicate that in the current research no significant change in pH was observed during ozonation alone and catalytic ozonation on alumina. It is, however, important to mention that Nawrocki et al [11] studied pH changes and ozone decomposition in the absence of pollutants. In the current investigation pH changes have been studied in the presence of pollutants.…”

“…Qi et al [10] also confirmed that alumina promotes the generation of hydroxyl radicals but the group claimed that surface hydroxyl groups of ␥-alumina do not interact with aqueous ozone. It has been recently highlighted by Nawrocki et al [11] that alkaline impurities present in alumina oxides can play an important role in ozone decomposition and hydroxyl radicals formation. This is because their desorption into the bulk solution results in pH changes of the aqueous solution, which then affect stability of molecular ozone in water.…”