Abstract: The ZnFe0.25Al1.75O4 spinel type catalyst prepared by the sol-gel method was tested for catalytic wet air oxidation of phenol. High activity and stability were obtained for the catalyst. After five successive reactions, there were still 100% of phenol conversion and 88.7% of COD removal. During the phenol degradation, the returning of leached iron to the catalyst surface was observed, and as a result the amount of iron leaching in the final effluent was very low. After the fifth reaction run, the amount of iron leaching was 2.15 mg/L, and the zinc leaching was 1.53 mg/L.

Key words: spinel, phenol, catalytic wet air oxidation, iron ion, leaching