Role of Mg in mesoporous MgFe2O4 for efficient catalytic ozonation of Acid Orange II

BACKGROUND An ozonation catalyst needs to be recycled easily and to exhibit high activity in view of its practical application in wastewater treatment. In this study, magnetic mesoporous MgFe 2 O 4 was successfully prepared and used as a new ozonation catalyst for degradation of Acid Orange II (AOII). The role of Mg in MgFe 2 O 4 was revealed to explain the high activity by catalytic experiments and XPS analysis. RESULTS The degradation efficiency of AOII in the MgFe 2 O 4 /O 3 process exceeds 90% over a wide pH range of 4.6–9.6, slightly affected by the solution pH. The catalytic activity of MgFe 2 O 4 is much higher than that of MgO, Fe 2 O 3 and also their mixture (MgO+Fe 2 O 3 ) with identical molar ratio of Mg 2+ to Fe 3+ , indicating the first role of Mg, i.e. coupling with Fe to present a synergistically catalytic effect. Furthermore, MgFe 2 O 4 possesses a reaction rate constant at least 2.3 times that of NiFe 2 O 4 , MnFe 2 O 4 , and CuFe 2 O 4 . It illustrates the second role of Mg, i.e. causing the high electron density on lattice oxygen in MgFe 2 O 4 indicated by XPS and thus favoring activation of the electrophilic ozone. CONCLUSIONS This study demonstrated the easy recycling and high activity of MgFe 2 O 4 in catalytic ozonation, and revealed the role of Mg in MgFe 2 O 4 . © 2015 Society of Chemical Industry