Role of Mg in mesoporous MgFe2O4for 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 MgFe2O4 was successfully prepared and used as a new ozonation catalyst for degradation of Acid Orange II (AOII). The role of Mg in MgFe2O4 was revealed to explain the high activity by catalytic experiments and XPS analysis. RESULTS The degradation efficiency of AOII in the MgFe2O4/O3 process exceeds 90% over a wide pH range of 4.6–9.6, slightly affected by the solution pH. The catalytic activity of MgFe2O4 is much higher than that of MgO, Fe2O3 and also their mixture (MgO+Fe2O3) with identical molar ratio of Mg2+ to Fe3+, indicating the first role of Mg, i.e. coupling with Fe to present a synergistically catalytic effect. Furthermore, MgFe2O4 possesses a reaction rate constant at least 2.3 times that of NiFe2O4, MnFe2O4, and CuFe2O4. It illustrates the second role of Mg, i.e. causing the high electron density on lattice oxygen in MgFe2O4 indicated by XPS and thus favoring activation of the electrophilic ozone. CONCLUSIONS This study demonstrated the easy recycling and high activity of MgFe2O4 in catalytic ozonation, and revealed the role of Mg in MgFe2O4. © 2015 Society of Chemical Industry