Degradation of shale gas produced water by magnetic porous MFe₂O₄ (M = Cu, Ni, Co and Zn) heterogeneous catalyzed ozone

Four magnetic spinel ferrite MFe₂O₄ (M = Co, Cu, Ni and Zn) were successfully prepared by the auto combustion reaction method and applied to catalyze ozone for treating the practical shale gas produced water (PW). This typical bio-refractory produced water was processed into a good biodegradability one. The catalytic performance of them was ranked as CuFe₂O₄ > NiFe₂O₄ > CoFe₂O₄ > ZnFe₂O₄. The B[Spsbackslash]C ratio was promoted from less than 0.1 to over 0.3, and the AOC concentration was improved 5 times, and AOC[Spsbackslash]TOC ratio could reach 8%. The bio-toxicity was decreased significantly which was evaluated by the EC₅₀ of Photobacterium phosphoreum T3 and the growth inhibition ratio of E. coli, and it was decreased significantly. With the help of Scatchard model and Weber-Morris model, the results illustrated that the catalytic performance depended on surface property, and a suitable surface property could be an advantage in catalytic oxidation for degrading high concentration organic wastewater. The four MFe₂O₄ all presented a good recycling performance. This study provided a significant insight into the rational design and the advisable practice application of heterogeneous catalysts for dealing with shale gas produced water.