Synthesis of recoverable and reusable granular MgO-SCCA-Zn hybrid ozonation catalyst for degradation of methylene blue

Heterogeneous catalytic ozonation is regarded as one of the efficient processes for degradation of organic pollutants in aqueous solution. The difficulty in separation of powder catalyst hampered the recovery and reusability of the catalyst, limiting its practical application in catalytic ozonation process (COP). Herein, Granular MgO-SCCA-Zn (G-MgO-SCCA-Zn) hybrid ozonation catalyst is synthesized by pelletizing the synthesized porous sludge derived char (SCCA-Zn) and Mg(OH)2 mixtures. Decolorization and COD removal efficiencies of methylene blue, which was evolved as the model pollutant, were tested to evaluate the catalytic activity. Complete decolorization of MB was achieved and 50% COD was removed in the presence of G-MgO-SCCA-Zn in a determined pH of about 9 within 60 min, being higher than those in the presence of G-AC and G-MgO at the same condition. Mg2+ was not detected in the aqueous solution. The catalytic activity was almost stable upon three successive batch experiments using the G-MgO-SCCA-Zn catalyst recovered by filtration. The preferable catalytic activity is ascribed to the coupled catalytic activities of surface exposed nano MgO particles and porous SCCA-Zn. The G-MgO-SCCA-Zn could be recovered and reused in the COP due to the advantageous separation. Important information for the potential of the G-MgO-SCCA-Zn as a substitute of catalyst in the practical COP was reported for providing a new insight into the utilization of sludge char.