The degradation of printing and dyeing wastewater by manganese-based catalysts

Printing and dyeing wastewater generally has high pH, high turbidity, poor biodegradability, complex composition, and high chroma, which make it one of the most difficult industrial wastewaters to treat. Herein, heterogeneous ozone oxidation technology is applied to oxidize and degrade printing and dyeing wastewater. A metal oxide catalyst supported on activated carbon (γ-MnO2/AC) was prepared by hydrothermal synthetic method and shown to enable synergistic catalysis involving MnO2 metal sites and N/C sites. A simulated methyl orange solution was used to determine the effects of various preparation and operation parameters. The results confirmed that the γ-MnO2/AC catalyst exhibited good chemical oxygen demand (COD) removal and reusability. Additionally, γ-MnO2/AC demonstrated excellent degradation of the secondary biochemical effluent of printing and dyeing wastewater (COD removal = 72.45% within 120 min). The γ-MnO2/AC catalyst was fully characterized, and the mechanism governing its catalytic ozone oxidation process was investigated experimentally.