Background and purpose: 2, 4-dinitrophenol (DNP) are carcinogenic and non-biodegradable pollutants that exist at high concentration in wastewater of chemical industries. In this study, treatment and removal of organic materials (COD) in wastewater was carried out by catalytic ozonation process (COP) using carbon Nano-composite catalysts.

Materials and methods: This study was conducted in cylindrical 250 mL semi-continuous reactor and the effects of several parameters including pH of the solution (4-10), the amount of catalyst concentrations (0 to 4 g/L), reaction time (0 to 60 min), and saturated catalyst was studied on treatment of high concentration of DNP and the COD removal efficiency. Also, the kinetics were compared with single ozonation (SOP).

Results: Removal efficiency of high concentrations of DNP (1500 mg/L) and kinetics of the COP process catalyst concentration of 4 g/L was 83% (0.0241 min^-1) while the results in SOP were 50% (0.0108 min^-1). The optimum pH was 6 with the reaction time of 60 min. However, the removal efficiency of COD at initial concentration of 610 mg/L in the SOP process was 61% which increased to 92% after addition of the catalyst. The main mechanism of process was chemical oxidation and a small share (3%) was due to adsorption.

Conclusion: The results showed that COP and this new catalyst effectively and quickly removed high concentrations of DNP and COD. This method is believed to be economic due to the short time of ozonation, recovery and reuse of the catalyst.