Hybrid electrocatalytic ozonation treatment of high-salinity organic wastewater using Ni-Ce/OMC particle electrodes.

Hybrid electrocatalytic ozonation is an efficient method for degrading high-salinity organic wastewater that has excellent oxidation ability and is environmentally friendly. Furthermore, the high salt content of the wastewater provides electrolyte to support the process, which avoids secondary pollution caused by the addition of electrolyte. In this work, Ni-Ce/ordered mesoporous carbon (OMC)/granular active carbon (GAC) particle electrodes with a Ni:Ce weight ratio of 1:1 were synthesized using a simple method. The electrodes were characterized by transmission electron microscopy and electron paramagnetic resonance spectroscopy, as well as other techniques. The catalytic performance was investigated using cyclic voltammetry and AC impedance. Higher reduction and oxidation peak currents were obtained with the Ni-Ce/OMC catalyst than with Ni/OMC or Ce/OMC, indicating that the bimetallic catalyst has higher activity for the reduction of O to HO and the oxidation of O to ·OH. The order of the k values-which represent the mass-transfer rate-was Ni-Ce/OMC (0.157) > Ni/OMC (0.017) > Ce/OMC (0.014). The results show that cooperation between Ni, Ce, and OMC promoted the dispersion of Ni and Ce and improved the catalytic performance. Ni-Ce/OMC enhances the catalytic reduction of O to HO, and, in addition, Ce is able to rapidly store and release oxygen through Ce/Ce conversions and reacting with O to generate ·OH, which increases the oxidation capacity of the material. Under the optimal conditions the chemical oxygen demand removal for high-salinity organic wastewater using Ni-Ce/OMC/GAC particle electrodes reached 93.7%.