Heterogeneous Fenton-like catalytic degradation of phenazine dye over CeO2 (CP-2) nanoscale powder

A heterogeneous Fenton-like process was explored for oxidation of phenazine dye using ceria polishing material (CP-2). XRD, SEM, FTIR, UV-vis DRS, and pHPZC techniques were applied to characterize the catalyst features. The performance of the heterogeneous Fenton-like process was investigated under various parameters (reaction time, pH, H2O2 concentration, catalyst dosage, initial dye concentration, temperature of the medium, and inorganic salt content). Results indicated that the main content of CP-2 catalyst was CeO2 (60-70%) with lower contents of La2O3 (30-40%), Pr6O11 (≤6%), Nd2O3, and CaF2 (≤5%). CP-2 possessed a typical CeO2 cubic fluorite structure with high content of rare earth oxides (REO) and α-Fe2O3. The average crystallite size and band gap energy of CP-2 were found to be 37.2 nm and 3.0 eV, respectively. Over 81.3% of neutral red (NR) oxidation efficiency was achieved in 60 min. Pseudo-first-order kinetic model gave the best fit with an acceptable coefficient of determination R2. The activation energy (Ea) was 16.4 kJ/mol suggesting that the degradation reaction proceeded with a low energy barrier and the removal process was feasible, spontaneous, and endothermic. The synergistic effect of Fe- and/or REO-CP-2 and H2O2 greatly enhanced the reactive oxygen species (ROS) such as •OH, O2 •-, 1O2, and HO2 • for effective oxidation of NR via a heterogeneous Fenton-like process.