Bismuth ferrite, BiFeO 3 (BFO) prepared via a coprecipitation method, was used as an effective photocatalyst for the degradation of methylene blue (MB) using a white light-emitting diode (LED-50 W) lamp. The as-prepared material was characterized by TGA, XRD, SEM-EDX, FTIR, and UV-vis-DRS techniques. The effects of experimental key parameters such as pH, catalyst dosage, initial dye concentration, and calcination temperature were investigated. Results showed that BFO-600 (calcined at 600 °C/3 h) was a rhombohedrally-distorted perovskite oxide with the R3c space group. The average crystal size and band gap energy for BFO-600 were found to be 24.8 nm and 2.1 eV, respectively. Under optimal operating conditions ([MB]=20 mg.L -1 , BFO-600/dye mass ratio=0.5 g.L -1 , pH=11, and 25 °C), MB/BFO-600/LED process exhibited an efficient photodegradation (up to 94.4%) within 120 min, much higher than the MB sorption process (MB/BFO-600/dark system, 69.4%) and the MB self-photolysis system (MB/ LED, 33.9%). The photocatalytic degradation of MB was found to fit well with the pseudo-first-order kinetic model. Thus, the MB photodegradation was attributed to the generation of reactive radicals such as • OH, h + , H 2 O 2 , and MB •+ via direct heterogeneous photocatalysis and mediated by MB through a self-photosensitization process of MB over BFO-600 NPs.

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 pH PZC techniques were applied to characterize the catalyst features. The performance of the heterogeneous Fenton-like process was investigated under various parameters (reaction time, pH, H 2 O 2 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 CeO 2 (60-70%) with lower contents of La 2 O 3 (30-40%), Pr 6 O 11 (≤6%), Nd 2 O 3 , and CaF 2 (≤5%). CP-2 possessed a typical CeO 2 cubic fluorite structure with high content of rare earth oxides (REO) and α-Fe 2 O 3 . 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 R 2 . The activation energy (E a ) 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 H 2 O 2 greatly enhanced the reactive oxygen species (ROS) such as • OH, O 2•-, 1 O 2 , and HO 2 • for effective oxidation of NR via a heterogeneous Fenton-like process.