Efficient catalytic degradation of trichloroethylene in persulfate system by Ca-Fe2O3 and Cu-Fe2O3 nanoparticles: Mechanistic insights

M-metal (Ca and Cu) doped Ca-Fe2O3 and Cu-Fe2O3 catalysts were synthesized using solvothermal method. The Ca-Fe2O3 and Cu-Fe2O3 catalysts were characterized by XRD, Raman spectroscopy, SEM, TEM and XPS spectroscopy. The catalytic performance of 6%Ca-Fe2O3 and 5%Cu-Fe2O3 catalysts for trichloroethylene (TCE) removal were improved by M-metal doping leading to TCE removal at 99.8% in 1 h, which were three folds greater than by simple alpha-Fe2O3 in the presence of persulfate (PS). Ca and Cu doping formed defective structure and created more oxygen vacancies thereby generating abundant active species during PS activation process. Further, the influence of catalysts' dosage, oxidant dosage, solution pH, inorganic anions, and dissolved oxygen were evaluated. Complete removal of TCE was also obtained at weak alkaline pH condition. The greater specific surface area and the improved electrical conductivity was attributed to the huge generation of O-2(center dot-) and O-1(2) species which played major part in TCE removal. Scavenging tests and ESR spectroscopy confirmed the dominant role of O-2(center dot-) and O-1(2) in TCE degradation. The stability and viability of 6%Ca-Fe2O3 and 5%Cu-Fe2O3 catalysts were evaluated by repetition tests and in the presence of surfactants, TCE removal in real water matrix, and in the degradation of multi-pollutants.

Automated summary

M-metal (Ca and Cu) doped Ca-Fe2O3 and Cu-Fe2O3 catalysts were synthesized using solvothermal method. The catalytic performance of these catalysts for trichloroethylene (TCE) removal were improved by M-metal doping, leading to significantly higher TCE removal efficiency. Doping created defective structures and increased oxygen vacancies, resulting in the generation of abundant active species during the activation process.