Enhanced visible light photo-Fenton catalysis by lanthanum-doping BiFeO3 for norfloxacin degradation.

Efficient photo-Fenton removal of antibiotic effluent is a widely followed and significant attempt to deal with the growing environmental pollution. In this study, BiFeO3 and lanthanum doped BiFeO3 catalysts were synthesized via one-step hydrothermal method as hydrogen peroxide activator for mineralization of norfloxacin (NOR). Various characterization measurements were used to verify La was successfully doped into the lattice of perovskite and investigated the effect of La doping molar ratio on BiFeO3 through the characterization of the morphology and physicochemical properties. The degradation experiment and reaction rate constants showed that the La-doped BiFeO3 particle exhibited superior photo-Fenton catalytic performance to undoped BiFeO3. Especially, the degradation efficiency of 15% La-doped BiFeO3 could reach up to 84.94%. And the first order kinetic constant of optimized conditions was 0.01638 min-1, which was about 6.9 times than that of undoped BiFeO3.The influence of pH, oxidizer content and catalyst dosage in photo-Fenton reaction were investigated detailedly. Besides, the synthetic catalyst possessed favorable stability and reusability with little metal leaching after many cycles of use. Radical scavenger experiments and electron spin resonance tests were carried out to conclude that the ·OH and holes were regarded as the dominate active species in the catalytic process. The narrow band gap and excellent electron transfer efficiency were the key factors for La-doped BiFeO3 to have high catalytic efficiency in the photo-Fenton system. Current works demonstrated the great promise of La-doped BiFeO3 in the elimination of antibiotic organics.

Improving dark fermentative hydrogen production through zero-valent iron/copper (Fe/Cu) micro-electrolysis.

OBJECTIVES: To investigate the effect of zero-valent iron and copper (Fe/Cu) micro-electrolysis on dark fermentative hydrogen production from glucose by a mixed bacterial consortium and the possible mechanisms of increasing hydrogen yield. RESULTS: Compared to zero-valent iron and activated carbon (Fe/C) micro-electrolysis, Fe/Cu micro-electrolysis could increase hydrogen yield by 32.2%, hydrogen production potential by 27.1%, and the maximum hydrogen production rate by 62.0%. Meanwhile, the number of ferrous ions released into the liquid phase with Fe/Cu micro-electrolysis was about 27.0% greater than that released by Fe/C micro-electrolysis, because the dispersion of copper on the surface of iron could markedly improve electrochemical corrosion activity. Metabolic analysis revealed that Fe/C micro-electrolysis promoted acetate formation, which may have been responsible for the observed improvement in fermentative hydrogen production. Further investigation indicated that Fe/Cu micro-electrolysis increased the activity of hydrogenases and stimulated the expression of the [FeFe]-hydrogenase gene. CONCLUSION: Fe/Cu micro-electrolysis is better than Fe/C micro-electrolysis or Fe corrosion alone for dark fermentative hydrogen production.