Efficient visible light photo-Fenton-like degradation of organic pollutants using in situ surface-modified BiFeO_3 as a catalyst

The visible light photo-Fenton-like catalytic performance of BiFeO3 nanoparticles was investigated using Methyl Violet （MV）, Rhodamine B （RhB） and phenol as probes. Under optimum conditions, the pseudo first-order rate constant （k） was determined to be 2.21 × 10^-2, 5.56 × 10^-2 and 2.01 × 10^-2 min〈 for the degradation of MV （30 μmol/L）, RhB （10 μmol/L） and phenol （3 mmol/L）, respectively, in the BiFeO3-H202-visible light （Vis） system. The introduction of visible light irradiation increased the k values of MV, RhB and phenol degradation 3.47, 1.95 and 2.07 times in comparison with those in dark. Generally, the k values in the BiFeO3- H202-Vis system were accelerated by increasing BiFeO3 load and H202 concentration, but decreased with increasing initial pollutant concentration. To further enhance the degradation of pollutants at high concentrations, BiFeO3 was modified with the addition of surface modifiers. The addition of ethylenediamineteraacetic acid （EDTA, 0.4 mmol/L） increased the k value of MV degradation （60 μmol/L） from 1.01 × 10.2 min^-1 in the BiFeO3-H202-Vis system to 1.30 min^-1 in the EDTA-BiFeO3-H2O2-Vis system by a factor of 128. This suggests that in situ surface modification can enable BiFeO3 nano-particles to be a promising visible light photo-Fenton-like catalyst for the degradation of organic pollutants.