Removing lignin model pollutants with BiFeO_3–g-C_3N_4 compound as an efficient visible-light-heterogeneous Fenton-like catalyst

BiFeO3-g-C3N4 nanoscaled composite was prepared with a hydrothermal method and evaluated as a highly efficient photo-Fenton like catalyst under visible light irradiation. The BiFeO3-g-CHN4 composite exhibited much stronger adsorption ability to lignin model pollutant （guaiacol） than that of BiFeO3, which may be due to the higher specific surface area （BiFeO3-g-C3N4：35.59 m2/g 〉 BiFeO3：7.42 m2/g） and the adsorption form of π-π stack between g-C3N4 and guaiacol. The composite exhibited excellent visible light-Fenton like catalysis activity, being influenced by the solution pH value and the proportions of BiFe03 and g-C3N4 nanosheets. Under optimal conditions with visible light irradiation, the BiFeO3- g-C3N4 composite yielded fast degradation of guaiacol with an apparent rate constant of 0.0452 rain-I, which were 5.21 and 6.80 folds of that achieved by using BiFeO3 and the mixture of BiFeO3 and g-C3N4 nanosheets, respectively. The significantly enhanced visible light-Fenton like catalytic properties of the BiFeO3-g-C3N4 composite in comparison with that of BiFeO3 was attributed to a large surface area, much increased adsorption capacity and the semiconductor coupling effect between BiFe03 and g-C3N4 in the composite.