Magnetic g-C3N4/NiFe2O4 composite with enhanced activity on photocatalytic disinfection of Aspergillus flavus

Abstract

Aspergillus flavus can cause crop loss and produce mycotoxin that bring serious threats to human health. The large usage of chemical pesticides or fungicides might cause environmental problems and fungal resistance. Therefore, developing the novel, low possibility of resistance and pro-environment way to control and reduce this fungi is meaningful. Herein, an efficient, environmental-friendly and photocatalytic method to disinfect Aspergillus flavus was demonstrated on magnetic and Z-schematic composites. The composites were composed of rhombic NiFe2O4 nanosheets and g-C3N4 nanosized sheets, and 0.2 g-C3N4/NiFe2O4 (mass ratio) showed the excellent activity with above 90% disinfection rate under 90 min visible light irradiation. The efficient disinfection activities were ascribed to the favorable charges separation, well photoelectric properties and suitable band structure. It was found that the •O2− and •OH were the main active radical species in photocatalytic disinfection. The attack of these species could cause the destruction of fungal cell structure and the leakage of intracellular contents as proved by the fluorescence staining of spores, biological scanning electron microscope and the detection of extracellular protein and DNA. Moreover, the composites also showed high photocatalytic disinfection activity of Aspergillus flavus on peanuts, which can reduce aflatoxin B1 from 315.21 µg kg−1 to 18.50 µg kg−1. This efficient method might be considered as a potential way to control the contamination of Aspergillus flavus, and as a reference to the mitigation of other pathogenic fungi in future.