Efficient photocatalytic degradation of herbicide glyphosate in water by magnetically separable and recyclable BiOBr/Fe3O4 nanocomposites under visible light irradiation

Glyphosate is a highly effective non-selective organophosphorous herbicide with wide global usage. The increasing presence of glyphosate and its byproducts has raised considerable concerns about its potential impact on the aquatic environment and human health. In this research, magnetic BiOBr/Fe3O4 nanocomposites photocatalysts, were successfully prepared through a facile solvothermal process. The photocatalysts were characterized by scanning and transmission electron microscopy (SEM and TEM), X-ray powder diffraction (XRD), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance spectroscopy. The catalysts exhibited excellent photocatalytic activity toward glyphosate degradation in water under visible light irradiation. The rate of glyphosate degradation reached 97%, which was higher than that of the pure BiOBr (85%) within 60 min. Quenching experiments were done to study the degradation mechanism of glyphosate. Photo-generated holes (h+) were determined to be the major reactive species in the photodegradation process. Ion chromatography was used to monitor the reaction intermediates to clarify the photodegradation pathway of glyphosate. Moreover, the BiOBr/Fe3O4 photocatalysts have magnetic recyclability properties. After five repeated trials, the percent of degradation of glyphosate was still more than 90%, indicating that the BiOBr/Fe3O4 nanocomposites have excellent reusability and great potential in the treatment of industrial wastewater.