Magnetite nanoparticles as efficient materials for removal of glyphosate from water

Concentrations of glyphosate, a common herbicide, in water can be problematic due to its toxicity. Using both artificial and real water samples, this study shows the sustainability advantages of using magnetite (Fe3O4) nanoparticles to remove glyphosate from water. Glyphosate is one of the most commonly used herbicides, but, due to its suspected toxicity, it is simultaneously the most disputed one. Its worldwide application in huge quantities may lead to water concentrations that locally exceed statutory contamination levels. Therefore, a simple toolkit is required to remove glyphosate and its major metabolite from water. Here we show a method for the magnetic remediation of glyphosate from artificial and real water samples to below the maximum permissible value or even below the analytical detection limit. The chemical structure of glyphosate enables fast and stable covalent binding on the surface of magnetite (Fe3O4) nanoparticles, which act as catchers and carriers for magnetic removal. The small size of the nanoparticles (~20 nm diameter) provides a large active area. The glyphosate binding was analysed by infrared spectroscopy, thermogravimetric analysis and dynamic light scattering, while the remediation was investigated by liquid chromatography-mass spectrometry. Results from molecular dynamics simulations support the proposed binding mechanism. The combination of efficient remediation with inexpensive and recyclable magnetite nanoparticles suggests a simple method for the sustainable removal of glyphosate, and the concept may lead to a general approach to eliminate this class of organophosphorus compounds from water.