Efficient removal of antibiotic oxytetracycline from water using optimized montmorillonite-supported zero-valent iron nanocomposites

In this study, montmorillonite-supported nanoscaled zero-valent iron (Mt-nZVI) composites were fabricated using a facile liquid-phase reduction method to avoid serious agglomeration of nZVI particles in suspensions due to magnetic effect. The morphology, crystal structure, functional groups, and magnetic properties of as-prepared composites were explored using scanning and transmission electron microscope, X-ray diffractometer, Fourier transform infrared spectroscope, X-ray photoelectron spectroscope, zeta potential analyzer, and superconducting quantum interference device. The fabricated composites were then applied to remove antibiotic oxytetracycline from water. The optimal weight ratio of the Mt particles (mean size, 25 μm) to the nZVI particles (size, 60–100 nm) was first determined to be 2:1 (simply denoted as 2Mt-nZVI). Experimental results showed that 99% of 100 mg/L oxytetracycline at pH 5.0 was removed using 0.6 g/L of the 2Mt-nZVI composite and the mineralization reached 70% after 20 min of reaction. Finally, the transformation products and intermediates were detected and identified by a high-resolution liquid chromatography mass spectrometry (LC-MS) and the pathways were proposed during the degradation of oxytetracycline over the 2Mt-nZVI composite.