Fast methylene blue removal by MoO₃ nanoparticles

Hexagonal and orthorhombic phases of MoO₃ were synthesized using microwave radiation. The synthesized micrometric particles were ground in a high energy mechanical mill in order to obtain a nanostructured powder to be used for methylene blue (MB) removal. Approximately a 98 % of MB was removed from 20 ppm content in water, without using photon radiation in about 25 min. The evidence of the dye removal process was studied by ultraviolet–visible (UV–Vis), infra-red and Raman spectroscopies. According to the results, the main mechanism in the MB removal is the adsorption phenomena promoted by the high energy on the nanoparticle surface, which was induced by the milling. The materials morphology and microstructure were characterize by electron microscopy techniques and X-ray diffraction. The surface area and band gap was determine by Brunauer–Emmett–Teller method and from UV–Vis spectra, respectively. According to studies by thermogravimetric technique, the adsorbed MB on the material is possible to decompose to be re-utilize it.