Chitosan/PEO/NiFe2O4 Composite for the Removal of Methyl Orange Dye from Aqueous Solutions: the Effect of NiFe2O4 Nanoparticle Size

This manuscript presents a simple method to obtaining a chitosan/PEO/NiFe2O4 composite with photocatalytic activity under sunlight for the Methyl Orange organic dye degradation. Such composite is made up of two polymers that form a matrix containing nickel ferrite nanoparticles, NiFe2O4. The polymeric matrix is made up of 70% chitosan and 30% polyethylene oxide (PEO). Due to its chemical structure and microstructure, each polymer provides specific properties to the chitosan/PEO/NiFe2O4 film. The PEO provides mechanical stability to the polymeric substrate and the chitosan provides catalytic properties for the removal of the organic dye. NiFe2O4 nanoparticles are a semiconductor oxide with photocatalytic activity in the range of the visible radiation (bandgap of 1.9 eV); therefore, the dye degradation occurs under sunlight. These NiFe2O4 nanoparticles (NP) are obtained with different NP average size (around 10, 12, and 19 nm). The effect of NiFe2O4 nanoparticles sizes on the properties of the composites, its thermal stability, and on the photocatalytic degradation of the organic dye is analyzed. The photocatalysis test is performed by introducing the chitosan/PEO/NiFe2O4 films into the methyl orange aqueous solution and irradiating them with sunlight for 1 h. The samples are characterized from the structural and morphological point of view, thermal stability, and percentage of photocatalytic degradation of the dye after 1 h of exposure to sunlight. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and ultraviolet-visible spectroscopy (UV-VIS) are used to carry out the study.