Synthesis and Dye Adsorption Studies of WO3/MoO3 Nanocomposites

Tungsten oxide/molybdenum oxide nanocomposites have been synthesized using a cost-effective internal combustion method by incorporating two different phases of tungsten oxide into hexagonal and orthorhombic molybdenum oxide nanostructures. The synthesized materials were subjected to different analytical techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy, to investigate their structural and morphological properties. The synthesized materials were employed for the adsorption of methylene blue by varying different parameters, such as the initial dye concentration, contact time, adsorbent dose, pH, and temperature of the solution. The thermodynamical parameters were calculated to validate the adsorption phenomenon in terms of its spontaneity and feasibility. Various kinetic studies, such as pseudo-first-order, pseudo-second-order, and intra-particle diffusion models, were used to determine kinetic parameters and understand the adsorbate-adsorbent interactions. The detailed characteristics of adsorbent surface and adsorption behavior were studied using the Langmuir, Freundlich, and Temkin isotherms. Among these, monoclinic tungsten oxide/orthorhombic molybdenum oxide exhibits the best adsorption efficiency and higher kinetic rate constant, followed by the orthorhombic tungsten oxide/orthorhombic molybdenum oxide nanocomposite. Dye adsorption over the adsorbent surface was confirmed by investigating the materials characteristics before and after the process using Fourier infrared transform spectroscopy. The enhanced adsorption efficiency and higher rate constant can be attributed to the improved surface properties of these materials.