Efficient adsorption of methylene blue on hybrid structural phase of MoO3 nanostructures

Abstract

Mixed phase molybdenum oxide (mp-MoO3) nanocomposite (NC) along with hexagonal (h-MoO3) and orthorhombic (o-MoO3) nanoparticles (NPs) were synthesized via easy and cost-effective internal combustion method using water/ethanol mixture, water, and methanol solvents. The formation mechanisms of h-MoO3, o-MoO3, and mp-MoO3 have been investigated using different physical methods such as XRD (X-ray diffraction), FTIR (fourier transform infrared spectroscopy), FESEM (field emission scanning electron microscopy), HRTEM (high resolution transmission electron microscopy, and SAED (selected area electron diffraction). The potential of prepared NPs and NC on the adsorptive removal of methylene blue (MB) was investigated through the adsorption batch process with variation in the adsorbent dosage, pH, and temperature of the solution. The confirmation of dye adsorption over adsorbent surfaces has been elucidated by employing FTIR and FESEM after the adsorption process. The influence of different NPs and NC on the adsorption efficiency indicates the possibility of physical, chemical as well as electrostatic interaction between adsorbent-adsorbate interface. Thermodynamical parameters were calculated and analyzed for the validity of the adsorption phenomenon. Various kinetic study models such as pseudo-first-order (PFO), pseudo-second-order (PSO), and Intra-particle diffusion (IPD) were fitted to the experimental data to explore the rate-controlling step and for understanding the adsorption mechanism. The mp-MoO3 NC was observed to have the best adsorption efficiency as well as a better adsorption rate. Therefore synthesized mp-MoO3 NC showed great potential for dye adsorption and would be seen as the futuristic adsorbent materials for sustainable water treatment technology.