Green synthesis and characterization studies of biogenic zirconium oxide (ZrO2) nanoparticles for adsorptive removal of methylene blue dye

Abstract In this current study, Zirconium oxide nanoparticles were prepared using the pericarp extract of Sapindus mukorossi as a powerful capping and reducing agent. The prepared nanoparticles were characterized using UV-Visible spectrophotometer, FTIR, XRD, SEM-EDX and HR-TEM. The absorption spectra at 275 nm confirmed the presence of Zirconium oxide nanoparticle with an optical band gap value of 5.535 eV. The prepared nano zirconia was tetragonal, crystalline in nature with 5 nm average size. The adsorptive capacities of synthesized nanoparticles were studied for Methylene blue (MB) dye as a function of pH, dosage, initial adsorbate concentration and time in batch trials. 94% removal efficiency was registered with an adsorptive capacity of 23.26 mg/g which fitted well with non linear Langmuir isotherm model. The experimental data finds highest suitability with Pseudo-second-order kinetics followed by Elovich model in its non linear form which was evidenced from higher R2 and reduced error values. Thermodynamic analysis described the endothermic and spontaneous nature of adsorption. Intra particle diffusion acts as the rate limiting step in the mobility of adsorbate molecules across the boundary. With 0.1 M HCl as an eluent, the prepared nano zirconia exhibited good regenerative capacity which makes it a suitable adsorbent for methylene blue removal.