Structural characterization and adsorptive ability of green synthesized Fe₃O₄ nanoparticles to remove Acid blue 113 dye

In the current study, Thunbergia grandiflora (Bengal clock vine) leaf extract has been used as green-resource to prepare Fe₃O₄ nanoparticles. SEM image showed agglomerated spherical (25 nm) particles, and EDS ascertained the existence of elemental iron (between 6 – 7 k eV) and oxygen (at 0.5 keV). XRD and XPS designated signature peaks for Fe₃O₄. BET studies revealed a high specific surface area of 114.42 m²/g with mesoporous structure. FTIR showed the distinct band for iron-oxide at 542 cm⁻¹. A very low coercivity (1.5812 Oe) and retentivity (2.216 memu/g) indicated the paramagnetic properties of Fe₃O₄ nanoparticles. Batch adsorption of Acid blue 113 considering several factors conceded 95% removal within 3.5 h of contact time at pH 2 with the adsorbent dosage of 1 g/L, the concentration of 25 mg/L, 150 rpm, and the temperature of 303 K. The pseudo-second-order equation was best suited for the adsorption data indicating chemisorption. Freundlich isotherm model indicated a good fit for the equilibrium data. Thermodynamic parameters indicated exothermicity and spontaneity of the adsorption process. The maximum sorption capacity gained under an optimized environment was 138.89 mg/g. Hence, this study convincingly recognized the feasibility of the green synthesized Fe₃O₄ adsorbent for efficient Acid blue 113 dye removal with a suggestively greater sorption capacity.