Biosynthesis and characterization of iron oxide nanoparticles from Enteromorpha spp. extract: determination of adsorbent properties for copper (II) ions

Abstract

Iron oxide nanoparticles (IO-NPs) were synthesized via a biosynthesis method using marine algae Enteromorpha spp. extract as a biological reductant agent in this study. Moreover, the total phenolic content of Enteromorpha spp. was found as 9.81± 4.8 mg gallic acid equivalents/g dry algae. The biosynthesized IO-NPs were characterized by zeta potential, DLS, SEM/EDX, and FTIR analysis methods and also the formation of IO-NPs was approved with the UV-vis spectrum. The characteristic surface plasmon resonance (λSPR, nm) value showing the formation of IO-NPs was observed at nearly 410 nm in terms of UV–vis analysis. According to DLS analysis results, the mean hydrodynamic diameter of IO-NPs was determined as 78.83 nm. According to SEM results, spherical nanoparticles are formed, and EDX analysis showed that the signals in the Fe and O elements confirmed the formation IO-NPs. According to FT-IR analysis results, the formation of IO-NPs was approved by the absorption bands at 599.83, and 475 cm−1, which corresponded to the Fe-O stretches of Fe3O4 and Fe2O3. Subsequently, the synthesized IO-NPs were utilized as an adsorbent for the removal of Cu2+ from aqueous solutions. Batch adsorption experiments were conducted to examine the optimum adsorption environmental conditions and the equilibrium, kinetics, and mass transfer modeling was also evaluated. The optimum adsorption conditions were found as initial pH 5.0; temperature 35°C, initial Cu2+ concentration 275 mg/L, and adsorbent concentration 0.5 g/L. The experimental equilibrium data were in the best agreement with Langmuir isotherm model, and the maximum monolayer coverage capacity of IO-NPs for Cu2+ adsorption found to be 188.68 mg/g at optimum temperature value of 35°C. The adsorption kinetic data were consistent with the pseudo second order kinetic model, and Weber Morris model showed that both the film (boundary layer) and intraparticle diffusion affected the adsorption process.