Adsorption behaviour of magnesium ferrite nanoparticles synthesized by co-precipitation and combustion methods

Adsorption of Cr (VI) from aqueous solution by magnesium ferrite (MgFe₂O₄) nanoparticles (NPs) synthesized by co-precipitation and combustion methods was studied using batch mode. The factors influencing adsorption viz. solution pH, adsorbent dose, contact time, initial metal ion concentration and temperature were ascertained. Cr (VI) content was estimated spectrophotometrically. The maximum adsorption of Cr (VI) ions was achieved at pH 2.0. Thermodynamic parameters such as change in Gibb's free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were evaluated. NPs synthesized by different methods displayed small variation in the percent removal although BET surface area of NPs showed significant differences. The equilibrium adsorption data were analyzed by the Freundlich, Langmuir and Dubinin-Radushkevich adsorption isotherm models.