Adsorption of hexavalent chromium from aqueous stream by maghemite nanoparticles synthesized by the microemulsion method

Abstract

The magnetic nanoparticles maghemite were synthesized by the co-precipitation reaction and then used for the removal of hexavalent chromium from the synthetic aqueous stream. The maghemite nanoparticles were synthesized by the co-precipitation reaction of ferric and ferrous salts with oleic acid and into a water-in-oil micro emulsion using Sodium dioctyl sulfosuccinate surfactant. Dynamic light scattering and X-ray diffraction were used for the characterization of formed nanoparticles. The nanoparticles thus obtained were used as adsorbent for the adsorption of hexavalent chromium from the synthetic aqueous stream in a batch experiment and subsequently the adsorption kinetic mechanism of hexavalent chromium uptake was investigated. The uptake of hexavalent chromium was also found to be pH dependent. Experimental values of hexavalent chromium adsorption were fitted with Freundlich, Langmuir, Sips, Redlich-Peterson and Koble-Corrigan isotherms models. The best possible fits were yielded through five error functions. Adsorption thermodynamics was also studied.

Keywords

• Microemulsion
• Hexavalent chromium
• Maghemite nanoparticles
• Adsorption equilibrium isotherms
• Adsorption thermodynamics