Adsorption efficiency of magnetite nanoparticles for chromium(VI) removal from water

Department of Chemical Engineering, Malaviya National Institute of Technology, Jaipur-302 017, Rajasthan, India E-mail : madhunaresh@gmail.com, magarwal.chem@mnit.ac.in Manuscript received online 17 January 2015, revised 09 May 2015, accepted 09 June 2015 Iron oxide nanoparticles were synthesized and used to remove hexavalent chromium from water solution and tannery effluent. SEM images showed that the nanoparticles were spheroid-shaped and in clustered forms. The average sizes of 15.38 nm for these nanoparticles were determined using diffraction analysis. FT-IR spectrum revealed those functional groups which were responsible for adsorption of chromium species. Batch adsorption studies suggested that pH of 2.0 and a temperature of 30 ºC was optimum to achieved highest chromium removal. The adsorption process followed pseudo-second order kinetic model and there was no intra-particle diffusion in these nanoparticles. The process of CrVI sorption on iron oxide nanoparticles followed Langmuir isotherm and the maximum CrVI adsorptive capacity was found out as 16.3934 mg/g. Thermodynamic analysis revealed that the adsorption process was spontaneous and endothermic, while randomness increased at the solid-liquid interface during CrVI adsorption. These nanoparticles achieved 72.45% CrVI removal from tannery effluent