Removal of Hexavalent Chromium by Frrite Nono Particles

Heavymetals، present in many industrial wastewaters،are considered as majorpollutants of environment. Magnetic iron nanoparticles are known for their superior adsorption، ion exchange and electro-static forces characteristics. The aim of this study was to evaluate the efficiency of magnetic nanoparticles for removal of hexavalent chromium from wastewater and the parameters that influence the removal. The magnetite nanoparticles were prepared by co-precipitation method where produced Fe3O4 nanoparticle’s average size was 40 nm. Various factors influencing the adsorption of metal ions، e. g.، pH، temperature، amount of adsorbent (magnetic nanoparticles)، initial concentration of chromium، andcontact time were investigated to optimize the operational conditions of the process and to detect particles of X-Ray Diffraction (XRD) pattern was used. Results indicated that the mechanism was strongly influencedby solution pH، similar to many adsorption processes. At pH= 2، while initial concentration of chromium was 30 mg/L and a dose of 3. 5 g/L synthesized magnetite nanoparticles was added، in 20 minutes contact time 94 % of chromium (VI) was removed. At higher pH levels of the solution، efficiency of removal declined. Final results proved that magnetite nanoparticles have high capacity for removal of chromium (VI) from solutions containing this salt، and removal efficiency for chromium (VI) is reversely related to pH. The results also showed the adsorption was decreased by increasing the initial concentrations of chromium (VI) in solutions. As expected an increase in adsorbent dosage increased the removal of chromium (VI). Equilibrium isotherms were analyzed by Langmuirand Freundlichadsorption models and the results proved that the behavior of chromium adsorption by Ferro-magnetic nano-particles is best expressed by Langmuir isotherm.