The present work was conducted for the synthesis of nano size zerovalent iron (nZVI) and hexavalent chromium (Cr(VI)) removal as a highly toxic pollutant by using this nanoparticles. Batch experiments were performed to investigate the effects of Cr(VI), nZVI concentration, pH of solution and contact time variation on the removal efficiency of Cr(VI). nZVI was synthesized by reduction of ferric chloride using sodium borohydrid. SEM and XRD examinations applied for determination of particle size and characterization of produced nanoparticles. The results showed that the removal efficiency decreased with Cr(VI) concentration and pH of solution and increased with adsorbent dosage and contact time. The Langmuir and Freundlich isotherm models were used for the adsorption equilibrium data and the Langmuir isotherm model was well fitted. Nanoparticle ZVI presented an outstanding ability to remove Cr(VI) due to high surface area, low particle size and high inherent activity., {"references":["S. Gupta and B. V. Babu, Removal of toxic metal Cr(VI) from aqueous\nsolutions using sawdust as adsorbent: Equilibrium, kinetics and\nregeneration studies. Chemical Engineering Journal, 150, 2009, pp. 352-\n365.","M. Kobya, Removal of Cr(VI) from aqueous solutions by adsorption onto\nhazelnut shell activated carbon: kinetic and equilibrium studies.\nBioresource Technology, 91, 2004, pp. 317-321.","Y. C. Sharma, Cr(VI) removal from industrial effluents by adsorption on\nan indigenous low-cost material. Colloids and Surfaces A:\nPhysicochemical and Engineering Aspects, 215, 2003, pp. 155-162.","K. Selvi, S. Pattabhi and K. Kadirvelu, Removal of Cr(VI) from aqueous\nsolution by adsorption onto activated carbon. Kidlington, ROYAUMEUNI:\nElsevier 2001.","D. Kaplan and T. Gilmore, Zero-Valent Iron Removal Rates of Aqueous\nCr(VI) Measured Under Flow Conditions. Water, Air, & Soil Pollution,\n155, 2004, pp. 21-33.","N. Shao-feng, L.Yong, X. Xin-hua, and L. Zhang-hua, Removal of\nhexavalent chromium from aqueous solution by iron nanoparticles,\nJournal of Zhejiang University Science-B, 6(10), 2005, pp. 1022-1027.","Kanel, Sushil Raj, Manning, Bruce, Charlet, Laurent and Choi, Heechul,\nRemoval of arsenic(III) from groundwater by nanoscale zero-valent iron,\nEnviron. Sci. Technol, 39, 2005, pp. 1291-1298.","H. Sung, and I. Francis, Nanotechnology for Environmental Remediation,\nSpringer Science+Business Media, Inc, 2006.","He Feng and Zhao Dongye, Preparation and Characterization of a New\nClass of Starch-Stabilized Bimetallic Nanoparticles for Degradation of\nChlorinated Hydrocarbons in Water. Environmental Science &\nTechnology, 39, 2005, pp. 3314-3320.\n[10] APHA, AWWA, WEF, Standard Methods for the Examination of Water\nand Wastewater. (19th ed.), Washington DC, APHA, 1998.\n[11] Kanel, Sushil Raj, Greneche, Jean-Mark and Choi, Heechul, Arsenic (V)\nRemoval from Groundwater Using Nano Scale Zero-Valent Iron as a\nColloidal Reactive Barrier Material, Environ. Sci. Technol, 40, 2006, pp.\n2045-2050.\n[12] M. Ponder Sherman, G. Darab John, E. Mallouk, Thomas, Remediation\nof Cr(VI) and Pb(II) Aqueous Solutions Using Supported, Nanoscale\nZero-valent Iron. Environmental Science & Technology, 34, 2000, pp.\n2564-2569.\n[13] Xue Song Wang, Yu Jun Tang, Li Fang Chen, Fei Yan Li, Wen Ya Wan,\nYe Bin Tan, Removal of Cr(VI) by Zero-valent, Iron-encapsulated\nAlginate Beads, 2009, pp. 263-267.\n[14] C. K. Lai Keith and M. C. Lo Irene, Removal of Chromium (VI) by Acid-\nWashed Zero-Valent Iron under Various Groundwater Geochemistry\nConditions. Environmental Science & Technology, 42, 2008. pp. 1238-\n1244.\n[15] M.J. Alowitz and M.M. Scherer, Kinetics of nitrate, nitrite, and Cr(VI)\nreduction by iron metal. Environ. Sci. Technol. 36, 2002, pp. 299-306.\n[16] D. Karabelli, C. Uzum, T. Shahwan, A. E. Eroglu, T. B. Scott, K. R.\nHallam, Batch Removal of Aqueous Cu2+ Ions Using Nanoparticles of\nZero-Valent Iron: A Study of the Capacity and Mechanism of Uptake.\nIndustrial & Engineering Chemistry Research, 47, 2008, pp. 4758-4764.\n[17] K.K.H, Choy, G. McKay and JF Porter, Sorption of acid dyes from\neffluents using activated carbon. Resour. Conserv. Recycl, 27, 1999, pp.\n57-71."]}