* Corresponding Author: Roozbehani@put.ac.ir
Light expanded clay aggregate (LECA) coated with iron oxide (Fe2O3) was tested as a sorbent in the removal of Ni (II) from contaminated water. The efficiency of sorbent was investigated using operational parameters including contact time, initial pH, sorbent dosage and initial Ni (II) concentration in a batch wise mode. Furthermore, adsorbent characteristics were examined before and after modification using X-ray Fluorescence Spectroscopy, Scanning Electron Microscopy, X-Ray Diffraction and Fourier Transform Infrared spectroscopy analysis. Kinetics study was conducted to assess adsorption mechanism. The results showed that the Ni (II) sorption kinetic data fitted better by a pseudo second–order kinetic model. The Freundlich, Langmuir, Brunauer-Emmett-Teller and Temkin isotherm models were used to express the equilibrium sorption data. The Freundlich isotherm model had the best agreement with the equilibrium data compared to other isotherm models. The modified LECA had a sorption capacity of 25.2 mg of Ni (II) ions per gram adsorbent. A 97% removal efficiency of Ni (II) from aqueous medium was reached at pH 6.
 X. Zeng, X. Xu,H. M.Boezen and X.Huo,Children with health impairments by heavymetals in an e-waste recycling area, Chemosphere, 148, 408, 2016.
 S. Varma, D. Sarode, S. Wakale, B. A. Bhanvase and M. P. Deosarkar, Removal of nickel from waste water using graphene nanocomposite, International Journal of Chemical and Physical Sciences, 2, 132, 2013. M. Cempel and G. Nikel, Nickel: A Review of its sources and environmental toxicology, Polish Journal of Environmental Studies, 15, 375, 2006.
 S. A. Khan, Z. U. Din, Z. A. Ihsanullah and A. Zubair, Levels of selected heavy metals in drinking water of Peshawar city, International Journal of Science and Nature, 2, 648, 2011.
 S. Babel and T. A.Kurniawan, Low-cost adsorbents for heavy metals uptake from contaminated water: a review, Journal of Hazardous Materials, 97, 219, 2003. N. Haque, G. Morrison, I. Cano-Aguilera and J. L. Gardea-Torresdey, Iron-modified light expanded clay aggregates for the removal of arsenic (V) from groundwater, Microchemical Journal, 88, 7, 2008.
 S. K. R. Yadanaparthi, D. Graybill and R. von Wandruszka, Adsorbents for the removal of arsenic, cadmium, and lead from contaminated waters, Journal of Hazardous Materials, 171, 1, 2009.
 H. Amiri, N. Jaafarzadeh, M. Ahmadi and S. S. Martínez, Application of LECA modified with Fenton in arsenite and arsenate removal as an adsorbent, Desalination,272, 212, 2011. M. Malakootian, J. Nouri and H. Hossaini, Removal of heavy metals from paint industry’s wastewater using Leca as an available adsorbent, International Journal of Environmental Science and Technology, 6, 183, 2009.
 M. A. Nkansah, A. A. Christy, T. Barth and G. W. Francis, The use of lightweight expanded clay aggregate (LECA) as sorbent for PAHs removal from water, Journal of Hazardous Materials, 217, 360, 2012.
 S. Boudaghpour and S.Hashemi, A Study on light expended clay aggregate (LECA) in a geotechnical view and its application on greenhouse and green roof cultivation, International journal of geology, 4, 59, 2008. E. M. Kalhori, K. Yetilmezsoy, N. Uygur, M. Zarrabi and R. M. A. Shmeis, Modeling of adsorption of toxic chromium on natural and surface modified lightweight expanded clay aggregate (LECA), Applied Surface Science, 287, 428, 2013.
 T. Shojaeimehr, F. Rahimpour, M. A. Khadivi and M. Sadeghi, A modeling study by response surface methodology (RSM) and artificial neural network (ANN) on Cu2+ adsorption optimization using light expended clay aggregate (LECA), Journal of Industrial and Engineering Chemistry, 20, 870, 2013.
 M. Edwards and M. M. Benjamin, Adsorptive filtration using coated sand: a new approach for treatment of metal-bearing wastes, Research Journal of the Water Pollution Control Federation, 61, 1523, 1989.
 M. Matouq, N. Jildeh, M. Qtaishat, M. Hindiyeh and M. Q. Al Syouf, The adsorption kinetics and modeling for heavy metals removal from wastewater by Moringa pods, Journal of Environmental Chemical Engineering, 3, 775, 2015.
 Y. S. Hoand G. McKay, Pseudo-second order model for sorption processes, Process Biochemistry, 34, 451, 1999. A. Abdolali, H. H. Ngo, W.Guo, S. Lu, S. S. Chen, N. C. Nguyen and Y. Wu, A breakthrough biosorbent in removing heavy metals: Equilibrium, kinetic, thermodynamic and mechanism analyses in a lab-scale study, Science of the Total Environment, 542, 603, 2016.
 O. O. Ltaief, S. Siffert, S. Fourmentin and M. Benzina, Synthesis of Faujasite type zeolite from low grade Tunisian clay for the removal of heavy metals from aqueous waste by batch process: Kinetic and equilibrium study, Comptes Rendus Chimie, 18, 1123, 2015.
 M.Monier, D. M.Ayad and D. A. Abdel-Latif,Adsorption of Cu(II), Cd(II) and Ni(II) ions by cross-linked magnetic chitosan-2-aminopyridine glyoxal Schiff’s base, Colloid. Surface. B, 94, 250, 2012. B. Kiran and A.Kaushik, Chromium binding capacity of Lyngbyaputealisexopoly-saccharides, Biochemical Engineering Journal, 38, 47, 2008.
 A. Rastegar, B. Anvaripour, N. Jaafarzadeh, Application of Modified LECA in Removing Nickel from Wastewater, Iranian Journal of Oil & Gas Science and Technology, 5, 1, 2016.
 N. Marinoni, M. P.Birelli, C.Rostagno,and A. Pavese, The effects of atmospheric multipollutants on modern concrete, Atmospheric Environment, 37, 4701, 2003.
 P. S. Kumar, K.Ramakrishnan andR.Gayathri,Removal of nickel (II) from aqueous solutions by ceralite IR 120 cationic exchange resins, Journal of Engineering Science and Technology, 5, 232, 2010.
 F.Güzel, H. Yakut and G.Topal, Determination of kinetic and equilibrium parameters of the batch adsorption of Mn (II), Co (II), Ni (II) and Cu (II) from aqueous solution by black carrot (Daucuscarota L.) residues, Journal of Hazardous Materials, 153, 1275, 2008. P. S. Kumar, S. Ramalingam, S. D. Kirupha, A. Murugesan, T. Vidhyadevi and S. Sivanesan, Adsorption behavior of nickel (II) onto cashew nut shell: Equilibrium, thermodynamics, kinetics, mechanism and process design, Chemical Engineering Journal, 167, 122, 2011.
 S. R. Shukla and R. S. Pai, Adsorption of Cu (II), Ni (II) and Zn (II) on dye loaded groundnut shells and sawdust, Separation and Purification Technology, 43, 1, 2005.
 N. Feng, X.Guo, S. Liang, Y. Zhu and J. Liu, Biosorption of heavy metals from aqueous solutions by chemically modified orange peel, Journal of Hazardous Materials, 185, 49, 2011.
 M. E. Argun, S. Dursun, C. Ozdemir and M. Karatas, Heavy metal adsorption by modified oak sawdust: Thermodynamics and kinetics, Journal of Hazardous Materials, 141, 77, 2007. I. Alomá, M. A. Martín-Lara, I. L. Rodríguez, G.Blázquez and M. Calero, Removal of nickel (II) ions from aqueous solutions by biosorption on sugarcane bagasse, Journal of the Taiwan Institute of Chemical Engineers, 43, 275, 2012.
 V. C.Srivastava, I. D. Mall and I. M. Mishra, Equilibrium modelling of single and binary adsorption of cadmium and nickel onto bagasse fly ash, Chemical Engineering Journal, 117, 79, 2006.