ARTICLE IN PRESS JID: JTICE [m5G;May 18, 2015;13:56] Journal of the Taiwan Institute of Chemical Engineers 000 (2015) 1–9 Contents lists available at ScienceDirect Journal of the Taiwan Institute of Chemical Engineers journal homepage: www.elsevier.com/locate/jtice Solvo-thermal synthesis, characterization of aluminon-functionalized magnetic nanoparticles and investigation of its adsorption performance for Cr(VI) and Cr(III) Amr A. Yakout a,b,∗ , Hassan M. Albishri c a Department of Chemistry, Faculty of Science, University of Jeddah, Jeddah, Saudi Arabia b Chemistry Department, Faculty of Science, Alexandria University, Alexandria, Egypt c Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia article info Article history: Received 18 December 2014 Revised 14 April 2015 Accepted 18 April 2015 Available online xxx Keywords: Magnetic nanoparticles MNPs Cr(VI) Cr(III) Aluminon Adsorption abstract The aluminon functionalized MNPs (Fe 3 O 4 @aluminon) as a novel magnetic nano-sorbent have been syn- thesized by a simple hydro-thermal method for the removal of Cr(VI) and Cr(III) from aqueous solu- tion. Fe 3 O 4 @aluminon MNPs were characterized using SEM, HRTEM, FTIR, VSM and TGA techniques. The Fe 3 O 4 @aluminon nano-sorbent has good dispersibility and valuable magnetic property. The effects of pH, equilibration time, mass of nano-sorbent and initial concentration of adsorbate on the percentage recovery of Cr(VI) and Cr(III) by Fe 3 O 4 @aluminon were investigated. The adsorption equilibrium was attained in 20 min at 25 °C and the adsorption kinetics obeyed the pseudo-second order model. The experimental data for the ad- sorption of Cr(VI) and Cr(III) better fitted the Langmuir isotherm and the maximum adsorption capacities were 263.2 mg/g for Cr(VI) at pH 1.0 and 400.0 mg/g for Cr(III) at pH 7.0. The adsorption–desorption cycles revealed that Fe 3 O 4 @aluminon nanoparticles had high stability and appropriate reusability. The removal efficiencies of chromium ions from different water samples were successfully accomplished ( 95.0–96.7 ± 1.4–2.1%). © 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved. 1. Introduction Chromium is the 22nd element in abundance in the earth’s crust with an average concentration of 100 ppm [1]. Chromium is charac- terized by its ability to exist in different oxidation states that show variable levels of toxicity to humans, animals and plants. Only Cr(III) and Cr(VI) are adequately stable to exist in the aquatic life [2]. The relation between Cr(III) and Cr(VI) intensely depends on the medium pH and its oxidative characters, but in most cases, Cr(III) is the domi- nating species. Cr(III) is usually found bound to organic matter in soil and in aquatic environments, while Cr(VI) usually existed as chromate (CrO 4 2− ) and dichromate (Cr 2 O 7 2− ). These two oxyanions are highly water soluble, poorly adsorbed by soil and organic matter, thus are mobile in soil and groundwater [3]. Cr(III) ions are required in trace amounts for stabilization and activation of enzymes, proteins and nu- cleic acids as well as for sugars, lipid metabolism, although the issue remains in debate [1,4]. In larger amounts, Cr(III) ions show different levels of toxicity. Cr(VI) anions are found to be highly toxic, carcino- genic, mutagenic, and teratogenic to both human and animal health [5]. The toxicity of Cr(VI) is determined by two main factors, the first ∗ Corresponding author: Tel.: +96 6565484044/+20 1001609201. E-mail address: aayakout@yahoo.com, Amryakout157@gmail.com (A.A. Yakout). one is related to the oxidative nature in water while the other one is related to its ability to form free radicals during the reduction of Cr(VI) to Cr(III) inside the living cell [6,7]. The maximum contami- nant level of Cr(VI) in drinking water is 0.05 mg/L and < 2.0 mg/L for the total chromium as given by WHO and US–EPA regulations [8,9]. Cr(VI) is present in wastewater discharged from hard chromium plat- ing, textile industries, refractory industrial processes and pigments applications [1,10]. A common method which has been employed for the removal of Cr(VI) from industrial effluents is the reduction to Cr(III) state followed by a chemical precipitation. Some of the draw- backs of this method include the hazard of Cr(VI) contamination due to partial reduction of Cr(VI) to Cr(III). Other available methods in- cluding filtration, membrane separation and adsorption have high operational cost [11]. Great efforts of many researchers are directed toward the adsorption of Cr(VI) from its contaminated industrial ef- fluents by nanomaterials and functionalized nanomaterials due to its simplicity, cost effectiveness and non-hazardous operation [12,13]. The efficiency of extraction of Cr(VI) ions depends on the choice of adsorbent. Various nanomaterials have been used as adsorbents for removal of Cr(VI) from aqueous media. Magnetic nanomaterials are applied as powerful adsorbents in multidiscipline applications par- ticularly in environmental purification due to their great ability to disperse with high surface area and excellent chemical selectivity [14–18]. In addition, the particle shape and surface functional groups http://dx.doi.org/10.1016/j.jtice.2015.04.023 1876-1070/© 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Please cite this article as: A.A. Yakout, H.M. Albishri, Solvo-thermal synthesis, characterization of aluminon-functionalized magnetic nanopar- ticles and investigation of its adsorption performance for Cr(VI) and Cr(III), Journal of the Taiwan Institute of Chemical Engineers (2015), http://dx.doi.org/10.1016/j.jtice.2015.04.023