Int. J. Nano Dimens., 9 (3): 246-259, Summer 2018 ORIGINAL ARTICLE Adsorption study of Zinc ion onto halloysite nanotubes using taguchi’s design of experimental methodology Gholamreza Kiani 1, * ; Mehdi Soltanzadeh 1 ; Iraj Ahadzadeh 2 1 School of Engineering-Emerging Technologies, University of Tabriz, Tabriz, Iran 2 Department of Physical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran Received 13 January 2018; revised 06 March 2018; accepted 27 April 2018; available online 28 April 2018 * Corresponding Author Email: g.kiani@tabrizu.ac.ir How to cite this article Kiani G, Soltanzadeh M, Ahadzadeh I. Adsorption study of Zinc ion onto Halloysite nanotubes using taguchi’s design of experimental methodology. Int. J. Nano Dimens. 2018; 9 (3): 246-259. Abstract In this paper, Taguchi method was applied to determine the optimum conditions for Zn (II) removal from aqueous solution by halloysite nanotubes (HNTs). An orthogonal array experimental design (L 16 (4 5 ) which is of fve control factors including pH, t (contact time), m (adsorbent mass), T (temperature) and C 0 (initial concentration of Zn (II)) having four levels was employed. Adsorption capacity (mg/g) and removal percent (%) were investigated as the quality characteristics to be optimized. In order to determine the optimum levels of the control factors precisely, range analysis and analysis of variance were performed. For removal percent, the optimum condition was found to be pH=6, T=35 ° C, w=0.4 g, and C 0 =50 mg/L. Under these optimum conditions, adsorption capacity and removal percent can reach to 132.16 mg/g and 99.76%, respectively. Keywords: Adsorption; Halloysite Nanotubes; Heavy metal ions; Optimization; Taguchi method. INTRODUCTION Environmental polluton caused by toxic heavy metals is one of the most serious problems in many densely populated cites worldwide. The industrial and domestc wastes responsible for various damages to the environment adversely afect the health of the human populaton. Several catastrophic events resultng from heavy metal contaminaton in the aquatc environment increased the awareness of the heavy metal toxicity [1]. Most of these processes are not widely accepted due to their high costs, low efciency, disposal of sludge, inapplicability to a wide range of pollutants [2]. The adsorpton process is arguably one of the more popular methods for the removal of heavy-metal ions because of its simplicity, convenience, and high removal efciency [3-9]. Halloysite is a clay mineral with a nano- scaled tubular structure that acts as an efectve adsorbent. Halloysite has atracted much atenton due to its excellent propertes such as availability, biocompatbility, and ecofriendly feature [10]. Recently, halloysite and its composite structures have been used for adsorpton of various molecules and contaminants such as dyes, benzene, alcohols, halides, carboxylic acids, drugs, and heavy metals [10-15]. Zinc is a trace element that is essental for human health. When people absorb too litle zinc they can experience a loss of appette, decreased sense of taste and smell, slow wound healing and skin sores. Zinc-shortages can even cause birth defects. Although humans can handle proportonally large concentratons of zinc, too much zinc can stll cause eminent health problems, such as stomach cramps, skin irritatons, vomitng, nausea and anemia. Very high levels of zinc can damage the pancreas and disturb the protein metabolism, and cause arteriosclerosis. Extensive exposure to zinc chloride can cause respiratory disorders [16, 17]. So the removal of zinc from environment is essental. Design of experiments (DOE) develops a scheme of experimental diferent conditons. The Taguchi method was established by Genichi Taguchi [18]. Taguchi optmizaton technique is a Tis work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.