Removal of Zn (II) from aqueous solution using Halloysite Nanotubes: Optimization of Process by Taguchi Method

Environmental pollution caused by toxic heavy metals is one of the most serious problems in many densely populated cities worldwide [1]. The adsorption process is arguably one of the more popular methods for the removal of heavy-metal ions because of its simplicity, convenience, and high removal efficient [2]. Taguchi optimization technique is a unique powerful optimization discipline that allows optimization with minimum number of experiments [3].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 experiment design (L16(45) which is of five control factors (pH), t (contact time), m (sorbent mass), T(temperature )and C0 (initial concentration of Zn (II)) having four levels was employed. Sorption capacity (mg/g) and percent removal (%) 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. And for percent removal, the optimum condition was found to be pH=6, T=35°C, w=0.4 g, and C0=50 mg/L. Under these optimum conditions, sorption capacity and percent removal can reach 132.16 mg/g and 99.76%, respectively.