Application of the Taguchi Method and Central Composite Design for the Highly Selective and Efficient Extraction of Cu(II) ions from an Aqueous Solution Containing Mn(II), Co(II), Ni(II), Zn(II), Cu(II), and Pb(II) ions Mixture Using Benzyl Bis(thiosemicarbazone)

Abstract

A simple method was developed for the highly selective and efficient extraction of Cu(II) ions from an aqueous source solution containing Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Pb(II) ions using benzyl bis(thiosemicarbazone) (LH2) as the chelating agent. The parameters involved in selectivity and efficiency of extraction were concurrently investigated by multivariate optimization methods with rapidity and reliability. First, the organic solvent (A = Chloroform, 1,2-dichloroethane, dichloromethane, nitrobenzene), extraction time (B = 2, 6, 10, 14 h), pH (C = 3.6), shacking rate (D = 320,560 rpm), and LH2 concentration (F = 0.0001, 0.0005 mol/L) influence on selectivity of the system were investigated using the Taguchi design. The obtained results reveal that B, D, and F have notable effects on the selectivity of the extraction procedure, whereas the A and C presented little influence. Then, to maximize the percentage of Cu(II) ion extraction, the significant parameters were further optimized using central composite design (CCD). Eventually, optimum conditions were achieved as dichloromethane, 12 h, 6, 400 rpm, and 1 × 10−3 mol/L for A, B, C, D, and F, respectively. At the above-specified conditions, Cu(ΙΙ) ion with acceptable high recoveries was extracted from the mixed cations solution, while other cations remained in the source phase. In this work, by the right choice of the extraction conditions, a general chelating agent has been converted to a highly selective and efficient chelating agent for Cu(II) ions. The high selectivity and efficiency of this method make it suitable for the successful extraction of Cu(ΙΙ) ion in various real samples with the recoveries ranged from 91.27 to 99.20%.