Polarographic and Voltammetric Determination of Some Toxic Heavy Metal Ions in the Treated Wastewater at Abu-Dhabi, U.A.E.

Abstract

Differential pulse polarographic (DPP) and anodic stripping voltammetric (DP-ASV) techniques were employed for determination of Zn, Cu, Pb and Cd in the treated wastewater at Abu-Dhabi, U.A.E. Four samples were collected from two different treated wastewater plants at Al-Ain and Abu-Dhabi cities during the period of May-Nov, 1996. The collected samples were subjected to UV-irradiation, before the direct analysis, to eliminate the interference effect of the organic compounds on the determination of the metal ions. Double step solvent extraction was used to minimize the effect of interference of the organic compounds on the methods of analysis. Also, the solvent extraction techniques was used for preconcentration of the four metal ions from the collected samples. The pre-treated samples with UV-irradiation and/or solvent extraction techniques were subjected to full analysis using DPP and DP-ASV methods in order to determine the operational and solution parameters for trace determination of the metal ions. A multi-step standard addition method was applied on the polarographic and voltammetric peaks of the four metal ions for calculation of the concentration level of each metal ion in the collected samples. the results indicated that the concentration range of the four metal ions in the investigated samples were 0.11-0.16, 0.020-0.025, 0.01-0.02 and 0.008-0.012 ppm for Zn(II), Cu(II), Pb(II) and Cd(II), respectively. It should be mentioned that the treated wastewater in Abu-Dhabi was used for irrigation of ornamental plants.