Spectrophotometric Determination of Copper(II) in Natural Waters and High Purity Thermal Boiler Water

Abstract

A facile, highly sensitive and selective spectrophotometric procedure was developed for the determination of copper(II) in thermal boiler water using a newly synthesized reagent, N,N'-bis(salicylidene)ethylenediamine (Salen). It is based on the reaction at pH 4-9 between the synthesized Salen and Cu(II) forming a deep green complex, Cu(II) Salen (1:1), that floats quantitatively with oleic acid surfactant. It exhibits a constant and maximum absorbance at 550 nm in both aqueous and surfactant layers. Beer's law is obeyed over the concentration range 0.25- 6.35 mg L^-1 with a detection limit of 0.005 mg L^-1 for a standard aqueous solution of Cu(II) with a concentration of 3.82 mg L^-1, molar absorptivities of 5.5 × 10³ and 1.3 × 10⁴ mol L^-1 cm^-1 in aqueous and surfactant layers, respectively. Sandell's sensitivity was calculated to be 0.244 μg cm^-2 and the relative standard deviation (n = 9) was 0.19 %. The different analytical parameters affecting the flotation and determination processes were examined. The proposed procedure has been successfully applied to the analysis of Cu(II) in natural waters and high purity thermal water samples. The results obtained agree well with those samples analyzed by atomic absorption spectrometry.