Estudo da determinação e extração de cádmio(II) empregando o l-(2-piradilazo)-2-naftol e a mistura homogênea dos solventes água-etanol-clorofórmio

Abstract

In this work it was studied a liquid-liquid single phase extraction procedure for the extraction and spectrophotometric determination of cadmium(II) with l-(2-pyrydilazo)-2-naftol (PAN). A homogeneous mixture of the solvents water-etanol-chloroform, denominated of single phase solution, was used for the complexation reaction. Addition of an excess of aqueous solution, breaking the equilibrium of phases of the single pahse solution in two phases, it extracted the compound formed for the organic phase. With procedure of study of modelling of mixtures, it was verified that the composition of the solvents of the single phase solution influences in the sensibility of the cadmium(II) determination. Is this behavior described by the equation Abs = 0,269 - 0,290 X + 0,364 Y + 0,344 Z + 0,086 XY - 1,989 YZ (are X, Y and Z %m/m water-etanol-chloroform, respectively) and, in this work, was the composition 2:61:37 %m/m adopted that corresponds, respectively, to the proportion of 1:41:13 v/v water-etanol-chloroform. In a single phase solution optimized composition, it is observed that the maximum complexation of cadmium(II) with PAN happened when was used the so­lution of PAN 0,010 %m/m in chloroform, time of reaction to 10 minutes and tem­peratura to 20 °C ± 2. The quantitative extraction was obtained adding xx mL of aqueous solution of NaNCh 10’7 mol L’1 and pH 9,0 for the separation of the phases and the organic phase was used for the cadmium(II) spectrofotmetric determination, 5478 nm. Under optimized conditions of the extraction and determination procedure, was it obtained an analytical curve of calibration described for Abs = 0,139Cc<f+ -0.001 (r2 = 0.9999), lineal at 6,0 mg L'1 of cadmium(H) and detection limit and of quantification, done make calculations in relation to the standard deviation of the white, same the 0,18 mg L'1 and 0,58 mg L1 cadmium(II) in the aqueous portion of the single phase solution, respectively. Then, the proposed system for the quantitative extraction and spectrophotometric determination of cadmium(II) it is viable at 6,0 mg L’1 cadmium(II) concentration in aqueous Solutions.