Estudo da extração e pré-concentração de Hg2+ em pregando naftaleno modificado com ditizona e determinação espectrofotométrica

Abstract

In environment, the mercury is found in low concentrations and the human action is a significant source of contamination for this element. Due her toxicity and to the fact of being bio-accumulative, the tolerable concentrations of mercury are very low. For the analytical determination of mercury the methods available colorimeters are the one of lower cost, however these don't present satisfactory detection limit for the demanded concentrations. Like this, in this work we presented a study of viability of the pre-concentration and determination ions colorimétrica mercury(II) using extraction solid-liquid and ditizona impregnated in naftaleno, to 0.020% m/m, as solid support. The analytical curve of calibration was obtained percolating 1.0 mL of aqueous solution of mercury(II) to pH 2.0 through a glass column containing 130.0 mg of the naftaleno modified with ditizona to 0.020% m/m. After the percolation, the solid mass is dissolved with a mixture 2-propanol/chloroform 1:1 v/v, collecting it in volumetric flask of 1.0 mL and determination to 485 nm. The analytical curve is described by the equation Abs = 0.211 Cng2+ -0.002 (r2 - 99.89%) and it is lineal up to 0.80 mg/dm3 with ld = 0.035 mg/dm3, made calculations in relation to the standard deviation of the white. The factors of pre-concentration of 50, 100, 150, and 200 times for of solution containing 0.40 g of ions mercury(II) was appraised and obtained factors of recovery of 88, 77, 74 and 67% respectively. The appraised procedure presents an alternative to improve the detection limits in determination ions colorimétrica mercury(II) in aqueous Solutions; however it suffers signifícant interference of the ions presence silver(I) and ions copper(II).