Desenvolvimento de método adaptado de extração com ponteiras descartáveis para determinação de íons Pb(II) e Mn(II) utilizando taboa (Typha angustifólia L.) como adsorvente
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Data
2020-12-18
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Universidade Federal de Goiás
Resumo
In this work, the extraction technique with disposable tips (DPX - from English disposable pipette extraction) was used using Typha angustifolia L. (cattail) as an adsorbent. An adapted DPX method was developed for the determination of Pb(II) and Mn(II) ions in aqueous samples, using the Flame Atomic Absorption Spectrometry (FAAS) technique for quantification. The characterization of the cattail was performed through X-Ray Diffraction, Infrared Spectroscopy, X-Ray Fluorescence Spectroscopy, Determination of the pH at the Zero Charge Point and Buoyancy, with results consistent with those observed in the literature. The zero load point of the material was determined at 6.39. The pH of the solution was univariate optimized by selecting the solutions of Pb(II) and Mn(II) ions at a concentration of 1.0 mg L-1
at pH 8. Tests to optimize the parameters that influence the adsorption and desorption of the ions were made in a multivariate manner. Through Doehlert planning, it was possible to obtain optimal values for mass of adsorbent and number of adsorption cycles, being defined in 30 mg and 7 cycles, respectively, for Pb(II) and Mn(II) ions and the concentration of HNO3 and number of desorption cycles, in 0.8 mol L-1 and 7 cycles. The kinetic study indicated that the adsorption of the Pb(II) and Mn(II) ions obey a pseudo-first order and Avrami kinetics, respectively. The maximum adsorption capacity was obtained through the construction of adsorption isotherms, with values of 29.17 and 5.64 mg g-1 being found for the Pb(II) and Mn(II) ions, respectively. Under optimized conditions the extraction method presented detection limits of 17.51 μg L-1 (Pb (II)) and 35.02 μg L-1 (Mn (II)), quantification limits of 58.37 μg L-1 (Pb (II)) and 116.7 μg L-1 (Mn (II)), and a pre-concentration factor of 10 (Pb (II)) and 2 (Mn (II)), being a linear range of 116.7 to 2000 μg L-1 method for Mn (II) and from 58.37 to 2500 μg L-1 for Pb (II). Accuracy was evaluated separately in terms of repeatability and reproducibility, obtaining D.P.R. values of 0.31 and 0.25% for Pb (II), respectively, and 7.00 and 9.88% for Mn (II), respectively. The evaluation was evaluated by means of recovery tests in river water collected near a mining company, recovery values in the range of 80-120% and through the use of certified reference materials, indicating high reliability of the method.
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DPX, Typha angustifolia L., Chumbo, Manganês, Adsorção, DPX, Typha angustifolia L., Lead, Manganese, Adsorption
Citação
FERREIRA, M. M. Desenvolvimento de método adaptado de extração com ponteiras descartáveis para determinação de íons Pb(II) e Mn(II) utilizando taboa (Typha angustifólia L.) como adsorvente. 2020. 96 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2020.