Desenvolvimento de metodologia analítica utilizando sistema em fluxo e casca de arroz para pré-concentração de chumbo em amostras de sedimento
Data
2018-06-20
Autores
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Universidade Federal de Goiás
Resumo
The present work presents a study of use of the rice husk as adsorbent material for the determination
of lead ions in sediment samples obtained at different points of Rio Doce region (Espírito Santo),
using flow injection system. With detection metal determination wes used Atomic Flame
Absorption Spectrometry. The physico-chemical characterization of the material was done by
Infrared Region Spectroscopy, Scanning Electron Microscopy, X-ray Dispersive Energy Analysis
and X-ray Diffraction and determination of the zero load point. In adsorptive processes, the pH
directly influences the extraction of the ion and the study of this parameter indicated that in pH
6,00 better extraction conditions are obtained. After pH determination, a multivariate optimization
2
4 of the parameters influencing the ion adsorption process was performed. The variables evaluated
were adsorbent mass, preconcentration flow, volume and eluent concentration. Subsequently, a
univariate study of the mass and preconcentration flow variables was performed, as well as a study
of the elution flow rate. The best responses for flow system operation were obtained using:
adsorbent mass 70.0 mg, eluent concentration (HNO3) 0,50 mol L-1
, eluent volume 1000 μL,
preconcentration flow 2.0 mL min-1
and elution flow 1.0 mL min-1
. From the optimized conditions,
the procedure showed to be effective for the Pb2+ species, with limits of detection (LD) and
quantification (LQ), respectively, equal to 0.015 and 0.05 mg L-1, with a relative standard deviation
(DPR) of 6.821% and a preconcentration factor of 49.5. Recovery values were obtained between
87 - 100% for fortified sediment samples. In order to analyze the selectivity of the method, the
evaluation of possible interferences was carried out, based on the calculation of the interference
factor (FI). The Cu (II), Ni (II), Co (II), Fe (III) and Zn (II) ions were analyzed in different
proportions. The procedure presented was satisfactory for preconcentration of Pb2+ ions, and it can
be used for extraction of the same. As it proved to be fast, efficient, low cost, besides the reduction
in reagent consumption and waste generation. Factors that favor the development of a system based
on the principles of "Green Chemistry".
Descrição
Palavras-chave
FIA, Casca de arroz, Chumbo, Sedimento, FIA, Rice husk, Lead, Sediment
Citação
TAVARES, L. Q. Desenvolvimento de metodologia analítica utilizando sistema em fluxo e casca de arroz para pré-concentração de chumbo em amostras de sedimento. 2018. 83 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catlão, 2018.