Desenvolvimento de uma metodologia de pré-concentração em fluxo utilizando cascas tratadas de Moringa oleifera como biadsorvente para determinação de Zn(II) em matrizes alcoólicas

Abstract

This work describes the development of analytical methodology for Zn(II) determination in alcoholic matrices with significance to alcohol fuel and sugar cane spirits samples, using flow injection (FI) preconcentration systems and flame atomic absorption spectrometry (FAAS). The flow manifold was made up of a peristaltic pump, four three-way solenoid valves and a minicolumn packed with the coal obtained from Moringa oleifera husks. Middle Infrared Spectroscopy, Thermogravimetric Analysis and X-ray Diffraction were used to characterize the biosorbent in order to identify the main groups responsible for interaction zinc ions, and to evaluate the thermal stability of material. The construction of adsorption isotherms was used in order to identify the mechanisms involved between the material and the Zn2+. Chemical and flow variables and the effect of concomitant ions were studied in the proposed procedures, using multivariate methods. A full factorial design (24) and response surface were used to identify the variables that influence the adsorption system. The results were: sample flow rate 4.0 mL min-1, eluent concentration of 1.0 mol L-1, adsorbent mass equal to 30.0 mg and sample initial pH 4.0.The accuracy of the proposed method was evaluated by recovery test applied in the samples, and also by comparing the analytical performance using commercial adsorbents. The proposed methodology was successfully applied for Zn2+ determination in alcohol fuel samples and sugar cane spirits were found recovery to 100%.