Flow injection analysis of ethyl xanthate by gas diffusion and UV detection as CS2 for process monitoring of sulfide ore flotation

Tipo
Artigo
Data de publicação
2010
Periódico
Talanta
Citações (Scopus)
20
Autores
Cordeiro T.G.
Hidalgo P.
Gutz I.G.R.
Pedrotti J.J.
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Resumo
A sensitive and robust analytical method for spectrophotometric determination of ethyl xanthate, CH3CH2OCS 2 - at trace concentrations in pulp solutions from froth flotation process is proposed. The analytical method is based on the decomposition of ethyl xanthate, EtX-, with 2.0 mol L-1 HCl generating ethanol and carbon disulfide, CS2. A gas diffusion cell assures that only the volatile compounds diffuse through a PTFE membrane towards an acceptor stream of deionized water, thus avoiding the interferences of non-volatile compounds and suspended particles. The CS2 is selectively detected by UV absorbance at 206 nm (ε = 65,000 L mol -1 cm-1). The measured absorbance is directly proportional to EtX- concentration present in the sample solutions. The Beer's law is obeyed in a 1 × 10-6 to 2 × 10-4 mol L-1 concentration range of ethyl xanthate in the pulp with an excellent correlation coefficient (r = 0.999) and a detection limit of 3.1 × 10-7 mol L-1, corresponding to 38 μg L -1. At flow rates of 200 μL min-1 of the donor stream and 100 μL min-1 of the acceptor channel a sampling rate of 15 injections per hour could be achieved with RSD < 2.3% (n = 10, 300 μL injections of 1 × 10-5 mol L-1 EtX-). Two practical applications demonstrate the versatility of the FIA method: (i) evaluation the free EtX- concentration during a laboratory study of the EtX- adsorption capacity on pulverized sulfide ore (pyrite) and (ii) monitoring of EtX- at different stages (from starting load to washing effluents) of a flotation pilot plant processing a Cu-Zn sulfide ore. © 2010 Elsevier B.V. All rights reserved.
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Assuntos Scopus
Correlation coefficient , Ethyl xanthate , Flotation process , Flow analysis , Froth flotation process , Gas diffusion , Robust analytical methods , Spectrophotometric determination
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