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Please use this identifier to cite or link to this item: http://repositorio.ufba.br/ri/handle/ri/14035

Title: Evaluation of transversal and longitudinal dispersion in a flow injection system by exploiting laser induced fluorescence: influence of flow-cell positioning
Other Titles: Analytica Chimica Acta
Authors: Quintella, Cristina Maria Assis Lopes Tavares da Mata Hermida
Watanabe, Yuji Nascimento
Lima, Angelo Marcos Vieira
Korn, Mauro
Pepe, Iuri Muniz
Embiruçu, Marcelo
Musse, Ana Paula Santana
Keywords: Flow injection analysis;Dispersion;Microfluidics;Solid–liquid interfacial tension;Laser induced fluorescence
Issue Date: 2004
Abstract: A fully mechanized set-up was built for the experimental determination of bi-dimensional dispersion with high spatial resolution (2400 μm2). Gravitational and wall effects in a single stream were evaluated by using time-based sampling and a micro-flow cell. Vertical upward and downward flows as well as horizontal flows were investigated. Ethylene glycol (MEG) and Rhodamine B in MEG were used as carrier and sample solutions, respectively. Longitudinal profiles were obtained by laser induced total fluorescence (LIF) at up to 19 transversal sites and combined to generate high-resolution bi-dimensional profiles. A two frontal maxima pattern was observed for all flows. The volumetric fraction of RB shape was highly stretched for downward flow and there was high asymmetry for horizontal flow. The sensitivity of three dispersion parameters was evaluated: maximum peak value, peak half-width at half-height, and peak area. Data modeling showed that the tanks-in-series was more sensitive to wall effects, had good adjustment with only one tank for upward and horizontal flow and needed two tanks for downward flow which was attributed to the latter having higher dispersion. A black box empirical modeling described better the gravitational effect and allowed to identify a parameter sensitive to upward and downward flow as well as hinting to two inner streams within the horizontal flow. It also pointed to a wall dispersion contribution of twice that of the liquid–liquid dispersion.
Description: Texto completo: acesso restrito. p. 293–300
URI: http://repositorio.ufba.br/ri/handle/ri/14035
ISSN: 0003-2670
Appears in Collections:Artigos Publicados em Periódicos (Quimica)

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