Dissertação
Modelagem e estimação de parâmetros da adsorção de corantes em carvão ativado
Fecha
2011-09-30Registro en:
GALLON, Roger. MODELING AND PARAMETER ESTIMATION OF DYES ADSORPTION IN
ACTIVATED CARBON. 2011. 73 f. Dissertação (Mestrado em Engenharia) - Universidade Federal de Santa Maria, Santa Maria, 2011.
Autor
Gallon, Roger
Institución
Resumen
The adsorption of dyes on activated carbon has been extensively studied in
the past three decades. However, much due to the difficult to implement numerical
procedures, these studies have been carried out without the necessary statistical
background to make reliable conclusions. The main objective of this work was to
perform the early stages of modeling and parameter estimation applied to the
process of dyes adsorption on activated carbon, collaborating to the systematization
of a computer routines set for the study of such process. The methodology has
focused especially on the evaluation of the experimental error influence and
linearization of the equilibrium models influence in the values of parameters and its
confidence regions. The main routines used are part of a package called ESTIMA
(PEQ/COPPE/UFRJ) which uses, basically, a stochastic method (Particle Swarm)
together with a Gauss-Newton method in order to minimize the objective function.
The parametric uncertainties have been compared by the elliptical approximation, the
evaluation of several points obtained during minimization procedure, which are
smaller than a determined limit, and an adapted method (SBA) from the Bootstrap
method to build the parameters confidence region. Also, a methodology for model
discrimination has been used and the effects of model linearization and proper
characterization of experimental error have been studied. The realization of several
replicates and subsequent error characterization have been shown of extremely
importance to the study as the search for an alternative to obtain a more accurate
estimate of the error in experimental conditions that have not been performed yet. It
has been possible to experimentally show that the error on the amount adsorbed is
indeed dependent of the error in the equilibrium concentration of adsorbate solution,
a fact that, despite being known a priori, had not been yet demonstrated in other
works. The comparison between linear and nonlinear methods also demonstrated
how the linearization process negatively influences the correct data analysis and
parameter determination. Through de analysis of the probabilities distribution of the
equilibrium concentrations of the adsorbate solution (Ce), it has been shown that
confidence region methods present a better performance when the dependent
variable is transformed to the Log-Normal distribution, using the operation Neperian
logarithm of Ce.