SANTOS, E. G.; http://lattes.cnpq.br/3306805345463372; SANTOS, Elba Gomes dos.
Resumen:
The use of adsorption as separation process has become more attractive the last years,
mainly after the discovery of new adsorbents such as zeolites and other molecular sieves. In
order to project and optimize adsorption equipment, the knowledge of the dynamics of
adsorption of the components in experimental systems is very important. In this work, a study
of the dynamics of adsorption of ethanol and the co-adsorption of methanol-ethanol solutions
in a fixed bed column of 4A zeolite pellets has been made. Breakthrough curves were
obtained by means o f analysis o f ethanol and methanol-ethanol concentrations in the effluents
at the top of the bed. The column o f 2.94cm internal diameter had temperature sensors at the
inlet and outlet of the fixed bed, to observe the thermal evolution during the process of
adsorption and co-adsorption. In the order to get a more detailed study of the input variables,
a 23 factorial experimental planning, plus star configuration with three experiments in the
central point was employed. Influence o f input concentration of the solution, operational flow
rate and height of the fixed bed on the dynamic behavior of the experimental runs was
investigated. The experimental conditions were: (a) input concentrations ranging from 2.5 to
12.0% (w/w) ethanol in toluene and 2.5 to 5.7% method in ethanol; (b) flow rates ranging
from 2.5cm3/s to 12.0cm3/s and (c) height of the fixed bed ranging from 6.6 to 23.4cm. The
breakthrough curves of ethanol adsorption were analyzed by Thomas model, valid for
isothermal systems and Langmuir equilibrium. The experimental data showed a good fitting
with the model, in spite of the inherent simplifications o f the model. The values o f adsorption
capacity of the 4A zeolites at the equilibrium calculated from the breakthrough curves showed
a good agreement with those found in previous works, obtained by the static method, except
for those obtained with smaller fixed bed heights. The breakthrough curves obtained for the
methanol-ethanol system presented characteristic format of the co-adsorption without inert
and strong isothermal deviation as expected. The methanol adsorption capacity was higher
than that obtained for ethanol. Statistic analysis of the results showed that, under the
employed experimental conditions, fixed bed height is the main parameter affecting ethanol
adsorption while co-adsorption is mainly influenced by the input methanol concentration.