Modelagem e simulação de purificação de cefalosporina C em coluna de leito fixo

AUTOR(ES)
DATA DE PUBLICAÇÃO

1996

RESUMO

In the "cephalosporin C" production process, the purification is the second step, after the antibyotic been produced by Cephalosporium acremonium in submerged cultures. The purification is carried on in ionic exchange columns. In this work a mathematical model to describe the adsorption process is suggested. The model was obtained from a mass balance and kinetic equations for ionic exchange adsorption, previously determinated in XAD-2 resin. Resistance to the internal and external mass transfer and axial dispersion were also considered in the model. The analytic equations to describe the process were transformed to numeric algorithms using Crank-Nicholson method for the partial differential equations and the 4th order Runge - Kutta method for ordinary differential equations. The computer program was developed using Turbo Pascal language to calculate the distribution of cephalosporin in the column as a time function, both in the liquid phase and in the solid phase. The influence of kinetics and operation parameters in the column efficiency was verified by means of a parametric study. It was observed that the main parameters were the bed porosity, the cephalosporin concentration, and the column diameter. On the other hand, some parameters as Qm (maximum capacity of adsorption), Kl and K2 (kinetics constants of adsorption) must be previously optimized in terms of adsorbent selection and appropriated adsorption conditions. It was also verified that the increase in the column length and the superficial velocity intrances the column efficiency. lt was demonstrated that the fixed bed adsorption column is stable considering that there is no critical parameter for the column operation. It was verified that the axial dispersion is not significant, and the increase both in the effective diffusivity and in the mass transfer coefficient gives a better process efficiency. It was observed that the adsorption process limitation in the column is caused by internal mass transfer, that is the diffusion is the process critical step. Finally, the XAD-2 resin used in this work show low efficiency. Which is a disadvantage in the cephalosporin C adsorption process.

ASSUNTO(S)

troca ionica cefalosporinas - purificação

ACESSO AO ARTIGO

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