Fluidized Bed Electropolymerization of Thin Films: Modeling and Experimentation

Abstract

A one-dimensional mathematical model is developed to describe the electropolymerization of diacetone acrylamide in a two-compartment cylindrical coaxial fluidized bed reactor. This is believed to be the first mathematical model to describe the complex electro-organic process of electropolymerization in a fluidized bed reactor. The particulate and electrolyte phase were considered as two overlapping continuous homogenous media obeying Ohm’s law. A cathodic polarization equation with exchange current density varying with bed expansion, suggesting that the reaction kinetics vary with the extent of fluidization, described the electrode kinetics with good accuracy. The potential distribution for different bed expansions predicted by the model compared well to experimental results reported earlier by Teng (F. S. Teng, Ph.D Thesis, Washington State University, Pullman, WA, 1979.) The predicted current distribution confirmed that the two phases obeyed Ohm’s law. The reaction rate was also studied as a function of bed expansion and radial position in the bed. The model predicts an increase in the electropolymerization reaction rate with an increase in bed expansion. A single reaction and a constant current efficiency are assumed for all bed expansions. The experimental results showed a decline in the mass of polymer formed at higher bed expansions. Since the amount of polymer formed in a given time can be considered indicative of the reaction rate under the assumptions used, the present model is useful in understanding the electropolymerization process at bed expansions up to about 20%. © 2003 The Electrochemical Society. All rights reserved.