Visual study of mass transfer characterization in the process of biological catalytic hydration of acrylonitrile using pendant drop method

Abstract

In this work, a pendant drop method was utilized to observe visually the mass transfer process of an acrylonitrile droplet during bio-hydration. At a temperature of 293 K, the droplet radius was reduced from 100 μm to 49.8 μm within 55 seconds and the value of the diffusion coefficient of acrylonitrile in water was 9.51 × 10⁻¹⁰ m² s⁻¹. The reduction of the droplet radius is conducive to the acceleration of the mass transfer rate. Cells without enzyme activity to some degree decrease the mass transfer rate of acrylonitrile. At the same temperature, the droplet radius is reduced from 100 μm to 50.4 μm within 135 seconds at a cell concentration of 0.204 g L⁻¹. The bio-hydration reaction can greatly strengthen the mass transfer process, with the intensifying factor ranging from 1.70 to 4.78. The increase of acrylamide concentration shortens the critical droplet radius of acrylonitrile, and hence also strengthens the mass transfer process.