Light Intensity Profile in Gas-Liquid Dispersion

Applicability of effective absorption coefficient

Abstract

The light intensity profiles in a rectangular aerated cell produced by a low-pressure mercury lamp were measured by two Cs-Te photoprobes having quite different angular characteristics. The profiles observed with a less directional photoprobe A in air as a pattern of homogeneous systems were well explained by the diffuse line source model. The effective absorption coefficients were evaluated by fitting the model equation to the profiles measured by probe A for nitrogen bubbles-dispersed potassium nitrate aqueous solution as a pattern of heterogeneous systems. A convenient method was also presented to obtain the coefficients applying the radial light model to the profiles observed with a sharp directional photoprobe B.
The effective absorption coefficient was found to be a unique function of dispersed phase hold-up, particle diameter, specific surface area and the optical properties of each phase, and a simple empirical correlation was obtained.
The observed rates of the photoreduction of potassium ferrioxalate in the presence of nitrogen bubbles agreed well with the results computed using the coefficients for the dispersion.