Laser capillary spectrophotometry for drop‐size concentration measurements

Abstract

A laser capillary spectrophotometric technique (LCS), based on the method of Verhoff et al. (1969, 1977), is developed for the rapid and accurate determination of the bivariate drop size-concentration distribution for reactive liquid-liquid dispersions. The method employs a precision bore capillary, through which a sample is drawn from the mixing vessel by a vacuum pump. An appropriate light source is used to distinguish between the slugs of dispersed phase and continuous phase as the sample passes by two detection points in the capillary. The optical device is designed to measure drop size by the difference of light refraction between the two phases and drop concentration by the light absorbance of the organic phase in the drop. The new technique can automatically measure drop-size and drop-concentration distributions of thousands of drops within a few minutes. This technique can provide important information on the state of a reactive dispersion in situ and can provide information on the influence of dispersed-phase mixing effects on mass transfer and/or reactions in liquid-liquid dispersions. Further, the LCS technique provides the capability for on-line monitoring and control of units processing liquid dispersions.