The use of statistical properties of transmission signals for particle characterization

Abstract

The measurement of transmission is an often used measuring principle in technology. The evaluation algorithms of fluctuating transmission signals are well known in the case of single particle measurement. By evaluating fluctuating transmission signals the particle characterization is also possible at high particle concentrations (0.01 to 30 v01.-To). In comparison with conventional photometers a significant gain of information can be received. Fluctuating signals are caused by the statistical probability of a limited number of particles being present in a defined measuring volume. The evaluation of such signals allows the determination of particle concentration, particle size of monodisperse particles (extinction diameter) and information about structure of agglomerates independent from each other. Mathematical fundamentals and practical ways to measure these parameters are shown. Experimental results are examplarily presented for monodisperse, polydisperse and agglomerated suspensions.

On‐line Determination of Aggregate Size and Morphology in Suspensions

“…Using the results of the present study (respectively Aello measurements and settling data from Table 2) and equations (5)(6)(7)(8), w e can now verify relation (6) in our case and determine exponent c'. Good agreement is found, w hich validates the mathematical form of Equation (6) and respective values of c' are: 0.24 and 0.19.…”

“…Turbidimetry is based on light scattering by suspensions and rests on the Mie theory [4].How ever, the scattering properties of small aggregates of micronic particles, for instance, is not completely know n and requires additional research. Since the w orks of W essely et al [5], analysis of turbidity fluctuations has been show n as particularly interesting for the determination of particle number and size; this principle has given rise to a commercial instrument (Aello 4000). The present w ork is devoted to the characterization of aggregates of silica formed in a stirred vessel.…”

Dispersion of Colloidal Suspensions and Their Stability

“…Even though these papers explicitly focussed on non-stabilised systems, they inherently confirm the usefulness of the method to characterise the suspension stability. A further measurement technique that can be employed for this purpose is the turbidity or transmission fluctuation spectroscopy, which is sensitive to number fluctuations of micrometre-sized aggregates (Wessely et al 1996;Gregory 2009). It thus detects the changes when the aggregation proceeds to its end.…”

Influence of nonwetting on the aggregation dynamics of micronic solid particles in a turbulent medium

“…The principle of the commercial Aello 4000 turbidimeter is described by Wessely et al [26]. Calculated data are the number of particles per unit volume and the mean value of their light scattering cross section.…”