A simple method for determination of the average particle size of coarse suspensions from measurements of apparent specific turbidity

Abstract

If the turbidity of a suspension of large spherical polydisperse particles is independent of the wavelength of light, the apparent specific turbidity, as measured by an inexpensive commercially available spectrophotometer, is inversely proportional to the average radius of the particle size distribution. It is shown experimentally that this relation holds for suspensions of monomodal polydisperse styrenedivinylbenzene copolymer latices of average radius from 12 to 50 μm. This observation permits development of a quick method for determination of the various average particle sizes of coarse monomodally polydisperse suspensions from apparent specific turbidity measurements using a simple spectrophotometer such as the Spectronic-20. Attempts to verify similar relations for the determination of the average floc size of suspensions of silica and carbon black were unsuccessful, since it was not possible to obtain comparison values of the floc size distributions by the Coulter Counter because of extensive deflocculation of the aggregates on passage through the aperture.