Experiment 57 Particle Size Analysis

Part A Particle Size Distribution (Screen Analysis)  

In this experiment, a solid material, such as pecan hulls, are crushed, ground, and separated into various sizes to observe the effects of the variation of size distribution with screening time and the variation of size distribution on rate of vibration. The size and distribution of particles may be determined by several methods. Screening is commonly used for this purpose. In this method a known mass of material of various sizes is passed over a series of standard screens and the amount of material collected on each screen is determined. The rate of vibrating the screen and the time allowed for vibrating have definite effects on the distribution of particles. 

Obtain approximately 2 lb of material to be crushed. Determine accurately the amount obtained. 

If necessary, use a hammer or mallet to break the material into pieces no larger than 1/2 in. (Note Wear safety glasses.) 

Place the material into the grinder and collect in hopper bag. 

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This book is the most comprehensive text on particle size measurement published to date and expresses the experience of the author gained in over fifty years of research and consulting in particle technology. Previous editions have found wide use as teaching and reference texts. For those not conversant with particle size analysis terminology, techniques and instruments, the book contains basis information from which instrument selection can be made. For those familiar with the field, it provides an update of new instrumentation - particularly on-line or in - process instruments -upon which the control of particle processes is based. 

Figure 5.12. Particle size analysis in supix>]ted catalysts through XPS/ion sputtering experiments. Led predicted profiles for several suf rted particle sizes in monodisperse particle model Right experimental data for oxidized and reduced ex-chloride and ex-nitrate RhyCeO samples (from ref 170).

In their earlier work, the experiments were conducted without determining the particle size analysis in the water slurry in the reactor. Later, they installed a particle size analyzer externally to the reactor to obtain the data with the particle size analysis. " Recently, they installed a particle size analyzer in the high-pressure reactor for their experiments. ... 

Different methods of particle size analysis yield different distribution functions as primary information, depending on what parameters are measured in the course of experiment. These parameters may be converted into different ones. It is, however, important for one to realize that such a conversion may yield errors of different magnitudes in different size ranges. 

Syvitski, . P. M., K. W. G. LeBlanc K. W. Asprey, 1991a. Interlaboratory, interinstrument calibration experiment. In Syvitski, J. P. M. (ed.) Principles, Methods, and Application of Particle Size Analysis. Cambridge University Press, New York 174-193. 

Btirkholz, A., Polke, R., Laser Diffraction Spectrometers/Experience in Particle Size Analysis, Part. Charact., 1984, 1, 153-160. 

To measure the strength of the forces exerted on particles, various analytical techniques have been developed [6, 7]. Unfortunately, since most of these techniques are based on hydrodynamics, assumption of the potential profiles is required and the viscosities of the fiuid and the particle sizes must be precisely determined in separate experiments, for example, using the viscous flow technique [8,9] and power spectrum analysis of position fluctuation [10]. Furthermore, these methods provide information on ensemble averages for a mass of many particles. The sizes, shapes, and physical and chemical properties of individual particles may be different from each other, which will result in a variety of force strengths. Thus, single-particle... 

Stationary phase. Supelcosil Cig ABZ (Supelco Scientific, Bellefonte, PA, USA) was the most often employed support and gave the best correlations. This stationary phase should be selected in a first instance with a geometry adapted to the application for conventional gradient experiments, supports of 150X4.6 mm, 5 pm represent a good choice while a shorter column (i.e. 50 mm or lower) with smaller particle size (i.e. 3-3.5 pm) must be preferentially selected for fast gradient analysis. 

These columns have been used for separation of proteins of over 200 kDa MW in our experiments as shown by analysis using a ID gel. In addition, columns with larger particle sizes have been used to separate proteins of over 400 kDa (55-56). The NPS RP-HPLC method provides a liquid phase method for separating large intact proteins for further analysis. More specifically, it provides a means of separating proteins for interfacing to mass spectrometric analysis. 

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