Particle size distribution experimental investigations

The influence of various gas pressure conditions within the laser ablation cell on the particle formation process in laser ablation has also been investigated.69 In LA-ICP-MS studies at low pressure (down to 2kPa) a small particle size distribution and a reduction in elemental fractionation effects was obtained. But with decreasing pressure and transport volume of ablated material, a significant decrease in the ion intensities was observed as demonstrated for uranium measurements in the glass SRM NIST 610.69 However, the laser ablation of solid materials at atmospheric pressure in LA-ICP-MS is advantageous for routine measurements due to lower experimental effort and the possibility of fast sample changing in the ablation chamber. Fractionation... 

When fine powders of vitreous silica, quartz, tridymite, cristobalite, coesite, and stishovite of known particle-size distribution and specific surface area are investigated for their solubility in aqueous suspensions, final concentrations at and below the level of the saturated concentration of molybdate-active silicic acid are established. Experimental evidence indicates that all final concentrations are influenced by surface adsorption of silicic acid. Thus, the true solubility, in the sense of a saturated concentration of silicic acid in dynamic equilibrium with the suspended silica modification, is obscured. Regarding this solubility, the experimental final concentration represents a more or less supersaturated state. Through adsorption, the normally slow dissolution rates of silica decrease further with increasing silicic acid concentrations. Great differences exist between the dissolution rates of the individual samples. 

The aims of the investigations presented in this paper are to estimate accurately fugitive dust emissions resulting from wind erosion. Thus, a model which allows to quantify emissions resulting from an exposed particle bed to a turbulent flow has been developed. Its originality is to take into account the wide particle size distribution of materials used, as example, at steelwork sites. Typically, the finer particles can have a size of about 10 xm and the larger running to centimetres. This characteristic is very important. In fact, Meunier [2] observed for various experimental tests carried... 

The conditions necessary for equality of particle size distribution were determined under ambient conditions. The nozzles used in the investigation can be classified as swirl-spray pressure nozzles. They accommodate a swirl insert which imparts a tangential velocity to the exiting fluid and results in a conical spray pattern. These nozzles were sufficiently different from conventional swirl nozzles (see Putnam et al., Ref. 6) to require an experimental study of particle size distribution. 

Turbidity has been widely used for determining the particle size distribution (PSD) of particles in suspension, since it is experimentally simple, can be used over a wide size range and does not disturb the system under investigation. It is also fast, reproducible and inexpensive. 

Reactant particle size distributions Kinetic characteristics of some reactions of solids depend sensitively on reactant particle sizes (29). Ideally, reactants to be used in kinetic studies should be composed of crystallites of identical (known) sizes and shapes, to which the geometry of interface advance can be related quantitatively. This is not, however, always (or easily) achieved in experimental studies, and most powder samples contain particles of disparate sizes for example, sometimes crystals are mixed with fine powder. The kinetic model giving the best apparent fit to the data then may not accurately represent the reaction. Dependencies of rate on particle size are only rarely investigated. The state of subdivision of a solid reactant is most frequently described in literature reports only by qualitative terms, such as single crystals or crushed powder. 

There is clearly a need to investigate the mechanism of attrition to relate it to the fracture properties of the solids, and to develop a realistic attrition index , similar to that used for abrasion in cyclones. Such an index would indicate the relative importance of operating conditions and design variables such as inlet velocity, feed solids concentration or cyclone diameter. This could then be used in scale-up to predict (or minimize) the effect of the shape, the particle size distribution or the hardness and strength of the feed solids, if known, may allow such predictions without any experimental tests. Generally, better understanding of attrition and its relation to abrasion may lead to better equipment design and operation. 

Chang J.S., Tsai L.J., Vigneswaran S. (1996), experimental investigation of the effect of particle size distribution of suspended particles on mictofiltration. Water Science Technology, 34, 9,133-140. 

Fang, Z. and Patterson, B. R., Experimental investigation of particle size distribution influence on diffusion controlled coarsening, Acta MetalL Mater., 41, 2017-24, 1993. 

Hostun sand, selected as the modeling sand for this experimental investigation, is a clean and uniform sand (Table 24.1) with a particle size distribution (PSD) curve that lies well within the bounds of soils most susceptible to liquefaction (Fig. 24.5). Its properties are described in detail by Havigny et al. (1990). 

Table 14.5 gives the data of all 19 mannitol batches, which were dried in the framework of the DoE (Sect. 2.2.5) including factors and levels as well as the responses. The improved experimental setup was applied to narrow the particle size distribution. In addition to the results of earlier experiments, bulk flowability and BET surface area were investigated. 

The experimental routine developed by Collins et and Lopez-Haro et al. ° for quantifying the adsorption of CO on Au/CZ catalysts has also been applied to the study of forms strongly chemisorbed on the support. In that study, two Au/CZ samples with a similar metal loading and the same CZ support were used. The only significant difference between the two investigated catalysts was the Au nano-particle size distribution, and consequent to this, the metal dispersion, D = Au /Au-j- = 0.68 for the sample referred to as Au/ CZ-HD and D = Aus/Auj- = 0.49 for the sample referred to as Au/ CZ-MD. Volumetric adsorption data and Au nanoparticle size distributions, as determined by HAADF-STEM, were the experimental basis for the study carried out by Cfes et al Figure 2.25 summarizes their results. 

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