Particulate heterogenous characteristics

Measurement of aqueous particle size distributions presents a number of challenges to the analyst because of the heterogeneous characteristics of particulates. Shape, density, refractive index, and other physical properties are usually nonuniform throughout the six- to seven-decade... 

Cooper, P. L. and Abbatt, J. P. D. Heterogeneous interactions of OH and HO2 radicals with surfaces characteristic of atmospheric particulate matter, J. Phys. Chem., 100,2249-2254,1996. 

In multiphase reactors, the dispersed phase moves in one of two characteristic regimes, depending upon the nature of dispersion. The two regimes are homogeneous and heterogeneous. These regimes are commonly known as particulate and aggregative, respectively. 

Nevertheless, classical heterogeneous catalysts like particulate noble metals may be immobilized on the nanotube surface as well. Nanoparticles of platinum or rhodium, for instance, can be deposited on cup-stacked carbon nanotubes by reductive precipitation (Figure 3.114b). The catalysts obtained this way suit an application in fuel cells run on methanol. Electrodes made from the nanotube material exhibit twice the efficiency as compared to the classical material XC-72-carbon. The particles of noble metal on the nanotube surface catalyze the direct conversion of methanol into CO2 (MeOH -1- H2O CO2 -1- 6 H -1- 6e ). A material to be employed in such fuel cells has to meet some essential requirements, including a maximal specific surface, a defined porosity and a high degree of crystalhnity. Carbon nanotubes are endowed with exactly these characteristics, which is why they are the most suitable material for electrodes. Their high price, however, is still prohibitive to an industrial scale application. 

Quenching of Products of Direct UFe Decomposition in Thermal Plasma. Integrating kinetic equation (7-48), derive formula (7-49) for the mass decrease of uranium-containing product particles due to their gasification by fluorine. Analyze the effect of initial particulate size on the rate and characteristic time of the heterogeneous reverse reactions. Compare the efficiencies of quenching of UF4 and metallic uranium. 

Many polymerizations are performed in heterogeneous media, so that the final polymer product is obtained as a particulate material. The characteristics of the final particle size distribution (PSD) of the product maybe of fundamental importance for many applications. 

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