Quartz charged dust

A most important observation by Whitman, which substantiates Knoblauch s earlier work, was that the net charge acquired by a dust-cloud depends on the nature of the surface from which it is raised. By blowing ground fused quartz and other substances through tubes made of different materials, Whitman found that the net amount of charge on the dust per gram was by no means constant. Some of Whitman s results are given in Tables 30 and 31. 

Qzm and A50 have different affinities for BSA. Since the experiment was done at constant pH and ionic strength, the observed differences in the amount of BSA adsorbed, and the different conformation of BSA on the two silica dusts, is ascribed to the intrinsic properties of the two silica forms such as size and morphology (down to a micro- and nano level), surface hydrophilicity, impurities at the surface, and surface charge. Qzm and A50 particles are, in fact, very different entities they differ in particle dimensions (Qzm mean diameter 1600 nm, A50 40 nm) and bulk structure, which involves different surface features such as silanol population, (quartz exhibits around 5 SiOH/nm2, A50 2-3 SiOH/nm2), hydrophilicity, micromorphology (quartz particles exhibit steps and edges due to the grinding processes, fumed silica is made up by roundish particles) and the presence of metal ion impurities. 

Experiments to study the influence of electrostatic charges of dust particles on their retention in rat lungs showed that electric charges do not influence the retention of quartz dust particles in deep... 

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