Surface grinding experiments

The mechanical electrochemishy equipment is different from conventional electrochemistry equipment, which can exert pressure to the surface of the electrode by adjusting die height of the lifting platform and change the pressure of electrode (see Fig. 8.1). Before the experiment, the electrode surface was polished, and the grinding media, electrolyte and reagent were added in order. 

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. 

This conclusion was confirmed by other experiments. Indeed, an increasing active surface area produced by grinding promotes grafting to cotton however, the yield of the grafted polymer and the grafting efficiency were considerably lower than in the treatment with 40-80% ethylene diamine solution or 20% aqueous alkali16,17). 

Sample preparation requires extreme care to avoid the introduction of contamination in the cutting and grinding operations. This is an area where operator experience is of prime importance. Extensive cleaning and etching may be required to provide an analysis representative of the sample composition. A further cleaning step is provided In the instrument itself by sparking the sample surface energetically to clean away the first few atomic layers. This prespark can be recorded on the photoplate to provide qualitative information about the chemistry of the surface. 

This hypothesis is corroborated by the kinetic interpretation of experiments using KF which has been previously activated by sonication or grinding some pathways can be favoured over others depending on the surface state (Table 29) ... 

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