Collector experiments

Double- and triple-band electrodes have been constructed in a similar fashion by placing thin insulating films (e.g., Mylar) between the metal foils. These have been used in generator-collector experiments, in which one electrode (the collector) is used to monitor a product formed at the other electrode (the generator). This can be considered the microelectrode equivalent of the rotated ring-... 

In this paper it is shown that the rate of deposition of Brownian particles on the collector can be calculated by solving the convective diffusion equation subject to a virtual first order chemical reaction as a boundary condition at the surface. The boundary condition concentrates the surface-particle interaction forces. When the interaction potential between the particle and the collector experiences a sufficiently high maximum (see f ig. 2) the apparent rate constant of the boundary condition has the Arrhenius form. Equations for the apparent activation energy and the apparent frequency factor are established for this case as functions of Hamaker s constant, dielectric constant, ionic strength, surface potentials and particle radius. The rate... 

Manifold drying has several advantages over batch tray drying. Because vessels are attached to the manifold separately, each vial or flask has a direct path to the collector. This eliminates some of the competition for molecular space created in a batch system and is most ideally realized in a cylindrical drying chamber where the distance between each product and the collector will be identical. In a tee manifold, the water molecules leaving the product in vessels farthest from the collector experience some traffic congestion as they travel past ports of other vessels. 

Figure 10.2 Generator/coUector scheme oxidation of 2 mM ferrocene (Fc) in 0.1 M nBu4BF4/ CHjCN. Dashed line single band experiment (only one electrode is biased). SoUd lines generator/ collector experiment with = 0 V/SCE. Band width, w = 5 pm gap width, g = 2.5 pm and...

The design of industrial-scale collectors still rests essentially on empirical or semiempirical methods, although it is increasingly guided by concepts derived from theory. Existing theoretical models frequently embody constants that must be evaluated by experiment and that may actually compensate for deficiencies in the models. 

With the addition of appropriate additives as needed, the flotation of refineiy wastewaters reduced their oil content to less than 10 mg/L in pilot-plant operation [Steiner, Bennett, Mohler, and Clere, Chem. Eng. Frog., 74(12), 39 (1978)] and full-scale operation (Simouseu, Hydrocaih. Froce.ss. Fet. Refiner, 41(5), 145, 1962]. Experiments with a cationic collector to remove oils reportedly confirmed theoiy [Angehdon, Keskavarz, Richardson, and Jameson, Jnd. Eng. Chem. Frocess Des. Dev., 16, 436 (1977)]. 

Cyclone collectors are popularly used both for particle removal and for particle sampling (Fig. 13.1). The separation process of a cyclone relies on the centrifugal accelerations that are produced when particle-laden fluid experi-... 

Some petroleum geologists believe that there may be more methane trapped in hydrates than what is associated with natural gas reserves. However, as an energy source, there is considerable uncertainty whether this methane can ever be recovered safely, economically, and with minimal environmental impact. The Russians have experimented with the use of antifreeze to break down hydrates at some onshore locations in Siberia. But perhaps a more promising approach would be to pipe warm surface water to the bottom to melt the hydrates, with a collector positioned to convey the gas to the surface. Another approach might be to free methane by somehow reducing the pressure on the methane hydrates. 

Yet we must agree, there are advantages to the direct vision type of experiment. Often more detailed information can be obtained this way. Is the garbage collector tall Does he have a mustache Could the garbage collector be a woman This type of information is less easily obtained from other methods of observation. It is worthwhile setting the alarm clock, even after we have become convinced there is a garbage collector. 

FIGURE 10.5 Elution profile on OH-B12 treated by microwave heating for 6 min during silica gel 60 column chromatography. Fifty milliliters of the treated OH-B12 solution (5 mmol/1) was evaporated to dryness and dissolved in a small amount of w-butanol/2-pro-panol/water (10 7 10, v/v) as a solvent. The concentrated solution was put on a column (1.4 X 15.0 cm) of silica gel 60 equilibrated with the same solvent and eluted with the same solvent in the dark. The eluate was collected at 4.0 ml with a fraction collector. Fractions I to V were pooled, evaporated to dryness, dissolved with a small amount of distilled water, and analyzed with silica gel TLC. Inset represents the mobile pattern of the OH-B12 degradation products of fractions I to V on the TLC plate. Data are typical, taken from one of five experiments. (Reprinted with permission from Watanabe, F. et al., J. Agric. Food Chem., 46, 5177-5180, 1998. Copyright (1998) American Chemical Society.)... 

In a typical generation-collection experiment, two barrels of the 0-pipette are filled with water [10,11]. If one of the barrels ( generator ) contains a cation, it can be transferred to the outer organic solvent by biasing this pipette at a sufficiently positive potential (Eg). A significant fraction of ejected cations reaches the negatively biased second pipette ( collector ) and gets transferred back into the aqueous phase [Fig. 5(a)]. When only one... 

Also, Schier s experiments revealed the necessity to consider the directional influence of the walls of the filter bed on the bed porosity e. This effect is very important especially for small sized beds that are usually used in laboratories for investigations. For beds made of spherically shaped collectors several correlations exist describing the e(y/dc) function where y denotes the distance from the wall in the radial direction. However, for relative large bed diameters DB/dc ranging from 5 to 25 it proved to be sufficient to use an averaged e in Eq. (3.2.5), as proposed by Jeschar [6],... 

Early tests [37] utilized a cell design similar to that of early MCFC experiments. The assembled cell, machined from graphite blocks, is shown as Fig. 24. The electrodes and current collectors were machined from graphite and dense carbon, respectively. The electrolyte was a mixture of 63% Na2S, 37% Li2S, believed to melt near 850 °C the melting point after several days of operation was below 700 °C, probably because of polysulfide formation. The electrolyte was immobilized in a matrix of MgO, the whole formed by hot-pressing a mixture of electrolyte and ceramic powders. 

In many cases, data can be obtained offline and analyzed in a comprehensive manner from a fraction collector. For example, LC and gas chromatography (GC) can be utilized to form a 2D experiment — LC/GC. This is quite useful as the retention... 

Collect fractions starting from the bottom of the gradient, while recording an absorbance profile at 254 nm (which is dominated by the very abundant ribosomal RNA). We use a setup consisting of a peristaltic pump, ultraviolet (UV) detector, and fraction collector commonly used for chromatography experiments (GE Healthcare Life Sciences). 

Figure 18.1 shows the rate of flotation of different sulphides from operation A (UG2 Complex). In these experiments, xanthate was used as the primary collector with dithiopho-sphate as the secondary collector. 

From the data generated, higher dosages of NaHS are required to achieve activation of malachite. From plant and laboratory experience [13], the sulphidization method using xanthate collector is sensitive to the following, major factors ... 

The initial research work on oxide zinc flotation dates back to the 1930s at the University of Liege, Belgium [7]. This research work was based on the earned experience of flotation of oxide copper ores. Fatty acids, which are good collectors for copper carbonates, were not applicable because the gangue minerals in the zinc oxide ores were also floatable in the presence of fatty acids. 

The collector used in this experiment was sodium oleate at additions of 300 g/t. In addition to sodium oleate, other fatty acid collectors were examined. The results are given in Table 24.10. From these data, the saturated fatty acid soap was a poor collector for monazite, as well as sodium laurate. 

Figure 5. Generation/collection experiment with poly(I)-coated microelectrodes in CH3CN/O.I M [n-Bu4N]PFg at 10 mV/s. The lower cyclic voltammograms are for the generator electrode as its potential is swept between -0.2 V and -0.9 V vs. Ag+/Ag while the potential of the collector electrodes is held at 0.0 V vs. Ag+/Ag.

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