Surface area effective 8, meter

This result, obtained for the case L specific catalytic activity of semiconductors with an increase in the degree of dispersion, so frequently mentioned in the literature. The effect should evidently become important the earlier (i.e., the less the degree of dispersion) the greater the screening length I in the specimen. One could expect to observe it at S/V > 10 cm. i, i.e., when the surface area is of the order of tens of square meters per gram. 

FIG. 14-60 Effect of structured packing surface areas, loads, and inclination angle on packing efficiency. Efficiency expressed as number of theoretical stages per meter, the reciprocal of HETP. Sulzer data, chlorobenzene-ethylbenzene, 100 mbar, at total reflux 250-mm-diameter test column. (Reprinted courtesy of Sulzer... 

Hemoperfusion differs from hemodialysis in that the blood is passed over a resin or charcoal column. The drug becomes bound to the column and the clean blood returned to the body. Hemoperfusion units have adsorptive surface areas of several thousand square meters while hemodialysis devices have an effective dialysis surface limited to several square meters. Obviously, relatively sophisticated technology is required for these procedures and there is the need to prevent clotting in the circuit, which can produce complications. 

This test, which lasts 64 days and is described in Dutch standard NEN 7345, is intended to determine leaching from products or stabilized waste materials as a function of time. The product is immersed in acidified demineralized water. This eluate is refreshed at seven specified times. Analysis of the eluates enables the leaching per square meter of product surface area and the effective diffusion coefficient to be calculated. 

Gravity separators need to be designed both to contain a defined oil spill size, as well as for managing routine process wastewater flows. Gravity oil separators for these apphcations should be designed for rise rate loadings to accommodate peak flows, if practical. Experience dictates rise rates in the range of 10 to 20 L/min per square meter of effective separator surface area. 

An interesting effect of autocatalysis by deposited sulfur was identified by Steijns and coworkers [27, 28]. Studying adsorption of hydrogen sulfide on various adsorbents, they found that deposition of sulfur at the beginning of the removal process increases the catalytic activity of the carbon. Then, when sulfur starts to block microporosity, a rapid decrease in activity follows. It was postulated that elemental sulfur is rather in the form of radical chains than Sg rings [28]. Steijns and Mars found that the catalytic activity per square meter of total surface area is approximately proportional to the amount of adsorbed sulfur. On the other hand, no evidence of sulfur autocatalysis was found by Ghosh and ToUefson [20, 21]. 

ISEs it is common practice to use potential measuring instruments with input impedances >10 Cl to ensure that there is no error in the potential measurement. Most modern pH/mV meters constructed with field-effect transistor-type input amplifiers fulfill this requirement. However, as the electrode surface area becomes smaller, the resistance of the ISE increases dramatically. Thus, for microsized electrodes, specially designed amplifier circuits with even higher input impedances are required to obtain accurate intracellular ion values and to help eliminate noise. In many instance, the micro-type measurements must also be made within the confines of a Faraday cage to reduce noise further by shielding the electrodes finm environmental noise. In automated clinical chemistry analyzers, confinement of the electrodes within the outer metal cabinet of the instrument serves a similar purpose. 

Assume that the surface area is A square meters in each eifect and that the overall coefficient 17 is also the same in each effect. Then Eq. (16.15) can be written... 

Figure 23,2.6. GCW process diagram. Effective hydrocarbon stripping in the water column is observed in these systems using a vacuum extraction. A circulation cell is created by directional flow of water in the vertieal direetion creating a capture zone extending several meters from the well. In addition a bioreactor (high surface area baeteiial biofilm) can be used in the system to degrade low volatile contaminants [Adapted from Bemhartt et al., U.S. Patent 5,910,245,1999]...

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