Selectivity flow rate, effect

In the present paper, flow rate effects on leaching are analyzed from a theoretical point of view and are rationalized in a consistent, generic leaching model incorporating the dependence of the mechanisms of selective leaching and network dissolution on solution feedback effects. 

The selectivity to PO (S) was drastically varied as S=13 55 and S=5 12 % depending on the C-up and C-down operations respectively. The total gas flow rate effectively contributed to the enhancement of S as S=18 41 % with increasing the flow rate, indicating an advantage of the membrane reactor (which was characterized by a convection flow in membrane pores) rather than conventional packed bed reactors (which were characterized by molecular diffusion in the pores of catalyst particles). 

Adsorption systems employing molecular sieves are available for feed gases having low acid gas concentrations. Another option is based on the use of polymeric, semipermeable membranes which rely on the higher solubiHties and diffusion rates of carbon dioxide and hydrogen sulfide in the polymeric material relative to methane for membrane selectivity and separation of the various constituents. Membrane units have been designed that are effective at small and medium flow rates for the bulk removal of carbon dioxide. 

The effects of each selective removal function on CSD can be described in terms of the population density function n. It is convenient to define flow rates in terms of clear Hquor, which requires the population s density function to be defined on a clear-Hquor basis. In the present discussion, only systems exhibiting invariant crystal growth are considered. 

The duration of the response results primarily from the rate of elution of the sample, and not on any inherent limitation in the response time of the electrode. This is a characteristic of ion-selective electrodes, but amperometric responses depend not only on the duration of elution but also on flow rate because of the hydrodynamic effects discussed previously. 

Refrigerating capacity is the product of mass flow rate of refrigerant m and refrigerating effect R which is (for isobaric evaporation) R = hevaporator outlet evaporator mJef Powei P required foi the coiTipressiou, necessary for the motor selection, is the product of mass flow rate m and work of compression W. The latter is, for the isentropic compression, W = hjisehatge suction- Both of thoso chai acteristics could be calculated for the ideal (without losses) and for the ac tual compressor. ideaUy, the mass flow rate is equal to the product of the compressor displacement per unit time and the gas density p m = p. 

I have carried out widespread studies on the application of a sensitive and selective preconcentration method for the determination of trace a mounts of nickel by atomic absorption spectrometry. The method is based on soi ption of Cu(II) ions on natural Analcime Zeolit column modified with a new Schiff base 5-((4-hexaoxyphenylazo)-N-(n-hexyl-aminophenyl)) Salicylaldimine and then eluted with O.IM EDTA and determination by EAAS. Various parameters such as the effect of pH, flow rate, type and minimum amount of stripping and the effects of various cationic interferences on the recovery of ions were studied in the present work. 

The particles most likely to cause adverse health effects are the fine particulates, in particular, particles smaller than 10 p and 2.5 mm in aerodynamic diameter, respectively. They are sampled using (a) a high-volume sampler with a size-selective inlet using a quartz filter or (b) a dichotomous sampler that operates at a slower flow rate, separating on a Teflon filter particles smaller than 2.5 mm and sizes between 2.5 mm and 10 mm. No generally accepted conversion method exists between TSP and PM,o, which may constitute between 40% and 70% of TSP. In 1987, the USEPA switched its air quality standards from TSP to PMk,. PM,q standards have also been adopted in, for example, Brazil, Japan, and the Philippines. In light of the emerging evidence on the health impacts of fine particulates, the USEPA has proposed that U.S. ambient standards for airborne particulates be defined in terms of fine particulate matter. 

Some GPC analysts use totally excluded, rather than totally permeated, flow markers to make flow rate corrections. Most of the previously mentioned requirements for totally permeated flow marker selection still are requirements for a totally excluded flow marker. Coelution effects can often be avoided in this approach. It must be pointed out that species eluting at the excluded volume of a column set are not immune to adsorption problems and may even have variability issues arising from viscosity effects of these necessarily higher molecular weight species from the column. 

Fig. 2-11. The effect of flow rate on the selectivity of a-methyl-a-phenyl succinimide on teicoplanin CSP (250 X 4.6 mm) in normal phase. The mobile phase was ethanol hexane (20/80 v/v) at ambient temperature (23 °C).

This is because the increased turbulence from higher flow rates decreases the possibility for inclusion complexation, a necessary event for chiral recognition in reversed phase. Some effect has also been observed in the new polar organic mode when (capacity factor) is small (< 1). Flow rate has no effect on selectivity in the typic normal-phase system, even at flow rates up to 3 inL miir (see Fig. 2-11). 

Figure 9.22. Effect of catalyst potential, UWr, on conversion of acetylene (a) and selectivity towards ethene formation (b) with H2 C2H2=9 1. Conditions pH2-60 kPa, Pc2h2=7 kPa. pHe=34 kPa, total flow rate Fv=30.3 cm3 STP/min. UWr was initially set at +400 mV and was increased in steps until the maximum negative voltage was applied. Uwr was then returned to its original value of +400 mV and the open symbols correspond to measurements taken at this point.31 Reprinted with permission from Academic Press.

The fact that APCl and electrospray are soft ionization techniques is often advantageous because the molecular ion alone, in conjunction with HPLC separation, often provides adequate selectivity and sensitivity to allow an analytical method to be developed. Again, method development is important, particularly when more than one analyte is to be determined, when the effect of experimental parameters, such as pH, flow rate, etc., is not likely to be the same for each. Electrospray, in particular, is susceptible to matrix effects and the method of standard additions is often required to provide adequate accuracy and precision. 

Liquid phase oxidation reaction of acetaldehyde with Mn acetate catalyst can be considered as pseudo first order irreversible reaction with respect to oxygen, and the reaction occurred in liquid film. The value of kinetic constant as follow k/ = 6.64.10 exp(-12709/RT), k2 = 244.17 exp(-1.8/RT) and Lj = 3.11.10 exp(-13639/RT) m. kmor. s. The conversion can be increased by increasing gas flow rate and temperature, however the effect of impeller rotation on the conversion is not significant. The highest conversion 32.5% was obtained at the rotation speed of 900 rpm, temperature 55 C, and gas flow rate 10" m. s. The selectivity of acetic acid was affected by impeller rotation speed, gas flow rate and temperature. The highest selectivity of acetic acid was 70.5% at 500 rpm rotation speed, temperature of 55 C... 

Figure 3. Effect of temperature on the selectivity of the SCR reaction over CoZSM-5 (A) and HZSM-5 (B) catalysts. Feed contained 0.28% CH4, 0.21% NO and 2.6% O2 in He at a flow rate of 75 ml/min ( flow rates of CH4 and NO were 9.375 and 7.03//mol/min).

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