Separation capacity efficiency

Foi a veiy liigli quality baiiiei (p oo), the separative capacity of a stage having a mixing efficiency of 100% and operating at a cut of one-half would be ... 

Electrodriven techniques are useful as components in multidimensional separation systems due to their unique mechanisms of separation, high efficiency and speed. The work carried out by Jorgenson and co-workers has demonstrated the high efficiencies and peak capacities that are possible with comprehensive multidimensional electrodriven separations. The speed and efficiency of CZE makes it possibly the best technique to use for the final dimension in a liquid phase multidimensional separation. It can be envisaged that multidimensional electrodriven techniques will eventually be applied to the analysis of complex mixtures of all types. The peak capacities that can result from these techniques make them extraordinarily powerful tools. When the limitations of one-dimensional separations are finally realized, and the simplicity of multidimensional methods is enhanced, the use of multidimensional electrodriven separations may become more widespread. 

Inside diameter 0.1mm High pressure drop required Lowest sample capacity Fast separations Most efficient but usually short column... 

Pluym et al. compared the use of CE to that of HPLC in chemical and pharmaceutical quality control. They stated that CE could be considered as a complementary technique to HPLC because of its large separation capacity, its simplicity, and its economical benefits. Jimidar et al. decided that CE offers high separation efficiency and can be applied as an adjunct in HPLC method validation. Mol et al. evaluated the use of micellar electrokinetic chromatography (MEKC) coupled with electrospray ionization mass spectrometry (ESI—MS) in impurity profiling of drugs, which resulted in efficient separations. 

Until now, it has been possible to quantitatively evaluate the separation efficiency based on the spatial distribution of each component in the vessel. It is obvious that the separation capacity should be evaluated based on the change in separation efficiency with time. However, investigations on the separation capacity based on the change in separation efficiency with time are few. This fact depends on the flow separation system being the main current and the batch separation system being the secondary current. 

Wide scope vs. high sensitivity Time constant The separation Capacity factor Selectivity Efficiency Resolution... 

In the course of the development of CSPs, a broad variety of chiral molecules (and materials) has been the subject of scrutiny with respect to chromatographic enantiomer separation capacity. The chiral molecules studied as potential SOs cover virtually the entire chemical and structural diversity space, ranging from low-molecular-weight compounds to polymers of both synthetic and biological origin. So far, the (stiU ongoing) quest for efficient SOs has resulted in the synthesis of more than 1400 CSPs [94], the properties of which are documented in an almost intractable number of dedicated scientific publications. The outcome of these efforts is manifest in an enormously rich toolbox of more than 200 commercially available CSPs offered by various speciahzed suppliers. 

A annual cost, /year A tower cross-sectional area b defined by Eq. (13.36) c defined by Eq. (13.35) c unit cost D separative capacity E efficiency F molar feed rate... 

Equation (14.111) for the minimum power of 0.0923 kW to produce 1 kg of separative work per year in uranium isotope separation was derived for cross flow on the low-pressure side of the barrier, with the composition of gas on that side y equal to the composition of the net flow u. The purpose of this section is to show that the minimum power requirement could be reduced further by having v greater than y by an appropriate amount and to derive an expression for the optimum difference between v and y and the corresponding power consumption per unit separative capacity. For this minimum wer case, pressures on the high-pressure and low-pressure sides of the barrier must be so low the only flow through the barrier is of the separating, molecular type, and the mixing efficiency on each side of the barrier is unity. 

Cohen [C6] has shown that the first factor represents the maximum possible separative capacity per unit length for a centrifuge operating at peripheral speed Va, in the absence of axial back diffusion. The second factor, termed the circulation efficiency E c takes into account reduction in separative capacity caused by axial back diffusion. It approaches unity as the circulation rate N increases or the radius a decreases. Values of the first factor for separating from (Am = 3) at 300 K, using the value of Dp = 2.161 X 10" g UF6/(cm-s) recommended by May [M6] are... 

The flow pattern efficiency decreases from 0.56 at = 400 m/s to 0.19 at 700 m/s. When combined with the in the first factor of Eq. (14.226), the overall effect is to cause the separative capacity per unit length to vary as over this range of v, instead of as Vg. 

In Table 14.16, the feed rate is held constant at 0.03171 g UF /s (1000 kg UF /year) and the circulation rate is varied. The separative capacity has a maximum of 10.03 kg uranium SWU/year at an optimum circulation rate N = 0.1884 g UFe/s and decreases rather rapidly with changes from this rate. The axial separation factor has a maximum of 1.41 at the optimum circulation rate. The height of a transfer unit increases almost proportionally with circulation rate. The circulation efficiency increases from 0.9095 at the lowest circulation rate of 0.0942 g/s to practically unity at the highest, showing the decreasing influence of axial back diffusion as circulation rate increases. 

Unlike the internals discussed in previous chapters, poor tray layout of one- or two-pass trays rarely causes spectacular column failures such as flooding at 50 percent of design rates or extremely poor separation. Ill effects resulting from poor tray layout seldom extend beyond suboptimum design or performance a moderate reduction in capacity, efficiency, or turndown and some increases in capital or... 

R Resolution 4 a k+1) The degree to which one peak is separated from another. Distance between peaks at the peak bases. This is the separation criterion for a chromatographic system, since everything depends on the resolution, which influences the separation capacity, selectivity and efficiency. 

A detailed review of existing equipment s design and construction drawings will also provide insights into various equipment and plot limitations. For example, increased feed rate, improper internals and level controls can adversely affect a separator s efficiency. A review of these details in the existing separators will be very useful for revamp projects. Similarly, careful review of column internal details is required to check possible modification to increase capacity/efficiency and reduce flooding/weeping. 

The separation characteristics of a considerable variety of other TLC supports were also tested using different dye mixtures (magnesia, polyamide, silylated silica, octadecyl-bonded silica, carboxymethyl cellulose, zeolite, etc.) however, these supports have not been frequently applied in practical TLC of this class of compounds. Optimization procedures such as the prisma and the simplex methods have also found application in the TLC analysis of synthetic dyes. It was established that six red synthetic dyes (C.I. 15580 C.I. 15585 C.I. 15630 C.I. 15800 C.I. 15880 C.I. 15865) can be fully separated on silica high-performance TLC (HPTLC) layers in a three-solvent system calculated by the optimization models. The theoretical plate number and the consequent separation capacity of traditional TLC can be considerably enhanced by using supports of lower particle size (about 5 fim) and a narrower particle size distribution. The application of these HPTLC layers for the analysis of basic and cationic synthetic dyes has also been reviewed. The advantages of overpressured (or forced flow) TLC include improved separation efficiency, lower detection limit, and lower solvent consumption, and they have also been exploited in the analysis of synthetic dyes. 

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