Separating improvement

As expected, the separation improves if the sources of variation are reduced as in the situation represented in Fig. 8.13 in comparison with Fig. 8.12 where various wine-growing areas are considered. 

The phase structure of glasses has a significant effect on their physical properties, which is discussed below with reference to chemical durability. The magnitude of the phase separation can be altered by heat treatment, and enhanced or reduced by the addition of various oxides to the melt. In particular, the addition of alumina to commercial soda-lime-silica glasses reduces the tendency to phase separation, improving chemical resistance (Doremus, 1973). A detailed study of the microstructure of soda-lime-silica glasses has been published by Burnett and Douglas (1970). The control of phase separation in the melt is now commercially important for processes such as the... 

Step 2 The separation improves as the sample moves further through the column. 

Sweetening of light hydrocarbon streams n-paraffin separation improving jet fuel quality purification of aromatics... 

Revamps. The pressure drop advantage is invaluable in vacuum column revamps, can be translated to a capacity gain, an energy gain, a separation improvement, or various combinations of these benefits. Likewise, for towers in the suction of compressors, replacing trays by packings reduces the compression ratio and helps debottleneck the compressor. 

If a partial separation is found, adjust the pH + 0.5 pH units and perform the additional runs. If the separation improves, continue adjusting the pH in the direction in which improvement was noted. If the pAy s of the solutes are known, the pH equal to the average pKa may provide the best separation. In other cases, the fully ionized solutes yield the best separation. A mobility (or migration time) plot covering a wide range of pH can be performed if desired. The short end can be used to minimize run times. The most promising pH values can then be studied on the long end of the capillary. 

GTC Technology offers complete implementation of the technology and overall plant reviews for selective improvements to reduce operating and overall production costs. Some separate improvements available are ... 

Whereas R-(+)-MTPA esters of 2-hydroxyacids can be resolved on packed columns (Vl ), the separation of R- (+) -MTPA derivatives of chiral 3-hydroxyacids requires an efficient capillary column. The R-(+)-MTPA-esters possess higher separation factors than the PEIC derivatives, which depend on the chain length of the acid. The separation of R-(+)-MTPA derivatives of 3-hydroxyacid esters is influenced by the stationary phase. The efficiency of separation improves with increasing polarity of the phase, the highest 04-value was obtained with a bonded trifluoro-propylmethylsilicone phase ( 1 2). ... 

Despite the absence of a hydrophobic surface, a clear separation according to the analyte hydrophobicity was obtained. Since separation improves with increasing IPR concentration and hydrophobicity, the CE method demonstrates ion-pairing in solution... 

In RPC systems, the retention is weaker on weakly or moderately polar stationary phases such as on phenyl- or cyanopropyl-bonded phases than on an alkylsilica phase. RPC separations on phenyl or cyanopropyl columns may show selectivities differing from those observed on Cix or Cs phases, but their main advantage is lower concentration of organic solvent required to elute weakly polar samples, which may potentially reduce the separation time. For the great majority of samples, however, the selectivity of separation is generally better on alkylsilica-bonded phases. On the other hand, retention of hydrophilic samples can be increased and their separation improved on columns with a high amount of bonded carbon (polymeric bonded phases) or on hydrophobic organic polymeric materials such as styrene-divinylbenzene copolymers. 

Schnabel, S. Moulin, P. Nguyen, T. Roizard, D. Aptel, P. Removal of volatile organic components (VOC) from water by pervaporation with dense silicone hollow fibres. Separation improvement by Dean vortices. J. Membr. Sci. 

Figure 3.16 Separation improvement due to the principle of hydrophobic interaction. The chromatogram of a mixture of proteins of decreasing hydrophUicity ohtained hy gradually reducing the saline concentration (reproduced courtesy of Supelco).

Phase separation improvements are based on either surface modification, fluid property control, or physical separation. Studies have shown that organic liquid membranes can be developed in a microchannel device using surface modification [207,208]. An organic liquid membrane consists of an organic phase with aqueous phases on either side. An analyte can be extracted from the aqueous phase, into the organic phase and then back-extracted into the second aqueous phase. These three phases can flow stably within a single microchannel, but better separation of the three phases is possible with surface modification of the organic phase channel (Fig. 7.16). 

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