Liquid flow contaminants applications

With electrospray ionization, a fine mist of highly charged particles is produced when a liquid flows from a capillary tube into a strong electrical field (3 to 6kV).In practice, electrospray ionization sources are often directly coupled with reversed phase HPLC or capillary columns. The ability to couple a liquid chromatograph with an electrospray ionization source and a mass spectrometer allows the online removal of salts and contaminants and the analysis of complex mixtures. Although different from MALDI, electrospray provides similar sensitivity and application to the analysis of large proteins. 

Related to this last process enhancement is the use of an EK barrier, or fence. The EK barrier has two different objectives depending on its use (a) to precipitate or transform heavy metals transported by electric fields or (b) to stop a hydraulic generated flow of liquid with contaminants by the application of an electric field in the opposite direction. In the first approach, zero-valent iron has mainly been used... 

Researchers operating with the TLC technique have some general options, shown in Fig. 1. The pure (unencapsulated) TLC substance applied in very thin films onto a flat surface offers temperature field measurements with a spatial resolution of about 800 nm. But, unencapsulated TLCs require sophisticated application techniques and the pure TLC substance is very sensitive to UV light and contaminations, particularly oxygen from the air. More common are micro-encapsulated TLCs which are stable and easier to handle. They are available as complete foils, in binder mixtures for spray applications and as tracers. With the latter it is possible to acquire the temperature distribution in liquid flows. 

Bubble columns and various modifications such as airlift reactors, impinging-jet-reactors, downflow bubble columns are frequently used in lab-scale ozonation experiments. Moderate /qa-values in the range of 0.005-0.01 s l can be achieved in simple bubble columns (Martin et al. 1994 Table 2-4 ). Due to the ease of operation they are mostly operated in a cocurrent mode. Countercurrent mode of operation, up-flow gas and down-flow liquid, has seldom been reported for lab-scale studies, but can easily be achieved by means of applying an internal recycle-flow of the liquid, pumping it from the bottom to the top of the reactor. The advantage is an increased level of the dissolved ozone concentration cL in the reactor (effluent), which is especially important in the case of low contaminant concentrations (c(M)) and/or low reaction rate constants, i. e. typical drinking water applications... 

Gel permeation chromatography (GPC) is essentially a process for the separation of polymer molecules according to their size. The separation occurs as the solute molecules in a flowing liquid move through a stationary bed of porous particles. The method has been used extensively in biochemistry to separate biological polymer molecules from small molecule contaminants (with the use of Sephadex column). Application of the method to synthetic polymer chemistry in the 1970s has revolutionized the procedures for polymer characterization and molecular weight determination. 

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