Granular Packed Columns

The traditional operating mode of CEC with a conventional packed column is the use of commerdally available chromatographic resins, as used for HPLC or (iHPLC. Examples are RP Qg-modified silica particles of typical diameter 3-5 pm, ion-exchange resins and stationary phases for chiral separations. The latter indude 

In order to improve robustness and suppress bubble formation [23], pressurized flow generated by an LC pump was introduced as pressurized flow electrochromatography (PEC). Additionally it has a benefit with respect to retention time, since EOF is now superimposed by pressurized flow. Applied voltage and pressure are two tunable parameters for the adjustment of selectivity in PEC [18,66]. Most important, it is amendable for the gradient elution technique similarly to conventional HPLC, hence with PEC the promises of CEC can be fully exploited [67]. 

---

Removal of Refractory Organics. Ozone reacts slowly or insignificantly with certain micropoUutants in some source waters such as carbon tetrachloride, trichlorethylene (TCE), and perchlorethylene (PCE), as well as in chlorinated waters, ie, ttihalomethanes, THMs (eg, chloroform and bromoform), and haloacetic acids (HAAs) (eg, trichloroacetic acid). Some removal of these compounds occurs in the ozone contactor as a result of volatilization (115). Air-stripping in a packed column is effective for removing some THMs, but not CHBr. THMs can be adsorbed on granular activated carbon (GAG) but the adsorption efficiency is low. 

Acid Orange 7 Granular activated carbon-biofilm configured packed column With initial 500 mg L-1 dye concentration, a complete decolorization was achieved in all runs although the cosubstrates added into the BGAC-packed column system reduced until to zero [177]... 

Ong SA, Toorisaka E, Hirata M, Hano T (2006) Decolorization behavior of azo dye with various co-substrate dosages under granular activated carbon-biofilm configured packed column operation. ARPN J Engin Appl Sci 1 29-34... 

Flow of Fluids Through Granular Beds and Packed Columns... 

FLOW OF FLUIDS THROUGH GRANULAR BEDS AND PACKED COLUMNS... 

The Bioscrubber technology is based on the use of granular activated carbon (GAC) in packed columns. The GAC acts as a filter on which microorganisms can attach and create an environment in which they degrade the organic contaminants in the gaseous waste streams passed through the filter. 

Separative flow often occurs in a packed bed—typically a tube filled with a granular material. Chromatography in packed columns is the most important example of packed-bed flow. Similar flow is found in porous membranes used for membrane separation. The fluid flowing through such media can be a gas, a liquid, or a supercritical fluid. 

Column chromatography is of two kinds. In one the column is packed full of granular sorptive material, giving a packed column. In the other the column is empty except for a thin layer of sorptive material (usually a liquid film or bonded layer) coated on the wall of the column. Such columns, usually of small diameter (see Figure 1.3), are called capillary columns. They are used mainly in GC (20) but are undergoing rapid development in LC and SFC [21-23]. 

---