Sorption washing columns

Generally, SPE consists of four steps (Figure 2.42) column preparation, or prewash, sample loading (retention or sorption), column postwash, and sample desorption (elution or desorption), although some of the recent advances in sorbent technology reduce or eliminate column preparation procedures. The prewash step is used to condition the stationary phase if necessary, and the optional column postwash is used to remove undesirable contaminants. Usually, the compounds of interest are retained on the sorbent while interferences are washed away. Analytes are recovered via an elution solvent. 

Cesium Separation. Cesium will be removed from the waste super-nate by sorption on a phenol-sulfonic ion exchange resin such as Duolite (Diamond Shamrock Chemical Co.) ARC 359, as shown in Figure 3. This flowsheet is a modification of one currently being used by ARHCO at Hanford (3), Cesium will be absorbed on the two columns in tandem until breakthrough from the first column exceeds a predetermined level, after which the column will be washed with water (not shown in the diagram) and eluted with a mixture of ammonium carbonate and ammonium hydroxide. Breakthrough will be detected by a gamma ray monitor on the line between the two columns. 

Although less frequently exploited, placement of a mini-column before the main analytical channel can also be used for in-line analyte concentration in segmented flow analysis. The sample flows through the minicolumn, where the analyte is retained, and the carrier/wash stream also acts as the eluting/conditioning solution. Increasing the sample flow rate and/or the available time interval for analyte sorption improves the sensitivity. 

The mini-column can be placed between the injection port and the detection unit (Fig. 8.19), and the solutions involved (sample, wash, eluent and conditioning) are sequentially passed through the column. The flow system can be manual or computer-controlled. This manifold geometry is exemplified by the flow injection chemiluminometric determination of zinc and cadmium [207], After sorption of the analytes as chloro-complexes, two different eluting solutions were injected, allowing sequential determinations the resin was reconditioned by the water carrier stream. This geometry can also be implemented in sequential injection analysis and bead injection analysis, as demonstrated in the... 

The separation typically is performed by adding from a few milliliters to a few liters of the radionuclide-bearing sample to a resin column of about 5-50 ml, and then washing the radionuclides sorbed on the column with water or a dilute reagent. In the sorption phase, radionuclides of interest either are retained at the... 

Metal-ion uptake in a dynamic system Sorption experiments in a dynamic system were carried out using a glass column (length 10 cm, internal diameter 1.2 cm) filled with 1.0 g resin. The resin was washed with distilled-deionized water (10 bed volumes), then a solution containing 40 ppm Cu was passed through at a flow rate of 3 mLmin . For determination of the breakthrough curve, the eluate from the column was collected in 50 mL fractions and the copper cation concentration was determined by atomic absorption spectroscopy. 

After the sorption step, the column was washed with 8 M HCl (containing a little concentrated HNOg) until the effluent was practically free from -activity. 

Abstract The paper reports on lab-scale column studies for in situ surfactant washing of oil-contaminated soils. The displacment efficiency of nonionic surfactants and their blends was tested on small columns. The kinetics of oil displacement and surfactant sorption-desorption were studied. Further, the viscosity behavior of emulsions of varying compositions was investigated. No single optimum HLB value was found for the displacement of a selected oil. 

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