Phase splitting contaminants

The influence of traces of contaminants on phase splitting is demonstrated in Fig. 6.3-9. The pretreatment of the water, either by a fresh or a used deionization agent, changes the phase splitting time by two orders of magnitude. The effect of surface active contaminants (sodium lauryl sulfate) is even larger as the experiments with MIBK/water clearly prove. 

For optimum splitting, a contamination of less than 2% was found. By operating at slightly higher flow rates, one stream could be made contamination free. Thus, a clean product phase can be obtained when performing the nitration in the T-piece/ tube reactor. 

When applied as a unit operation, adsorption can be used to split mixtures containing significant percentages of adsorbable components or purify streams containing trace amounts of contaminants. These separations, whether for gases or liquids, are accomplished by allowing the fluid and solid phases to interact under controlled conditions. Molecules that are selectively taken up are called adsorbates, and the solid surface that attracts the adsorbate is called the adsorbent. Jargon used in connection with adsorbents and adsorption, as well as some prominent definitions, are listed in Table 14.1. Fundamental causes and effects of adsorption are discussed in Section 14.3. 

Another environmental effect that cannot be overlooked is the problem of disposal of possibly large volumes of polymer dispersion should such quantities become so contaminated that they cannot be used. Such disposal is difficult and expensive, involving the splitting of the emulsion, separation of the aqueous and non-aqueous phases, treatment of these and safe and responsible disposal. 

The overall ELM process is shown in Figure 4. The selenium contaminated wastewater is contacted with the emulsion in one or more stirred tanks or in a coimter-current contactor extractor, as illustrated in Figure 4. The selenium concentration in the treated wastewater is reduced to nearly zero, and the concentration in the interior phase of the emulsion increases. The emulsion and wastewater are separated in a settler the cleaned effluent water is ready for discharge the emulsion phase is then taken and split in an electrostatic coalescer. After the emulsion is coalesced, a much smaller volume of greatly concentrated selenium must be treated further and disposed. The oil phase from the coalescer is then mixed with fresh NaCl at high shear rates to reform the emulsion, and returned... 

Several techniques for interfacing flow injection analysis to CE have been reported in the literature [11]. In most of the systems designed, buffer contamination took place as a result of the sample solution passing through the buffer reservoir, and hence sample consumption increased as the polluted buffer was removed. Han et al. [12] developed an improved split-flow interface to protect the running buffer from contamination and thus reduce its consumption. The technique involved coupling online solid-phase extraction... 

It is possible to introduce oxygen as a gas to the spray chamber to help with the organic solvent content of some mobile phases. In speciation methods where a lot of organic solvent is required for the chromatography, e.g. for lead compounds, if the concentrations of the analytes are high then it would be possible to split the flow from the LC column and mix with an aqueous solution to reduce the carbon contamination of the sample cones. 

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