Liquid emulsion techniques

Autoradiographs may be obtained by pressing a photographic plate or film on the surface of the sample or by the stripping-film or liquid emulsion techniques. 

The choice of scale-up technique depends on the particular system. As a general guide, constant tip speed is used where suspended solids are involved, where heat is transferred to a coil or jacket, and for miscible liquids. Constant power per unit volume is used with immiscible liquids, emulsions, pastes and gas-liquid systems. Constant tip speed seems more appropriate in this case, and hence the rotor speed should be 0.66 Hz. The... 

C. These freeze-dried sections were dry mounted on microscope slides which had been precoated with either Kodak NTB-3 or NTB-10 emulsion. Other techniques which thawed the frozen section, embedded the tissue in paraffin or dipped the section in liquid emulsion were demonstrated to translocate diffusible compounds. Many other similar attempts have been and are currently being made to localize diffusible compounds by autoradiography at the electron microscope level. 

Autoradiography offered an alternative technique. The earliest experiments followed the uptake of radioiodine into the thyroid by placing the tissue sections in direct contact with photographic plates (Hamilton, Soley, and Eichom, 1940 Leblond, 1943). Belanger and Leblond introduced the use of liquid emulsion in 1946. Initially this was painted onto sections mounted on microscope slides. Later, slides were dipped into liquid emulsion (Joftes and Warren, 1955) or wrapped around with stripping film (Doniach and Pelc, 1950). Semiquantitative comparisons... 

In order to develop the liquid membrane techniques, i.e., emulsion Hquid membrane (ELM), supported liquid membrane (SLM), non-dispersive extraction in hollow fiber membrane (HFM), etc., for practical processes, it is necessary to generate data on equilibrium and kinetics of reactive extraction. Furthermore, a prior demonstration of the phenomena of facilitated transport in a simple liquid membrane system, the so-called bulk liquid membrane (BLM), is thought to be effective. Since discovery by Li [28], the liquid membrane technique has been extensively studied for the separation of metal ion, amino acid, and carboxyHc acid, etc., from dilute aqueous solutions [29]. 

The processes developed initially were based essentially on liquid-liquid extraction techniques, but the chemical problems encountered in the treatment of irradiated Pu/Al targets (e.g. considerable interface fouling in the extractors and formation of stable emulsions) and the intensification of safety requirements led to use of extraction chromatographic techniques. 

In these techniques, a strip of a thin photographic layer or a liquid emulsion are directly placed on the surface of the sample. After exposure and developing, sample and photographic emulsion can be investigated by means of a microscope (microautoradiography). 

Eroglu I, Kalpakici R, and Gunduz G. Extraction of strontium ions with emulsion liquid membrane technique. J Membr Sci 1993 80 319-325. 

Table 31.3 gives a few typical examples on recovery of actinides by ELM. Myriad literature reports exist on the use of HDEHP for metal extraction involve ELMs. Comparative studies between column and batch liquid emulsion membrane techniques based on HDEHP/HCl system were carried out to develop a system for the isolation of Th from natural uranium, which showed that, kineticaUy, the equilibrium for thorium separation using batch technique is faster than the continuous column system [37]. The effective separation of Th from natural uranium was found to be independent of time. El-Sherif studied... 

Pure tetrafluoroethylene monomer under ambient conditions is an odorless, colorless, tasteless gas with low toxicity. It may be polymerized by either suspension or emulsion techniques. Both procedures require use of high pressures in an autoclave in order to maintain the monomer in liquid form. These techniques produce chemically identical product, the first a granular resin, and the second a fine powder (Eq. 23.7). 

Gurel, L., Alias, L. and Buyukgungor, H. (2005). Removal of lead from wastewater using emulsion liquid membrane technique. Environ. Eng. Sci., 22, 411-20. 

If solvent extraction may be considered a source technique, derived liquid-liquid separation techniques include configurations in which an extraction solvent is physically immobilized by a coating or impregnation process onto a solid support such as silica, porous resin beads, or foam [13,84—87]. Other derived techniques include membranes of various configurations bulk liquid membranes, supported liquid membranes, emulsion membranes, and polymer-impregnated membranes [88]. Many derived liquid-liquid techniques have been developed, especially for use in analytical applications [13,60,62,64,75,84,85,87]. In each of these derived techniques, the... 

MacFarlane, D. R., and Angell, C. A., An emulsion technique for the study of marginal glass formation in molecular liquids, J. Phys. Chem., 86, 1927-1930 (1982). 

In lab-scale SWE, separation of the compounds from the aqueous extract obtained is the critical stage. A liquid-liquid extraction technique often causes emulsion and breaking this can be very difficult. It has been found that solid phase extraction is a better technique for the removal of compounds from the aqueous environment of SWE when comp>ared with liquid-liquid extraction (Rovio et al., 1999 Ozel et al., 2003). Headspace solid phase microextraction with GC-MS may be another alternative (Deng et al., 2005). 

The utility of a thin layer of liquid as a selective membrane for separations has been explored extensively over the last thirty years. Three techniques have been used traditionally to exploit a thin liquid layer as a membrane emulsion liquid membranes (ELM) for separation of liquid solutions (7) supported liquid membranes (SLM) in the pores of a porous/microporous support membrane for the separation of liquid feeds and immobilized liquid membranes (ILM) in the pores of a porous/microporous support membrane for separating a gas mixture. SLM and ILM are different names for the same liquid membrane technique and have been briefly reviewed by Majumdar et aL (2) and Boyadzhiev and Lazarova (i). 

Emulsion Liquid Membrane Separation. The principle of the emulsion liquid membrane technique, which was discovered by Li (77), is based on the separation of internal (receiving phase) and external (source phase) aqueous solutions by an organic liquid membrane that contains an emulsifying agent (surfactant) and carrier... 

Radical polymerizations are versatile and can be initiated effectively in gas, solid, and liquid phases. Polymerizations can be carried out in bulk, solution, precipitation, suspension, and emulsion techniques. Each process has its own merits and special characteristics. 

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