Surface distillation technique

Another vacuum distillation technique, including for water removal in large-scale operations, is evaporation. Thin-film evaporators are designed to expose large surface areas of liquid to heat and/or vacuum in order to speed the evaporation process. The design principle is illustrated in Figure 5. 

TiTany authors (I, 2, 3) have compared the surface behavior of macro- molecules, especially proteins, with the behavior of low molecular weight monolayers. This paper notes a series of effects that occurred when bovine serum albumin (BSA) was spread on various clean liquid surfaces and was compressed or decompressed. The transfer of the protein monolayer and of some small chain monolayers was also studied using a surface distillation technique. 

Hydrodiffusion is a steam distillation method, whereby steam is fed to the plant material from the top. Steam penetrating the plant matrix condenses and forces the essential oil to diffuse to the surface. Because of gravity, oil leaves the vessel together with the condensate water from the bottom of the still. Powdering the material results in better oil yields. This technique is suitable both for superficial and subcutaneous oils. The disadvantage of this technique is the undesired extraction of coumarins, psoralens, and chlorophyll into the oil. Therefore, hydrodiffusion has not become a widely used distillation technique. 

NR with standard recipe with 10 phr CB (NR 10) was prepared as the sample. The compound recipe is shown in Table 21.2. The sectioned surface by cryo-microtome was observed by AFM. The cantilever used in this smdy was made of Si3N4. The adhesion between probe tip and sample makes the situation complicated and it becomes impossible to apply mathematical analysis with the assumption of Hertzian contact in order to estimate Young s modulus from force-distance curve. Thus, aU the experiments were performed in distilled water. The selection of cantilever is another important factor to discuss the quantitative value of Young s modulus. The spring constant of 0.12 N m (nominal) was used, which was appropriate to deform at rubbery regions. The FV technique was employed as explained in Section 21.3.3. The maximum load was defined as the load corresponding to the set-point deflection. 

Materials. Na-Kaolinite A homoionic sample of kaolinite was prepared from a well-crystallized sample purchased from Source Clays, University of Missouri, using a standardized technique (14) which involved repeated washing with distilled water and by treatment with NaCl solutions to remove exchangeable ions such as Ca, and freeze-drying of the final product. Nitrogen specific surface area of this kaolinite was estimated to be 9.4nr/g and X-ray analysis showed the characteristic pattern of kaolinite. 

Surface tension measurements. Solutions of the betaines were prepared with quartz-condensed, distilled water, specific conductance, 1.1 X 10" mho cm" at 25°C. All surface tension measurements were made by Wilhelmy vertical plate technique. Solutions to be tested were immersed in a constant-temperature bath at the desired temperature 0.02°C and aged for at least 0.5 h before measurements were made. The pH of all solutions was > 5.0 (usually, in the range 5.5-5.9), where surface properties show no change with pH. 

Impedance diagram technique. The polarization cell consisted in a transparent plastic tube that was adhered to the paint surface by means of a silicone sealer. The tube contained distilled water and a 25 cm platinized titanium sheet, which was used as auxiliary electrode. Measurements were made with... 

Another technique for studying the absorption of CO2 into water uses an interferometer to obtain the concentration gradients as close as 0.01 cm. to the surface (Bl) a cine-camera permits results to be obtained within 5 sec. of the admission of the CO2. Though various corrections are I c fiuired, it is claimed that this method eliminates convection difficulties and that resistances as low as 0.25 sec. cm. i can be detected. Experimental results for CO2 into distilled water show no detectable interfacial resistance, though, when surface-active agents (Lissapol, Teepol) are dissolved in the water, the values of Rj are about 35 sec. cm.. ... 

Sublimation differs from ordinary distillation because the vapour condenses to a solid instead of a liquid. Usually, the pressure in the heated system is diminished by pumping, and the vapour is condensed (after travelling a relatively short distance) on to a cold finger or some other cooled surface. This technique, which is applicable to many organic solids, can also be used with inorganic solids such as aluminium chloride, ammonium chloride, arsenious oxide and iodine. In some cases, passage of a stream of inert gas over the heated substance secures adequate vaporisation. 

Traditionally, diazonium tetrafluoroborates are decomposed neat in the solid state. This solid, placed in a flask with large outlets and which must not be more than half full of the salt, is gently heated near its surface until decomposition starts. Often no more heat is required, the decomposition continuing spontaneously with evolution of dense vapors of boron trifluoride. The reaction medium is often brought to dull redness and the fluorinated product distills if sufficiently volatile.1,3 The filled reaction flask can also be immersed in a fluid brought to ca. 20 to 50 C above the decomposition temperature of the diazonium salt, previously determined in a capillary tube.1,3,200,201 In another procedure, the reaction flask can be heated to this temperature while empty, then the diazonium tetrafluoroborate is added little by little 200-201 This latter method has been adapted to perform the decomposition of diazonium tetrafluoroborates in a continuous way by two techniques ... 

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