Hydrogen separation liquid carriers

A Perkin-Elmer 5000 AAS was used, with an electrically heated quartz tube atomizer. The electrolyte is continuously conveyed by peristaltic pump. The sample solution is introduced into the loop and transported to the electrochemical cell. A constant current is applied to the electrolytic cell. The gaseous reaction products, hydrides and hydrogen, fonued at the cathode, are flowed out of the cell with the carrier stream of argon and separated from the solution in a gas-liquid separator. The hydrides are transported to an electrically heated quartz tube with argon and determined under operating conditions for hydride fonuing elements by AAS. 

The discussion so far implies that membrane materials are organic polymers, and in fact most membranes used commercially are polymer-based. However, in recent years, interest in membranes made of less conventional materials has increased. Ceramic membranes, a special class of microporous membranes, are being used in ultrafiltration and microfiltration applications for which solvent resistance and thermal stability are required. Dense, metal membranes, particularly palladium membranes, are being considered for the separation of hydrogen from gas mixtures, and supported liquid films are being developed for carrier-facilitated transport processes. 

The produced fluids and gases are typically directed into separation vessels. Under the influence of gravity, pressure, heat, retention times, and sometimes electrical fields, separation of the various phases of gas, oil, and water occurs so that they can be drawn off in separate streams. Suspended solids such as sediment and salt will also be removed. Deadly hydrogen sulfide (H2S), is sometimes also encountered, which is extracted simultaneously with the petroleum production. Crude oil containing H2S can be shipped by pipeline and used as a refinery feed but it is undesirable for tanker or long pipeline transport. The normal commercial concentration of impurities in crude oil sales is usually less than 0.5% BS W (Basic Sediment and Water) and 10 Ptb (Pounds of salt per 1,000 barrels of oil). The produced liquids and gases are then transported to a gas plant or refinery by truck, railroad tank car, ship, or pipeline. Large oil field areas normally have direct outlets to major, common-carrier pipelines. 

Facilitated transport of penicilHn-G in a SLM system using tetrabutyl ammonium hydrogen sulfate and various amines as carriers and dichloromethane, butyl acetate, etc., as the solvents has been reported [57,58]. Tertiary and secondary amines were found to be more efficient carriers in view of their easy accessibility for back extraction, the extraction being faciUtated by co-transport of a proton. The effects of flow rates, carrier concentrations, initial penicilHn-G concentration, and pH of feed and stripping phases on transport rate of penicillin-G was investigated. Under optimized pH conditions, i. e., extraction at pH 6.0-6.5 and re-extraction at pH 7.0, no decomposition of peniciUin-G occurred. The same SLM system has been applied for selective separation of penicilHn-G from a mixture containing phenyl acetic acid with a maximum separation factor of 1.8 under a liquid membrane diffusion controlled mechanism [59]. Tsikas et al. [60] studied the combined extraction of peniciUin-G and enzymatic hydrolysis of 6-aminopenicillanic acid (6-APA) in a hollow fiber carrier (Amberlite LA-2) mediated SLM system. 

The mobile phase in vapour phase chromatography is a gas (e.g. hydrogen, helium, nitrogen or argon) and the stationary phase is a non-volatile liquid impregnated onto a porous material. The mixture to be purified is injected into a heated inlet whereby it is vaporised and taken into the column by the carrier gas. It is separated into its components by partition between the liquid on the porous support and the gas. For this reason vapour-phase chromatography is sometimes referred to as gas-liquid chromatography. 

More recently the use of membrane contactors to solve the stability problem of liquid membranes has been proposed [19-21], The concept is illustrated in Figure 11.4. Two membrane contactors are used, one to separate the organic carrier phase from the feed and the other to separate the organic carrier phase from the permeate. In the first contactor metal ions in the feed solution diffuse across the microporous membrane and react with the carrier, liberating hydrogen counter ions. The organic carrier solution is then pumped from the first to the second membrane contactor, where the reaction is reversed. The metal ions are... 

The stationary phase consists of a thin layer (ca. 0.2 pm) of a non-volatile liquid, such as methylsilicone or methylphenylsilicone, tightly adsorbed to the inert surfaces of the column. The liquid stationary phases are classified according to their polarity, non-polar phases are used most often because they are easier to handle and are stable over a wide temperature range. The mobile phase is an inert carrier gas such as nitrogen, helium or hydrogen which flows at a constant, but adjustable rate through the column. Current capillary columns, with internal diameters between 0.1-0.6 mm, are constructed of fused silica, specially prepared from pure silicon tetrachloride, and formed into spirals up to 100 m long. Injectors, columns and detectors are located in separately thermostatable compartments. 

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