Separation electrochemical

The aforementioned fact is also the basis for the separation of co-occurring metals from each other. Whenever feasible, such electrochemical separation is an interesting and effective technique, in principle. In practice, however, such selective deposition is not considered very feasible, particularly for elements which are close neighbors in the electrochemical series. For example, the decomposition potentials of nickel and of cobalt are -0.25 V and -0.27 V, respectively. This small 0.02 V difference makes the selective deposition of nickel, leaving cobalt in the solution, or vice versa, rather difficult to achieve in practice. On the other hand, it is quite easy to co-deposit nickel and cobalt and to obtain an alloy. 

As the most electroactive gas, H2 was the first object of electrochemical separation. In an unusual circumstance, separation was not proposed from a mixture of chemically dissimilar species such as N2, C02, etc., but rather, from deuterium, D2. It had been noted as early as the late 1930 s [4] that H2 is preferentially evolved on several cathode materials over HD or D2 during electrolysis of water ... 

The more standard electrochemical separation of H2 from gas mixtures was first described in October, 1963, by Langer [12]. Using a simple cell composed of five... 

The Osl-Nl-N2-Os2 axis is not perfectly linear. The inequality of the bond distances (which would assign the oxidation states III to the Osl atom and II to the Os2 atom, respectively) should classify the monocation as a charge localized (Class I) mixed-valent species. Nevertheless, this result is in contrast with the electrochemical separation of the two... 

Large scale enrichment of lithium for thermonuclear uses took place at the Oak Ridge National Laboratory in the 1950 s. The enrichment primarily employed ion exchange between aqueous/organic solutions and amalgam, commonly mercury-based (Palko et al. 1976). Electrochemical separation has also been employed for such operations (Umeda et al. 2001). These practices have not been taken up in academic laboratories in the intervening years, partly as they tend to be most effective only with relatively pure starting materials, partly because of the difference in scales involved. Enrichment factors of Li of 1-7% are typical for these techniques (Symons 1985). 

From ancient times, humans have pondered what the universe is made of Early philosophers proposed fire, earth, water, and air either individually or in combination as the building blocks of nature. Lavoisier defined an element operationally as a substance that cannot be broken down chemically. Using this definition, the number of elements has increased from around 30 in Lavoisier s time to over 115 today. The initial search for elements involved classical methods such as replacement reactions, electrochemical separation, and chemical analysis. New methods such as spectroscopy greatly advanced the discovery of new elements during the twentieth century. The last half century has been marked by the synthesis of elements by humans. 

The electrochemical separation of polonium from irradiated bismuth has not been investigated to any extent it appears, however, that electrodeposition from hydrofluoric acid solution offers a practical means of separation (131). 

J. Winnick, Electrochemical Separation of Gases V Brusic et al., Electrochemical Aspects of Thin-Film Storage Media... 

Subsequent individual chapters discuss membranes in organic solvent separation, gas separation and electrochemical separation. A whole chapter is focused on the fundamentals of fouling molecular separation by membranes are completed by a chapter focused on fouling, and another on energy and environmental issues. 

Significantly, Ni dithiolenes have been shown to be effective for the electrochemical separation of alkenes ft om complex streams. No poisoning was observed with common impurities including hydrogen, carbon monoxide, acetylene, or hydrogen snlfide. Reactivity of these complexes occurs via... 

Studies on the electrochemical treatment and removal of these gaseous pollutants have increased considerably since the 1970s. In many cases, the electrochemical routes may be cleaner than currently existing technologies, and/or more economically viable. Furthermore, reaction products from gas treatment may be salable by-products. A review on electrochemical separation of gases has been published in an earlier volume of this series [101]. 

Electrochemical separations have not found wide commercial application. The cost per unit mass cannot, in general, compete with conventional techniques such as distillation or extraction. However, for high-specific-value components the selectivity available with electrophoresis or enhanced membrane transport often makes these the processes of choice. 

In an electrochemical separation, the quantitative deposition of one metal (Mi) on a solid or mercury electrode is desired without appreciable deposition of a second metal (M2). The considerations of Section 11.2.1, concerning the degree of completion of electrolysis as a function of potential, apply. If is the formal potential for the ni-electron reduction... 

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