Electrochemical removal

Electrolysis at a Hg cathode, -1.2 V (Ag wire), CH3CN, DMF, Bu4N Bp4", 2,6-lutidine." LiCl or LiC104 have been used as electrolytes in the electrochemical removal of haloethyl phosphates. ... 

Drogui, P., Asselin, M., Brar, S.K., Benmoussa, H., and Blais, J.F., Electrochemical removal of pollutants from agro-industry wastewaters, Separation and Purification Technology, 61, 301-310, 2008. 

Zirconia cells similar to the ones employed in the present study, have been used i) by Mason et al (18) to electrochemically remove oxygen from Pt and Au catalysts used for NO decomposition. It was shown that electrochemical oxygen pumping causes a dramatic increase in the rate of NO decomposition (18,19), ii) by Farr and Vayenas to electrochemically oxidize ammonia and cogenerate NO and electrical energy (20,21), iii) by Vayenas et al (11,12,22,23) to study the mechanism of several metal catalyzed oxidations under open circuit (potentiometric) conditions. 

Stubbs JL Jr, Bolick II RE, Hauser EF Jr (1992) Electrochemical removal of thiosulfate from hydrosulfite solutions, US, US Pat 5,112,452 Chem Abstr 117 (1992) 71946h... 

Kiener LV, Uhrich KD (1987) Electrochemical removal of color from dye laden wastewater, Water and Pollution Control Assoc of South Carolina Fall Conf, Nov 24 cited in Ref [312]... 

Tincher W, Weinberg M, Stephens S (1988) Electrochemical removal of dyes and chemicals from textile wastewater, AATCC Annual Technical Conf, Knoxville, Tenn, through Ref [312]... 

Electrochemical removal of the flux By suspending the melt anode in the bath, the crystals can fall free as the etching proceeds and, if not attacked by the electrolyte, they can be easily recovered. 

The carrier concentration depth profile can be monitored by repeated CV measurement and controlled electrochemical removal of the substrate. An optimum... 

G. Horner and J. Duffey (1983), "Electrochemical Removal of Heavy Metals from Wastewater," American Electroplaters Society Seminar, Indianapolis, Indiana. 

Scull, G., Uhrich, K., "Electrochemical Removal of Heavy Metals in the Presence of Chelating Agents, " Inhouse Report, Andco Environmental Processes, Inc. 

Duffey, J., Gale, S., and Bruckenstein, S., "Electrochemical Removal of Chromates and Other MetalsCooling Towers, pp. 44-50. 

The Diels-Alder adduct of fulvene and di(2,2,2-trichloroethyl)azodiearboxylate after selective monohydrogenation of the endocyclic pi bond can lead to the bicyclic biscarbamate 107. The electrochemical removal of the TV-protecting carbamoyl groups in a DMF—LiC104—(Hg) system is followed by the oxidation with potassium ferricyanide to give the azo compound 108 which on thermal decomposition forms the linearly fused tricydopentanoid 109 in over 50 % yield (from 107, Scheme 3-41)88a). 

A very important case is contamination of soils by radionuclides. Here, uranyl ions have been removed satisfactorily from some types of clay, but radium does not form an ion of sufficient solubility to allow electrochemical removal. 

As discussed in the next section, lithiated carbon electrodes are covered with surface films that influence and, in some cases, determine their electrochemical behavior (in terms of stability and reversibility). They are formed during the first intercalation process of the pristine materials, and their formation involves an irreversible consumption of charge that depends on the surface area of the carbons. This irreversible loss of capacity during the first intercalation/deintercalation cycle is common to all carbonaceous materials. However, several hard, disordered carbons exhibit additional irreversibility during the first cycle, in addition to that related to surface reactions with solution species and film formation. This additional irreversibility relates to consumption of lithium at sites of the disordered carbon, from which it cannot be electrochemically removed [346-351],... 

Shen, F., Chen, X.M., Gao, P. and Chen, G. (2003) Electrochemical removal of fluoride ions from industrial waste water. Chem. Eng. Sci. 58, 987-993. 

Kimbrough, D.E. and Suffet, I.H. (2002) Electrochemical removal of bromide and reduction of THM formation potential in drinking water. Water Res. 36,4902-4906. 

Boye, B., Brillas, E., Buso, A., Farnia, G., Flox, C., Giomo, M. and Sandonh, G. (2006) Electrochemical removal of gallic acid from aqueous solutions. Electrochim. Acta 52, 256-262. 

Bruce, D. Kuhn, A. Sojic, N. Electrochemical Removal of Metal Cations from Wastewater Monitored by Differential Pulse Polarography, J. Chem. Educ. 2004, 81, 255-258. 

Electrochemical removal rates can be correlated with the current densities between 10 and lOOmA/cm [23]. The limiting current density for a mass-transfer limited process is given by the Levich equation [20]... 

The electrochemical removal of both bulk and remaining copper is referred to as full-sequence ECMP (FS-ECMP), and it has been investigated by many researchers [20,32]. In FS-ECMP the entire wafer has to be contacted to the anode throughout the polishing process. A conductive polishing pad provides a path for current to flow even when copper islands are formed and allows for residual copper to clear. The research focus has been on developing polishing... 

Weaver and Winnick [111] studied the performance of a nickel/nickel sulfide cathode for the electrochemical removal of hydrogen sulfide gas from a gas stream. At 650 °C, the porous nickel cathode was converted in situ to Ni3+ S2 by the H2S in the feed gas stream. The exact composition of the nickel sulfide was found to be a function of the H2S/H2 ratio in the gas stream. A current density of 150 mA/cm was attained at an iR free cathodic overpotential of 300 mV. A maximum H2S removal of 40% was reported. The low removal percentage was due to mass transport limitations of the reactant gas to the electrode. 

More recently, Brennsteiner et al. [ 175] noted that the electrochemical removal efficiency for nickel is dependent on the pH of the contaminant solution. Maximum efficiency was achieved at pH = 7.0, but only when the carbon electrode was preplated with a layer of copper the role of surface chemistry was not investigated. Seco et al. [172] did characterize the surface chemistry of a commercial activated carbon (pHp r = 6.1) and studied its uptake of heavy metals (Ni, Cu, Cd, Zn), as well as of some binary systems. They interpreted the monotonic uptake increase with pH to be consistent with the surface complexation model a decrease in competition between proton and metal species for the surface sites and a decrease in positive surface charge, which results in a lower cou-lombic repulsion of the sorbing metal. In the binary uptake studies, they concluded that Ni (as well as Cd and Zn) is not as strongly attracted to the. sorbent as Cu. 

Koile, R.C. Johnson, D.C. Electrochemical removal of phenolic films from a platinum anode. Anal. Chem. 1979, 51, 741-744. 

The reductive loss of the acetoxy function from the C-3 substituent in cephalosporin C derivatives [390, 391] is another example of an electrochemical removal of an activated hydroxyl function, which seems rather general [392]. 

The electrochemical removal of a cyano group in an aliphatic nitrile is dependent on the electrode material, solvent, and electrolyte best results were obtained at a zinc cathode in DMF with Et4NOTs as supporting electrolyte [17]. 

Reductive cleavage of a C-0 bond requires activation of the bond such activation can be obtained in different ways. Conjugated carbinols, like allylic and benzylic alcohols, tt-electron-deficient heterocyclic carbinols, and a-hydroxyketones and the ethers of these compounds, may be reductively cleaved. Reductive elimination of two vicinal hydroxyl groups or derivatives thereof may also be possible. These reactions have been exploited in the electrochemical removal of protecting groups [40,41]. 

Cryolite is utilized in the manufacture of aluminum, in the processing of aluminum waste (as a flux in the electrochemical removal of magnesium), as a flux in the aluminization of steel and in welding technology, in the manufacture of glass and enamel, as an additive in the manufacture of abrasives and as an auxiliary product in the remelting of light metals. 

In general, the benefit of ultrasound upon metal electrodeposition (discussed in length in Section 3) offers promise for the electrochemical removal of metals from solution, although it should be recognized that the systems are somewhat different. Thus, commercial metal electrodeposition requires high concentrations of metal ions in solution while wastewater treatment involves very dilute concentrations of metal ions. However studies are in hand to define the scope of sonication for metal-ion removal [253], and this area offers great promise. 

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