Electrolytes cyanide

Corrective Action Application At a hazardous waste treatment storage and disposal facility in Washington State, a cyanide-bearing waste required treatment. The influent waste stream contained 15 percent cyanide. Electrolytic oxidation was used to reduce the cyanide concentration to less than 5 percent. Alkaline chlorination was used to further reduce the cyanide concentration to 50 mg/1 (the cleanup objective). The electrolytic process was used as a first stage treatment because the heat of reaction, using alkaline chlorination to treat the concentrated cyanide waste, would be so great that it would melt the reactor tank. 

Electroplating Cadmium is usually electroplated from a cyanide solution. Zinc is also deposited from cyanide electrolyte, but for some applications mildly acidic and alkaline non-cyanide electrolytes are increasingly being used. Typical cyanide-based electrolyte formulations for both metals taken from Specifications DTD 903 and 904 are given in Table 13.6. 

Ruthenium, iridium and osmium The use of a fused cyanide electrolyte is the most effective means for the production of sound relatively thick coatings of ruthenium and iridium, but this type of process is unattractive and inconvenient for general purposes and does not therefore appear to have developed yet to a significant extent for industrial application. This is unfortunate, since these metals are the most refractory of the platinum group and in principle their properties might best be utilised in the form of coatings. However, several interesting improvements have been made in the development of aqueous electrolytes. 

Two representative examples of this behavior are reflected in two distinct different chemical systems, namely (a) copper deposition from an acid sulfate electrolyte containing the co-inhibitors PEG-C1 and a bi-functional catalytic species SPS-C1 [12, 136, 243, 264] and (b) silver deposition from a cyanide electrolyte where inhibition is provided by adsorption of silver cyanide species and catalysis is achieved through adsorption of selenocyanate, SeCN [72-75]. Similar behavior is evident in some electrolytes used for the deposition of bright soft gold films [121, 180, 255-261, 267]. 

The generality of the CEAC mechanism has been demonstrated by extension to at least two other chemical systems, selenocyanate catalyzed silver deposition from a cyanide electrolyte [72-75] and iodine catalyzed CVD of copper from Cu(I)(hfac) (vtms) and related compounds [15, 77]. As shown in Figure 2.40, a one-to-one correlation between the SeCN-coverage and the silver deposition rate was established... 

Copper cyanide (electrolytical) Determination of Cu2+ after preparation with strong acids, hexacyano ferrates... 

Copper Copper is mostly plated from acid, fluoroborate, or cyanide baths (see Table 4). Among these, the cyanide electrolyte reveals the best throwing power but needs intensive convection. 

The mechanism of deposition from sulfuric acid electrolytes proceeds via two consecutive steps with Cu+ij as intermediate (Bockris-Mattson mechanism). But the dependence of the intermediate of the experimental parameters is not in agreement with all expectations. The mechanism of deposition of copper from copper cyanide electrolytes is more complex. The mechanism of deposition could be similar to the described mechanism of Ag from silver cyanide electrolytes. Some mechanisms were proposed in the literature. ... 

Silver is an example of a metal that shows the surface-enhanced Raman effect. After a special surface treatment, the signal of a molecular group on the surface of the metal is enhanced by several orders of magnitude. One successful surface treatment is deposition of silver. So, after starting silver deposition from a cyanide electrolyte on a platinum electrode, a Raman signal of the CN-stretch vibration develops and reaches a limiting value (Figure 7.28). ... 

The different complexes in a silver cyanide electrolyte show different Raman signals of the CN-stretch vibration. The peak observed in Figure 7.28 is usually explained as the Ag(CN)3 peak. The peak around 2110 cm (2080-2140 cm" ) was observed at -0.7 Vg ,g. Switching to 0 a shift to 2140 cm (2110-2175 cm" ) was observed, which is the frequency of Ag(CN)2. Compared to the deposition mechanism (Section 7.5.2) one has to conclude that the Ag(CN)3 complex dominates even on the surface. 

Fig. 18 Photocurrent-voltage curves of illuminated single crystal n-CdSe immersed in alkaline potassium ferrocyanide electrolytes with and without added cyanide. Inset Photocurrent stability of in several electrolytes, e is the only electrolyte with cyanide. Electrolytes d and e contain low ferricyanide. Electrolyte b contains high ferricyanide. Specifically, e 0.25 m K4fe(CN)g,...

Cyanide Electrolytic plating sewage With and without cyanide distillation... 

Hmssanova A, Krastev I, Beck G, Zielonka A (2010) Properties of silver-tin alloys obtained from pyrophosphate-cyanide electrolytes containing EDTA salts. J Appl Electrochem 40 2145-2151... 

Lacconi, G., Reents, B. and Plieth, W. (1992) Raman spectroscopy of silver plating from a cyanide electrolyte. Journal of Electroanalytical Chemistry, 325,101-1X1. 

Gold cyanide (electrolytic) Determination of Au(CN)2, Au(CN)4, Co(CN)g , cyanide, chloride, orthophosphate, and hexacyano ferrates... 

Langford, K. and Parker, J.E. (1971) Analysis of Electroplating and Related Solutions, R. Draper LTD, Teddington. Zhukov, B.D., Borodikhina, L.I., Shchekochikhin, V.M, Poddubny, N.P, and Bek, R.Y. (1973) Study of dec-trodeposition of copper horn cyanide electrolytes. The composition of the cyanide copper plating electrolyte. Izv. 

Dudek, D.A. and Fedkiw, P.S. (1999) Electrodeposition of copper from cuprous cyanide electrolyte I. Current distribution on a stationary disk. / Electroanal. Chem., 474 (1), 16—30. 

Bek, R.Y., Nechaev, E.A., and Kudryavcev, N.X. (1967) Chronopoten-tiometric study of electrolytic evolution of silver from cyanide electrolytes. Elektrokhimiya, 3 (12), 1465-1467. 

Vagramyan, T., Leach, J.S.L., and Moon, J.R. (1979) On the problems of elec-trodepositing brass from non-cyanide electrolytes. Electrochim. Acta, 24 (2), 231-236. 

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