Cadmium discharge

Elgersman, F., Emission Factors for Aqueous Industrial Cadmium Discharges to the Rhine Basin. A Historical Reconstruction of the Period 1970-1988, International Institute for Applied Systems Analysis, Laxenburg, Austria, 1994. 

Broida and Carrington58 used the 2144-A line of a cadmium discharge to excite selectively the thirteenth rotational level of the first excited vibrational level of the A2H + state. From the emission intensity and eq. (d), quenching efficiencies were computed (Table 3-3). The cadmium arc heated the reactants, the temperature sometimes reaching 550°K. For the computations, an average temperature of 400°K was used. The value found for k% is nearly three times as large as that obtained by Callear and Smith. This high value probably reflects the fact that corrections were not made for the reabsorption of emission. 

Cadmium is listed as a definite health hazards, and standards for cadmium discharges are very low. It is heartening that processes have been demonstrated on pilot-scale to remove it from fertilizer, its principal source. 

Council Directive of 26 September 1983 on limit values and quality objectives for cadmium discharges (OJ No L291, 24. 10. 83, p. 1). 

Recently, stationary electrode polarography has been used to study the electrode kinetics of several metal-ion systems on mercury in DMSO solutions. In cadmium discharge, the rate-determining step was believed to be a chemical reaction, the loss of molecules of solvation from the reactant ion, preceding a reversible charge transfer. The sensitivity of the rate towards the electrolyte cation suggests that the slow step is essentially confined to the double layer. 

Table 14.2 Limit values and time limits for cadmium discharges from industry as per European Directive 83/513/EEC of September 1983...

In a helium-cadmium discharge, selective excitation by charge-transfer reactions produces steady-state population inversions between the levels of the (4d 6g - 4d 4f) and (4d °6f - 4d °6d) configurations, producing C.W. laser oscillation on the lines listed in Table 11.3 and shown dia-... 

Lasers act as sources and sometimes as amplifiers of coherent k—uv radiation. Excitation in lasers is provided by external particle or photon pump sources. The high energy densities requked to create inverted populations often involve plasma formation. Certain plasmas, eg, cadmium, are produced by small electric discharges, which act as laser sources and amplifiers (77). Efforts that were dkected to the improvement of the energy conversion efficiencies at longer wavelengths and the demonstration of an x-ray laser in plasma media were successful (78). 

Tlierefore, tlie cadmium electrode is being electrically charged and chemically discharged at tlie same rate. 

Lower cost and lower weight cylindrical cells have been made using plastic bound or pasted actwe material pressed into a metal screen. Tliese cells suffer slightly in utilization at high rates compared to a sintered-plate cylindrical cell, but they may be adequate for most applications. Tlie effect of temperature and discharge rate on the capacity of sealed nickel-cadmium cells is illustrated in Figure 8 and Table 3. 

Fig. 8. Discharge capacity of small sealed nickel—cadmium cells where the hiitial charge is 0.1 C x 16 h at 20°C and the discharge is 1 C at temperatures of...

A number of manufacturers started commercial production of nickel—MH cells in 1991 (31—35). The initial products are "AA"-size, "Sub-C", and "C -size cells constmcted in a fashion similar to small sealed nickel —cadmium cells. Table 6 compares the Ovonics experimental cell and a similar sized nickel—cadmium cell. Ovonics also deUvered experimental electric vehicle cells, 22 A-h size, for testing. The charge—discharge of "AA" cells produced in Japan (Matsushita) are compared in Figure 22. 

From these data, the hydride cells contain approximately 30—50% more capacity than the Ni—Cd cells. The hydride cells exliibit somewhat lower high rate capabiUty and higher rates of self-discharge than nickel—cadmium cells. Life is reported to be 200—500 cycles. Though not yet in full production it has been estimated that these cells should be at a cost parity to nickel—cadmium cells on an energy basis. 

Cadmium 0.005 0.005 Kidney damage Corrosion of galvanized pipes erosion of natural deposits discharge from metal refineries runoff fiom waste batteries and paints... 

Nickel Cadmium (Ni-Cad) 25+ 1000+ 120+ Low hydrogen emission. Periodic equalizing charge is not required for float service, but is required for recharging to full capacity. High shock tolerance. Can be deep cycled. Least susceptible to temperature. Can remain discharged without damage... 

Candler, J., et al., Source of mercury and cadmium in offshore drilling discharges, SPE Drilling Engineering December, 1992. 

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