Extraction cadmium

The quaternary ammonium salts (QAS) are widely used as ionofores of ion-selective electrodes and extractants of metals halogenic anion complexes. The influence of the QASes nature with various methyl groups contents on the cadmium extraction from bromide media has been investigated. 

Cadmium Extraction of ammonium pyrrolidine dithiocarbamate complex with chloroform AAS 0.0006 xg/l [134,863]... 

Standing Committee of Analysts (DoE) (1979) The Analysis of Agricultural Materials -Cadmium, Extractable in Soil Method 10, MAFF Technical Bulletin RB 427, HMSO, London, UK. 

This strategy is summarised in Box 1 illustrated by the example in Box 2. It is of course possible to make different types of cadmium in soil measurements. For example, instead of the total cadmium, the amount of cadmium extracted by a specific method, or the amount of cadmium in the sample as received, or dried in a different way could be measured. These are different measurements (measurands) and likely to give different measurement values, but all can be made traceable to SI, including the amount of substance. Hence the importance of adequately defining the measurand, in addition to establishing measurement traceability. 

NiCd consumer cells are small, sealed-cell batteries, which are most familiar to consumers, are rechargeable battery power packs for cordless drills, cellular and cordless phones, camcorders, household appliances, and battery-operated toys. The batteries in power packs are typically contained in a plastic case, which must be removed prior to cadmium extraction. The plastic is removed in a two-step process including INMETCO s patented rotary thermal oxidizer. In this process, the plastic, paper, and moisture are removed without fuming off cadmium. 

Gent DB, Bricka RM, Alshawabkeh AN, Larson SL, Fabian G, Granade S. (2004). Bench-and field-scale evaluation of chromium and cadmium extraction by electrokinetics. Journal... 

FIGURE 32.5 Cadmium extraction behavior in HFSD. (From Rathore, N.S. et al., Hydrometallurgy, 96, 81, 2009.) (a) [Cd(II)] in feed phase as a function of [H ] with time in HFSD system, (b) [Cd(ll)] in the strip phase as a function of [H+] with time in HFSD system, (c) [Cd(II)] in organic phase as a function of [HT with time in HFSD system Feed phase [CF] 1 M, [Cd(ll)] 0.05 g/L strip phase single distilled water organic phase 5% (v/v) Cyanex 923 in Exxsol DlOO. 

A wide variety of inorganic materials have been used to precipitate or collect trace metals from solution. The most direct approach is a cementation process, which is one that removes the trace pollutants from solution by reduction with a metal and plating onto that metal surface. Although this process may be slow, the filtration is usually quick, since decantation is often sufficient. Finely divided cadmium extracts copper, selenium, and mercury from nitric and sulfuric acid solutions (66). When copper was used to preconcentrate mercury from water or biological fluids prior to atomic absorption analysis, the detection limit was 1-2 X 10 g (67, 68). Iron (69), zinc (70), and tungsten (71), as metals, have also been used to obtain a deposit of several trace metals from aqueous systems as dilute as 10 ppb for subsequent analysis. Elemental tellurium can be produced in solution by reduction using tin(II) chloride or sulfur dioxide, and coprecipitates silver (72) and selenium (73). Granulated silicon-metal alloys were used to remove metal ions from water and brine by reduction as well (74, 75). 

Figure 3.39 shows spatial distribution of photoelectric gain within a p jin mercury cadmium extraction photodiode for different bias voltages. The detector parameters are given in the Fig. 3.39. Gain is given for the whole stmcture, including not only the depleted region, but also highly doped parts. An important...

Figure 8.14 Kinetics of the cadmium extraction by the RDE detoxification method.

Cadmium is usually found in zinc ores and is extracted from them along with zinc (p. 416) it may be separated from the zinc by distillation (cadmium is more volatile than zinc. Table 14.2) or by electrolytic deposition. 

Selective solution of the aluminum from the ahoy using a volatile metal, such as mercury, lead, bismuth, cadmium, magnesium, or zinc, has been investigated. After extracting the aluminum from the original ahoy into the volatile metal, the volatile metal is distilled, leaving pure aluminum. Neither electrolysis nor volatile metal extraction can extract aluminum from iron aluniinide [12004-62-3J, EeAl, titanium aluniinide [12004-78-3] TiAl, or Al C. ... 

EFFECT OF QUATERNARY AMMONIUM SAET EXCHANGE CENTER STERIC ACCESSIBILITY ON EXTRACTION OF CADMIUM BROMIDE COMPLEXES... 

Brombenztiazo (BBT) is known to be one of the best reagents for extraction-photometric determination of cadmium(II). The reagent also fonus complexes with Co(II), Cu(II), Fe(II), Ni(II), Zn(II). The aim of this work was to develop a solid-phase reagent on the base of BBT immobilized on silica gel for sorption-spectroscopic and visual test determination of Cadmium, and also for soi ption-atomic-adsoi ption determination of total heavy metals contents in natural waters. 

Solutions in contact with polyvinyl chloride can become contaminated with trace amounts of lead, titanium, tin, zinc, iron, magnesium or cadmium from additives used in the manufacture and moulding of PVC. V-Phenyl-2-naphthylamine is a contaminant of solvents and biological materials that have been in contact with black rubber or neoprene (in which it is used as an antioxidant). Although it was only an artefact of the separation procedure it has been isolated as an apparent component of vitamin K preparations, extracts of plant lipids, algae, livers, butter, eye tissue and kidney tissue [Brown Chem Br 3 524 1967]. 

In addition to systems of the above type, i.e. involving adduct formation, various other types of synergistic extraction systems are recognised and have been reviewed.4 An example is the synergistic influence of zinc in the extraction and A AS determination of trace cadmium in water.5... 

EXTRACTION AND DETERMINATION OF LEAD, CADMIUM, AND COPPER USING AMMONIUM PYROLLIDINE DITHIOCARBAMATE... 

Theory. Conventional anion and cation exchange resins appear to be of limited use for concentrating trace metals from saline solutions such as sea water. The introduction of chelating resins, particularly those based on iminodiacetic acid, makes it possible to concentrate trace metals from brine solutions and separate them from the major components of the solution. Thus the elements cadmium, copper, cobalt, nickel and zinc are selectively retained by the resin Chelex-100 and can be recovered subsequently for determination by atomic absorption spectrophotometry.45 To enhance the sensitivity of the AAS procedure the eluate is evaporated to dryness and the residue dissolved in 90 per cent aqueous acetone. The use of the chelating resin offers the advantage over concentration by solvent extraction that, in principle, there is no limit to the volume of sample which can be used. 

Insoluble fluorosilicates are brought into solution by fusion with four times the bulk of fusion mixture, and extracting the melt with water. In either case, the solution is treated with a considerable excess of ammonium carbonate, warmed to 40 °C, and, after standing for 12 hours, the precipitated silicic acid is filtered off, and washed with 2 per cent ammonium carbonate solution. The filtrate contains a little silicic acid, which may be removed by shaking with a little freshly precipitated cadmium oxide. The fluoride in the filtrate is determined as described in Section 11.59. 

As is the case with assessments of the toxicity of dissolved trace metals, the development of sediment quality criteria (SQC) must be based on the fraction of sediment-associated metal that is bioavailable. Bulk sediments consist of a variety of phases including sediment solids in the silt and clay size fractions, and sediment pore water. Swartz et al. (1985) demonstrated that the bioavailable fraction of cadmium in sediments is correlated with interstitial water cadmium concentrations. More recent work (e.g., Di Toro et al, 1990 Allen et al., 1993 Hansen et al, 1996 Ankley et ai, 1996, and references therein) has demonstrated that the interstitial water concentrations of a suite of trace metals is regulated by an extractable fraction of iron sulfides. 

The synthetic approach is very simple and does not require any special set up. In a typical room temperature reaction, 1.0 mL aqueous solution of cadmium chloride was added to 20 mL aqueous solution of soluble starch in a 50 mL one-necked round-bottom flask with constant stirring at room temperature. The pH of the solution was adjusted from 6 to 11 using 0.1 M ammonia solution. This was followed by a slow addition of 1.0 mL colourless selenide ion stock solution. The mixture was further stirred for 2 h and aged for 18 h. The resultant solution was filtered and extracted with acetone to obtain a red precipitate of CdSe nanoaprticles. The precipitate was washed several times and dried at room temperature to give a material which readily dispersed in water. The same procedure was repeated for the synthesis of PVA and PVP - capped CdSe nanoparticles by replacing the starch solution with the PVA and PVP polymers while the synthesis of elongated nanoparticles was achieved by changing the Cd Se precursor ratio from 1 1 to 1 2. The synthesis of polymer capped ZnSe nanoparticles also follows the same procedure except that ZnCb solution was used instead of CdCb solution. 

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