Cadmium natural resources

Cadmium (Cd) anode cells are at present manufactured based on nickel-cadmium, silver-cadmium, and mercury-cadmium couples. Thus wastewater streams from cadmium-based battery industries carry toxic metals cadmium, nickel, silver, and mercury, of which Cd is regarded the most hazardous. It is estimated that globally, manufacturing activities add about 3-10 times more Cd to the atmosphere than from natural resources such as forest fire and volcanic emissions. As a matter of fact, some studies have shown that NiCd batteries contribute almost 80% of cadmium to the environment,4,23 while the atmosphere is contaminated when cadmium is smelted and released as vapor into the atmosphere4 Consequently, terrestrial, aquatic, and atmospheric environments become contaminated with cadmium and remain reservoirs for human cadmium poisoning. 

The ASTM F 1185 designation specifies chemical and crystallographic requirements for hydroxyapatite applied to the surfaces of surgical implants. Elemental analyses for calcium and phosphorus will confirm the expected stoichiometry of hydroxyapatite. The calcium and phosphorus contents will be determined by a suitable method such as ion chromatography. A quantitative X-ray diffraction analysis will determine a hydroxyapatite content of at least 95%. The concentration of deleterious trace elements such as arsenic, cadmium, mercury and lead will be assessed for hydroxyapatite derived from natural resources. The analysis of other trace elements may be required, based on the conditions, apparatus or environments specific to the manufacturing techniques and raw materials. Inductively coupled plasma/mass spectroscopy (ICP/MS), atomic absorption (AAS) or the... 

Nonetheless, concern exists that after the useful lives of these batteries has ended, they may become a source of cadmium and nickel that reaches the environment. Recycling Ni-Cd batteries addresses this concern and also conserves valuable natural resources. 

Table 5.2. Proposed cadmium criteria for the protection of human health and natural resources.

This book is a general survey of the nature of trace metals in petroleum and includes analytical methods for their determination. Vanadium, iron, nickel, cadmium, copper, and molybdenum— their nature, determination, chemical aspects, geochemistry, occurrence in new and used petroleum byproducts and their recovery for resource use—are dealt with in detail by the expert authors in this volume. Among the methods covered are instrumental analysis, neutron activation, activation analysis, oxidative demetallation and kinetic studies. Includes 54 figures and 60 tables. 

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