New Way to Remove Heavy Metals from Water
Joseph M. Calo, Ph.D
NIEHS Grant P42ES013660
A system developed by NIEHS-supported engineers can cleanly and efficiently remove trace heavy metals from water. The low concentrations of these metals make them difficult to extract.
The engineers created a cyclic electrowinning/precipitation (CEP) system that increases the concentration of the heavy metals so that electrowinning can be used. Electrowinning employs an electrical current to transform positively charged metal ions into a stable solid state that can be easily separated from the water and removed.
In tests, the CEP system lowered levels of cadmium, copper, and nickel — both individually and as a mixture — to near or below maximum contaminant levels established by the U.S. Environmental Protection Agency. The system produced a very large reduction in the volume of the heavy metal contaminants, turning them into a solid metal deposited on particles that can be safely discarded or further processed to recover particular metals.
The technique is scalable and the researchers say it can be used to remove other heavy metals, such as lead, mercury, and tin.
Citation: Grimshaw P, Calo JM, Hradil G. 2011. Cyclic electrowinning/precipitation (CEP) system for the removal of heavy metal mixtures from aqueous solutions. Chem Eng J 175:103-109.
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