Removal of heavy metal ions using a novel integrated electrolytic-electrodialytic process
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Saudi Digital Library
Abstract
Wastewater containing toxic metal ions, such as cadmium, copper, gold, lead, nickel,
silver, and zinc ions, are generated in large quantities in the mining, metal finishing,
microelectronic fabrication, and photographic film processing industries. The heavy
metal ions in wastewater can be recovered in their metallic form by electrodeposition at
the cathode of an electrolytic cell. The concentration limits for safe discharge of metal
ions to waste streams are typically less than 1 ppm. At these low concentrations, the
current efficiency for electrodeposition becomes extremely low, which results Into high
energy consumption. The electrodialysis method, on the other hand, is able to reduce the
metal ion concentrations to a low level by permeating the metal ions through an ion-
exchange membrane with low energy requirement. The method, however, produces a by
product of concentrated solution containing mixed metal ions and impurities, which
requires further purification or treatment with other processes.