Heavy metals removal from water by strong interaction with a Ni-H surface

摘要

Aqueous effluents from mineral processing and metal finishing industries contain small amounts of heavy metals (arsenic, mercury, cadmium, chromium, lead...) in the ionic form. Heavy metals are very harmful (cancers, kidney disorders...) and they are bio-accumulative. According to the underpotential metal deposition process, M~(x+) ions can be reduced by hydrogen adsorbed on an active surface and deposited as "adatoms" on the "host" metallic surface. A nickel surface covered by hydrogen can remove cadmium ions from aqueous solution. Hydronium ions are produced and they are neutralized by controlled addition of a sodium hydroxide solution. This process for water treatment differs from cementation since only hydronium ions are produced. Levels of remaining Cd~(2+) ions as low as 20 ppb can be achieved.