Novel Technique to Remove Nickel from Contaminated Seawater

This deposit is the same that is found mostly in the water pipes or in other areas where calcium – rich water is the basis. It might be the cheapest way to get rid of contaminated seawater of all kinds of toxic metals. This has been revealed according to a research team headed by Charlotte Carre of the University of New Caledonia.

The scientists dipped various electrodes prepared from the galvanized steel into contaminated seawater and ran an electronically weak current through it. Within numerous days, up to 24 percent of the nickel it primarily contained was trapped in a calcareous structure build-up of limestone.

The mining activities of Nickel in New Caledonia itself are resulting in the subsequent pollution of local coastal water. The remediation of metals brings drastic challenges since such elements, offered their chemical properties, can never be diminished but just stabilized. Therefore, Carre’s research group set out to find an effective, rapid and most importantly cost-effective method by which to eradicate such toxic metals from the contaminated waters.

The scientific group dipped cheap and commercially available galvanized steel electrode into nickel-enrich seawater and enabled a fairly weak electronic current to operate through it for almost seven days.

According to Carre, this method is quite inexpensive and convenient to use and needs just regular monitoring. “Metal contaminants are linked and trapped inside a calcareous deposit as long as the entire structure is connected to a power source,” explains Carre.

After completion of seven days, the calcareous deposits, which were formed on the electrode were washed off with distilled water, and examined utilizing optical and Raman spectroscopy techniques. The deposits were identified to comprise the chemical calcium carbonate or CaCO3 made from mixing equal proportions of aragonite, which is one of the naturally occurring forms of crystal of calcium carbonate, and brucite, which is the mineral form of magnesium hydroxide.

The technique did not significantly deplete the level of magnesium and calcium in the water. Most important is that though water up to a level of 24 percent of the nickel initially added to the water was trapped within the build-up in this way. “Such ratios are quite higher after just seven days,” says Carre.

After completion of seven days, the macroscopic pictures were clicked of the deposit that formed at the surface of the galvanized steel wire. It indicated that the presence of nickel in the solution does not inhibit the entire formation of the deposit as its thickness remains the same.

“Our studies reveal a novel and effective method, known as calcareous electrochemical precipitation that possesses the potential applications to eradicate toxic metals from contaminated waters,” says Carre, who believes that it can be employed to salvage metals for feasible reuse.