Removal of nickel from aqueous solution using cathodic deposition of nickel hydroxide at a modified electrode

Background In the present study, an electrochemical technique was used to remove nickel from aqueous solutions on a laboratory scale using a self-made Plexiglas cell. Electrodes comprising a stainless steel net coated with single-walled carbon nanotubes (SWCNTs@SSN) were used as both the anode and the cathode. The effects of various parameters on the percentage of nickel removed were investigated, including the solution pH, applied voltage, electrolyte concentration, and the amount of SWCNTs coated on the electrodes. Results The optimal parameters were found to be pH 10.0, applied voltage 2.5 V, and electrolyte concentration 10 g dm-3. Under optimal conditions, 95.1% of the nickel present in nickel-contaminated factory wastewater was removed. The mechanism of nickel removal was also investigated. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analyses showed that the nickel ions were being removed in the form of Ni(OH)2, which was deposited on the cathode. The SWCNTs@SSN electrodes were regenerated easily. Conclusion The results of the study proved that the method is a potential technique for the treatment of industrial wastewater containing heavy-metal ions. © 2013 Society of Chemical Industry