Electrolytic generation of nickel hydroxide and nickel oxide nanoparticles for advanced applications

Abstract

Nano nickel hydroxides and nano nickel compounds attract great attention because it is a significant industrial material of commercial importance and applications in nickel-metal hydride batteries, supper capacitors, water treatment, etc. This investigation gives the results of electrolytic preparation of nickel hydroxide powder by anodic dissolution technique and conversion of this nickel hydroxide to nano nickel oxide via heat treatment. The obtained operating conditions for anodic dissolution of nickel substrate in saline solution were 75mA/cm2, pH 6, 3g/l. sodium chloride, 20oC, electrode gap distance 3cm, electrode reverse polarity interval time 5min. at 150rpm stirring rate. The obtained nickel hydroxide powder completely converted to nano nickel oxide at 500oC for 6hr. Morphology, particle size and crystallographic patterns of prepared nickel hydroxide and nano nickel oxide were investigated by transmission electron microscope (TEM) and the scanning advanced electronic diffraction (SAED) pattern. It was found that average particle size of synthesized nano nickel hydroxide were of nano tube shapes with smooth surface and average diameters in the range of 2.16 - 3.32 nm. Obtained results affect the design of nickel hydroxide electrodes for charge storage applications. The obtained nano nickel oxide was tested for the removal of Methylene blue dye (MB) from its solutions via adsorption. For MB solution of 100mg/l. concentration the optimum conditions for complete removal were found to be: pH 11, 100mg/l. MB, 10g/l. nano nickel oxide dose, 20oC, stirring rate 150rpm, at contact time 90min. the results show that the adsorption capacity of MB on the nano nickel oxide surface was 25mg.g-1, and with cleaning and drying then reuse of the nano nickel oxide more than 12 times of MB adsorption process without any significant change of adsorption capacity indication that nano nickel oxide is very good dye adsorbent.