Protection of NiO nanoparticles against leaching in acid medium by grafting of polyacrylic acid

Grafting polyacrylic acid onto the surface of nickel oxide nanoparticles was performed in order to impart to this metal oxide protection against leaching in acid solution (sulfuric acid 0.5 M). Infrared spectroscopy showed the chemical changes implicated in the different stages of the surface treatment. Open circuit potential as a function of time showed to be an excellent technique for characterizing the leaching resistance of the modified nanoparticles. This resistance was attributed to the formation of a layer of polyacrylic acid grafted and physically deposited onto the surface of the nanoparticles, which prevented the direct contact of the acid solution with the nanoparticles avoiding, consequently, leaching. (C) 2007 Elsevier B.V. All rights reserved.