Abstract
Formation of the sludge by ferrite process was studied by two methods. The one was the approach from oxidation-reduction potential (ORP) change in ferrite reaction process, the other was surface analysis of the sludge by X-ray photoelectron spectroscopy (XPS). The aqueous solution of various Ni ion concentrations as model wastewater was examined.
With increasing Ni ion concentration in original solution, the interval from the beginning of air oxidation to the rapid rising of ORP increased. As compared with the theoretical Ni ratio of the NiFe2O4, the experimental result suggests the existence of incomplete Ni ferrite or impure Ni compounds. XPS measurement of sludges formed by ferrite process indicated the existence of Ni(OH)2 at surface of 1,000mg/dm3-Ni and 2,500mg/dm3-Ni sludges. Hydoroxide was also observed not only at surface but inside particles of 2,500mg/dm3-Ni sludge by the measurement after Xe+ sputterring.
