Facile precipitation and phase formation of iron oxide with in situ Fe(II) in Fe-2(SO4)(3)-NaOH-(N2H4)(2)H2SO4-H2O medium

Abstract

Present study deals with the precipitation of iron oxides in NaOH-H2O and NaOH-H2O-NH2NH2H2SO4 system. The precipitates at different pH are collected. Total iron and ferrous analysis of both the filtrate and residue are reported. Sulphate content of the samples are also included. All the precipitates at different pH are characterized by XRD for phase identifications. The precipitation of ferric sulphate in absence and in presence of hydrazinium sulphate (reducing agent) is investigated. The results indicate that the reducing agent has an influence not only on the species, the amount as well as the type of products but also on the transformation rate of ferrihydrite. XRD patterns consistent with a mixed ferrihydrite and schwertmannite when the precipitation of ferric sulphate is carried out in absence of hydrazinium sulphate. However by adding only 0.05 M of hydrazinium sulphate, the natures as well as the composition of precipitates change. At a of 3 6-line ferrihydrite is obtained. The precipitate at a pH of 7 contain only goethite phase where as at a pH of 10 both goethite as well and magnetite phases are observed.