Dissolution Studies on Nickel Ferrite in Dilute Chemical Decontamination Formulations

摘要

Nickel ferrite is one of the important corrosion products in the pipeline surfaces of water-cooled nuclear reactors.The dissolution of the nickel ferrite by chelat-ing agents is very sensitive to the nature of the chelant,the nature of the reductant used in the formulation and the temperature at which the dissolution studies are performed.The dissolution is mainly controlled by the reductive dissolution of the ferrite particles,but com-plexing agents also play a significant role in the dissolution process.This study deals with the leaching of iron and nickel from nickel ferrite prepared by the solid-state method.The dissolution studies are performed in pyridine-2,6-dicarboxylic acid (PDCA),nitri-lotriacetic acid (NTA),and ethylenediaminetetraacetic acid (EDTA) formulations containing organic reduc-tants like ascorbic acid and low oxidation state transition metal ion reductants like Fe(ll)-L (where L=PDCA,NTA,EDTA) at 85 °C.The dissolution of nickel ferrite in PDCA,NTA and EDTA formulations is influenced by the presence of reductants in the formulations.The addition of Fe(ll)-L in the formulation greatly enhances the dissolution of nickel ferrite.The preferential leaching of nickel over iron during the dissolution of nickel ferrite was observed in all the formulations.