title: Role of magnetite and humic acid in radionuclide migration in the environment.
abstract: Sorption of (137)Cs, (90)Sr, (154)Eu and (141)Ce by magnetite has been studied at varying pH (4 to 11) in the presence and absence of humic acid. The sorption studies have also been carried out at varying ionic strength (0.01 to 0.2 M NaClO(4)) and humic acid concentration (2 to 20 mg/L). Percentage sorption of (137)Cs and (90)Sr was found to be pH dependent, with the sorption increasing with increasing pH of the suspension. At any pH, the percentage sorption of (90)Sr was higher than that of (137)Cs. The results have been explained in terms of the electrostatic interaction between the positively charged metal ions and the surface charge of the magnetite which becomes increasingly negative with increasing pH. On the other hand, (154)Eu and (141)Ce were found to be strongly sorbed by the magnetite at all pH values, with the sorption being independent of pH. The strong sorption of trivalent and tetravalent metal ions suggests the role of complexation reactions during sorption, apart from the electrostatic interactions. However, in the case of (141)Ce surface precipitation of Ce(III) formed by reduction of Ce(IV) in the presence of magnetite cannot be ruled out. Presence of humic acid (2 mg/L) was found to have negligible effect on sorption of all metal ions.
authors.affiliation: School of Studies in Chemistry, Jiwaji University, Gwalior, M.P., India.
authors.forename: B K
authors.initials: BK
authors.lastname: Singh
authors.forename: Aishwarya
authors.initials: A
authors.lastname: Jain
authors.forename: Sumit
authors.initials: S
authors.lastname: Kumar
authors.forename: B S
authors.initials: BS
authors.lastname: Tomar
authors.forename: Radha
authors.initials: R
authors.lastname: Tomar
authors.forename: V K
authors.initials: VK
authors.lastname: Manchanda
authors.forename: S
authors.initials: S
authors.lastname: Ramanathan
mesh_terms: D000042:Absorption; D002565:Cerium Radioisotopes / Q000737:chemistry; D002588:Cesium Radioisotopes / Q000737:chemistry; D005063:Europium / Q000737:chemistry; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D011868:Radioisotopes / Q000737:chemistry*
chemical_list: D002565:Cerium Radioisotopes; D002588:Cesium Radioisotopes; D006812:Humic Substances; D011868:Radioisotopes; D005063:Europium; D052203:Ferrosoferric Oxide