title: An investigation of Cr(VI) removal with metallic iron in the co-presence of sand and/or MnO2.
abstract: This study focused on the influence of sand and/or MnO2 co-presence on the mechanism and kinetics of Cr(VI) removal with Fe(0). The process was investigated under acidic and well-mixed conditions, over the temperature range of 6-32 °C. It was shown that both mechanism and kinetics of the removal process were highly dependent on composition and dose of reactive mixture added to Cr(VI) solution. At 22 °C, indirect chemical reduction with Fe(II) was the main removal path in H2O-Fe(0)-Cr(VI) and H2O-Fe(0)-Sand-Cr(VI) system, while in H2O-Fe(0)-MnO2-Cr(VI) and H2O-Fe(0)-MnO2-Sand-Cr(VI) system removal of Cr(VI) occurred mainly via adsorption on MnO2. The pseudo zero-order kinetic model provided the best match for H2O-Fe(0)-Cr(VI) and H2O-Fe(0)-Sand-Cr(VI) system, while in H2O-Fe(0)-MnO2-Cr(VI) and H2O-Fe(0)-MnO2-Sand-Cr(VI) system the process fitted well to the pseudo second-order model. Temperature influenced the efficiency and kinetics of the process in all investigated systems, and the removal mechanism only in H2O-Fe(0)-MnO2-Cr(VI) and H2O-Fe(0)-MnO2-Sand-Cr(VI) system.
authors.affiliation: Politehnica University Timisoara, Faculty of Industrial Chemistry and Environmental Engineering, Bd. V. Parvan Nr. 6, Et. 4, 300223 Timisoara, Romania. Electronic address: marius.gheju@upt.ro.
authors.forename: M
authors.initials: M
authors.lastname: Gheju
authors.affiliation: National Institute for Research and Development in Electrochemistry and Condensed Matter, Str. Dr. Aurel Paunescu Podeanu Nr. 144, 300587 Timisoara, Romania.
authors.forename: I
authors.initials: I
authors.lastname: Balcu
authors.affiliation: Politehnica University Timisoara, Faculty of Industrial Chemistry and Environmental Engineering, Bd. V. Parvan Nr. 6, Et. 4, 300223 Timisoara, Romania.
authors.forename: C
authors.initials: C
authors.lastname: Vancea
mesh_terms: D000327:Adsorption; D055598:Chemical Phenomena; D002857:Chromium / Q000737:chemistry*; D006801:Humans; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D017895:Manganese Compounds / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D014876:Water Pollution / Q000517:prevention & control; D018508:Water Purification
chemical_list: D017895:Manganese Compounds; D010087:Oxides; D002857:Chromium; C074702:chromium hexavalent ion; D012822:Silicon Dioxide; D007501:Iron; C016552:manganese dioxide
keywords: Hexavalent chromium; Manganese dioxide; Metallic iron; Sand; Water pollution