title: Cr(VI) retention and transport through Fe(III)-coated natural zeolite.
abstract: Cr(VI) is a group A chemical based on the weight of evidence of carcinogenicity. Its transport and retention in soils and groundwater have been studied extensively. Zeolite is a major component in deposits originated from volcanic ash and tuff after alteration. In this study, zeolite aggregates with the particle size of 1.4-2.4mm were preloaded with Fe(III). The influence of present Fe(III) on Cr(VI) retention by and transport through zeolite was studied under batch and column experiments. The added Fe(III) resulted in an enhanced Cr(VI) retention by the zeolite with a capacity of 82mg/kg. The Cr(VI) adsorption on Fe(III)-zeolite followed a pseudo-second order kinetically and the Freundlich adsorption isotherm thermodynamically. Fitting the column experimental data to HYDRUS-1D resulted in a retardation factor of 3 in comparison to 5 calculated from batch tests at an initial Cr(VI) concentration of 3mg/L. The results from this study showed that enhanced adsorption and retention of Cr(VI) may happen in soils derived from volcanic ash and tuff that contains significant amounts of zeolite with extensive Fe(III) coating.
authors.affiliation: School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China.
authors.forename: Gaoxiang
authors.initials: G
authors.lastname: Du
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Li
authors.forename: Libing
authors.initials: L
authors.lastname: Liao
authors.forename: Renee
authors.initials: R
authors.lastname: Hanson
authors.forename: Samantha
authors.initials: S
authors.lastname: Leick
authors.forename: Nicole
authors.initials: N
authors.lastname: Hoeppner
authors.forename: Wei-Teh
authors.initials: WT
authors.lastname: Jiang
mesh_terms: D000327:Adsorption; D002857:Chromium / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D009994:Osmolar Concentration; D013696:Temperature; D017641:Zeolites / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D002857:Chromium; D017641:Zeolites