title: Metal removal and associated binding fraction transformation in contaminated river sediment washed by different types of agents.
abstract: In ex-situ washing, HCl, EDTA and H2O2 solutions can effectively extract heavy metals in river sediment. Nevertheless they often target different sediment components, possibly transforming metal species into more bioavailable and hence toxic ones. This study, in batch settings, investigated the influences of different types of washing agents (i.e. HCl, EDTA and H2O2) on metal (i.e. Cu and Zn) removal from contaminated river sediment, destroy or dissolution of sediment components, and transformation of metal fractions during chemical washing treatment. Additionally, bioavailability of these metals left in the washed sediment was assessed. Results showed that HCl obtained the highest Cu and Zn removal through destroying the reducible, oxidizable and residual sediment components. Meanwhile, it transformed metal fractions to acid extractable one, resulting in an increase in metal bioavailability. Thus, the feasibility of washing with HCl for sediment remediation shall be reconsidered due to the caused high metal bioavailability. EDTA was capable of removing metals via direct complexation of labile metal species and indirect dissolution of reducible and oxidizable sediment components, where the transformation of corresponding metal binding fraction may occur. H2O2 obtained the lowest total Cu and Zn removal, but it preferentially removed the oxidizable metal species by oxidizing sulfides in the sediment. The bioavailable levels of Cu and Zn in the sediment washed by EDTA or H2O2 seemed not increase. To maintain a good balance between labile metal species removal and avoiding increase of metal bioavailability, EDTA and H2O2 are promising additives for metal removal by sediment washing.
authors.affiliation: School of Environmental Science and Engineering, South University of Science and Technology of China, Shenzhen, P. R. China.|Engineering Innovation Center (Beijing), South University of Science and Technology of China, Beijing, P. R. China.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Harbin Institute of Technology Shenzhen Graduate School, Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control, Shenzhen, P. R. China.
authors.forename: Tongzhou
authors.initials: T
authors.lastname: Liu
authors.affiliation: Harbin Institute of Technology Shenzhen Graduate School, Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control, Shenzhen, P. R. China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Feng
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, P.R.China.|Shenzhen Research Institute of Sun Yat-sen University, Shenzhen, P. R. China.
authors.forename: Weihua
authors.initials: W
authors.lastname: Zhang
mesh_terms: D002681:China; D003300:Copper / Q000032:analysis / Q000302:isolation & purification; D004492:Edetic Acid / Q000737:chemistry / Q000494:pharmacology; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005843:Geography; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000494:pharmacology; D019216:Metals, Heavy / Q000032:analysis* / Q000302:isolation & purification; D008855:Microscopy, Electron, Scanning; D015203:Reproducibility of Results; D045483:Rivers / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D014873:Water Pollutants / Q000032:analysis* / Q000302:isolation & purification; D014876:Water Pollution / Q000517:prevention & control; D014961:X-Ray Diffraction; D015032:Zinc / Q000032:analysis / Q000302:isolation & purification
chemical_list: D019216:Metals, Heavy; D014873:Water Pollutants; D003300:Copper; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D015032:Zinc; D006851:Hydrochloric Acid