Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/66407
Title: Selective dissolution followed by EDDS washing of an e-waste contaminated soil : extraction efficiency, fate of residual metals, and impact on soil environment
Authors: Beiyuan, JZ
Tsang, DCW 
Valix, M
Zhang, WH
Yang, X
Ok, YS
Li, XD 
Keywords: Chelating agents
Enzyme activity
Leachability/bioaccessibility
Organic acids
Reductants
Soil remediation
Issue Date: 2017
Publisher: Pergamon Press
Source: Chemosphere, Jan. 2017, v. 166, p. 489-496 How to cite?
Journal: Chemosphere 
Abstract: To enhance extraction of strongly bound metals from oxide minerals and organic matter, this study examined the sequential use of reductants, oxidants, alkaline solvents and organic acids followed by a biodegradable chelating agent (EDDS, [S,S]-ethylene-diamine-disuccinic-acid) in a two-stage soil washing. The soil was contaminated by Cu, Zn, and Pb at an e-waste recycling site in Qingyuan city, China. In addition to extraction efficiency, this study also examined the fate of residual metals (e.g., leachability, bioaccessibility, and distribution) and the soil quality parameters (i.e., cytotoxicity, enzyme activities, and available nutrients). The reductants (dithionite-citrate-bicarbonate and hydroxylamine 'hydrochloride) effectively extracted metals by mineral dissolution, but elevated the leachability and bioaccessibility of metals due to the transformation from Fe/Mn oxides to labile fractions. Subsequent EDDS washing was found necessary to mitigate the residual risks. In comparison, prior washing by oxidants (persulphate, hypochlorite, and hydrogen peroxide) was marginally useful because of limited amount of soil organic matter. Prior washing by alkaline solvents (sodium hydroxide and sodium bicarbonate) was also ineffective due to metal precipitation. In contrast, prior washing by low-molecular weight organic acids (citrate and oxalate) improved the extraction efficiency. Compared to hydroxyl amine hydrochloride, citrate and oxalate induced lower cytotoxicity (Microtox) and allowed higher enzyme activities (dehydrogenase, acid phosphatase, and urease) and soil nutrients (available nitrogen and phosphorus), which would facilitate reuse of the treated soil. Therefore, while sequential washing proved to enhance extraction efficacy, the selection of chemical agents besides EDDS should also include the consideration of effects on metal leachability/bioaccessibility and soil quality.
URI: http://hdl.handle.net/10397/66407
ISSN: 0045-6535
EISSN: 1879-1298
DOI: 10.1016/j.chemosphere.2016.09.110
Appears in Collections:Journal/Magazine Article

Access
View full-text via PolyU eLinks SFX Query
Show full item record

SCOPUSTM   
Citations

5
Citations as of Aug 18, 2017

WEB OF SCIENCETM
Citations

4
Last Week
0
Last month
Citations as of Aug 20, 2017

Page view(s)

15
Last Week
4
Last month
Checked on Aug 20, 2017

Google ScholarTM

Check

Altmetric



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.