title: The reductive degradation of 1,1,1-trichloroethane by Fe(0) in a soil slurry system.
abstract: Most studies on the treatment of chlorinated contaminants by Fe(0) focus on aqueous system tests. However, few is known about the effectiveness of these tests for degrading chlorinated contaminants such as 1,1,1-trichloroethane (TCA) in soil. In this work, the reductive degradation performance of 1,1,1-TCA by Fe(0) was thoroughly investigated in a soil slurry system. The effects of various factors including acid-washed iron, the initial 1,1,1-TCA concentration, Fe(0) dosage, slurry pH, and common constituents in groundwater and soil such as Cl(-), HCO3 (-), SO4 (2-), and NO3 (-) anions and humic acid (HA) were evaluated. The experimental results showed that 1,1,1-TCA could be effectively degraded in 12 h for an initial Fe(0) dosage of 10 g L(-1) and a soil/water mass ratio of 1:5. The soil slurry experiments showed two-stage degradation kinetics: a slow reaction in the first stage and a fast reductive degradation of 1,1,1-TCA in the second stage. The reductive degradation of 1,1,1-TCA was expedited as the mass concentration of Fe(0) increased. In addition, high pHs adversely affected the degradation of 1,1,1-TCA over a pH range of 5.4-8.0 and the reductive degradation efficiency decreased with increasing slurry pH. The initial 1,1,1-TCA concentration and the presence of Cl(-) and SO4(2-) anions had negligible effects. HCO3(-) anions had a accelerative effect on 1,1,1-TCA removal, and both NO3(-) and HA had inhibitory effects. A Cl(-) mass balance showed that the amount of Cl(-) ions released into the soil slurry system during the 1,1,1-TCA degradation increased with increasing reaction time, suggesting that the main degradation mechanism of 1,1,1-TCA by Fe(0) in a soil slurry system was reductive dechlorination with 1,1-DCA as the main intermediate. In conclusion, this study provides a theoretical basis for the practical application of the remediation of contaminated sites containing chlorinated solvent.
authors.affiliation: State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai, 200237, China.
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Wu
authors.forename: Shuguang
authors.initials: S
authors.lastname: Lu
authors.forename: Zhaofu
authors.initials: Z
authors.lastname: Qiu
authors.forename: Qian
authors.initials: Q
authors.lastname: Sui
authors.forename: Kuangfei
authors.initials: K
authors.lastname: Lin
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Du
authors.forename: Qishi
authors.initials: Q
authors.lastname: Luo
mesh_terms: D060587:Groundwater / Q000737:chemistry; D054879:Halogenation; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D012987:Soil / Q000737:chemistry*; D014240:Trichloroethanes / Q000032:analysis / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D012987:Soil; D014240:Trichloroethanes; D014874:Water Pollutants, Chemical; C024566:1,1,1-trichloroethane; D007501:Iron
references.citation: Environ Sci Technol. 2003 Mar 15;37(6):1208-18
references.pmid: 12680677
references.citation: Environ Sci Technol. 2005 Nov 15;39(22):8948-57
references.pmid: 16323799
references.citation: Sci Total Environ. 2010 Jul 15;408(16):3418-23
references.pmid: 20471666
references.citation: Water Res. 2011 Mar;45(7):2401-14
references.pmid: 21376362
references.citation: Water Res. 2005 Sep;39(15):3531-40
references.pmid: 16095659
references.citation: J Contam Hydrol. 2003 Aug;65(1-2):121-36
references.pmid: 12855204
references.citation: Environ Sci Technol. 2005 Mar 15;39(6):1868-74
references.pmid: 15819249
references.citation: Environ Sci Technol. 2009 Aug 1;43(15):5975-81
references.pmid: 19731706
references.citation: Water Res. 2009 Sep;43(17):4296-304
references.pmid: 19580986
references.citation: J Hazard Mater. 2001 May 30;83(3):243-54
references.pmid: 11348735
references.citation: J Biosci Bioeng. 2001;92(5):453-8
references.pmid: 16233127
references.citation: Environ Sci Technol. 2008 Jun 15;42(12):4513-9
references.pmid: 18605579
references.citation: Chemosphere. 2010 Nov;81(7):940-5
references.pmid: 20723967
references.citation: Environ Pollut. 2001;111(1):21-7
references.pmid: 11202712
references.citation: Environ Sci Technol. 2002 Oct 15;36(20):4326-33
references.pmid: 12387405
references.citation: Environ Sci Technol. 2002 Feb 1;36(3):299-306
references.pmid: 11871541
references.citation: Chemosphere. 2013 Feb;90(8):2303-8
references.pmid: 23102698
references.citation: J Hazard Mater. 1999 Aug 12;68(1-2):97-108
references.pmid: 10518666
references.citation: Environ Sci Technol. 2008 Mar 15;42(6):2092-8
references.pmid: 18409642
references.citation: Chemosphere. 2008 Jun;72(6):952-8
references.pmid: 18472136
references.citation: Environ Sci Technol. 2007 Mar 15;41(6):2022-7
references.pmid: 17410800
references.citation: Environ Sci Technol. 1994 Nov 1;28(12):2045-53
references.pmid: 22191743
references.citation: Chemosphere. 2000 Oct;41(8):1263-70
references.pmid: 10901257
references.citation: Water Res. 2004 Jun;38(11):2631-42
references.pmid: 15207593
references.citation: Water Res. 2001 Apr;35(6):1453-60
references.pmid: 11317892
references.citation: J Contam Hydrol. 2004 Oct;74(1-4):133-44
references.pmid: 15358490
references.citation: Water Res. 2001 Dec;35(18):4435-43
references.pmid: 11763046