Document Detail


Effect of TCE concentration and dissolved groundwater solutes on NZVI-promoted TCE dechlorination and H2 evolution.
MedLine Citation:
PMID:  18075103     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Nanoscale zero-valent iron (NZVI) is used to remediate contaminated groundwater plumes and contaminant source zones. The target contaminant concentration and groundwater solutes (NO3-, Cl-, HCO3-, SO4(2-), and HPO4(2-)) should affect the NZVI longevity and reactivity with target contaminants, but these effects are not well understood. This study evaluates the effect of trichloroethylene (TCE) concentration and common dissolved groundwater solutes on the rates of NZVI-promoted TCE dechlorination and H2 evolution in batch reactors. Both model systems and real groundwater are evaluated. The TCE reaction rate constant was unaffected by TCE concentration for [TCE] < or = 0.46 mM and decreased by less than a factor of 2 for further increases in TCE concentration up to water saturation (8.4 mM). For [TCE] > or = 0.46 mM, acetylene formation increased, and the total amount of H2 evolved at the end of the particle reactive lifetime decreased with increasing [TCE], indicating a higher Fe0 utilization efficiency for TCE dechlorination. Common groundwater anions (5mN) had a minor effect on H2 evolution but inhibited TCE reduction up to 7-fold in increasing order of Cl- < SO4(2-) < HCO3- < HPO4(2). This order is consistent with their affinity to form complexes with iron oxide. Nitrate, a NZVI-reducible groundwater solute, present at 0.2 and 1 mN did not affect the rate of TCE reduction but increased acetylene production and decreased H2 evolution. NO3- present at > 3 mM slowed TCE dechlorination due to surface passivation. NO3- present at 5 mM stopped TCE dechlorination and H2 evolution after 3 days. Dissolved solutes accounted for the observed decrease of NZVI reactivity for TCE dechlorination in natural groundwater when the total organic content was small (< 1 mg/L).
Authors:
Yueqiang Liu; Tanapon Phenrat; Gregory V Lowry
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Environmental science & technology     Volume:  41     ISSN:  0013-936X     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2007 Nov 
Date Detail:
Created Date:  2007-12-13     Completed Date:  2008-02-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7881-7     Citation Subset:  IM    
Affiliation:
Department of Civil & Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213-3890, USA.
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MeSH Terms
Descriptor/Qualifier:
Anions
Chemistry, Organic / methods
Chlorine / analysis,  chemistry*
Ferric Compounds / chemistry
Halogenation
Hydrogen / chemistry
Hydrogen-Ion Concentration
Iron / chemistry
Models, Chemical
Nanoparticles / chemistry
Nitrates / chemistry
Time Factors
Trichloroethylene / analysis*,  chemistry*
Water / chemistry
Water Pollutants / analysis*
Chemical
Reg. No./Substance:
0/Anions; 0/Ferric Compounds; 0/Nitrates; 0/Water Pollutants; 1309-37-1/ferric oxide; 1333-74-0/Hydrogen; 7439-89-6/Iron; 7732-18-5/Water; 7782-50-5/Chlorine; 79-01-6/Trichloroethylene

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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