Document Detail


Adsorption and photocatalyzed oxidation of methylated arsenic species in TiO2 suspensions.
MedLine Citation:
PMID:  17822119     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) are used as herbicides in the agriculture industry. We have demonstrated that MMA and DMA are readily degraded upon TiO2 photocatalysis. DMA is oxidized to MMA as the primary oxidation product, which is subsequently oxidized to inorganic arsenate, As(V). The adsorption of MMA and DMA on Ti02 surface was measured as a function of initial arsenic concentration and solution pH. The pH of the solution influences the adsorption and photocatalytic degradation to a similar degree, due to the speciation of the arsenic substrates and surface charge of TiO2 as a function of pH. The mineralization of MMA and DMA by TiO2 photocatalysis follows the Langmuir-Hinshelwood kinetic model. Addition of tert-butyl alcohol, a hydroxyl radical scavenger, during TiO2 photocatalysis dramatically reduces the rate of degradation, indicating that *OH is the primary oxidant. For dilute solutions, TiO2 may also be applicable as an absorbent for direct removal of a variety of arsenic species, namely As(III), As(V), MMA, and DMA, all of which are strongly adsorbed, thus eliminating the need for a multistep treatment process.
Authors:
Tielian Xu; Yong Cai; Kevin E O'Shea
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Environmental science & technology     Volume:  41     ISSN:  0013-936X     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2007 Aug 
Date Detail:
Created Date:  2007-09-07     Completed Date:  2007-11-29     Revised Date:  2012-10-30    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  5471-7     Citation Subset:  IM    
Affiliation:
Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
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MeSH Terms
Descriptor/Qualifier:
Adsorption / radiation effects
Arsenicals / chemistry*
Cacodylic Acid / chemistry*
Catalysis / radiation effects
Hydrogen-Ion Concentration
Kinetics
Light*
Oxidation-Reduction / radiation effects
Solutions
Suspensions
Titanium / chemistry*
tert-Butyl Alcohol / chemistry
Grant Support
ID/Acronym/Agency:
S11 ES011181/ES/NIEHS NIH HHS; S11 ES011181-06/ES/NIEHS NIH HHS; S11 ES011181-069003/ES/NIEHS NIH HHS; S11 ES011181-07/ES/NIEHS NIH HHS; S11 ES011181-079003/ES/NIEHS NIH HHS; S11ES11181/ES/NIEHS NIH HHS
Chemical
Reg. No./Substance:
0/Arsenicals; 0/Solutions; 0/Suspensions; 124-58-3/monomethylarsonic acid; 13463-67-7/titanium dioxide; 7440-32-6/Titanium; 75-60-5/Cacodylic Acid; 75-65-0/tert-Butyl Alcohol
Comments/Corrections

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


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