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Adsorption and photocatalyzed oxidation of methylated arsenic species in TiO2 suspensions.
Environ Sci Technol. 2007 Aug 01; 41(15):5471-7.ES

Abstract

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+Show Affiliations

Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17822119

Citation

Xu, Tielian, et al. "Adsorption and Photocatalyzed Oxidation of Methylated Arsenic Species in TiO2 Suspensions." Environmental Science & Technology, vol. 41, no. 15, 2007, pp. 5471-7.
Xu T, Cai Y, O'Shea KE. Adsorption and photocatalyzed oxidation of methylated arsenic species in TiO2 suspensions. Environ Sci Technol. 2007;41(15):5471-7.
Xu, T., Cai, Y., & O'Shea, K. E. (2007). Adsorption and photocatalyzed oxidation of methylated arsenic species in TiO2 suspensions. Environmental Science & Technology, 41(15), 5471-7.
Xu T, Cai Y, O'Shea KE. Adsorption and Photocatalyzed Oxidation of Methylated Arsenic Species in TiO2 Suspensions. Environ Sci Technol. 2007 Aug 1;41(15):5471-7. PubMed PMID: 17822119.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Adsorption and photocatalyzed oxidation of methylated arsenic species in TiO2 suspensions. AU - Xu,Tielian, AU - Cai,Yong, AU - O'Shea,Kevin E, PY - 2007/9/8/pubmed PY - 2007/12/6/medline PY - 2007/9/8/entrez SP - 5471 EP - 7 JF - Environmental science & technology JO - Environ Sci Technol VL - 41 IS - 15 N2 - 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. SN - 0013-936X UR - https://www.unboundmedicine.com/medline/citation/17822119/Adsorption_and_photocatalyzed_oxidation_of_methylated_arsenic_species_in_TiO2_suspensions_ L2 - https://doi.org/10.1021/es0628349 DB - PRIME DP - Unbound Medicine ER -