Date of Award

5-2006

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

Advisor

Aria Amirbahman

Second Committee Member

Barry Goodell

Third Committee Member

Jody Jellison

Abstract

The oxidation state of arsenic has direct implications on its mobility, toxicity, and removal efficiency in nearly all treatment technologies. As(II1) is considerably more difficult to remove than As(V) and an oxidation step is generally required for most removal procedures. Kinetic experiments were conducted to evaluate the rate and extent of As(II1) oxidation via Fenton's reagent and various chelator-mediated Fenton systems in moderately acidic solutions. Fenton's reagent consisting of Fe(I1) and H202 demonstrated rapid reaction kinetics, but complete oxidation of As(II1) could not be attained due to the irreversible consumption of Fe(I1). The chelator-mediated Fenton systems were considerably more effective at oxidizing As(II1) due to the iron-reducing capability of the chelators. Fenton systems mediated by varying concentrations of catechol, gallic acid, dihydroxybenzoic acid and dimethoxyphenol were able to attain complete or near complete oxidation of As(II1) within 5 - 60 min under the same initial conditions as treatment with Fenton's reagent. The regeneration of Fe(I1) by the chelators allowed for the continual production of OH. by the Fenton reaction and subsequently advanced the extent of As(II1) oxidation. The catechol-mediated Fenton system was the most efficient treatment method where complete oxidation of As(II1) was reached in the shortest time. This suggests that the two hydroxyl groups in ortho position on the benzene ring of catechol is the most efficient functional group arrangement for Fe(II1) reduction in mediated Fenton systems.

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