Semester

Summer

Date of Graduation

2008

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Chemistry

Committee Chair

Ronald B Smart

Abstract

Ultrasound extraction was used to compare the accelerated release rates of arsenic and selenium from pulverized rocks associated with mountain-top removal/valley fill method of coal mining. The kinetic studies demonstrated that the release rates are dependent on rock lithology as well as the total concentrations found in the rocks. Se (IV) was found to be stable under ultrasonic irradiation (200 W/cm2) but As (III) was quickly oxidized to As (V). Rocks such as BT700 were found to have more Se (IV) compared to Se (VI) and others such as BT571 were found to contain more Se (VI) than Se (IV).;Continuous application of ultrasound energy at 200 W/cm2 for 20 and 25 minutes was found effective in the extraction of bioavailable selenium and arsenic from 1 g of pulverized rocks, respectively. The amounts extracted were similar to the concentrations obtained in the combined water and phosphate buffer fractions from the sequential extractions.;Selenium concentration in stream at MT15 and MT18 sampling points decreased over a period of seven years but remained almost constant at MT 34B during the same period. The sediment MT 34B had the highest amount of extractable selenium and arsenic and both elements appear to be closely associated with organic matter. Most of the selenium in the MT 34B sediment was Se (IV).;The reduction of Se (VI) through Se (IV) occurs at pH 7 and pH 4 when reacted with kaolin and combined HA--kaolin mixtures. HA alone can reduce Se (VI) at pH 4 but not at pH 7.;A chemometric analysis of extraction data using principal component analysis suggested that released selenium is associated with 14 A´ d spacing clays and extracted arsenic is associated with illite in rocks analysed.

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