Date of Award

5-1-2010

Degree Type

Thesis

University or Center

Clark Atlanta University(CAU)

School

School of Arts and Sciences

Degree Name

M.S.

Department

Chemistry

First Advisor

Dr. Eric A. Mintz

Second Advisor

Dr. Conrad Ingram

Third Advisor

Dr. David Logan

Abstract

The photocatalytic inactivation of fungi with P25 a mixed phase TiO2 material (25 % rutile and 75 % anatase) was examined using four fungal species: A. niger and M. racemosus, both spore forming fungi, and C. albicans and S. cerevisiae, yeast forming fungi. All four fungi species were found to be highly resistant to photocatalytic inactivation with P25 at room temperature under warm white light. The photocatalytic inactivation of fungi with P25 and alumina, in the presence of bicarbonate, chloride, phosphate, and silver were studied under warm white light to determine if these additives could enhance the inactivation activity. The addition of chloride and phosphate did not improve the inactivation of the fungi. Alumina lead to slight improvement in photocatalytic inactivation and sliver/P25 inactivated the fungi even in the dark. The addition of bicarbonate, which is found in natural waters, dramatically increased the photocatalytic inactivation activity of the P25. The photocatalytic inactivation activity of P25 in bicarbonate was found to be pH dependent, with activity increasing with decreasing pH. However, the pH cannot be reduced below 6, because of H2C03 formation followed by its decomposition to CO2 and water. The rate of photocatalytic inactivation C. albicans with P25 and bicarbonate was studied at pH 6.06 and 10. The morphology of C. albicans was examined microscopically at 60x. Upon photocatalytic inactivation in the presence of bicarbonate it was observed that the cells were totally fragmented and it appeared that most of the cytoplasm had leaked out.

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