Date of Award

Spring 5-2015

Degree Type

Dissertation

Degree Name

Ph.D.

Degree Program

Engineering and Applied Science

Department

Civil and Environmental Engineering

Major Professor

Enrique La Motta

Second Advisor

J. Alex McCorquodale

Third Advisor

Bhaskar Kura

Fourth Advisor

Patricia Williams

Fifth Advisor

Martin Guillot

Abstract

A bench-scale tubular reactor with recirculation was built in order to study the efficiency of the photocatalytic oxidation of phenol on fluidized titanium oxide-coated silica gel beads. A UV-C lamp placed along the central vertical axes of the reactor was used as source of photons. A bed of silica gel beads was fluidized by means of fluid recirculation and forced to follow upward helical flow around the lamp. Anatase was successfully synthetized on silica gel particles of average diameters 224, 357 and 461 µm, as confirmed by scanning electron micrographs, through a sol-gel technique using a titanium (iv)isopropoxide / hydrochloric acid / ethanol precursor.

Data was obtained from multiple 8-hours photocatalytic experiments using a determined mass of beads fluidized in an aqueous solution of known initial phenol concentration. Contaminant degradation with irradiation time was measured as COD. Beads that had been subjected to three consecutive coating procedures produced an 8-h removal efficiency 10% higher than beads with a single coat. 20 g L-1 of silica beads was found to be the optimum load for the experimental reactor configuration regardless of beads size, although efficiency increased with decreasing size of the latter.

Experimental results confirmed that the efficiency of phenol photocatalytic degradation decreases with increasing pollutant concentration. Also, the highest removal was achieved with initial pH 3, and it decreased with increasing pH. When NaCl was added to the solution, COD removal increased with increasing salinity. Additionally, it was found that dissolved oxygen is indispensable for photocatalysis to proceed, and that saturation of the treated mixture with oxygen was effectively achieved by keeping the liquid surface in contact with pure oxygen at 1 atm.

Finally, statistical analysis of the data showed that photocatalytic mineralization of phenol-derived COD under the experimental conditions follows exponential decay. Based on this finding, a correlation model was proposed for the accurate prediction (minimum R2 = 0.9840) of the COD removal efficiency of the reactor for any given initial COD.

Rights

The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.

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