Date of Award

Summer 2002

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Environmental Science - (Ph.D.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

S. Mitra

Second Advisor

Barbara B. Kebbekus

Third Advisor

Kamalesh K. Sirkar

Fourth Advisor

Larisa Krishtopa

Fifth Advisor

Nicholas Harrer Snow

Abstract

This research involved the development of membrane-based analytical techniques as applied to various aspects of water quality analysis. Gas injection membrane extraction was developed for fast on-line analysis of volatile organic compounds in water. Gas injection of aqueous samples increased the speed of membrane extraction. The aqueous boundary layer effects encountered during water elution was reduced. Axial mixing of the sample with a gaseous eluent was minimal, and this eliminated the tailing in the permeation profiles. The overall effect was significantly faster penneation. The overall diffusion coefficient during gas injection was found to be seven times the value during aqueous elution. The simulated permeation profile, using the calculated value, was in good agreement with the experimental results. The effects of system parameters on the analytical performance were investigated. Fast on-line analysis of water containing ppb level pollutants as listed in EPA method 602 was demonstrated.

Simultaneous extraction and concentration with membranes during on-line analysis of semivolatile organic compounds was studied. The influences of distribution coefficient, solvent polarity, solvent and water flow rates, as well as membrane material on enrichment factor and extraction efficiency were investigated. It was observed that solvent loss during extraction had significant impacts on enrichment factor and extraction efficiency. Continuous on-line monitoring of semivolatile organic compounds was demonstrated using this technique.

Haloacetic acids are a major group of harmful disinfection by-products in potable water generated during chlorination. A simple, economical, and highly efficient method was developed for the determination of all nine haloacetic acids in water. The extraction and preconcentration were accomplished using Supported Liquid Membrane Mircoextraction. Enrichment factor as high as 3000 was obtained with 60 minutes of extraction. The extract was directly analyzed, without derivatization, by a novel Ion-pair chromatographic method with flow programming. Low detection limits at ppb or sub-ppb level was obtained with relative standard deviation in the range of 3-12%. Various supported liquid membranes were tested. The extraction conditions were optimized by varying pH, ionic strength, stirring speed, and extraction time. This method was successfully applied to the analysis of tap water.

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