| Summary: | The surfactant 4-nonylphenol (4-NP) is a component of
many industrial and domestic cleaning products, and has been
demonstrated to elicit estrogenic effects in organisms. 4-NP
enters waterways through surface runoff and as a microbial
breakdown product in secondary sewage treatment plant (STP)
effluents. This research project examined the feasibility of
applying a passive concentrator called the semipermeable
membrane device (SPMD) to the collection and concentration of
4-NP from water. A derivatization method was developed to
improve peak separation by GC-FID and provide better
integration of peaks.
Laboratory tests with SPMDs indicated they could be used
successfully to sequester waterborne 4-NP. An established
acetylation method for chlorinated phenolics was then applied
to the 4-NP present in SPMD dialysates. The results indicated
that only a small portion of the 4-NP was undergoing reaction.
A procedure specific to 4-NP in STP effluents and sludges was
attempted next, but the results confirmed that only partial
derivatization was occurring. An experiment designed to track
the progress of 4-NP through the acetylation reaction
determined that the majority of the target analyte was
remaining in the hexane-based SPMD dialysate, where it was
unavailable for reaction with acetic anhydride in the water based potassium carbonate solution.
Subsequent attempts at derivatization continued to yield
only partial acetylation of the 4-NP. Solvent exchange
procedures, aimed at transferring the target analyte from
hexane to a water-miscible solvent, produced no improvement.
A method which incorporated a methanol solvent exchange with
substantially reduced solvent volumes appeared promising with
laboratory samples, but failed to yield satisfactory results
when applied to SPMD dialysates. Finally, successful
acetylation of 4-NP in hexane was achieved using a method
designed to acetylate analytes in an organic solvent.
A replicate test conducted using the new acetylation
method provided unexpected insights into the reasons for the
difficulties encountered with achieving complete
derivatization. The replicate test results suggested that the
length of time taken to perform the acetylation procedure was
critical to derivatization success. Subsequent experiments
confirmed that although the initial reaction favored formation
of the acetylated product, if left in contact with base, an
equilibrium was established between acetylated and nonacetylated
4-NP.
Preliminary testing with secondary sewage treatment plant
effluent confirmed that the conventional SPMD system
successfully sequestered waterborne 4-NP. Resulting
dialysates had estimated NP concentrations of 4 to 5 mg/L. When performed under controlled conditions, the derivatization
procedure developed in this research project quantitatively
acetylated NP present in hexane-based SPMD dialysates. Final
cleanup of acetylated dialysates using 5% deactivated silica
gel isolated NP into the second eluting fraction, but failed
to separate it from a significant number of background
interferences. Further field testing and additional cleanup
methods are needed to complete the techniques developed in
this project and confirm their application under actual field
conditions. === Applied Science, Faculty of === Civil Engineering, Department of === Graduate
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