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Proceedings Paper

Sensor development for in situ detection of concentration polarization and fouling of reverse osmosis membranes
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Paper Abstract

The purpose of this research is to evaluate three polymer electroding techniques in developing a novel in situ sensor for an RO system using the electrical response of a thin film composite sensor. Electrical impedance spectroscopy (EIS) was used to measure the sensor response when exposed to sodium chloride solutions with concentrations from 0.1 M to 0.8 M in both single and double bath configurations. An insulated carbon grease sensor was mechanically stable while a composite Direct Assembly Process (DAP) sensor was fragile upon hydration. Scanning electron microscopy results from an impregnation-reduction technique showed gold nanoparticles were deposited most effectively when presoaked in a potassium hydroxide solution and on an uncoated membrane; surface resistances remained too high for sensor implementation. Through thickness carbon grease sensors showed a transient response to changes in concentration, and no meaningful concentration sensitivity was noted for the time scales over which EIS measurements were taken. Surface carbon grease electrodes attached to the polyamide thin film were not sensitive to concentration. The impedance spectra indicated the carbon grease sensor was unable to detect changes in concentration in double bath experiments when implemented with the polyamide surface exposed to salt solutions. DAP sensors lacked a consistent response to changes in concentration too. A reverse double bath experiment with the polysulfone layer exposed to a constant concentration exhibited a transient impedance response similar to through thickness carbon grease sensors in a single bath at constant concentration. These results suggest that the microporous polysulfone layer is responsible for sensor response to concentration.

Paper Details

Date Published: 30 March 2009
PDF: 14 pages
Proc. SPIE 7292, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2009, 72921P (30 March 2009); doi: 10.1117/12.816111
Show Author Affiliations
Kahlil T. Detrich, Virginia Polytechnic Institute and State Univ. (United States)
Nakhiah C. Goulbourne, Virginia Polytechnic Institute and State Univ. (United States)

Published in SPIE Proceedings Vol. 7292:
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2009
Masayoshi Tomizuka, Editor(s)

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