HR: 17:30h
AN: OS44B-07    [Abstracts]
TI: Evaluation of Electrodialysis as Part of an Improved Method to Concentrate Dissolved Organic Matter from Seawater
AU: * Chang, V
EM: vchang@usfca.edu
AF: Georgia Institute of Technology, Earth and Atmospheric Sciences 311 Ferst Drive, Atlanta, GA 30332-0340
AU: Koprivnjak, J
EM: jfk@eas.gatech.edu
AF: Georgia Institute of Technology, Earth and Atmospheric Sciences 311 Ferst Drive, Atlanta, GA 30332-0340
AU: Ingall, E
EM: ingall@eas.gatech.edu
AF: Georgia Institute of Technology, Earth and Atmospheric Sciences 311 Ferst Drive, Atlanta, GA 30332-0340
AU: Pfromm, P
EM: pfromm@ksu.edu
AF: Kansas State University, Chemical Engineering, Manhattan, KS 66506
AU: Perdue, E M
EM: michael.perdue@eas.gatech.edu
AF: Georgia Institute of Technology, Earth and Atmospheric Sciences 311 Ferst Drive, Atlanta, GA 30332-0340
AB: A major obstacle in the study of marine dissolved organic matter (DOM) has been isolating from seawater sufficient quantities for analysis of this highly dilute and chemically complex material. This research explores the application of electrodialysis (ED) in combination with reverse osmosis (RO) as a method to concentrate DOM from seawater. RO methods recover a significant fraction (90%) of DOM from fresh waters with little physical or chemical alteration, and similar high recoveries of DOM have been observed in preliminary tests using estuarine waters of varying salinity. Unfortunately, the extent to which DOM in saline waters can be concentrated by RO is very limited, because RO membranes co-concentrate inorganic salts with DOM. At an early stage of processing, osmotic pressures become too high and/or inorganic salts precipitate from solution and foul the RO membrane. To realize the potentially high recoveries of DOM from saline waters, RO must be coupled with an independent method for removal of inorganic salts. Electrodialysis, which is a well-established process for removal of inorganic salts from aqueous solutions, is such a method. In ED, a feed stream of the sample to be de-ionized and a receiving stream of a solution that will accept the removed ions are pumped through adjacent layers of a membrane stack, which consists of several layers of alternating anion and cation exchange membranes. The membranes are made from highly crosslinked polymers and are non-porous. The direction and velocity of diffusion of the cations and anions are further mediated by a DC electrical current that flows through the membrane stack. In the first stage of testing of the ED process, samples of near-seawater salinity (28 ppt) containing 4 ppm of dissolved organic carbon were collected at the Skidaway Institute of Oceanography in Savannah Georgia. Using ED, salinity was reduced by 87% in these samples with retention of more than 95% of the DOM. These experiments indicate that ED can significantly reduce salt concentrations in saline waters with little or no loss of DOM, thus making it possible to use efficient RO methods to concentrate marine DOM.
DE: 4806 Carbon cycling
DE: 4850 Organic marine chemistry
DE: 4894 Instruments and techniques
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting