Equilibrium dialysis and ultrafiltration investigations of perchlorate removal from aqueous solution using poly(diallyldimethylammonium) chloride

Use of perchlorate salts in military activities and the aerospace industry is widespread. These salts are highly water-soluble and are, to a large extent, kinetically inert as aqueous species. As a groundwater contaminant, perchlorate is now being detected in an increasing number of locations and is believed to interfere with the uptake of iodide by the thyroid, which can result in decreased hormone production. The United States Environmental Protection Agency (US EPA) has established a reference dose for perchlorate of 0.0007 mg/kg/day, which translates to a drinking water equivalent level of 24.5 ppb. This study investigated the application of polyelectrolyte-enhanced ultrafiltration (PEUF) for the selective removal of perchlorate from aqueous solution through equilibrium dialysis and ultrafiltration experiments. Using poly(diallyldimethylammonium) chloride, the effectiveness and efficiency of PEUF in the removal of perchlorate from other aqueous solution components was investigated by testing parameters such as polyelectrolyte concentration, pH, and ionic strength. Removal of perchlorate from synthetic groundwater initially containing 10.3 ppm perchlorate and also containing chloride, sulfate, and carbonate was also examined. Perchlorate separations of greater than 95% were achieved, even in the presence of 10-fold excesses of competing ions.