Ion exchange for the remediation of perchlorate‐contaminated drinking water

Abstract

This research explored options for removing perchlorate from drinking water using commercially available ion exchange resins. Experimental data provided perchlorate selectivity, capacity, and thermodynamic properties of the resins. With these data, computer models using equilibrium multicomponent chromatography theory evaluated treatment options based on different water chemistry and operating characteristics; computer predictions were validated by bench-scale tests. Three treatment approaches emerged as viable options for removing perchlorate to concentrations below proposed maximum concentration limits:(1) partial exhaustion-regeneration using polyacrylic resins, with a process similar to current nitrate treatment techniques, (2) partial exhaustion-regeneration using polystyrene resins with elevated temperature regeneration, and (3) use of highly perchlorate-selective resins with resin replacement following exhaustion.

Application of a Re–Pd bimetallic catalyst for treatment of perchlorate in waste ion-exchange regenerant brine

“…Research is underway to develop new ReePd/C catalysts with improved activity at circumneutral pH conditions (Hurley et al, 2009;Zhang et al, 2011), and buildup of HCO 3 À may be an issue if brine acidification is no longer necessary as part of the recycling process. Sulfate is not removed, and further studies are needed to examine the effect of its buildup, particularly for IX resins that may exhibit comparable or greater selectivity for SO 4 2À uptake than ClO 4 À and NO 3 À (Tripp and Clifford, 2006). Buildup of SO 4 2À over repeated regeneration cycles may ultimately limit the number of times that brine can be recycled before discarding.…”

“…4), with an observed rate constant that was nearly identical to that measured in synthetic NaClonly brine (Table 2, entries 16 vs. 5). It follows that sequential treatment of waste IX brine with InePd and ReePd catalysts (e.g., Scheme 1) is a promising strategy for recycling brines containing both ClO 4 À and NO 3 À , which are common cocontaminants at many sites, and IX is the most common process for treating such source waters (Gingras and Batista, 2002;Tripp and Clifford, 2006;Srinivasan and Sorial, 2009 w a t e r r e s e a r c h 4 7 ( 2 0 1 3 ) 9 1 e1 0 1 reduction between resin regeneration cycles. Buildup of bicarbonate will also largely be prevented, because acidifying the brine to the working range of the current generation of ReePd/C catalyst (i.e., pH < 4) will lead to outgassing of CO 2 from supersaturated solutions.…”

Anion Exchange in Coordination‐Network Materials

“…[3] Ion exchange is the most common treatment technology for perchlorate removal. [4,5] The anion-exchange resins usually employed may have stability limitations, owing to their organic polymer nature. [6] Crystal engineering of coordination polymers [and particularly metal-organic frameworks (MOFs)] with structure-based properties is experiencing great interest among the scientific community, [7][8][9][10] owing to their potential applications in various areas of chemistry, such as gas adsorp-hibit void spaces that contain anions and neutral guest molecules, namely, water for 1, 3 and 5, and water/4,4Ј-bpy for 4.…”

Simultaneous removal of perchlorate and arsenate by ion-exchange media modified with nanostructured iron (hydr)oxide

“…Because perchlorate is considered a non-coordinating ligand, existing removal technologies generally utilize strong base ion-exchange media. These have been applied to simultaneous removal of heavy metals such as uranium [15][16][17]. In contrast, arsenic adsorbs onto metal (hydr)oxide surfaces by forming inner-sphere bidentate ligands [18,19].…”