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

Jinyong Liu, Jong Kwon Choe, Zachary Sasnow, Charles J. Werth, Timothy J. Strathmann

Research output: Contribution to journalArticlepeer-review

Abstract

Concentrated sodium chloride (NaCl) brines are often used to regenerate ion-exchange (IX) resins applied to treat drinking water sources contaminated with perchlorate (ClO4-), generating large volumes of contaminated waste brine. Chemical and biological processes for ClO4- reduction are often inhibited severely by high salt levels, making it difficult to recycle waste brines. Recent work demonstrated that novel rhenium-palladium bimetallic catalysts on activated carbon support (Re-Pd/C) can efficiently reduce ClO4- to chloride (Cl-) under acidic conditions, and here the applicability of the process for treating waste IX brines was examined. Experiments conducted in synthetic NaCl-only brine (6-12 wt%) showed higher Re-Pd/C catalyst activity than in comparable freshwater solutions, but the rate constant for ClO4- reduction measured in a real IX waste brine was found to be 65 times lower than in the synthetic NaCl brine. Through a series of experiments, co-contamination of the IX waste brine by excess NO3- (which the catalyst reduces principally to NH4+) was found to be the primary cause for deactivation of the Re-Pd/C catalyst, most likely by altering the immobilized Re component. Pre-treatment of NO3- using a different bimetallic catalyst (In-Pd/Al2O3) improved selectivity for N2 over NH4+ and enabled facile ClO4- reduction by the Re-Pd/C catalyst. Thus, sequential catalytic treatment may be a promising strategy for enabling reuse of waste IX brine containing NO3- and ClO4-.

Original languageEnglish (US)
Pages (from-to)91-101
Number of pages11
JournalWater Research
Volume47
Issue number1
DOIs
StatePublished - Jan 1 2013

Keywords

  • Brine reuse
  • Catalytic reduction
  • Ion exchange
  • Nitrate
  • Palladium
  • Perchlorate
  • Rhenium

ASJC Scopus subject areas

  • Ecological Modeling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution

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