Production of Acids and Bases for Ion Exchange Regeneration from Dilute Salt Solutions Using Bipolar Membrane Electrodialysis

Jake R. Davis, Yingying Chen, James C Baygents, James Farrell

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

The acids and bases used for ion exchange regeneration contribute significantly to the increasing salinity of potable water supplies. This research investigated the use of bipolar membrane electrodialysis (BMED) for producing acids and bases from dilute salt solutions that are produced during reverse osmosis or evaporative cooling. Using single pass BMED, acids and bases were produced with concentrations equal to ∼75% of the feed salt concentration with current utilizations >75%. Current utilization increased with increasing feed salt concentrations due to decreased leakage current through the monopolar membranes. The maximum current density at which the BMED stack could be operated depended on the feed salt concentration and the flow velocity and was limited by water dissociation at the interface between the diluate solutions and the monopolar membranes. The stack resistance was dominated by the bipolar membranes, even for the most dilute feed solutions. The energy required per mole of acid or base produced increased linearly with increasing current density. The energy costs for producing acids and bases were significantly less than costs for purchasing bulk HCl and NaOH, and the process is scalable to large systems. (Graph Presented).

Original languageEnglish (US)
Pages (from-to)2337-2342
Number of pages6
JournalACS Sustainable Chemistry and Engineering
Volume3
Issue number9
DOIs
StatePublished - Sep 8 2015

Keywords

  • Acid production
  • Base production
  • Bipolar membrane electrodialysis
  • Ion exchange regeneration
  • Water softening

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Environmental Chemistry

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