Intricacies of caustic production from industrial green liquor using bipolar membrane electrodialysis

Bhuvanesh Eswaraswamy, Priyabrata Mandal, Priya Goel, Anusha Chandra, Sujay Chattopadhyay

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Lime based causticization of green liquor (GL, rich in Na2CO3) to white liquor (rich in NaOH) followed by lime recycling in pulp and paper mills is an energy intensive and environmentally hazardous technique. Recently membrane electrolysis is proposed to be an alternative to this, where use of single cation exchange membrane (CEM) between two electrodes limits the processing volume of the feed stream. This can be overcome through BMED (bipolar membrane electrodialysis) technique, where multiple cell pairs can be applied to process larger feed volume. Current report investigates optimization of NaOH production from synthetic-GL using a BMED stack with variation of current density (25, 50, 75 and 100 mA·cm−2), GL concentration (100%, 75%, and 50% v/v), and feed temperature (27, 40 and 50 ℃) along with multiple cell pair arrangement (1, 2 and 3). With 50 mA·cm−2, ~1.6 mol·L−1 of NaOH could be produced from 500 mL of synthetic-GL in 5 h using a three-cell pair BMED setup (effective area of 32 cm2 per cell pair), where current efficiency and energy consumption estimates were ~88.0% and ~4.7 kWh·kg−1, respectively. Under identical conditions, NaOH production performance from industrial-GL was quite comparable (deviation < 5%) to that of synthetic-GL.

Original languageEnglish
Article number107628
JournalJournal of Environmental Chemical Engineering
Volume10
Issue number3
DOIs
StatePublished - 1 Jun 2022

Keywords

  • Bipolar membrane
  • Caustic
  • Electrodialysis
  • Green liquor
  • Ion transport
  • Pulp and paper

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Waste Management and Disposal
  • Pollution
  • Process Chemistry and Technology

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