A1 Journal article (refereed), original research

A process combination of ion exchange and electrodialysis for the recovery and purification of hydroxy acids from secondary sources


Open Access publication

Publication Details
Authors: Heinonen Jari, Zhao Yan, Van der Bruggen Bart
Publisher: Elsevier
Publication year: 2020
Language: English
Related Journal or Series Information: Separation and Purification Technology
ISSN: 1383-5866
eISSN: 1873-3794
JUFO-Level of this publication: 2
Open Access: Open Access publication
Location of the parallel saved publication: http://urn.fi/URN:NBN:fi-fe202002034279

Abstract


Ion exchange and electrodialysis processes for the
production of hydroxy acids (HAs) from alkaline soda and kraft black liquors (BLs)
were investigated. Ion exchange with a type-2 strong anion exchange resin in
sulfate form was used to separate thiosulfate from alkaline kraft-BL-based
mixture of sodium (Na+) salts of HAs. Efficient regeneration of the spent
resin to sulfate form was achieved only through hydroxide form. Ion exchange
with strong cation exchange (SAC) resins was successfully used to convert the
Na+ salts of HAs in soda-BL-based solution and thiosulfate-free
kraft-BL-based solution into free acids with complete removal of Na+
ions from the solution. The spent resin was efficiently regenerated with 1–2 mol/L
sulfuric acid (H2SO4). Electrodialysis with bipolar
membranes (EDBM) was used for the generation of H2SO4 and
sodium hydroxide (NaOH) from the spent SAC resin regenerants (sodium sulfate–sulfuric
acid mixtures). Overall, 1 mol/L H2SO4 with 95%
purity and 90% yield could be obtained, but excess water flux through the
membranes limited the maximum obtainable H2SO4
concentration to 1.17 mol/L. Simultaneously, 0.79 mol/L NaOH was
produced with 93% purity. EDBM-based H2SO4 was successfully
used for the regeneration of the SAC resin. With EDBM, a closed loop can be
built for the regeneration of SAC resin with the simultaneous generation of
NaOH. The results of this study demonstrate that a process combination of ion
exchange and electrodialysis decreases the overall chemical consumption related
to HA production and enables efficient chemical recycling.


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Last updated on 2020-03-02 at 09:43