Integration of ion exchange resins and membrane technology for purification of boron from seawater desalination brines
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Boron is considered a critical raw material (CRM) to the European Union (EU) due to its economic importance and supply risk. To ensure the sustainable supply of boron and other CRMs to EU industry in a circular economy approach the H2020 Sea4value project proposes the recovery of valuable minerals/metals from seawater desalination brines. Brines can cause damage to marine ecosystems when discharged into the sea. Sea4value aims to reduce the environmental impact of desalination plants while generating value from a waste stream. The project proposes a multi-mineral brine mining process divided in 3 stages: pre-treatment, concentration, and extraction/purification. This work investigates the extraction/purification of boron using nanofiltration as pre-treatment followed by an ion-exchange column for concentration and electrodialysis with bipolar membranes (EDBM) for boric acid production. The nanofiltration permeate (monovalent-rich stream) fed a column packed with the commercial boron selective resin CRB03 (Mitsubishi Chemical). After elution, a concentration factor of 17 was obtained for boron. Sorption of major elements present in the brine (sodium, chloride, magnesium, …) was not observed. However, besides boron, the resin sorbed indium and vanadium. Initial EDBM tests using borax solutions at different pHs showed a concentration factor of 2 for boric acid, at pH 12.
CitationFigueira, M. [et al.]. Integration of ion exchange resins and membrane technology for purification of boron from seawater desalination brines. "Science Talks", Maig 2023, vol. 6, núm. article 100221.