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Title: Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand

One simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, 1,4-benzene-bis(iminoguanidinium) (BBIG), is demonstrated. The ligand is synthesized as the chloride salt (BBIG-Cl) by in situ imine condensation of terephthalaldehyde with aminoguanidinium chloride in water, followed by crystallization as the sulfate salt (BBIG-SO4). Alternatively, BBIG-Cl is synthesized ex situ in larger scale from ethanol. Furthermore, the sulfate separation ability of the BBIG ligand is demonstrated by selective and quantitative crystallization of sulfate from seawater. These ligands can then be recycled by neutralization of BBIG-SO4 with aqueous NaOH and crystallization of the neutral bis-iminoguanidine, which can be converted back into BBIG-Cl with aqueous HCl and reused in another separation cycle. Finally, 35S-labeled sulfate and β liquid scintillation counting are employed for monitoring the sulfate concentration in solution. Overall, this protocol will instruct the user in the necessary skills to synthesize a ligand, employ it in the selective crystallization of sulfate from aqueous solutions, and quantify the separation efficiency.
 [1] ;  [2] ;  [3]
  1. Univ. of Texas, Austin, TX (United States). Dept. of Chemistry
  2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Division
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Visualized Experiments
Additional Journal Information:
Journal Volume: 115; Journal Issue: 115; Journal ID: ISSN 1940-087X
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Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; crystallization; separations; guanidinium; self-assembly; sulfate; water
OSTI Identifier: