Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand.
A 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. The sulfate separation ability of the BBIG ligand is demonstrated by selective and quantitative crystallization of sulfate from seawater. The ligand can 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, (35)S-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.
Chemical Sciences Division, Oak Ridge National Laboratory; Department of Chemistry, The University of Texas at Austin.
Charles A
CA
Seipp
Chemical Sciences Division, Oak Ridge National Laboratory; Department of Chemistry, The University of Tennessee.
Neil J
NJ
Williams
Chemical Sciences Division, Oak Ridge National Laboratory; custelceanr@ornl.gov.
Radu
R
Custelcean
D002712:Chlorides; D003460:Crystallization; D008024:Ligands; D013431:Sulfates; D014867:Water
D002712:Chlorides; D008024:Ligands; D013431:Sulfates; D014867:Water
Angew Chem Int Ed Engl. 2011 Jan 10;50(2):486-90
21132821
J Am Chem Soc. 2014 Oct 22;136(42):15079-85
25254498
Bioorg Med Chem Lett. 2006 Mar 1;16(5):1305-8
16377188
Angew Chem Int Ed Engl. 2016 Feb 5;55(6):1974-87
26612067
Chem Commun (Camb). 2013 Mar 18;49(22):2173-82
23340607
Chem Rev. 2015 Aug 12;115(15):8038-155
25996028
Chemistry. 2016 Feb;22(6):1997-2003
26643375
Angew Chem Int Ed Engl. 2015 Sep 1;54(36):10525-9
26252802
Inorg Chem. 2013 Apr 1;52(7):3473-90
23134587