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Updated: Feb 6, 2026

Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand
Published on: September 8, 2016
Surprisingly selective sulfate extraction by a simple monofunctional di(imino)guanidinium micelle-forming anion
Neil J Williams1, Charles A Seipp, Kathleen A Garrabrant
1Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830-6119, USA. williamsnj@ornl.gov moyerba@ornl.gov.
Abstract:
We report a novel di(imino)guanidinium anion extractant with unparalleled selectivity for sulfate in a liquid-liquid separation system. In addition to a 4.4 order-of-magnitude enhancement in affinity compared to a standard benchmark, our alkylated di(imino)guanidinium receptor is economically synthesized and features good compatibility with application-relevant aliphatic solvents. Small-angle X-ray scattering results reveal the formation of reverse-micelles, which together with the significant organic-phase water content challenge traditional notions of selectivity in extraction of superhydrophilic anions.
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