Efficient and selective separation of aqueous sulfate through recognition and precipitation. (10th February 2017)

• Record Type: Journal Article
• Authors: Ke, Ya-Ting; Chou, Wei-Tzu; Chiang, Yi-Fen; Hsieh, Chang-Chih; Horng, Yih-Chern
• Is Part Of: New journal of chemistry. Volume 41:Number 6(2017)
• Page Start: 2249
• Page End: 2254
• Publication Date: 2017-02-10
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c6nj03710k
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : Sulfate anions are selectively separated from aqueous solution in the form of precipitates by a mono-protonated organic receptor, constructed in situ through anion-templated chemical synthesis. Abstract : An effective and quick approach to selectively separate sulfate anions from ethanol solution or water/EtOH mixture (1 : 1, v/v) based on the precipitation of the neutral sulfate complex, without the slow crystallization process and by utilizing a positive-charged and low-solubility receptor, is illustrated in this paper. The cationic receptor [HL1 ] + with the tris(aminomethyl)ethane platform appended with three pyrrolic arms is capable of selectively separating HSO4 − or H2 PO4 − anions in the form of precipitates from EtOH. The mono-protonated tetrapodal receptor [HL2 ] +, based upon a cyclic C4N2 six-member chair-form platform equipped with four pyrrolic moieties, was constructed in situ through anion-templated chemical synthesis fromL1 and pyrrole-2-carboxaldehyde. This receptor shows the capability of selectively precipitating sulfate anions in EtOH or ethanol/water solution. A minor structural modification fromL1 toL2 through chemical synthesis in situ leads to an increase of selectivity for sulfate binding and precipitation. The solid-state crystal structure of the precipitates [HL2 ]2 [SO4 ] after recrystallization shows the encapsulation of a single sulfate within a cavity embraced by two receptors, thereby forming a supramolecular capsule. This tetrapodal receptor exhibits high affinity for sulfate anions as also revealed by a chloroform–water extraction experiment, and can be recycled after NaOH(aq) treatment for continuous usage.