Extraction Studies of Heavy Metal Ions Employing Benzothiaoxacrown Compounds

Abstract

Benzothiaoxacrown compounds with different numbers of sulfur and oxygen donor atoms (between 4 to 7 donors) dissolved in an organic diluent selectively extract the soft metal ions Ag(I) and Hg(II) from a mixture of Co(II), Ni(II), Cu(II), Zn(II), Ag(I) and Hg(II) present in an aqueous phase. Generally, the extraction efficiency depends on the specific structure of the benzothiaoxacrowns, on the organic diluent employed, as well as on the counter ion present in the aqueous phase. High extractions of Ag(I) and Hg(II) were achieved with all ligands from perchlorate and picrate aqueous media into nitrobenzene organic solutions. In the case of Cu(I) the extraction is significant lower; only ligand 5 with the O 2 S 4 donor atom set gives a moderate extractability. The composition of the extracted complexes depends on the crown ring size and ranges from 1:1 to 1:2 (M:L). Polarographic, UV-Vis and ESI mass spectrometric studies provide a further insight into the complex formation behavior.

A Comprehensive Extraction Study Using a Mono-alkylated Diglycolamic Acid Extractant: Comparison Between a Secondary Amide Group and a Tertiary Amide Group

“…Liquid-liquid extraction is an effective separation method for the purification of valuable metals [1][2][3], removal of toxic metals [4,5], and recovery of fission products [6][7][8][9]. The efficiency of metal separation with liquid-liquid extraction depends on the extractant.…”

Multifunctional Effect of the Polymer Extractant Thiomethylbenzoxazoyl-α-Methylstyrene on the Extraction of Au(III)

“…Waste materials, when used as secondary resources, often contain a variety of different metals, therefore more efficient extractants are required to provide selective and efficient SX processes. For the selective extraction of metals, size recognition is known to be effective when using macrocyclic ligands, such as calixarenes and crown ethers [3][4][5]. These cyclic ligands have some advantages of high selectivity for a specific metal ion, utilizing the size-recognition effect [6]; however, such ligands tend to be costly.…”