Chelating Extractants for Metals

Abstract

In the present review, works on the classes of chelating extractants for metals, compounds with several amide and carboxyl groups, azomethines, oximes, macrocyclic compounds (crown ethers and calixarenes), phenanthroline derivatives, and others are systematized. This review focuses on the efficiency and selectivity of the extractants in the recovery of metals from industrial wastewater, soil, spent raw materials, and the separation of metal mixtures. As a result of this study, it was found that over the past seven years, the largest number of works has been devoted to the extraction of heavy metals with amino acids (16 articles), azomethines and oximes (12 articles), lanthanids with amide compounds (15 articles), lanthanides and actinides with phenanthroline derivatives (7 articles), and noble metals with calixarenes (4 articles). Analysis of the literature showed that amino acids are especially effective for extracting heavy metals from the soil; thiodiglycolamides and aminocalixarenes for extracting noble metals from industrial waste; amide compounds, azomethines, oximes, and phenanthroline derivatives for extracting actinides; amide compounds for extracting lanthanides; crown ethers for extracting radioactive strontium, rhenium and technetium. The most studied parameters of extraction processes in the reviewed articles were the distribution ratios and separation factors. Based on the reviewed articles, it follows that chelate polydentate compounds are more efficient compounds for the extraction of metals from secondary resources compared to monodentate compounds.

Indium Recovery from Jarosite Pb–Ag Tailings Waste (Part 1)

“…Data from the literature show that liquid extraction enables the isolation and separation of almost all metals with high efficiency and selectivity [20]. Moreover, these data also show that using amino acids to conduct the extraction process requires a long time to establish an extraction equilibrium in the form of stable complexes, and the amino acids produced are toxic.…”

New Trends in Separation Techniques of Lithium Isotopes: A Review of Chemical Separation Methods

“…Chemical exchange methods in two liquid phases employ crown ethers as extractants that can be also used in combination with ion liquids as extraction solvents [11,12]. The crown ethers have the capacity to separate lithium from other alkaline ions [13] as well to differentiate between 6 Li and 7 Li isotopes. The ion liquids can separate lithium from other alkaline ions and complex metal matrices like lithium battery waste [14], but they cannot solely differentiate between 6 Li and 7 Li, and they must be used in combination with crown ethers [11].…”

Investigations into the Extraction of Copper (II) using Methyl Isobutyl ketone solvent

“…Solvent extraction with organic compounds (extractants) is the most promising method for the recovery of metals from industrial waste compared to other methods due to high productivity, economic feasibility, high speed, and simple process design [4–15] . Organophosphorus extractants are becoming increasingly important in hydrometallurgical processes [16] due to their high selectivity, good solubility of both extractants and their metal complexes in nonpolar solvents, high degree of stripping, chemical stability, acid resistance, and low cost.…”