Selective Extraction of Rare-Earth Elements from Rocks Using a High-Capacity cis-1,4-Butanedioic Acid-Functionalized Resin

Abstract

A high-capacity carboxylic acid-functionalized resin prepared by ring-opening metathesis polymerization containing cis-1,4-butanedioic acid (succinic acid) units was used for the extraction of rare-earth elements (REEs) from rock digests. Extraction efficiencies measured by means of ICP-AES were found to be in the range of 90−100% for standards containing 5 and 500 ppb of each REE, respectively. The optimum extraction pH was found to be between 5.3 and 5.5. Three different rock standard reference materials (SRMs), GSR-1 granite, GSR-2 andesite, and GSR-3 basalt, were digested by fusion of the corresponding rock with lithium metaborate (LiBO2) and subsequent dissolution in nitric acid. As a consequence of the different compositions of the three investigated SRMs, the resulting digest showed different concentrations of the REEs as well as of SiO2, Fe, Al, Mg, and Ca. The entire extraction procedure was additionally supported by masking of the interfering metal ions using 5-sulfosalicylic acid. Small amounts of methanol were added to prevent silicate from precipitating. Following this setup, REEs occurring in the digest solutions in the range of 40 ppt to 150 ppb were retained selectively, with recoveries ranging for most elements from 75 to 110%. The high performance of the entire system is underlined by the fact that relative standard deviations were <10% for most of the REEs.

Interactions of microorganisms with rare earth ions and their utilization for separation and environmental technology

“…Various kinds of phosphates or functionalized polymers have been widely used for these purposes (Chen et al 2012;Sun et al 2012;Buchmeiser et al 1998;Zahir and Masuda 1997). However, most of these reagents are expensive and may be toxic themselves.…”

Adsorption of rare earth ions onto the cell walls of wild-type and lipoteichoic acid-defective strains of Bacillus subtilis

“…There are many examples of functionalized polymers or phosphates used for the extraction of rare earth ions (Buchmeiser et al 1998;Sun et al 2012). However, most of these reagents are expensive and may be toxic themselves.…”

Stationary phases for chromatography prepared by ring opening metathesis polymerization

“…A first important finding was that the pH for lanthanide extraction could be extended to a range of 3.5 -5.5. This significantly improved complexation of the REEs by the new ligand was attributed to the presence of the additional ether-functionality in the ONDCA-derived repeat units, which was not present in the poly(norborn-5-ene-2,3-dicarboxylic acid)-derived system [39]. Recovery, HPLC as well as ICP-OES experiments confirmed the high selectivity of the new sorbent for lanthanides.…”

“…phases in the online SPE-RP ion-pair HPLC of lanthanides [38 -41] In the course of our investigations on the metal extraction capabilities of carboxylic acid derivatized, ringopening metathesis precipitation polymerizationderived SPE supports (vide supra), we found that these possessed excellent selectivity for lanthanides, even in the presence of other metal ions [38,39]. In a simple SPE setup, these allowed for concentrating rare earth elements (REEs) from various rock digests and their subsequent quantification by means of ICP-OES.…”