Crown ethers as synergistic agents in the solvent extraction of trivalent lanthanides with 8-hydroxyquinoline

Abstract

The liquid extraction of the 13 lanthanides with mixtures of 8-hydroxyquinoline (HQ) and crown ethers (S) dibenzo-18-crown-6 (DB18C6) and dibenzo-24-crown-8 (DB24C8) in 1,2-dichloroethane as a diluent from chloride medium at constant ionic strength µ = 0.1 was investigated. The composition of the extracted species was established as LnQ 3 with HQ alone and as LnQ 3 ·S in the presence of a crown ether. The values of the equilibrium constants were calculated. The addition of DB18C6 to the metal chelate system improved the extraction efficiency, while a weak synergistic enhancement was found when the metals were extracted with mixtures of HQ-DB24C8. The parameters of the extraction process were determined and the separation factors between two adjacent lanthanides(III) were calculated.

Synergistic Efficiency of 2-[(1-Aza-15-crown-5)-1-ylmethyl)]-4-(phenyldiazenyl)-naphthalen-1-ol in the Liquid Extraction of Light Lanthanoid(III) Ions with 4-Benzoyl-3-phenyl-5-isoxazolone: The Role of Aza-Crown and Azo-Dye Fragments on the Extraction Ability

“…The order of stability has also been explained by the decrease in electron density of the donor oxygen atoms resulting from the electron-withdrawing effect of the benzo-substituent in 15C5. Similar phenomena have been observed also by Reddy et al, Mathur and Choppin, Atanassova, and Gagabe et al with similar systems.…”

“…The effectiveness of B15C5 and 15C5 used as second extractant agents leads to increase of the values of the equilibrium constants approximately 2.6 to 4 orders of magnitude. The rate of increase Ln 3+ extraction is clearly higher, the log K I,S are approximately 15 orders higher in comparison with the cases when the chelating extractant was 8hydroxyquinoline (HQ) in combination with DB24C8, DB18C6, 41 or B18C6 and 18C6. 38 The comparison of K T,S values for HTTA−DB24C8 and HTTA−DB18C6 combinations shows that the values are 8 orders smaller 3 than the obtained log K I,S in the present study.…”

“…The rate of increase extraction is clearly higher using HPBI as a chelating extractant in comparison with HTTA, but the SFs for Eu/Nd pairs obtained with HTTA−DB24C8 (DB18C6) combinations (respectively 3.3 and 3.7) 3 do not differ to a large extent with the corresponding SFs obtained with the present mixtures. 8-Hydroxyquinoline is a weaker acid (pK a = 9.65 41 ) and a poorer extractant for lanthanoids than β-diketones but exhibits a quite high separation factor for Eu/Nd pair. The SFs of the pair Eu/Nd for some systems are listed in Table 4, from which it can be seen that the combination HFBPI−DB18C6 (3phenyl-4-(4-fluorobenzoyl)-5-isoxazolone) exhibits approximately the same selectivity as the used HPBI−CE combinations in the present study, although the fluorine substituent in the forth position of the benzoyl moiety in 4-benzoyl-3-phenyl-5isoxazolone significantly improves the extraction efficiency (pK a = 0.65) as compared to HPBI (pK a =1.23).…”

The role of macrocyclic compounds in the extraction and possible separation of platinum and rhodium from chloride solutions

“…The synergistic extraction behavior of platinum (or) rhodium using amines mixed with crown ethers as an extractant system the following reaction mechanism was expected based on reported literature 12 14 15 : …”

Investigating the best mixture extraction systems in the separation of rare earth elements from nitric acid solution using Cyanex272, D2EHPA, and 8-Hydroxyquinoline

“…HQ and its derivatives have been extensively investigated in the extraction of REEs and exhibited a high extraction efficiency and large separation ability (Atanassova, 2007(Atanassova, , 2008Han, Guo, & Bian, 2003;Li, Qu, & Liu, 2002;Tian et al, 2012;Wei et al, 2007;Wu, Zhang, & Bao, 2007, 2007Zhang, Wu, & Bao, 2008;Zhou & Wang, 1994a, 1994b. Organophosphorus extractants have been widely investigated in the synergistic solvent extraction of REEs (Bari, Saad, Rahman, & Saleh, 2007;Belova, Voshkin, Kholkin, & Payrtman, 2009;Bhattacharyya, Mohapatra, & Manchanda, 2006;Coupez, Boehme, & Wipff, 2003;Ionova et al, 2001aIonova et al, , 2001bJia, Li, Zhou, & Li, 2009a;Jia et al, 2009b;Joshi, Pathak, Pandey, & Manchanda, 2009;Reddy, Bosco Bharathi, Peter, & Ramamohan, 1999;Song et al, 2009;Song, Zhao, Jia, Zhou, & Liao, 2010;Sun et al, 2005Sun et al, , 2006Tong et al, 2009;Wang, Li, Meng, & Li, 2006;Wang, Liao, & Li, 2011;Wang, Zhu, & Jiao, 2001Wu, Li, & Li, 2007), and acidic Cyanex series extractants have attracted much attention because of their poor aqueous solubility and high extraction power (Miaomiao, Qiong, & Wuping, 2013).…”