Liquid extraction of some rare earth elements with aminomethylphosphine oxides

Abstract

Methods were developed of the solvent extraction from aqueous solutions of hydrochloric, nitric, and perchloric acids of the triply charged ions of rare earth elements including samarium, lutetium, dysprosium, neodymium, and ytterbium, using as reagents the lipophilic aminomethylphosphine oxides containing two or four dialkylphosphinyl groups, and toluene, chloroform, and methylene chloride as the organic media. The study of the effect of concentration of mineral acids on the degree of metal extraction showed that the highest extraction efficiency of lanthanides is achieved with bis(dihexylphosphinylmethyl)octylamine (I) from perchloric media: extraction degree 80%, whereas extraction from the solutions in two other acids did not exceed 30%. It was shown that the highest selectivity was reached at the extraction of scandium in all the extraction systems. A possible mechanism of extraction is discussed. Solvent extraction processes have been successfully used and do not yet have an adequate alternative in the industry of rare and scattered metals for the separation of compounds of the elements with similar properties, as well as for extraction, concentration, and separation of many other elements from the hydrometallurgical technological solutions [1]. Among the efficient and selective reagents used for these purposes an important place belongs to the neutral organophosphorus compounds (tributyl phosphate, tributyl-and trioctylphosphine oxides, etc.) [2], as well as to higher tertiary amines (trioctylamine, dilaurylamine, etc.) [3]. In recent years data has appeared in the literature on the possibility of effective use in the extraction technology of alkali, alkaline earth [4] and noble metals [5], as well as scandium and some other trace elements [6,7] of α-aminoalkylphosphoryl compounds that belong to the class of substances combining the structural features of the above two types of extraction reagents, the neutral organic phosphorus derivatives and amines. This combination of functional groups provides high efficiency and selectivity of these extractants in hydrometallurgical technologies of extraction and separation of metals [8], they are highly effective as a membrane transporter substrates of acidic nature [9] and the components of ion-selective electrodes [10]. However, together with the performance and prospects of use in addressing these challenges, the aminophosphonates, which were mainly used in the above cited studies, have one major drawback: a relatively low thermal and hydrolytic stability due to the presence in the molecules of labile ester bonds P-O-C that becomes a serious obstacle to the realization of technological processes of solvent extraction of metals, which as a rule is carried out in the industry from acidic aqueous media.The lipophilic aminomethylphosphine oxides (APO) with long chain substituents at the phosphorus and nitrogen atoms, which do not possess labile bonds, are devoid of this drawback. They are characterized by the hydrophilic-lipophilic characteristics appropriate for opt...

Phosphorylated Aminoacetal in the Synthesis of New Acyclic, Cyclic, and Heterocyclic Polyphenol Structures

“…We followed research in this direction studying the properties of previously unknown acetal containing the aminophosphine oxide fragment. Aminophosphine oxide derivatives are used as alkali and rare metal extractants due to their ability to complexation . A combination of several functional groups in one molecule (acetal and secondary amino group) would allow the use of the compounds of this type as a universal synthetic block for the design of macrocyclic and linear polyphenols, promising polydentate ligands containing the phosphine oxide fragment.…”

“…It was shown earlier that calix[4]arenes containing aminophosphonate fragments on the upper rim of molecule are effective and selective amino acid transfer agents compared with their linear counterparts and lipophilic derivatives of aminophosphine oxides participate both in membrane transport of amino acids and as metal ion extractants from acidic media . It is anticipated that the presence of lipophilic cavity with a long alkyl chain and four thermally and hydrolytically stable aminophosphine oxide fragments in synthesized calix[4]resorcinol would increase the binding efficiency and selectivity with organic and inorganic substrates compared with their linear counterparts and unsubstituted calix[4]resorcinol.…”

α-Aminophosphonates, -Phosphinates, and -Phosphine Oxides as Extraction and Precipitation Agents for Rare Earth Metals, Thorium, and Uranium: A Review

“…Because the syntheses of 29 and 31 were challenging, their extraction studies were only carried out in perchloric acid containing Lu( iii ). Cherkasov et al found out that the extraction efficiency of the synthesized extractants strongly depended on the nature of the acidic solution [ 36 ]. The extraction efficiencies of 29 and 31 were comparable with 22 in perchloric acid.…”

“…α-Aminophosphonates 8 – 14 together with α-aminophosphinate 21 and α-aminophosphine oxides 22 – 32 were synthesized using the same procedure, by refluxing the reagents either in benzene, toluene, or acetonitrile and using p -toluenesulfonic acid as the acid catalyst [ 11 , 36 , 37 , 39 , 40 , 41 , 42 , 43 , 44 , 50 , 51 ]. The progress of the reaction was monitored by measuring the amount of water formed into the Dean–Stark trap.…”

Studies on heavy metal removal efficiency and antibacterial activity of 2-(diphenylphosphino)aminopyridine

“…There are a number of efficient reagents used for metal extraction, most notably organophosphorus compounds [13][14][15][16][17][18][19][20][21][22][23] and amines [24]. The synergistic extraction of these divalent transition metal ions with mixtures of neutral organophosphorus extractants and amine extractants has been reported previously [25].…”