Separation and Recovery of Scandium from Sulfate Media by Solvent Extraction and Polymer Inclusion Membranes with Amic Acid Extractants

Abstract

We report on the separation and recovery of scandium(III) from sulfate solutions using solvent extraction and a membrane transport system utilizing newly synthesized amic acid extractants. Scandium(III) was quantitatively extracted with 50 mmol dm–3N-[N,N-di(2-ethylhexyl)aminocarbonylmethyl]glycine (D2EHAG) or N-[N,N-di(2-ethylhexyl)aminocarbonylmethyl]phenylalanine (D2EHAF) in n-dodecane at pH 2 and easily stripped using a 0.5 mol dm–3 sulfuric acid solution. The extraction mechanisms of scandium(III) extraction with D2EHAG and D2EHAF were examined, and it was established that scandium(III) formed a 1:3 complex with both extractants (HR), that is, Sc(SO4)2–aq + 1.5(HR)2org ⇄ Sc(SO4)R(HR)2org + H+aq + SO42–aq. The equilibrium constants of extraction were evaluated to be 4.87 and 9.99 (mol dm–3)0.5 for D2EHAG and D2EHAF, respectively. D2EHAG and D2EHAF preferentially extracted scandium(III) with a high selectivity compared to common transition metal ions under high acidic conditions (0 < pH ≤ 3). In addition, scandium(III) was quantitatively transported from a feed solution into a 0.5 mol dm–3 sulfuric acid receiving solution through a polymer inclusion membrane (PIM) containing D2EHAF as a carrier. Scandium(III) was completely separated thermodynamically from nickel(II), aluminum(III), cobalt(II), manganese(II), chromium(III), calcium(II), and magnesium(II), and partially separated from iron(III) kinetically using a PIM containing D2EHAF as a carrier. The initial flux value for scandium(III) (J0,Sc = 1.9 × 10–7 mol m–2 s–1) was two times higher than that of iron(III) (J0,Fe = 9.3 × 10–8 mol m–2 s–1).

Recent Advances in the Selective Transport and Recovery of Metal Ions using Polymer Inclusion Membranes

“…Rapid development of the new energy vehicle industry has brought pressure on the demand and supply of lithium resources; thus, massive efforts have been made by PIMs to recover and extract lithium from salt lake brines, which are the largest lithium resource reserves around the world. Cai et al [22] first fabricated CTA-based PIM containing TTA and TOPO as carriers for [71] PVC -Bi (III), [70] Gd (III), Yb (III), and La (III) [10] PVC DAO Zn (II) [39] PVC DOP Cu (II) [ 72,73] PVC 2-NPOE Zn (II), Cu (II) and Mg (II), [74] Cu (II), [75] Bi (III) [76] PVDF-HFP 2-NPOE Sc (III) [77] PVDF-HFP -Zn (II) [78] P227 PVDF -Lu (III) [79] B2EHP PVC DOP/kerosene Cd (II) [80] D2EHAG PVC 2-NPOE Au (III) [81] D2EHAF CTA 2-NPOE Sc (III) [ 26,82] Cyanex 272 PVC 2-NPOE/TBP/1-dodecanol Co (II) [36] LIX84I PVC 2-NPOE Zn (II), Cu (II), and Mg (II), [74] Cu (II) [83] LIX84I SBS -Cu (II), Zn (II), and Cr (VI) [67] Table 3. Example of PIMs with neutral or solvating carriers and their corresponding target metal species.…”

Separation and Recovery of Sc(III) and Y(III) from Aqueous Acidic Media with <i>N</i>-Lauroylsarcosine

“…The valuable Sc(III) resources being used in China are tungsten residue, dust in chlorinating magnetovanailmenite, effluents in the production of titanium white, and rare earth minerals rich in Y(III) [3,4]. In recent years, Sc(III) has been widely used in optical, electronic, and chemical industries, and aerospace, nuclear technology, and other fields and its demand has continued to grow [5][6][7][8]. Demand for Sc(III) has been expected to increase in the future because it is also used in fuel cells [8][9][10][11].…”

“…In recent years, Sc(III) has been widely used in optical, electronic, and chemical industries, and aerospace, nuclear technology, and other fields and its demand has continued to grow [5][6][7][8]. Demand for Sc(III) has been expected to increase in the future because it is also used in fuel cells [8][9][10][11]. However, Sc(III) is hard to separate and recover, and its production amounts are insufficient to satisfy the growing demand.…”

“…However it is difficult to back-extract Sc(III) from the organic phase. In addition, when Sc(III) was extracted from a simulated aqueous solution containing Ti(IV) and Zr(IV), the phase separation deteriorates [8,17]. Thus, alkylated carboxylic acids of the high pK a values have almost never been used as industrial extractants for Sc(III) and Y(III).…”

Ultrasonic assisted solvent extraction in synthesis of ceria nanofluids from rare earth material for heat exchange application

“…It is generally applied as power resource, which is transmitted throughout the liquid intermediate due to the cavitation phenomena by producing micro-bubbles considered as key in extraction of rare earth element [11,12]. This phenomenon helps to change physico-chemical properties of the solvent by removing the organo-aqueous phase [13] and selection of optimum diluentextractant pairs. When ultrasonic wave transmits in the liquid intermediate, it produces compression and rarefaction cycles inside the treated medium as shown in figure 1.…”