High‐performance polymer‐supported extractants with phosphonate ligands for scandium(III) separation

Abstract

in Wiley Online Library (wileyonlinelibrary.com) As the market demand for scandium has grown, a great deal of interest has been generated in its recovery. To substantially simplify the process and provide a green alternative for scandium separation, novel polymer-supported extractants containing di(2-ethylhexyl) phosphonate and bis(2,4,4-trimethylpentyl) phosphonate, [D201][DEHP] and [D201] [C272] are proposed because they demonstrate improved adsorption capacity and selectivity toward scandium(III). Scandium(III) adsorption is significantly affected by the solution pH, with the maximum adsorption occurring at a pH of approximately 0.78. The batch adsorption data fit well with the Langmuir isotherm and pseudo-second-order kinetic models. A combination of the Fourier transform infrared and XPS spectra suggest that the complexation of oxygen atoms in phosphate groups with scandium(III) is the predominant adsorption mechanism. Additionally, the two resins were used to recover scandium from leaching liquor of nickel laterite ore. [D201][DEHP] exhibits unusual selectivity for scandium and low competitive behavior with other metals, thus increasing its market potential. V C 2016 American Institute of Chemical Engineers AIChE J, 62: 2479-2489, 2016 Keywords: polymer-supported extractants, scandium(III), adsorption mechanism, nickel laterite ore IntroductionThe recovery of scandium has received considerable academic interest, owing to its potential importance in many applications-for instance, aluminum-scandium alloys, advanced ceramics, metal halide lamps, solid oxide fuel cells, nuclear materials and lasers.1 All of these applications have led to an increase in the industrial demand for scandium; unfortunately, the commercial application of scandium continues to be thwarted by its low availability; it remains difficult to obtain because it is distributed sparsely and occurs only in trace amounts in many complicated minerals.2 As a result, scandium is usually recovered as a byproduct of uranium and tungsten production 3,4 or the processing of nickel laterite ores 5 and bauxite. 6 For example, in Australia, the nickel laterite ores contain a relatively high content of scandium and are considered to be important scandium resources. Scandium can be recovered as a byproduct during nickel and cobalt extraction operations. A typical nickel laterite ore mainly consists of Ni (1-2%), Co (0.05-0.10%), Fe (15-50%), Al (2-5%), and trace amounts of Sc (0.005-0.006%).7 Considering their increasing demand and scarcity, the recovery of valuable minor elements-particularly scandium, which is associated with nickel laterite ore-is highlighted in research.After sulfuric acid leaching under atmospheric pressure, 8 scandium is normally separated and recovered by solvent extraction and ion exchange techniques in the processing of nickel laterite ore. 9-11 However, these processes that attempt to recover scandium still face the problem that the concentration of scandium is low (below 20 ppm), but the concentrations of iron and aluminum i...

Quaternization of algal/PEI beads (a new sorbent): Characterization and application to scandium sorption from aqueous solutions

“…Different types of sorbents have been reported for the sorption of scandium from dilute solutions, including (a) biosorbents such as yeast [17], bacteria [18] or algae [19], carbon-based materials [20], resins [21][22][23][24]; impregnated resins [25][26][27]. Recently a new generation of materials has been designed using the interactions of alginate and polyethyleneimine (PEI) for manufacturing bead sorbents [28].…”

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

“…The interference of Si(IV) was not studied because it is generally not present in the sulfuric acid leachate of Sc(III). 8,16,52,53 Figure 5 shows the plots of the degree of extraction of the metal ions listed above from a 0.1 mol dm –3 H 2 SO 4 /(NH 4 ) 2 SO 4 solution with 50 mmol dm –3 D2EHAG or D2EHAF as a function of the equilibrium pH.…”

“…Solvent extraction of various metal ions [i.e., Sc­(III), Fe­(III), Ni­(II), Al­(III), Co­(II), Mn­(II), Cr­(III), Ca­(II), and Mg­(II)] was performed using D2EHAG and D2EHAF. The interference of Si­(IV) was not studied because it is generally not present in the sulfuric acid leachate of Sc­(III). ,,, Figure shows the plots of the degree of extraction of the metal ions listed above from a 0.1 mol dm –3 H 2 SO 4 /(NH 4 ) 2 SO 4 solution with 50 mmol dm –3 D2EHAG or D2EHAF as a function of the equilibrium pH.…”

Microbe-Encapsulated Silica Gel Biosorbents for Selective Extraction of Scandium from Coal Byproducts

“…Solid–liquid extraction (SLE) has emerged as an attractive alternative for Sc extraction due to the elimination of toxic, inflammable, and expensive organic solvents (diluent + extractant) and the facile reuse of adsorbent materials . A number of adsorbent materials have been developed for Sc recovery, including polyelectrolytes, carbon-based materials, polymer resins, and silica. − These adsorbents exhibit high Sc adsorption capacity owing to their high surface area and abundant negatively charged functional groups, , but their utility to extract Sc in the presence of competing lanthanides remains largely unknown, a barrier for their application to low-grade Sc feedstocks. ,,,,, Microbe-mediated surface adsorption (biosorption) via metal complex formation with the surface functional group offers a potentially cost-effective and environmentally sustainable approach for SLE of REE from dilute feedstock sources. − Previous work has shown that Sc was preferentially adsorbed to Bacillus subtilis and Escherichia coli when Sc was present at the same concentrations as the lanthanides. , Several yeast species were found to preferentially adsorb Sc over Y, Fe, and Al in both synthetic solutions and red mud leachates . While these initial studies are promising, it remains an open question, however, whether biosorption can be effectively applied for selective and scalable Sc recovery from relevant industrial feedstocks.…”

“…17−32 These adsorbents exhibit high Sc adsorption capacity owing to their high surface area and abundant negatively charged functional groups, 25,32 but their utility to extract Sc in the presence of competing lanthanides remains largely unknown, a barrier for their application to lowgrade Sc feedstocks. 18,22,23,26,27,32 Microbe-mediated surface adsorption (biosorption) via metal complex formation with the surface functional group offers a potentially cost-effective and environmentally sustainable approach for SLE of REE from dilute feedstock sources. 33−36 Previous work has shown that Sc was preferentially adsorbed to Bacillus subtilis and Escherichia coli when Sc was present at the same concentrations as the lanthanides.…”