Search NASA⌕ Search

Engineering topics

Ellis, Ross J.

Publications and source records attributed to Ellis, Ross J..

15 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Magnetically enhanced phase separation for solvent extraction

Briefly, the invention provides a method for magnetically assisting demulsification of extraction phases, the method having the steps of contacting a first solution of a first solvent and a solvated paramagnetic metal ion with a second solvent, where the second solvent is immiscible with the first solvent; mixing the first and second solutions to create an emulsion having a first phase of the first solvent and second phase comprising the second solvent where the phases of the emulsion contain different concentrations of the paramagnetic metal ion; and applying a magnetic field gradient to the first and second phases of the emulsion to accelerate separation of the first phase from the second phase. Also provided is a system for demulsifying phases used in the extraction of paramagnetic moieties from solution having a lumen with an interior region, an interior surface, and exterior surface; and a magnetic field gradient present within the interior region.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Surprisingly selective sulfate extraction by a simple monofunctional di(imino)guanidinium micelle-forming anion receptor

Here, we report a novel di(imino)guanidinium anion extractant with unparalleled selectivity for sulfate in a liquid–liquid separation system. In addition to a 4.4 order-of-magnitude enhancement in affinity compared to a standard benchmark, our alkylated di(imino)guanidinium receptor is economically synthesized and features good compatibility with application-relevant aliphatic solvents. Small-angle X-ray scattering results reveal the formation of reverse-micelles, which together with the significant organic-phase water content challenge traditional notions of selectivity in extraction of superhydrophilic anions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Capping the calix: How toluene completes cesium( i ) coordination with calix[4]pyrrole

The role of solvent in molecular recognition systems is under-researched and often ignored, especially when the solvent is considered “non-interacting”. This study concerns the role of toluene solvent in cesium(I) recognition by calix[4]pyrrole. We show that π-donor interactions bind toluene molecules onto the open face of the cation-receptor complex, thus “capping the calix.” As a result, by characterizing this unusual aromatically-saturated complex, we show how “non-interacting” aromatic solvents can directly coordinate receptor-bound cations and thus influence recognition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Complexation Enhancement Drives Water-to-Oil Ion Transport: A Simulation Study

We address the structures and energetics of ion solvation in aqueous and organic solutions to understand liquid-liquid ion transport. Atomistic molecular dynamics (MD) simulations with polarizable force field are performed to study the coordination transformations driving lanthanide (Ln(III)) and nitrate ion transport between aqueous and an alkylamide-oil solution. An enhancement of the coordination behavior in the organic phase is achieved in contrast with the aqueous solution. In particular, the coordination number of Ce3+ increases from 8.9 in the aqueous to 9.9 in the organic solutions (from 8 in the aqueous to 8.8 in the organic systems for Yb3+). Moreover, the local coordination environ ment changes dramatically. Potential of mean force calculations show that the Ln(III)-ligand coordination interaction strengths follow the order of Ln(III-)nitrate> Ln(III)-water>Ln(III)-DMDBTDMA. They increase 2-fold in the lipophilic environment in comparison to the aqueous phase, and we attribute this to the shedding of the outer solvation shell. Our findings highlight the importance of outer sphere interactions on the competitive solvation energetics that cause ions to migrate between immiscible phases; an essential ingredient for advancing important applications such as rare earth metal separations. Some open questions in simulating the coordination behavior of heavy metals are also addressed.

Qiao, Baofu↗
DOE OSTI2016

“Straining” to Separate the Rare Earths: How the Lanthanide Contraction Impacts Chelation by Diglycolamide Ligands

The subtle energetic differences underpinning adjacent lanthanide discrimination are explored with diglycolamide ligands. Our approach converges liquid–liquid extraction experiments with solution-phase X-ray absorption spectroscopy (XAS) and density functional theory (DFT) simulations, spanning the lanthanide series. The homoleptic [(DGA)3Ln]3+ complex was confirmed in the organic extractive solution by XAS, and this was modeled using DFT. An interplay between steric strain and coordination energies apparently gives rise to a nonlinear trend in discriminatory lanthanide ion complexation across the series. Our results highlight the importance of optimizing chelate molecular geometry to account for both coordination interactions and strain energies when designing new ligands for efficient adjacent lanthanide separation for rare-earth refining.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Trapped in the coordination sphere: Nitrate ion transfer driven by the cerium(III/IV) redox couple

Redox-driven ion transfer between phases underpins many biological and technological processes, including industrial separation of ions. Here we investigate the electrochemical transfer of nitrate anions between oil and water phases, driven by the reduction and oxidation of cerium coordination complexes in oil phases. We find that the coordination environment around the cerium cation has a pronounced impact on the overall redox potential, particularly with regard to the number of coordinated nitrate anions. Our results suggest a new fundamental mechanism for tuning ion transfer between phases; by 'trapping' the migrating ion inside the coordination sphere of a redox-active complex. Here, this presents a new route for controlling anion transfer in electrochemically-driven separation applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

A simple primary amide for the selective recovery of gold from secondary resources

Waste electrical and electronic equipment (WEEE) such as mobile phones contains a plethora of metals of which gold is by far the most valuable. Herein a simple primary amide is described that achieves the selective separation of gold from a mixture of metals typically found in mobile phones by extraction into toluene from an aqueous HCl solution; unlike current processes, reverse phase transfer is achieved simply using water. Phase transfer occurs by dynamic assembly of protonated and neutral amides with [AuCl 4 ]– ions through hydrogen bonding in the organic phase, as shown by EXAFS, mass spectrometry measurements, and computational calculations, and supported by distribution coefficient analysis. In conclusion, the fundamental chemical understanding gained herein should be integral to the development of metal-recovery processes, in particular through the use of dynamic assembly processes to build complexity from simplicity.

36 MATERIALS SCIENCE↗