Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “SEPARATION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Separation of Xylene Isomers through Multiple Metal Site Interactions in Metal–Organic Frameworks

Purification of the C 8 alkylaromatics o-xylene, m-xylene, p-xylene, and ethylbenzene remains among the most challenging industrial separations, due to the similar shapes, boiling points, and polarities of these molecules. We report the evaluation of the metal-organic frameworks Co 2 (dobdc) (dobdc 4- = 2,5-dioxido-1,4-benzenedicarboxylate) and Co 2 ( m-dobdc) ( m-dobdc 4- = 4,6-dioxido-1,3-benzenedicarboxylate) for the separation of xylene isomers using single-component adsorption isotherms and multicomponent breakthrough measurements. Remarkably, Co 2 (dobdc) distinguishes among all four molecules, with binding affinities that follow the trend o-xylene > ethylbenzene > m-xylene > p-xylene. Multicomponent liquid-phase adsorption measurements further demonstrate that Co 2 (dobdc) maintains this selectivity over a wide range of concentrations. Structural characterization by single-crystal X-ray diffraction reveals that both frameworks facilitate the separation through the extent of interaction between each C 8 guest molecule with two adjacent cobalt(II) centers, as well as the ability of each isomer to pack within the framework pores. Moreover, counter to the presumed rigidity of the M 2 (dobdc) structure, Co 2 (dobdc) exhibits an unexpected structural distortion in the presence of either o-xylene or ethylbenzene that enables the accommodation of additional guest molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Unblocking a rigid purine MOF for kinetic separation of xylenes

The separation of xylene isomers still remains an industrially challenging task. Here, we synthesized and studied porous purine-based metal–organic frameworks (MOFs) for their potential in xylene separations. In particular, Zn(purine)I showed excellent para-xylene/ortho-xylene separation capability with a diffusion selectivity of 6 and high equilibrium adsorption selectivity as indicated by coadsorption experiments. This high selectivity is attributed to the shape and size of the channel aperture within the rigid framework of Zn(purine)I.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Charge separation at nanoscale interfaces: Energy-level alignment including two-quasiparticle interactions

The universal and fundamental criteria for charge separation at interfaces involving nanoscale materials are investigated. In addition to the single-quasiparticle excitation, all the two-quasiparticle effects including exciton binding, Coulomb stabilization, and exciton transfer are considered, which play critical roles on nanoscale interfaces for optoelectronic applications. We propose a scheme allowing adding these two-quasiparticle interactions on top of the single-quasiparticle energy level alignment for determining and illuminating charge separation at nanoscale interfaces. Employing the many-body perturbation theory based on Green's functions, we quantitatively demonstrate that neglecting or simplifying these crucial two-quasiparticle interactions using less accurate methods is likely to predict qualitatively incorrect charge separation behaviors at nanoscale interfaces where quantum confinement dominates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Highly concentrated nebular noble gases in porous nanocarbon separates from the Saratov (L4) meteorite

The majority of heavy noble gases (Ar, Kr, and Xe) in primitive meteorites are stored in a poorly understood phase called Q. Although Q is thought to be carbonaceous, the full identity of the phase has remained elusive for almost four decades. In order to better characterize phase Q and, in turn, the early solar nebula, we separated carbon-rich fractions from the Saratov (L4) meteorite. We chose this meteorite because Q is most resistant in thermal alteration among carbonaceous noble gas carriers in meteorites and we hoped that, in this highly metamorphosed meteorite, Q would be present but not diamond: these two phases are very difficult to separate from each other. One of the fractions, AJ, has the highest {sup 132}Xe concentration of 2.1 × 10{sup –6} cm{sup 3} STP g{sup –1}, exceeding any Q-rich fractions that have yet been analyzed. Transmission electron microscopy studies of the fraction AJ and a less Q-rich fraction AI indicate that they both are primarily porous carbon that consists of domains with short-range graphene orders, with variable packing in three dimensions, but no long-range graphitic order. The relative abundance of Xe and C atoms (6:10{sup 9}) in the separates indicates that individual noble gas atoms are associated with only a minor component of the porous carbon, possibly one or more specific arrangements of the nanoparticulate graphene.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Separable and non-separable multi-field inflation and large non-Gaussianity

In this paper we provide a general framework based on δN formalism to estimate the cosmological observables pertaining to the cosmic microwave background radiation for non-separable potentials, and for generic end of inflation boundary conditions. We provide analytical and numerical solutions to the relevant observables by decomposing the cosmological perturbations along the curvature and the isocurvature directions, instead of adiabatic and entropy directions. We then study under what conditions large bi-spectrum and tri-spectrum can be generated through phase transition which ends inflation. In an illustrative example, we show that large f{sub NL} ∼ O(80) and τ{sub NL} ∼ O(20000) can be obtained for the case of separable and non-separable inflationary potentials.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

2013 Actinide Separation Conference Presentations on Minor Actinide Separations by SRNL Participants [Slides]

Attached are copies of the presentations that will be given by Savannah River National Laboratory participants at the 37th Actinide Separations Conference in Spokane, Washington on June 24 – 27, 2013. This document represents the deliverable for milestone M4FT-13SR0303062, Prepare and present two papers on ion exchange separations at the 2013 Actinide Separations conference. Note that the completion of the milestone was delayed due to the rescheduling of the conference from late May 2013 to late June 2013.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1974

Ferrofluid separator for nonferrous scrap separation

Behavior of nonmagnetic objects within separator is essentially function of density, and independent of size or shape of objects. Results show close agreement between density of object and apparent density of ferrofluid required to float it. Results also demonstrate that very high separation rates are achievable by ferrofluid sink-float separation.

Kaiser, R.↗
DOE OSTI2013

Methods for separating a fluid, and devices capable of separating a fluid

Methods and apparatus for separating fluids are disclosed. We have discovered that, surprisingly, providing an open pore structure between a wick and an open flow channel resulted in superior separation performance. A novel and compact integrated device components for conducting separations are also described.

42 ENGINEERING↗
DOE OSTI2018

Control of Shell Morphology in p-n Heterostructured Water-Processable Semiconductor Colloids: Toward Extremely Efficient Charge Separation

This article describes p-n heterostructured water-borne semiconductor naonoparticles (NPs) with unique surface structures via control of shell morphology. The shell particles, comprising PC60-PC61BM composite, having n-type semiconductor characteristic, notably influence the charge carrier behavior in the core-shell NPs. A one- or two-phase methodology based on a PC60 surfactant-water phase and PC61BM n-type semiconductor-organic phase provided highly specific control over the shell structure of the NPs, which promoted their superior charge separation ability when combined with poly-3-hexyl-thiophene (P3HT). Moreover, the resulting water-borne NPs exhibit shell morphology-dependent carrier quenching and stability, which was characterized via luminescence studies paired with structural analysis. Corresponding to the results, outstanding performances of photovoltaic cells with over 5 % efficiency were achieved. The results suggest that the surrounding shell environments, such as the shell structure, and its electronic charge density, were crucial in determining the overall activity of the core-shell p-n heterostructured NPs. Thus, this work provides a new protocol in the current fields of water-based organic semiconductor colloids.

charge separation↗
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 OSTI2019

Tailored CO 2 -philic Gas Separation Membranes via One-Pot Thiol–ene Chemistry

Recently, thiol–ene chemistry attracts much attention in the construction of functional polymer materials due to its versatility and fast reaction kinetics, though only a few studies have been reported on its utilization in the fabrication of elastic polymer materials. Herein, a series of elastic, poly(dimethylsiloxane)–poly(ethylene glycol) methyl ether acrylate (PDMS–PEGMEA)-based co-polymer membranes are synthesized via a one-pot thiol–ene reaction. These membranes are highly stable and exhibit tunable thermal/mechanical properties by tailoring the cross-linker and side-chain functionality. When used for gas separation application, all grafted elastomer membranes show excellent gas permeability and selectivity, and the membrane with an optimal composition (PDMS–PEGMEA 30 –EOPDMS 10 ) has reached the Robeson upper bound (CO 2 permeability ~800 barrer and α[CO 2 /N 2 ] ~39). The high permeability originates from the extremely fast chain mobility of PDMS molecules at the ambient temperature. Tailoring the PEGMEA content allows control of the α[CO 2 /N 2 ] ranging from 21 to 39 by enhancing gas solubility within the membrane matrix. This study provides a promising strategy to be utilized for the gutter layer, selective layer, or their combination in the industrial gas separation modules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗