Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “IrN”

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.

11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Adsorption Equilibrium, Kinetics, and Column Breakthrough Data of Acetic Acid, Butyric Acid, and Lactic Acid on IRN-78 Ion-exchange Resin at Initial pH ~3 – 7 and Temperature 25 – 55 °C

This work presents systematic aqueous-phase adsorption equilibrium, kinetics, and column breakthrough measurements with three key biointermediates that are common compounds in many bioprocesses. Adsorption equilibrium experiments were carried out with acetic acid, butyric acid, and lactic acid on a commercial ion-exchange resin, Amberlite IRN-78, at wide ranges of acid concentration (8-500 mmol/L), initial pH (similar to 3-7), and temperature (25-55 degrees C), simulating the effluent characteristics from different fermenter operations. The kinetics and column breakthrough experiments were conducted at an initial pH of 6 and a concentration of 200 mmol/L. The equilibrium study shows a higher loading at the initial pH < pK(a) and a lower loading at the initial pH > pK(a). Overall removal varies between 16 and 99% depending on the initial pH, temperature, and organic acid concentration and type. The study further indicates monolayer adsorption at the equilibrium pH > 10 and multilayer adsorption at the equilibrium pH < 6. The thermodynamic modeling of adsorption isotherm data was carried out using Langmuir and Freundlich isotherms. IRN-78 presents fast adsorption kinetics as the maximum loading was attained in <= 10 min and nearly the same breakthrough time for all three organic acids involved in this study.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on IrN by Materials Project

IrN crystallizes in the tetragonal P4_2/mmc space group. The structure is three-dimensional. Ir3+ is bonded in a square co-planar geometry to four equivalent N3- atoms. All Ir–N bond lengths are 2.04 Å. N3- is bonded in a 4-coordinate geometry to four equivalent Ir3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on IrN by Materials Project

IrN is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ir3+ is bonded to six equivalent N3- atoms to form a mixture of edge and corner-sharing IrN6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ir–N bond lengths are 2.20 Å. N3- is bonded to six equivalent Ir3+ atoms to form a mixture of edge and corner-sharing NIr6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on IrN by Materials Project

IrN is Zincblende, Sphalerite structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Ir3+ is bonded to four equivalent N3- atoms to form corner-sharing IrN4 tetrahedra. All Ir–N bond lengths are 2.01 Å. N3- is bonded to four equivalent Ir3+ atoms to form corner-sharing NIr4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on IrN by Materials Project

IrN is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Ir3+ is bonded in a body-centered cubic geometry to eight equivalent N3- atoms. All Ir–N bond lengths are 2.39 Å. N3- is bonded in a body-centered cubic geometry to eight equivalent Ir3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on IrN by Materials Project

IrN is Tungsten Carbide structured and crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Ir3+ is bonded to six equivalent N3- atoms to form a mixture of distorted face, edge, and corner-sharing IrN6 pentagonal pyramids. All Ir–N bond lengths are 2.27 Å. N3- is bonded in a 6-coordinate geometry to six equivalent Ir3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on IrN by Materials Project

IrN crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Ir3+ is bonded in a square co-planar geometry to four equivalent N3- atoms. All Ir–N bond lengths are 2.05 Å. N3- is bonded in a square co-planar geometry to four equivalent Ir3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on IrN by Materials Project

IrN is Boron Nitride structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Ir3+ is bonded in a rectangular see-saw-like geometry to four equivalent N3- atoms. There are three shorter (2.04 Å) and one longer (2.10 Å) Ir–N bond lengths. N3- is bonded in a rectangular see-saw-like geometry to four equivalent Ir3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Adsorption Equilibrium, Kinetics, and Column Breakthrough Data for Aqueous Solutions of Binary-Acid and Ternary-Acid Mixtures of Acetic Acid, Butyric Acid, and Lactic Acid on IRN-78 Ion-Exchange Resin at Initial pH Levels of ∼3–7 and at 25–55 °C

This work is part of an effort to develop thermophysical property data and models supporting adsorptive process development for organic acid separation from a dilute aqueous solution of fermentation broth. It presents systematic experimental measurements for aqueous-phase adsorption equilibrium, kinetics, and column breakthrough for three binary-acid aqueous mixtures (acetic acid + lactic acid, butyric acid + lactic acid, and acetic acid + butyric acid) and one ternary-acid aqueous mixture (acetic acid + butyric acid + lactic acid) on Amberlite IRN-78 ion-exchange resin. The equilibrium measurements covered broad ranges of the initial acid concentration (100–400 mmol/L), initial pH (∼3–7), and temperature (25–55 °C). The equilibrium data for the binary-acid and ternary-acid aqueous mixtures indicate selective adsorption of lactic acid at initial pH levels of ∼3 and 4, while acetic acid and butyric acid are selectively adsorbed at initial pH levels of 5, 6, and 7. The subsequent kinetics and column breakthrough experiments were performed at 200 mmol/L with equimolar ratios, an initial pH of 6, and 25 °C. In conclusion, the measurements provide essential data sets for rigorous thermodynamic modeling and process simulation of adsorptive separation processes for organic acid separation from fermentation broth.

Adsorption↗
DOE OSTI2023

Ionomer-free nanoporous iridium nanosheet electrodes with boosted performance and catalyst utilization for high-efficiency water electrolyzers

Increasing the catalyst utilization efficiency and simplifying electrode fabrication processes are crucial to accelerate development of low-cost proton exchange membrane electrolyzer cells (PEMECs). Here, we develop a facile route to fabricate ionomer-free iridium nanosheet integrated electrodes, in which nanoporous iridium nanosheets (IrNS) with abundant exposed edges and nanopores are deposited on thin titanium liquid/gas diffusion layers (TT-LGDLs) via a low-temperature chemical synthesis strategy. Further, benefiting from high catalytic activity, good electrode conductivity and excellent liquid/gas transport properties, such nanoporous IrNS electrodes with low catalyst loadings require low cell voltages of 1.65 V and 1.78 V at 3000 and 6000 mA/cm 2 , respectively. More impressively, a stable performance can be well maintained under extremely high current density tests of 5000 mA/cm 2 , demonstrating the potential of low-loading nanoporous IrNS electrodes in solid-electrolyte based electrochemical conversion cells that require high current density operation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Performance characterization of nanofiltration, reverse osmosis, and ion exchange technologies for acetic acid separation

A major obstacle to widespread implementation of bio-based fuels and chemicals is the lack of efficient and costeffective separation methods. To purify acetic acid produced by biochemical conversion of biomass via anaerobic digestion, this work employs two commonly used separation technologies: (1) ion-exchange (IX) resin and (2) pressure-driven membranes. This study tested five commercially available strong- and weak-base anion-exchange resins and five commercially available nanofiltration (NF) and reverse osmosis (RO) membranes. The pH of the feed solution significantly affected adsorption capacity. At pH 6.3, a strong-base IX resin (IRN-78) performed best (95.1% acetate removal). With strong-base IX resins, the Langmuir isotherm model fit well, whereas for weak-base IX resins, the Freundlich isotherm provided a better fit. A pseudo-second-order kinetic model fit well for both IRN-78 and IRA-67. Regarding membrane separation, RO (BW30XFR membrane) achieved the highest rejection (98.6% acetate rejection), whereas an NF membrane (NF*) achieved the best combination of permeate flux (105 L/(h∙m 2 )) and rejection (83.1% acetate rejection). For membrane performance, the experimental data were fit using the solution diffusion model. Increased pH in the feed solution lowered permeate flux but increased acetic acid rejection. Finally, then the acetic acid concentration in the feed solution increased, both permeate flux and acetic acid rejection decreased for membrane NF*.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗