Search NASA⌕ Search

SEARCH · Search NASA

Results for “Aqueous solution”

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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Gamma-irradiation of malic acid in aqueous solutions

The gamma-irradiation of malic acid in aqueous solutions was studied under initially oxygenated and oxygen-free conditions in an attempt to determine the possible interconversion of malic acid into other carboxylic acids, specifically those associated with Krebs cycle. The effect of dose on product formation of the system was investigated. Gas-liquid chromatography combined with mass spectrometry was used as the principal means of identification of the nonvolatile products. Thin layer chromatography and direct probe mass spectroscopy were also employed. The findings show that a variety of carboxylic acids are formed, with malonic and succinic acids in greatest abundance. These products have all been identified as being formed in the gamma-irradiation of acetic acid, suggesting a common intermediary. Since these molecules fit into a metabolic cycle, it is strongly suggestive that prebiotic pathways provided the basis for biological systems.

Negron-Mendoza, A.↗
NASA NTRS1982

Formation of the thioester, N-acetyl, S-lactoylcysteine, by reaction of N-acetylcysteine with pyruvaldehyde in aqueous solution

N-acetylcysteine reacts efficiently with pyruvaldehyde (methylglyoxal) in aqueous solution (pH 7.0) in the presence of a weak base, like imidazole or phosphate, to give the thioester, N-acetyl, S-lactoylcysteine. Reactions of 100 mM N-acetylcysteine with 14 mM, 24 mM and 41 mM pyruvaldehyde yield, respectively, 86%, 76% and 59% N-acetyl, S-lactoylcysteine based on pyruvaldehyde. The decrease in the percent yield at higher pyruvaldehyde concentrations suggests that during its formation the thioester is not only consumed by hydrolysis, but also by reaction with some substance in the pyruvaldehyde preparation. Indeed, purified N-acetyl, S-lactoylcysteine disappears much more rapidly in the presence of pyruvaldehyde than in its absence. Presumably, N-acetyl, S-lactoylcysteine synthesis occurs by rearrangement of the hemithioacetal of N-acetylcysteine and pyruvaldehyde. The significance of this pathway of thioester formation to molecular evolution is discussed.

Weber, A. L.↗
DOE OSTI2025

Magnetic fly-ash geopolymer for heavy metal removal in aqueous solutions

Novel magnetic geopolymers were manufactured by synthesizing magnetic Fe 3 O 4 particles on the surface of prepared geopolymer (Method 1) or by incorporating pre-synthesized magnetic Fe 3 O 4 particles into the geopolymer during the manufacture of the geopolymer (Method 2). This study evaluated the effect of the incorporated magnetic Fe 3 O 4 on the geopolymer magnetic, physical, and adsorption properties and its separation in aqueous solutions. Based on several preliminary measurements on the synthesized magnetic geopolymers, Method 2 was found to be a better method for producing magnetic geopolymer. Magnetic geopolymer synthesized by Method 2 exhibited ferromagnetic properties comparable to that of magnetic Fe 3 O 4 , with a saturation magnetization of 8 emu·g −1 and an intrinsic coercivity of 265 Oe. The magnetic geopolymer was efficiently separated from an aqueous solution within 2 min using a 0.48-T magnetic field. In addition, the magnetic geopolymer has a maximum copper adsorption capacity of 111.1 mg·g −1 , which was similar to the non-magnetic reference geopolymer indicating that the addition of magnetic Fe 3 O 4 did not compromise the geopolymer adsorption capacity. The magnetic geopolymer is a promising material with good adsorption and separation properties that can be used for heavy metals removal and recovery in wastewater and metals separation in industrial processes.

fly ash↗
NASA NTRS1972

Spectral reflectance of selected aqueous solutions for water quality applications

The relative specular reflectances of individual aqueous solutions having a particular chemical salt content were measured in the 2 to 20 micrometers region of the infrared component or radiant flux. Distilled water was the reflectance standard. The angle of incidence was 70.03 deg plus or minus 0.23 deg. Absolute reflectances of the solutions for the same polarization and angle of incidence were computed by use of the measured relative reflectances, one of the Fresnel equations, and the optical constants of distilled water. Phase shift and phase difference spectra were obtained by respectively applying a Kramers-Kronig dispersion analysis to the absolute and relative reflectance spectra. The optical constants of the solutions were determined by algorithms commonly associated with the Kramers-Kronig analysis. Spectral signatures that qualitatively and quantitatively characterize the solute and that show structure of the infrared bands of water were noted in the phase difference spectra. The relative and absolute reflectances, the phase shift and phase difference spectra and the optical constants are presented in graphical form. Application of these results to remote sensing of the chemical quality of natural waters is discussed briefly.

Querr, M. R.↗
DOE OSTI2024

An ion specific continuum model on ionic surfactant's binary phase diagram in aqueous solution

Here, a continuum aggregation model is proposed to account for specific ion effects, enabling accurate phase diagrams calculations for the micellar, cylindrical and lamellar aggregates of sodium/potassium carboxylate surfactants in aqueous solution across a range of temperatures. Three groups of concentrations at distinctive temperatures are fitted to build empirical temperature dependence given the limited availability of relevant experimental measurements. The specific ion effects are manifested in the aggregates' surface tension as well as in the distributions of counter-ions' concentrations in the vicinity of the aggregates. The aggregates' geometric sizes are well-reproduced. The differential evolution algorithm is applied to address boundary conditions of the electrostatic potential, aggregate size optimization as well as the equilibrium of monomers transferring between the aggregate and aqueous region.

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

Internal pressures and molecular dimensions in aqueous solutions of some chlorides

On the basis of measurements of the velocity of ultrasounds in aqueous solutions of some alkaline-earth chlorides (MgCl2, CaCl2, BaCl2) the concentration and temperature dependences of the internal pressure were determined. Using these results, as well as surface tension measurements, the mean diameters of the molecular species as a function of concentration and temperature, were determined.

Auslaender, D.↗