ON THE MECHANISM OF THE DISSOLUTION OF MAGNESIUM IN ACIDIC SALT SOLUTIONS: I. PHYSICAL CONTROL BY SURFACE FILMS

1953 ◽  
Vol 31 (9) ◽  
pp. 849-867 ◽  
Author(s):  
E. J. Casey ◽  
R. E. Bergeron
Keyword(s):  
Ionic Strength ◽  
Chemical Control ◽  
Corrosion Potential ◽  
Surface Film ◽  
Surface Films ◽  
Salt Solutions ◽  
Acidic Solutions ◽  
Activity Temperature ◽  
Acidic Salt ◽  
High Concentrations

A kinetic study and analysis has been made of the effects of ionic strength, acid activity, temperature, and salt type on the dissolution of magnesium in acidic salt solutions. This is an example of the simplest type of corrosion involving hydrogen evolution. The results are interpreted in terms of the effects of the various factors on the structure of a surface film which must be magnesium oxide and/or hydroxide even in acidic solutions. The importance of internal dissolutions in the film at high concentrations of attacking reagent, for this and other cases, is shown. Owing to complex formation, under certain conditions an odd case of "chemical control" of the dissolution rate in this simplest case becomes evident. Corrosion potential measurements aid in the interpretation.

Corrosion Resistant Coatings for Aluminum by Hydrothermal Film Formation in Alkaline Li-Salt Solutions

1996 ◽  
Vol 432 ◽  
Author(s):  
R.G. Buchheit ◽  
M.A. Martinez ◽  
C.B. Cooper
Keyword(s):  
Transition Metal Oxides ◽  
Film Formation ◽  
Surface Film ◽  
Al Alloys ◽  
Surface Films ◽  
Salt Solutions ◽  
Corrosion Resistant ◽  
Inorganic Coatings ◽  
Coated Surfaces ◽  
Corrosion Resistant Coatings

AbstractNew methods of forming corrosion resistant inorganic coatings on Al and Al alloys are required due to environment and work safety hazards associated with the currently used Cr-based coatings technologies. In this paper we report on certain specific aspects of Al surface film formation that can be exploited to form highly corrosion resistant coatings. The aspects discussed include: formation of hydrotalcite surface films, Li2[Al2 (OH)6]2 CO3nH2O, by exposure to Li-salt solutions, elimination of unwanted Cu compounds that accumulate surface films formed on Cubearing Al alloys, and generation of high corrosion resistance by precipitating transition metal oxides on to alkaline hydrotalcite coated surfaces.

Surface Films on Zircaloy-2 Samples Cracked in Neutral Aqueous NaCl by Stress Corrosion

1973 ◽  
Vol 31 ◽  
pp. 46-47
Author(s):  
R.A. Ploc
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Stress Corrosion ◽  
Zirconium Dioxide ◽  
Surface Film ◽  
Surface Films ◽  
Continuous Layer ◽  
Transmission Electron ◽  
Product Film

Samples of low-nickel Zircaloy-2 (material MLI-788-see(1)), when anodically polarized in neutral 5 wt% NaCl solutions, were found to be susceptible to pitting and stress corrosion cracking. The SEM revealed that pitting of stressed samples was occurring below a 2000Å thick surface film which behaved differently from normal zirconium dioxide in that it did not display interference colours. Since the initial film thickness was approximately 65Å, attempts were made to examine the product film by transmission electron microscopy to deduce composition and how the corrosion environment could penetrate the continuous layer.

Endo-D-galacturonanase immobilized by adsorption on porous polyethyleneterephthalate

1982 ◽  
Vol 47 (10) ◽  
pp. 2716-2723 ◽  
Author(s):  
Lubomíra Rexová-Benková ◽  
Jiřina Omelková ◽  
Vladimír Kubánek
Keyword(s):  
Ionic Strength ◽  
High Stability ◽  
Relative Activity ◽  
Operational Stability ◽  
The Other ◽  
Fixation Strength ◽  
Action Pattern ◽  
Salt Solutions ◽  
Buffer Solution ◽  
Degradation Degree

Endo-D-galacturonanase of Aspergillus sp. was irreversibly adsorbed on polyethyleneterephthalate in an acetate 0.1 mol l-1 buffer solution of pH 4.2. Immobilization of the enzyme resulted in lowering of its activity, the measure of which depended on the amount of the enzyme fixed on the carrier. The highest relative activity (42.4%) had the preparation containing 5.25 mg of the enzyme per 1 g of the carrier. The velocity and intensity of the sorption of the enzyme depended on the ionic strength of the medium, whilst pH, on the other hand, was of no influence. Endo-D-galacturonanase immobilized in a 0.1 mol l-1 buffer was characteristic a) of its fixation strength in salt solutions of various ionic strength and pH, in a 3 mol l-1 guanidine solution, and also in sodium pectate and pectin solutions, b) of its high stability during a long-lasting storage at 4 °C, c) of its operational stability. The immobilization led to a partial change of the action pattern onto the high-molecular substrate, manifested in lowering the decrease of viscosity to degradation degree ratio.

scholarly journals A novel procedure for the rapid purification of plastocyanin from pea (Pisum sativum) leaves

1981 ◽  
Vol 193 (1) ◽  
pp. 375-378 ◽  
Author(s):  
A R Ashton ◽  
L E Anderson
Keyword(s):  
Ionic Strength ◽  
Pisum Sativum ◽  
Deae Cellulose ◽  
High Concentrations ◽  
Rapid Purification ◽  
Low Ionic Strength

Plastocyanin is soluble at high concentrations (greater than 3 M) of (NH4)2SO4 but under these conditions will adsorb tightly to unsubstituted Sepharose beads. This observation was utilized to purify plastocyanin from pea (Pisum sativum) in two chromatographic steps. Sepharose-bound plastocyanin was eluted with low-ionic-strength buffer and subsequently purified to homogeneity by DEAE-cellulose chromatography.

scholarly journals Elastic Properties of Natural Sea Surface Films Incorporated with Solid Dust Particles: Model Baltic Sea Studies

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Adriana Z. Mazurek ◽  
Stanisław J. Pogorzelski
Keyword(s):  
Baltic Sea ◽  
Surface Film ◽  
Contact Angles ◽  
Solid Particles ◽  
Sea Surface ◽  
Dust Particles ◽  
Surface Films ◽  
Particle Removal ◽  
Water Contact ◽  
Composite Surface

Floating dust-originated solid particles at air-water interfaces will interact with one another and disturb the smoothness of such a composite surface affecting its dilational elasticity. To quantify the effect, surface pressure (Π) versus film area (A) isotherm, and stress-relaxation (Π-time) measurements were performed for monoparticulate layers of the model hydrophobic material (of μm-diameter and differentiated hydrophobicity corresponding to the water contact angles (CA) ranging from 60 to 140°) deposited at surfaces of surfactant-containing original seawater and were studied with a Langmuir trough system. The composite surface dilational modulus predicted from the theoretical approach, in which natural dust load signatures (particle number flux, daily deposition rate, and diameter spectra) originated from in situ field studies performed along Baltic Sea near-shore line stations, agreed well with the direct experimentally derived data. The presence of seawater surfactants affected wettability of the solid material which was evaluated with different CA techniques applicable to powdered samples. Surface energetics of the particle-subphase interactions was expressed in terms of the particle removal energy, contact cross-sectional areas, collapse energies, and so forth. The hydrophobic particles incorporation at a sea surface film structure increased the elasticity modulus by a factor K (1.29–1.58). The particle-covered seawater revealed a viscoelastic behavior with the characteristic relaxation times ranging from 2.6 to 68.5 sec.

Hydrogen generation by both acidic and catalytic hydrolysis of sodium borohydride

2018 ◽  
Vol 5 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Olga V. Netskina ◽  
Tihon N. Filippov ◽  
Oksana V. Komova ◽  
Valentina I. Simagina
Keyword(s):  
Hydrogen Evolution ◽  
Sodium Borohydride ◽  
Hydrogen Generation ◽  
Hydrogen Release ◽  
Catalytic Hydrolysis ◽  
Hydrogen Storage Materials ◽  
Acidic Solutions ◽  
High Concentrations ◽  
Sulfuric And Hydrochloric Acids ◽  
Hydrolysis Of

Abstract Sodium borohydride tablets have been employed as hydrogen-storage materials. Hydrogen release was performed by acidic hydrolysis where solutions of sulfuric and hydrochloric acids were added to the tablets, and by catalytic hydrolysis where water was added tablets of solid-state NaBH4/Co composite. In acidic solutions hydrogen evolution occurred instantaneously, and at high concentrations of acids the releasing hydrogen contained an admixture of diborane. Hydrogen evolution from the solidstate NaBH4/Co composite proceeded at a uniform rate of 13.8±0.1 cm3·min-1, water vapor being the only impurity in the evolving gas.

Rupture and Reformation of Ultra-Thin Surface Films

2010 ◽  
Author(s):  
William W. F. Chong ◽  
Mircea Teodorescu ◽  
Homer Rahnejat
Keyword(s):  
Thin Film ◽  
Data Storage ◽  
Surface Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Surface Films ◽  
Disk Drives ◽  
Film Rupture ◽  
Near Surface ◽  
Ultra Thin Film

In lubricated contact conjunctions film ruptures close to the exit boundary. This significantly affects the load carrying capacity and can lead to direct surface interactions. Nano-scale films (several molecular diameters of the lubricant) are no exception, a fact that has been observed using ellipsometry studies for ultra-thin film conjunctions representative for high storage capacity hard disk drives. Immediately beyond the film rupture an area of cavitation occurs and the continuity of flow condition is breached. It has been shown that for molecularly smooth surfaces solvation effect becomes dominant. This means that the contact exit is subject to discrete drainage of lubricant and may be devoid of a sufficient lubricant for film reformation to occur. This can be a stumbling block in an increasing quest to increase the data storage density of hard disk drives. Wear can become a problem as well as non-uniformity of free surface film at the inlet meniscus. It has been noted that peaks of lubricant can gather in some places, a phenomenon referred to as lubricant mogul. These localized piles of lubricant can exceed the nominally aimed for lubricant film thickness necessary for a given data storage level. This paper carries out an in-depth prediction of ultra thin film lubricant behavior through the contact. Hydrodynamic as well as near surface effects and intermolecular interactions responsible for the supply, formation, cavitation and reformation of thin films in the slider-disk conjunction have been considered.

Temperature and Orientation Dependence of Surface Film Effects in Single Crystal Nial

1986 ◽  
Vol 81 ◽  
Author(s):  
R.D. Noebe ◽  
J.T. Kim ◽  
R. Gibala
Keyword(s):  
Single Crystal ◽  
Crystallographic Orientation ◽  
Surface Film ◽  
Orientation Dependence ◽  
Surface Films ◽  
Temperature Dependent ◽  
Paper Surface ◽  
Bcc Metals ◽  
Coated Materials ◽  
Ordered Alloys

AbstractDuring deformation of bcc metals and bcc-based ordered alloys, conditions of elastic and plastic constraint associated with the presence of thin adherent surface films can be responsible for introducing increased densities of mobile dislocations in the metal, resulting in enhanced ductility and reduced yield and flow stresses of the film-coated materials. In the present paper, surface film effects were investigated as a function of temperature and crystallographic orientation for single crystal β-NiAl. Appreciable temperature-dependent and orientation-dependent surface film effects were observed, as were significant effects of film adherence on the observation of surface film softening.

Aquatic Surface Film Organisms Collected On Glass Substrates For Evaluation By Scanning Electron Microscopy.

1999 ◽  
Vol 5 (S2) ◽  
pp. 1244-1245
Author(s):  
R. W. Smith
Keyword(s):  
Surface Film ◽  
Spatial Relations ◽  
Bulk Water ◽  
Surface Films ◽  
Simple Method ◽  
Blodgett Film ◽  
Langmuir Blodgett ◽  
Glass Substrates ◽  
Air Water Interface ◽  
Biological Films

Organisms found at the Air-Water Interface (AWI) are often difficult to collect and usually show distortion upon collection and fixation by traditional methods. Furthermore, the spatial relations between the organisms and the complexity of their biofilm community is disrupted or destroyed by collection methods that involve bulk water collection, filtration, settling or rotating drums. Samples shown here were collected on the Tualatin River, Oregon, a eutrophic rural/suburban stream with welldeveloped Aquatic Surface Films (ASF or Microlayers) in quiet waters.Here, I describe a simple method of collection for Aquatic Surface Films (Microlayers), by drawing a glass substrate slowly through the surface film, allowing both organic chemicals and small organisms to adhere to the surface of the glass. This is similar to the collection of a Langmuir-Blodgett film, and it has been proposed that chemical and biological films at the surface might allow this type of collection.

Determination of Iodide in Feeds and Plants by Ion-Selective Electrode Analysis

1971 ◽  
Vol 54 (4) ◽  
pp. 760-763
Author(s):  
William L Hoover ◽  
James R Melton ◽  
Peggy A Howard
Keyword(s):  
Ionic Strength ◽  
Solid State ◽  
Necessary Conditions ◽  
Ion Selective Electrode ◽  
Phosphate Solution ◽  
Selective Electrode ◽  
Aoac Method ◽  
Low Levels ◽  
High Concentrations

Abstract A method for determining low levels of iodide in feeds and plants is proposed. The samples are mixed with a 10% phosphate solution to maintain relatively constant ionic strength and pH and analyzed with a solid-state iodide electrode. Ashing is not required and there are no significant interferences by ions commonly found in feeds. The method is accurate in determining iodide content ranging from 10.0 ppm to high concentrations. Necessary conditions for storing and cleaning the electrodes are described. The proposed method is rapid and results compare favorably with AOAC method 7.091.

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