Showing papers on "Langmuir published in 1974"
TL;DR: In this paper, the Langmuir equation was used for describing P adsorption from solutions < 103 M P, if it was assumed that adorption occurs on two types of surfaces of contrasting bonding energies.
Abstract: Summary For forty-one soils (pH > 5·0) from southern England and eastern Australia, the Langmuir equation was an excellent model for describing P adsorption from solutions < 103 M P, if it was assumed that adsorption occurs on two types of surface of contrasting bonding energies. For most of these soils, which were relatively undersaturated with P, this equation may be written as:
178 citations
TL;DR: The rate and amount of protein adsorbed was found to be dependent upon both the nature of the polymer substrate and on the flow rate of the solution.
Abstract: Adsorption of albumin, γ-globulin, and fibrinogen from solution, under both static and flow conditions, onto several hydrophobic polymers was studied using internal reflection infrared spectroscopy. Isotherm curves experimentally found were consistant with Langmuir type adsorption. The rate and amount of protein adsorbed was found to be dependent upon both the nature of the polymer substrate and on the flow rate of the solution.
153 citations
TL;DR: In this article, the evaporation of InP under Knudsen and Langmuir conditions was investigated mass-spectrometrically using a modulated molecular beam technique combined with phase-sensitive detection and signal averaging to separate evaporating species from background species in the vacuum system.
Abstract: The evaporation of InP under Knudsen and Langmuir conditions has been investigated mass-spectrometrically using a modulated molecular beam technique combined with phase-sensitive detection and signal averaging to separate evaporating species from background species in the vacuum system. P2 was found to be the dominant species over InP under Knudsen conditions but significant evaporation fluxes of In and P4 were also detected. The P4 flux was attributed to P2+P2 association on the oven walls. A congruent evaporation point under these conditions was predicted at 629±5 K. Under Langmuir evaporation conditions the only evaporating species detected were In and P2. Up to 638±5 K the (100) surface evaporated congruently but above this temperature there was a disproportionate loss of P2 from the surface. The equilibrium vapour pressures of In, P2 and P4 over InP and of In over pure In are presented and enthalpies for the reactions InP(s)->In(s)+½P2 (g); 2P2 (g)->P4(g); In (s)-> In (g) calculated.
129 citations
TL;DR: In this article, the Hertz-Knudsen-Langmuir equation was used to measure the isothermal weight loss in vacuum from cleavage (10textdecoration:overline11) planes of calcite (CaCO3) single crystals.
Abstract: The Langmuir method for measurement of vapour pressures has been tested for use in studies of decomposition reactions. The isothermal weight loss in vacuum from cleavage (10text-decoration:overline11) planes of calcite (CaCO3) single crystals was measured continuously at temperatures from 934 to 1013 K. The rate was constant until approximately 80% of a 1 mm slice had decomposed. The apparent activation enthalpy was 205 kJ (49 kcal) mol–1. Micrographic examination showed an approximately 30 µm thick layer, probably a metastable form of calcium oxide, separating the calcite from the growing layer of oriented stable calcium oxide. The 30 µm layer yielded a single X-ray diffraction peak which was displaced slightly from the strongest (220) peak of the oriented normal calcium oxide. Lower apparent activation enthalpies measured in previous studies of calcite decomposition in inert atmospheres are suggested to result either from partial diffusion control of the process or from catalysis of the direct formation of normal calcium oxide by carbon dioxide or a component of the system atmosphere. The ratio of the measured decomposition rate in vacuum to the maximum rate, which can be calculated from the Hertz–Knudsen–Langmuir equation, is suggested to be a useful parameter in correlating and predicting decomposition reaction rates.
117 citations
TL;DR: In this paper, the amount of methane adsorbed on crushed and dried coal was measured as a function of pressure and isotherms were determined on Illinois No.6 (Herrin seam), Oklahoma Hartshorne, Pennsylvania Pittsburgh, and Virginia Pocahontas No.3 United States coal seams, using a volumetric method and an equation of state for methane.
80 citations
TL;DR: In this paper, the question of choice of appropriate standard states for adsorbed phases at electrode interfaces is reviewed and examined in relation to solvent displacement and the Langmuir and Flory-Huggins types of adsorption isotherms.
58 citations
TL;DR: In this paper, a small scale technique was used to study this phenomenon for the adsorption of water vapour and carbon dioxide on 4A type synthetic zeolites with helium as the carrier gas.
57 citations
TL;DR: In this article, boron desorption from soil was determined using 0.05M mannitol solutions to create pseudo first-order reaction conditions and showed two separate pseudo firstorder reactions and one very slow reaction for which detailed kinetic treatment was not attempted.
Abstract: Kinetics of boron desorption from soil were determined using 0.05M mannitol solutions to create pseudo first-order reaction conditions. The results showed two separate pseudo first-order reactions and one very slow reaction for which detailed kinetic treatment was not attempted. The relative amount of boron associated with the two fast reactions was independent of soil texture and of initial sample boron content. It was postulated that the two reaction rates were due to desorption from two independent boron retention sites. It was speculated that the two fast reactions were due to desorption from hydroxy iron, magnesium, and aluminum materials in the clay fraction. The third or slowest reaction rate was probably due to diffusion of boron from the interior of clay minerals to solution phase. Equilibrium studies showed that boron desorption followed a 2-site analog of a linear form of the 1-site Langmuir expression. Langmuir adsorption maximum values for each site corroborated those calculated from the kinetic study and supported the multisite interpretation of the kinetic data.
39 citations
TL;DR: Ordered phospholipid bilayers of the Langmuir type have been formed between aluminum electrodes and a variety of phenomena observed, including linear regions of log current vs. 1 T, and minima in the capacitance near known transition temperatures for the lamellar phase in aqueous solutions.
32 citations
TL;DR: In this paper, the equilibrium and kinetics of gas sorption by a silicone rubber filled with highly adsorptive molecular sieves were studied and all equilibrium parameters were determined experimentally.
Abstract: The equilibrium and kinetics of gas sorption by a silicone rubber filled with highly adsorptive molecular sieves was studied. Sorption in this system is by two mechanisms: gas is simply dissolved in the polymer matrix according to Henry's law, while it is adsorbed by the dispersed sieve phase in accordance with a Langmuir's isotherm. The latter effectively immobilizes the gas molecules preventing their further diffusion. All equilibrium parameters were determined experimentally. Immobilization greatly affects sorption kinetics and renders conventional analyses invalid. A theory to account for this process was adapted from a previous analysis by Vieth and Sladek which assumes that the kinetics of adsorption is very fast compared to diffusion. For this situation the kinetics always assume a Fickean form. The experimental data agreed very well with the predictions of this theory in a comparison where all parameters were defined by independent experiments. It was found that a single effective diffusion coefficient describes sorption kinetics, steady-state permeation, and time-lag results once the effects of immobilization are properly accounted for.
30 citations
TL;DR: In this article, it was shown that the transition state particles for desorption are free gas molecules and for surface diffusion in the self-adsorption layer are particles with gas-like velocities parallel to the surface.
Abstract: A theory of Langmuir exactly predicts the rates of many vaporization reactions as functions of temperature. For these reactions his theory is shown to be superior to absolute reaction rate theory, which can be made to yield the same rate equation, in requiring fewer and more general hypotheses and utilizing a kinetic factor that has been directly verified by experiment. Langmuir's theory is extended to provide an exact description of the kinetics of some dissociative vaporization reactions. It is pointed out that Langmuir's gas-like kinetic factor has been experimentally verified for the desorption step of two substances that undergo retarded vaporization. It is argued that the transition state particles for desorption are free gas molecules and for surface diffusion in the self-adsorption layer are particles with gas-like velocities parallel to the surface. Rate equations which utilize gas-translation kinetic factors are derived for substances that vaporized with nonequilibrium distributions of electronic states and for substances with vaporization rates limited by separation of self-adsorbed particles from catalytic surface sites or particles. The equations for dissociative vaporization reactions require that transition state particles consist sometimes of a coupled flux of particles of two or more different kinds.
TL;DR: In this article, a computer study of the formation and interaction of Langmuir solitons allowing for the generation of ion-sound waves has been presented for the first time.
TL;DR: In this article, a molecular sieve adsorption column operated isothermally under conditions of micropore diffusion control is reported, where the breakthrough curve is very sensitive to quite small deviations from linearity and regeneration is much slower than saturation.
01 Jan 1974
TL;DR: In this paper, the adsorption mechanism of starch at mineral-solution interface was investigated for the system, water soluble potato starchpar minerals, and the high occupation area of starch molecules suggested relatively flat orientation of starch molecule on the mineral surface.
Abstract: The adsorption mechanism of starch at mineral-solution interface was investigated for the system, water soluble potato starchspar minerals. Adsorption isotherms of the Langmuir type and the high occupation area of starch molecules suggested relatively flat orientation of starch molecules on the mineral surface. Mineral solubility, crystal lattice structure, associated mineral impurities and the ionic composition of the pulp were shown to control the adsorption process.
TL;DR: In this paper, it was shown that the attraction between the surface and the activator plays an important role in determining the flotation recovery of Ba2+-activated MnO2.
TL;DR: In this paper, the authors used a cylindrical Auger analyzer in fast scanning mode to measure absolute rates of desorption and these were shown to be strictly second order below θ = 1.50 × 1014 molecule cm−2.
Abstract: By monitoring the surface directly by Auger electron spectroscopy (AES), adsorption isotherms for nitrogen on polycrystalline tungsten ribbons have been determined in the temperature range 1200–1400 K. These are not of the Langmuir type, but can be linearized by plotting log P(eq) against coverage, θ, and therefore conform to the Temkin equation. The isosteric heat of adsorption (ΔHads) is initially about 370 kJ mol–1, but falls slightly with increasing coverage. Integral molar entropies of adsorption are determined and shown to fall between those calculated for an immobile layer and a 2-dimensional perfect gas.The cylindrical Auger analyzer has been used in the fast scanning mode to measure absolute rates of desorption and these are shown to be strictly second order below θ= 1.50 × 1014 molecule cm–2. This is taken to indicate that the adsorption of nitrogen is dissociative. The rate constants for desorption yield ΔEdes= 330 ± 50 kJ mol–1 in agreement with the ΔHads values. By considering the measured rates of desorption sticking probabilities have been determined and the mechanism of desorption shown to conform to a simple collision model. The residence times of nitrogen adatoms are calculated and shown to be in accord with the Frenkel equation.
TL;DR: Hydrophobicity and amounts of polar groups on the cell surface were determined by the use of fluorescent probe, colloid titration, and acid titration.
Abstract: Hydrophobicity and amounts of polar groups on the cell surface were determined by the use of fluorescent probe, colloid titration, and acid titration. Surface hydrophobicity of hydrocarbon-grown cells was about 7 times greater than that of glucose-grown cells of the same strain, while amounts of polar groups did not differ so much. Adsorption of cells to air bubbles was maximum at pH 3. Langmuir’s adsorption isotherm held for the adsorption. Affinity to air bubbles of hydrocarbon-grown cells was 1.8 times greater than that of glucose-grown cells, while the theoretical maximum amounts of cells to adsorb per unit area of bubbles were equal for the both cells.
TL;DR: In this paper, an analytical solution was obtained for the relevant set of non-linear equations and a relationship was derived for the concentration at the peak maximum, tmax., as a function of the retention time, where ka and kd are the rate constants of adsorption and desorption respectively, 2 is the column length, Ug is the linear carrier gas velocity and amax.
TL;DR: In this article, the authors measured trichlonoethylene adsorption on UO 2 gravimetrically in the range 0 to 50 °C and evaluated the results in terms of the Freundlich, Langmuir, BET, and potential theories of adorption, concluding that C 2 HCl 3 is nonlocalized and forms continuous monolayers.
TL;DR: In this paper, a straightforward method for calculating the sheath thickness surrounding a planar probe in a collisionless plasma assuming an initial ion velocity was presented, which was compared to those calculated from Langmuir's modified planar analysis.
Abstract: A straightforward method is presented for calculating the sheath thickness surrounding a planar probe in a collisionless plasma assuming an initial ion velocity. Sheath thicknesses are compared to those calculated from Langmuir's modified planar analysis.
TL;DR: In this paper, a change in the pH of the substrate leads to correlated changes in the pressure in a monolayer of PDEHS and the wettability by water of such layers, transferred to glass by the Langmuir method.
Abstract: 1.
Polydiethylethylhydrosiloxane (PDEHS) in monolayers on a water/air interface in the presence of acids and alkalis is hydrolyzed with the formation of more surface-active products. In the case of hydrolysis, the≡Si-H groups of the oligomer are affected first.
2.
The high sensitivity of PDEHS to the presence of H+ and OH− ions in the substrate permits us to assume that on the surface of glass, which is not, as a rule, neutral, appreciable hydrolysis of PDEHS molecules may occur.
3.
A change in the pH of the substrate leads to correlated changes in the pressure in a monolayer of PDEHS and the wettability by water of such layers, transferred to glass by the Langmuir method.
TL;DR: In this article, the question of choice of appropriate standard states for adsorbed phases at electrode interfaces is reviewed and examined in relation to solvent displacement and the Langmuir and Flory-Huggins types of adsorption isotherms.
Abstract: The question of choice of appropriate standard states for adsorbed phases at electrode interfaces is reviewed and examined in relation to solvent displacement and the Langmuir and Flory-Huggins types of adsorption isotherms. Comparison with the situation for gas/solid adsorption is made. Standard potentials for electrochemisorption are considered for electrochemical isotherms with and without interaction/heterogeneity terms.