Showing papers on "Langmuir published in 1976"
TL;DR: In this paper, the adsorption of Telon Blue (Acid Blue 25) on peat has been investigated and the effects of contact time, initial dye concentration and peat particle size were studied.
450 citations
01 Mar 1976
TL;DR: In this paper, a model system for arsenate adsorption on amorphous aluminum hydroxide was studied as a model for aqueous anion adaption on oxide surfaces.
Abstract: Arsenate adsorption on amorphous aluminum hydroxide was studied as a model system for aqueous anion adsorption on oxide surfaces. Adsorption and electrophoretic mobility of the suspended adsorbent particles were measured as functions of equilibrium pH. A transformation of variables allowed the adsorption to be explained in terms of the chemical and physical forces controlling the adsorption reaction. When used in conjunction with the Langmuir adsorption equation, the results allow calculation of levels of arsenate removal for any given amount of adsorbent and any pH.
306 citations
TL;DR: The surface potential produced by the adsorption of charged molecules to bilayer membranes is estimated by means of conductance measurements with "probe" molecules on planar black lipid membranes and by Means of electrophoresis measurements on multilaminar unsonicated vesicles.
Abstract: To describe the hydrophobic adsorption of charged molecules to bilayer membranes, one must recognize that the adsorption produces a change in the electrostatic potential at the surface of the membrane. The surface potential produced by the adsorption of the charged molecules can be described most simply by the Gouy equation from the theory of the diffuse double layer. This potential will tend to lower the concentration of the adsorbing ions in the aqueous phase immediately adjacent to the membrane, a phenomenon which can be described by the Boltzmann relation. The number of adsorbed ions is, in turn, a function of the aqueous concentration of these ions at the membrane solution interface and can be described, in the simplest case, by a Langmuir adsorption isotherm. If the ions are regarded as point charges, the combination of the Gouy, Boltzmann, and Langmuir relations may be considered a simplified Stern equation. To test experimentally the applicability of this equation, one should measure both the charge density and surface potential as a function of the concentration of adsorbing molecules in the bulk aqueous phases. Direct, accurate measurements of one of these parameters, the number of moles of 2, 6-toluidinylnaphthalenesulfonate ions bound to vesicles formed from phosphatidylcholine, are available in the literature (Huang, C., and Charlton, J.P. (1972), Biochemistry 11, 735). We estimated the change in the surface potential in two independent ways; by means of conductance measurements with "probe" molecules on planar black lipid membranes and by means of electrophoresis measurements on multilaminar unsonicated vesicles. The two estimates agreed with one another and all of the data could be adequately described by the Stern equation, assuming, at 25 degrees C, a dissociation constant of 2 X 10(-4) M and a maximum number of binding sites of 1/70 A2.
155 citations
TL;DR: In this article, the authors studied all of the Langmuir-wave linear parametric instabilities excited in cylindrical symmetry by an electron-stream-driven LWA propagating along the stream axis.
Abstract: Assuming that type III solar radio bursts are associated with electron streams moving at about c/3, Langmuir waves should be strongly excited. We have studied all of the Langmuir-wave linear parametric instabilities excited in cylindrical symmetry by an electron-stream--driven Langmuir wave-pump propagating along the stream axis. Included in this unified homogeneous treatment are induced backscattering off ions, the oscillating two-stream instability, and a new ''stimulated modulational instability,'' previously unconsidered in this context. Near a few solar radii, the latter two deposit Langmuir wave energy into a forward-scattering cone about the stream axis. It is concluded that the linear stage of the forward-scattering instabilities involves transfer of energy to Langmuir waves which remain in resonance with the stream, and therefore probably do not prevent rapid depletion of the electron stream due to quasilinear plateau formation at these distances from the Sun. (AIP)
90 citations
01 Mar 1976-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the adsorption of strongly surface active solutes is considered in terms of the ideal site-fillageor Langmuir isotherm, and the resulting equation for the depression of surface tension of a liquid metal by such a solute is σ P −σ = RTΓ i emphasis>/o In (1 +Ka i) where σ p − σ is the depression, where K is the saturation coverage by the solute.
Abstract: The adsorption of strongly surface active solutes is considered in terms of the ideal site-fillageor Langmuir isotherm. The resulting equation for the depression of surface tension of a liquid metal by such a solute is σ P −σ = RTΓ i Emphasis>/o In (1 +Ka i) where σ p − σ is the depression of surface tension of the pure liquid metal, Γ i Emphasis>/o is the saturation coverage by the solute,a i is the bulk activity of the solute, andK is a coverage independent adsorption coefficient. The isotherm is found to give a very good description of the available data for Group VI solutes on several metals. The derived values of the adsorption coefficient are applied to several kinetic studies and they are found to give good relative and possibly absolute measures of the interference by such solutes on interfacial reaction rates. The iron-sulfur system appears to differ, but only by a factor of two. The application of these adsorption coefficients in aiding the interpretation of kinetic studies is considered.
78 citations
TL;DR: In this paper, the maximum buffer capacity of a group of 24 soils was derived from the Lamgmuir high-energy adsorption parameters, and the results showed that changes in the intensities and quantities of labile P and equilibrium buffer capacities resulting from fertilization were related to the high energy adaption parameters.
Abstract: The Langmuir two-surface adsorption equation is used to derive a phosphate adsorption characteristic, the maximum buffer capacity, which integrates the intensive and extensive components of adsorption and is independent of P saturation. Changes in the intensities and quantities of labile P and equilibrium buffer capacities resulting from fertilization of a group of 24 soils are shown to be related to the Lamgmuir high-energy adsorption parameters and in particular the maximum buffer capacity.
73 citations
TL;DR: The Langmuir equation was found to describe Cd adsorption from dilute solutions at 5°C and 25°C for ten soils from Tuscany as mentioned in this paper.
Abstract: Summary
The Langmuir adsorption equation was found to describe Cd adsorption from dilute solutions at 5°C and 25°C for ten soils from Tuscany. The calculated Langmuir adsorption maxima (Q) and bonding energy coefficients (K) were well correlated with CEC and organic matter content.
On the basis of the temperature effect on Q and K, the mechanism of Cd adsorption is discussed.
72 citations
TL;DR: In this paper, the authors measured the Langmuir evaporation of Ga and As from the (100), (111A), and (111B) faces of GaAs above and below the congruent temperature T c.
71 citations
TL;DR: In this paper, isothermal countercurrent, cocurrent and finite bath adsorption has been modelled mathematically by using the method of orthogonal collocation, where the equilibrium between the solid and the fluid phase is assumed to be nonlinear and is described by either the Langmuir or the Freundlich type of equation.
55 citations
TL;DR: In this paper, the affinity of Pb for sorption sites in soil decreased logarithmically with an increase of surface coverage, and different adsorption mechanisms were discussed.
Abstract: Adsorption of Pb by soils in the presence of a large amount of Ca was studied. Adsorption was found to conform to the Langmuir and Freundlich isotherms over a large range of concentrations. Organic matter and clay were the dominant constituents contributing towards adsorption maxima for soils. In addition to the parameters derived from two isotherms, the following parameters, initial slope of the isotherms and 1/C at equilibrium for Δ=0.5, were also investigated. The affinity of Pb for sorption sites in soil decreased logarithmically with an increase of surface coverage. Different adsorption mechanisms of Pb in presence and absence of Ca are discussed.
TL;DR: It was elucidated that the hydrophobic bond play a major role in the adsorption of the lipase on substrate or hydrophilic surface and was treated in the Lineweaver-Burk's plot.
Abstract: The lipase from Chromobacterium was adsorbed on glass beads which was coated with olive oil, liquid paraffin or silicone oil. These adsorption was treated in the Lineweaver-Burk's plot and characters of the adsorption were similar each other regardless of their chemical structure of hydrophobic materials. On the other hand, esterase from porcine liver was not adsorbed on hydrophobic glass beads. The interaction between the lipase and hydrophobic surface conformed to the Langmuir's adsorption isotherm with a dissociation constant K=1.4×10-7M. At saturation of the surface with the lipase each protein molecule occupies an average area of 4500 A2 per molecule. The lipase adsorbed on hydrophobic surface did not inactivated but activated about 3-fold. It was elucidated that the hydrophobic bond play a major role in the adsorption of the lipase on substrate or hydrophobic surface.
TL;DR: In this paper, the initial interaction between an O 2 molecular beam and a cleaned Fe(110) surface has been studied by a combination of Auger electron spectrometric (AES) and Mass Spectrometric techniques.
TL;DR: The relationship between the molecular structure of nonionic surfactants and their adsorptivities on activated carbons was investigated in this paper, where the adsorption rate and the amount of adsorbed polyoxyethylene nonylphenyl ether (NP) at saturation decreased.
Abstract: The relationship between the molecular structure of nonionic surfactants and their adsorptivities on activated carbons was investigated. The adsorption isotherms for all water-soluble nonionic surfactants used in this study were Langmuir type and the adsorptivities were higher than ordinary organic compounds. With the increase in the length of polyoxyethylene chain of polyoxyethylene nonylphenyl ether (NP), activated carbons were saturated by NP in lower concentrations, and both the adsorption rate and the amount of adsorbed NP at saturation decreased. For the surfactants with a fixed length of polyoxyethylene chain, the adsorption was favored by the increase in the length of the alkyl chain. An unsaturated bond in the alkyl chain depressed the adsorption. The carbon activated with zinc chloride had large surface area and pores, and was effective for the adsorption of nonionic surfactants. When an aqueous solution of NP was passed through the column of activated carbon under certain conditions, the adsorption efficiency was 90.6%. These results suggest that the use of activated carbon may be very effective for the treatment of wastewater containing nonionic surfactants.
Journal Article•
TL;DR: The net heat of protein sorption has been determined from the direct measurement of the net overall enthalpy changes, hI(SLP)25 arising as a result of protein adsorption.
Abstract: 1. According to a working hypothesis put forward in the previous papers of this series2-4, the initial phases of native blood/foreign surface interactions have been considered within the framework of a physicochemical model of contact activation at the molecular level. The salient features of this hypothesis are: a) the arrival and adsorption of native plasma proteins on a contact surface overwhelmingly precedes that of the cellular blood components; b) the interaction energy that arises between a particular foreign surface and native plasma proteins settling on it, is a characteristic quantity depending upon the effective surface molecular structure as well as the nature of the proteins; c) the "intensity" of native protein/foreign surface interactions can be treated in terms of thermodynamic quantities since these energy terms are independent of the type of forces acting between protein and surface; and d) depending upon the degree to which the adsorption of a native protein is thermodynamically favored by enthalpy and/or entropy factors, the interaction energy can be utilized to induce conformational changes of varying degree in the sorbed protein. 2. Using glass and low temperature isotropic (LTI) carbon adsorbents, i.e., a known procoagulant and a relevant biomaterial, respectively, the adsorption properties and the potential surface-induced conformational changes of high-purity native human fibrinogen (clottability greater than or equal to 92%) were studied, at 25 degrees C, by 3 independent methods. In all of the experiments performed, a) both adsorbents were employed in the form of particles less than or equal to 1.0 mu representing specific surface areas of 9.85 M2/Gm and 27.7 (nominal) M2/Gm for the glass and LTI-carbon powders, respectively, and b) the fibrinogen was absorbed from a standaridized buffer (pH = 7.2, ionic strength 0.05) using the same fixed surface area/protein solution volume ratio with a given adsorbent. 3. The 25 degrees C adsorption isotherms of fibrinogen obtained for both the glass and LTI-carbon powder adsorbents are not amenable to Langmuir type analysis but indicate multilayer sorption with a possible change in binding mechanism after the completion of the first sorbed monolayer. The adsorptivities attained at first monolayer coverage were slightly greater on glass (approximately 0.76 mug/cm2) than on LTI-carbon (approximately 0.52 mug/cm2). 4. Using a custom-built, thermistorized, isothermal-jacketed microcalorimeter routinely capable of resolving temperature changes of 0.00001 degrees C in 100 ml of aqueous sample volume, the "intensity" of interaction between fibrinogen and each of the microparticulate adsorbents was studied by the direct measurement of the net overall enthalpy changes, hI(SLP)25 arising as a result of protein adsorption. From these values, the net heat of protein sorption has been determined...
TL;DR: In this article, the authors re-examined the new data given by Kazarinov et al. and showed that the lack of potential dependence of methanol adsorption in the region from ca. 0.2 to 0.5 V was confirmed; the reasons of the previous discrepancies have been discussed.
TL;DR: In this paper, it was shown that there are 1.9×1021 solubility sites per cm3 of glass for helium-nitrogen mixtures containing from 10 to 100% helium.
Abstract: Helium solubility in vitreous silica has been measured from 0.1 to 1360 atm for helium‐nitrogen mixtures containing from 10 to 100% helium. The results support previous contentions that the solubility process can be adequately explained by a simple statistical thermodynamical model, i.e., Langmuir adsorption. This model indicates that there are 1.9×1021 solubility sites per cm3 of glass.
TL;DR: In this paper, the binding of phenol and nine of its methyl derivatives by an aqueous solution of a hexadecyl polyoxyethylene ether, cetomacrogol, was found by a modified potentiometric method to be concentration dependent and to follow Langmuir's adsorption equation.
TL;DR: In this paper, the conductivity of mixed Langmuir multilayer films of (Cd arachidate)x − (cd palmitate)1−x has been measured as a function of the molar fraction x at liquid-nitrogen temperature.
Abstract: The conductivity of mixed Langmuir multilayer films of (Cd arachidate)x– (Cd palmitate)1−x has been measured as a function of the molar fraction x at liquid‐nitrogen temperature. The conductivity decreases exponentially with increasing x or the weighted average of the chain lengths of the fatty acid salts. The results are explained by the hopping conduction model for the multilayer films associated with interface states.
TL;DR: In this paper, the behavior of cellulose materials in aqueous solutions of polyethylenimine was investigated, and it was shown that the adsorption isotherms comply with the equation of Langmuir.
Abstract: The behavior of cellulose materials in aqueous solutions of polyethylenimine was investigated. Sulfite-bleached cellulose, sulfite unbleached, sulfate unbleached, and monocarboxylcellulose were used. The adsorption kinetics of polyethylenimine by monocarboxylcellulose were studied in detail. The velocity constants of the process, the velocity temperature coefficients, and the activation energies were calculated. The reaction order was established. The physical type of polyethylenimine adsorption by cellulose was established, and it was shown that the adsorption isotherms comply with the equation of Langmuir. On the basis of the data and on the dependencies obtained, the equations of adsorption in the temperature interval of 0°C to 60°C were derived.
TL;DR: In this paper, the authors discussed the expression for the total retention volume, treated as a pressure function, and the analytical methods for determination of the energy distribution function directly from gas-adsorption chromatagraphy data.
Abstract: In this paper we discuss the expression for the total retention volume, treated as a pressure function, and the analytical methods for determination of the energy distribution function directly from gas-adsorption chromatagraphy data. It is shown that by assuming Jovanovich and Langmuir local behavior for the adsorbed phase, the total retention volume may be expressed as Laplace and generalized Stieltjes transforms, respectively. The utility of our theoretical considerations is demonstrated for the hexane-Polsorb C adsorption system.
TL;DR: In this article, the problem of the form of isotherms for adsorption on homogeneous and inhomogeneous surfaces with and without dissociation when the adsorbate molecule occupies a single elementary site on the surface or several such sites, for polymolecular adorption, and for adoration in the micropores.
Abstract: The review deals with the problem of the form of isotherms for adsorption on homogeneous and inhomogeneous surfaces with and without dissociation when the adsorbate molecule occupies a single elementary site on the surface or several such sites, for polymolecular adsorption, and for adsorption in the micropores. The bibliography includes 74 references.
TL;DR: In this article, the one-dimensional Langmuir wave soliton is classified according to the relations among various smallness parameters and four different regimes are found to emerge depending on the relative importance of various forces acting on the electrons and are graphically represented in the parameter space.
Abstract: Various descriptions for the one-dimensional Langmuir wave soliton are classified according to the relations among various smallness parameters. Four different regimes are found to emerge depending on the relative importance of various forces acting on the electrons and are graphically represented in the parameter space. When the field energy becomes as large as the electron kinetic energy, second harmonic generation and local charge separation (in slow time scale) are found to occur, but their effect on the description of the Langmuir wave soliton is found insignificant. Dynamic behavior of the Langmuir wave soliton is discussed in terms of the trajectory in the parameter space and is compared with recent experimental and numerical analyses.
TL;DR: In this article, the gamma-type distributions in adsorption energies of sites, subject to the Langmuir probability of occupancy, are analyzed with the aim to develop criteria for the reliability of estimates of the energy distribution from experimental adsoreption data.
Abstract: The gamma-type distributions in adsorption energies of sites, subject to the Langmuir probability of occupancy, are analyzed with the aim to develop criteria for the reliability of estimates of the energy distribution from experimental adsorption data. For broad distributions this model leads to preferential occupation of sites with highest adsorption energies, which causes the breakdown of the virial expansion of adsorption isotherms. The resulting isotherms can be discriminated from simple Langmuir isotherms only for not too narrow distributions and the critical criterion is given. Finally, it is pointed out that experimental data do not allow to discern between a continuous and discrete distribution. All the conclusions can be generalized to other types of distribution in adsorption energies, including composite distributions.
01 Jan 1976
TL;DR: In this article, the effect of colloidal particles of SiO 2 (Ludox SM 30) and y Al 2 O 3 (Alon) as modal substances for common particulate matter of oxides in marine environment was investigated.
Abstract: Adsorption of ions of trace metals Zn, Pb, Cu and Cd in sea water samples is studied on colloidal particles of SiO 2 (Ludox SM 30) and y Al 2 O 3 (Alon), as modal substances for common particulate matter of oxides in marine environment. Experimental data are presented in forms of Langmuir adsorption isotherms. Surface coordination model and hydrogen bonding model are discussed in connection with the experissments.
TL;DR: In this paper, the surface pressure of the monolayers of cholesterol, cholesteryl acetate, CA, and Cholesteryl propionate on the aqueous solutions of disodium hexadecyl phosphate (SHP) was measured.
Abstract: The surface pressure of the monolayers of cholesterol (CH), cholesteryl acetate(CA), and cholesteryl propionate (CP) on the aqueous solutions of disodium hexadecyl phosphate (SHP) was measured. The monolayer exhibited a more expanded state on the solution than on pure water. The curves showing the surface pressure against the area per molecule of each monolayer had a kink point, which was considered to indicate the collapse of the monolayer. The amount of SHP penetrating into the insoluble monolayer was calculated by means of the Gibbs adsorption equation. It was found that the relation between the penetration amount and the activity of SHP in the aqueous solution could be expressed by a modification of the Langmuir adsorption equation. It was also found that the saturated amount of the penetration decreased, and the Langmuir coefficient increased, with the compression of the monolayer.
01 Jan 1976
TL;DR: In this article, the arsenate-aluminum hydroxide adsorption system is modeled using a modified stern equation, and the stern potential is experimentally derived as a function of the potential determining ions for the system.
Abstract: The arsenate-aluminum hydroxide adsorption system is modeled using a modified stern equation. The stern potential is experimentally derived as a function of the potential determining ions for the system. Results indicate that adsorption of arsenate can be modeled using a single specific adsorption energy (o). Adsorption data is quantitatively described in terms of pH and equilibrium arsenate concentration. Constant pH Langmuir isotherms and other adsorption models are discussed in relation to the data presented.