Showing papers on "Langmuir published in 1981"
354 citations
TL;DR: A survey of relationships in current use to quantify sorption of reactive solutes by soil is provided in this article, where both equilibrium and first-order kinetic sorption models are reviewed and a reasonably good basis for extrapolation and interpolation of data is provided.
Abstract: The present study provides a survey of relationships in current use to quantify sorption of reactive solutes by soil. Its purpose is to examine present concepts and to indicate active research directions. Both equilibrium and first-order kinetic sorption models are reviewed. Equilibrium models discussed include the linear, Freundlich, Langmuir, two-surface Langmuir, and competitive Langmuir isotherms. Kinetic sorption models reviewed are the reversible linear, reversible nonlinear, kinetic product, bilinear, mass transfer, Elovich, Fava and Eyring, and two-site kinetic model. The models reviewed appear to provide a reasonably good basis for extrapolation and interpolation of data. There is a continuing need, however, to upgrade these methodologies as demand for accuracy and realism increases. It is expected that the state-of-the-art review provided by this survey will assist in this process.
241 citations
01 Jan 1981
TL;DR: In this paper, a model was developed on the basis of the literature for binding of water on solid starch by means of a combined sorption mechanism, and the experimental isotherms of water vapour on native starch were affected by temperature, gelatinization, partial hydrolysis and separation in components.
Abstract: A model was developed on the basis of the literature for binding of water on solid starch by means of a combined sorption mechanism. Equations based on the theory of localized sorption on homogeneous surfaces (Langmuir and Brunauer, Emmett & Teller) were derived. An equation with three parameters from the theories of Guggenheim, Anderson and de Boer described experimental isotherms adequately up to a water activity of 0.9 and one based on polymersolvent interaction (Flory and Huggins) above that value. The experimental isotherms of water vapour on native starch were affected by temperature, gelatinization, partial hydrolysis and separation in components (amylose and amylopectin).
148 citations
01 Jan 1981
TL;DR: In this paper, a model was developed on the basis of the literature for binding of water on solid starch by means of a combined sorption mechanism, and the experimental isotherms of water vapour on native starch were affected by temperature, gelatinization, partial hydrolysis and separation in components.
Abstract: A model was developed on the basis of the literature for binding of water on solid starch by means of a combined sorption mechanism. Equations based on the theory of localized sorption on homogeneous surfaces (Langmuir and Brunauer, Emmett & Teller) were derived. An equation with three parameters from the theories of Guggenheim, Anderson and de Boer described experimental isotherms adequately up to a water activity of 0.9 and one based on polymersolvent interaction (Flory and Huggins) above that value. The experimental isotherms of water vapour on native starch were affected by temperature, gelatinization, partial hydrolysis and separation in components (amylose and amylopectin).
131 citations
TL;DR: In this paper, a model describing the kinetics of dissolution of calcium hydroxyapatite, Ca10(PO4)6(OH)2, microcrystals in aqueous solution is presented.
99 citations
TL;DR: In this article, four adsorption equations were fitted to phosphate isotherm data for 38 soils from northern New South Wales, and the two-surface Langmuir equation provided the best fit to the data.
Abstract: Four adsorption equations were fitted to phosphate isotherm data for 38 soils from northern New South Wales. The two-surface Langmuir equation provided the best fit to the data. The Freundlich equation, however, was almost as effective, provided that an estimate of native adsorbed phosphate was included. It required fewer adsorption points because the transformed data produced a straight line. A regression constant, a, from the Freundlich equation although underestimating adsorption capacity, calculated from the Langmuir II equation, was highly correlated with this parameter (r = 0.984) and a buffering index (r = 0.986), calculated from the Langmuir I equation. The other Freundlich regression constant, n, was significantly correlated (P <1%) with the intensive parameters of adsorption from the one- and two-surface Langmuir equations. Since only two adsorption points are required for fitting the Freundlich equation and the parameters are easier to derive, it is suggested that this equation may be more suitable for commercial soil-testing laboratories than the Langmuir one- and two-surface equations for routine determination of phosphate adsorption characteristics of soils.
97 citations
TL;DR: In this paper, the problem of diffusion controlled adsorption kinetics is solved by application of an implicite difference method, which can be used for all forms of adorption isotherms.
Abstract: The problem of diffusion controlled adsorption kinetics is solved by application of an implicite difference method. Thereby all forms of adsorption isotherms can be used in the calculations. Computation examples are given concerning Langmuir, Freundlich, Volmer, Frumkin, and van der Waals isotherms.
96 citations
TL;DR: In this article, two empirical three-parameter equations, an extended Freundlich and an extended Langmuir equation, are proposed and compared with other equations, such as the Langmuirus, the Freundlic, the Fitter-Sutton, the modified Langmuirs, the double-Langmuir, the Gunarys, the Langmires, and finally the Langmusir equation.
Abstract: Summary
Phosphate sorption was studied on surface and subsurface soils sampled from the old field experiments at Askov, Denmark. Two empirical three-parameter equations, an extended Freundlich and an extended Langmuir equation are proposed and compared with the Langmuir, the Freundlich, the ‘double’ Langmuir, the Gunary, and the Fitter-Sutton equations.
In the proposed equations the affinity parameter of the Langmuir equation and the exponent of the Freundlich equation are replaced by the term Bc −D the value of which decreases with increasing phosphate concentration, c. On average the Freundlich equation thus modified yielded the closest fit to the sorption data. This was followed by the Fitter-Sutton, the modified Langmuir, the ‘double’ Langmuir, the Gunary, the Freundlich, and finally the Langmuir equation. Out of the three equations that yielded the closest fit to the sorption data the correlation between the parameters within the equations, furthermore, was least for the proposed extended Freundlich equation. Therefore, this equation may be generally suitable for describing phosphate sorption by soils.
84 citations
TL;DR: In this article, the competitive electrodeposition of the monolayer of surface oxide on Pt electrodes is studied in the presence of co-adsorbed halide ions (X−, Cl−, Br−, I−), down to very low concentrations.
Abstract: The competitive electrodeposition of the monolayer of surface oxide on Pt electrodes is studied in the presence of co-adsorbed halide ions (X–= Cl–, Br–, I–), down to very low concentrations. These experiments give information essential to the understanding of the state of the surface of Pt anodes at which halogen evolution is occurring from aqueous halide ion solutions and hence provide a basis for interpretation of the kinetics of, and electrocatalysis in, anodic evolution of halogens, especially Cl2. The isotherms for competitive electrochemical adsorption of OH and O species in the surface oxide film, relative to that of X– ions, are evaluated quantitatively.Cl– selectively blocks the initially deposited OH monolayer at Pt while Br– and I– block the formation of the surface oxide non-selectively over a wide potential range, indicating a difference of the state of charge (‘electrosorption valency’) of adsorbed Br– and I–, in relation to that of adsorbed Cl–. This is confirmed by the forms of the competitive adsorption isotherms: Cl– gives linear-logarithmic behaviour in [Cl–], indicating strong lateral interactions, while Br– and I– effects conform more to Langmuir behaviour.A method for quantitatively treating the competitive adsorption, giving information on lateral interaction effects in the surface oxide film with co-adsorbed X– ions, is given in terms of a ‘differentiated’ adsorption isotherm function.
76 citations
TL;DR: In this article, carbon dioxide sorption isotherms in poly(methyl methacrylate) (PMMA) and poly(ethyl methacellitrile) (PEMA) are reported for pressures up to 20 atm.
Abstract: Carbon dioxide sorption isotherms in poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA) are reported for pressures up to 20 atm. Temperatures between 35 and 80°C were studied for PMMA and temperatures between 30 and 55°C were studied for PEMA. Typical dual mode sorption isotherms concave to the pressure axis were observed in all cases. The measured Langmuir sorption capacities of both polymers extrapolated to zero at the glass transition (Tg) consistent with the behavior of other glassy polymer/gas systems. Sorption enthalpies for CO2 in the Henry's law mode for PMMA and PEMA are in the same range (−2 to −4 kcal/mole) as has been reported for a variety of other glassy polymers such as poly(ethylene terephthalate), polycarbonate, and polyacrylonitrile. Some of the data suggest that postcasting treatment of the PEMA films left a small amount of residual solvent in the film. the presence of the trace residual solvent during quenching from the rubbery to the glassy state after annealing appears to cause a dilation of the Langmuir capacity and an alteration in the apparent Langmuir affinity constant of the PEMA film. These results suggest the possibility of tailoring physical properties of glassy polymers such as sorptivity, permeability, impact strength, and craze resistance by doping small amounts of selected residuals into polymers prior to quenching to the glassy state from the rubbery state.
45 citations
TL;DR: In this paper, the metal concentrations of four English rivers were extracted by extractants used to predict plant uptake of these elements from soils, and EDTA (0·1 n ) was the most efficient extractant, followed by ammonium acetate, while distilled water proved inefficient.
TL;DR: In this article, surface-enhanced second-harmonic generation and surfaceenhanced Raman scattering were used to study the adsorption of pyridine on silver in an electrolytic solution.
01 Oct 1981
TL;DR: In this paper, the adsorption of poly- l -glutamic and poly-l -aspartic acid and their monomers on precipitated nonstoichiometric hydroxyapatite was studied under mild basic conditions (∼pH 8).
Abstract: The adsorption of poly- l -glutamic and poly- l -aspartic acid and their monomers on precipitated nonstoichiometric hydroxyapatite (Ca 10-x (PO 4 ) 6-x (HPO 4 ) x (OH) 2-x · x H 2 O) were studied under mild basic conditions (∼pH 8). The adsorption isotherms of the amino acids were of the Langmuir type. The spectroscopic results are consistent with an adsorption mechanism in which terminal carboxyl groups are attached to surface calcium ions. These calcium ions are those originally associated with phosphate moieties in the hydroxyapatite surface. On the basis of the infrared spectra at variable relative humidity, a model of poly- l -glutamic chain adsorption is proposed in which chains lie with the majority of their segments on adsorbent surfaces.
TL;DR: In this paper, the authors analyzed the breakout behavior of axial diffusion in deep beds with adaption, assuming that a constant pattern wave has developed upstream of the bed outlet, and showed that breakout curves are much sharper than corresponding constant pattern profiles, especially for very favorable isotherms.
TL;DR: In this article, it was shown that the traditional equation of the Langmuir type is not the appropriate equation to describe ion exchange processes because the ion exchanger generally cannot be treated as an ideal solid solution.
Abstract: Classical thermodynamics was employed to derive equations of the Langmuir type with parameters having chemical meaning for homovalent and heterovalent ion exchange processes and for anion-fixation reactions wherein the anion is able to form an insoluble precipitate with some exchangeable cation. The analysis pointed out that the traditional equation of the Langmuir type is not the appropriate equation to describe ion exchange processes because the ion exchanger generally cannot be treated as an ideal solid solution. Nevertheless, for systems with low concentration of one ion in a supporting electrolyte, the solid-phase activity coefficient ratio should be a constant, and an equation of the Langmuir type may describe successfully this portion of the exchange isotherm. It was shown also that anion-fixation isotherms could be completely described by solving simultaneously three equations: a solubility product, a traditional equation of the Langmuir type for cation exchange, and an equivalence equation. Selected experimental data from the literature were utilized to demonstrate the applicability of the derived equations and to determine parameters for comparison and correlation with other data and for the identification of the ionic species undergoing ion exchange. Additional Index Words: adsorption, anion-fixation, ion exchange, specific adsorption. Elprince, A. M., and G. Sposito. 1981. Thermodynamic derivation of equations of the Langmuir type for ion equilibria in soils. Soil Sci. Soc. Am. J. 45:277-282. T APPLICABILITY of an adsorption isotherm equation of the Langmuir type (Langmuir/ 1918) to soil chemical phenomena continues to be the subject of controversy (Griffin and Au, 1977; Harter and Baker, 1977, 1978; Veith and Sposito, 1977; Holford, 1978; Sposito, 1979). The principal focus of discussion in both recent and earlier critiques of the equation 1 Contribution from the Dep. of Soils & Water, King Faisal Univ., Alhasa, Saudi Arabia; and the Dep. of Soil & Environmental Sciences, Univ. of California, Riverside. CA 92521. Received 5 Nov. 1979. Approved 19 Nov. 1980. 3 Associate Professor of Soil Chemistry and Professor of Soil Science, respectively. has been whether experimental data on the reactions between solid soil constituents and ions in aqueous solution should conform to the linear expression £ = _ L + £ q ab b [1] where c is the concentration of the reacting ion in aqueous solution at equilibrium, q is the quantity of the ion that has reacted with unit mass of the solid soil constituent, b is the maximum value of q, and a is an "affinity parameter." With the parameter a assumed to be independent of q, Eq. [1] often has been criticized on experimental grounds by investigators seeking to employ it purely as a means for correlating data on q as a function of c (Cole et al., 1953; Fried and Shapiro, 1956; Olsen and Watanabe, 1957; Rennie and McKercher, 1959; Weir and Soper, 1962; Gunary, 1970; Syers et al., 1973; Holford et al., 1974; Shuman, 1976; Griffin and Au, 1977; Harter and Baker, 1977). On the other hand, Eq. [1] has been criticized on theoretical grounds because it does not seem to account for nonuniformity with respect to affinity in soil adsorption sites (Holford et al., 1974; Holford, 1978); because it cannot be used to distinguish adsorption from secondary precipitation phenomena (Veith and Sposito, 1977) and because it does not show explicitly the effects of competition for adsorption sites in ion exchange phenomena (Griffin and Au, 1977; Harter and Baker, 1977, 1978; Sposito, 1979). Brunauer et al. (1967) have pointed out that many analyses concerning the validity of Eq. [1] overlook the crucial fact that nowhere in the original, kineticsbased derivation of the Langmuir equation (Langmuir, 1918) is it required that the parameter a be a constant, although in subsequent derivations based on statistical thermodynamics this condition was imposed along with other restrictions (Fowler and Guggenheim, 1949; Veith and Sposito, 1977; Sposito, 1979). Therefore, Eq. [ 1 ] could be employed to describe solute adsorption phenomena in a very general (if often inconvenient) fashion by permitting a to be an 278 SOIL SCI. SOC. AM. J., VOL. 45, 1981 arbitrary function of q. Moreover, as emphasized by Brunauer et al. (1967), factors such as nonuniformity in the adsorption sites, interactions among the adsorbed ions, and changes in the configuration of the adsorbed ions actually may compensate one another in such a way as to produce a constant value of a. This possibility was not considered in the statistical thermodynamic derivations of Eq. [ 1 ] (Fowler and Guggenheim, 1949; Sposito, 1979). The principal conclusions that can be drawn from past research on the Langmuir equation are: (i) the chemical significance of the affinity parameter in an equation of the Langmuir type will depend on the specific characteristics of the ion-solid phase reaction to which the equation is applied, and (ii) derivations of an equation of the Langmuir type prescribe sufficient conditions for the validity of the equation, not necessary conditions. In this paper, thermodynamic arguments will be developed to show how an equation of the Langmuir type, with a constant affinity parameter, may be used to interpret certain exchange adsorption and secondary precipitation phenomena in soils. The primary objective of the paper is to illustrate the broad variety of important soil chemical reactions that can be described by Eq. [ 1 ] without unnecessary restrictions being placed on the mechanisms of the reactions. DERIVATION OF EQUATIONS OF THE LANGMUIR TYPE Homovalent Ion-Exchange Processes The thermodynamic equilibrium constant, K, for homovalent ion-exchange processes may be written in the form (MAfAaB)/(MBfBaA) [2] where M is the mole fraction of a component in the solid exchanger phase, a is the activity of an ion, A or B, in aqueous solution, and / is an exchanger-phase activity coefficient. A body of experimental results (Gaines and Thomas, 1953, 1955; Merriam and Thomas, 1956; Frysinger and Thomas, 1960; Martin and Laudelout, 1963; Loven and Thomas, 1965; Helmy and Peineman, 1971; Gast, 1972; Jensen and Babcock, 1973; Udo, 1978) has shown that /A//B is a function of the exchanger composition and generally cannot be set equal to 1.0, as was suggested by Vanselow (1932), who treated the ion exchanger as an ideal solid solution. The experimental determination of fA and fB became possible after the rigorous thermodynamic formulation initiated by Hogfeldt et al. (1950) and Argersinger et al. (1950) and extended later by Gaines and Thomas (1953) and Elprince and Babcock (1975a). Considering A and B as the only ions in the ionexchange system, one may write MA + MB = 1 and employ Eq. [2] to yield the following competitive equation of the Langmuir type (cf. Sposito, 1979, Eq. [10]): (aA/aB)/MA = (aA/aB) [3] where is not a constant because of the dependence of /B//A on the exchanger composition. Hence, a plot of (aA/aB)/MA vs. (aA/aB) covering the whole exchange isotherm (i.e., 0 ^ MA < 1) is expected to be curvilinear instead of a straight line. However, for a short portion of the isotherm, the ratio /A//B sometimes is approximately a constant, and a straight-line plot can be obtained. Apparently this is often the case for relatively low values of the mole fraction of ion A, a result that cannot be predicted from thermodynamics alone but can be observed experimentally (see, e.g., Jensen and Babcock, 1973) as well as predicted from the application of mixture theories to the exchanger phase. For example, the Wilson (1964) mixture theory, when applied to ion-exchange systems with relatively low values of the mole fraction of ion A, yields = Lira (/B//A) = exp [5]
TL;DR: In this article, the authors consider two species competing for surface sites on a macroporous catalyst support during impregnation and identify the critical parameters which determine the profiles for each of the adsorbed species.
TL;DR: In this paper, the adsorption of maleic anhydride on a vanadium pentoxide-molybdenum trioxide catalyst has been studied using the transient techniques of temperature-programmed desorption and gas chromatography.
Abstract: The adsorption of maleic anhydride on a vanadium pentoxide–molybdenum trioxide catalyst has been studied using the transient techniques of temperature programmed desorption and gas adsorption chromatography. The desorption spectra obtained over a range of adsorption temperatures show two peaks having maxima at between 220 and 250 °C and 340 and 350 °C. Solution of the Redhead equation for an assumed value of 1013 s–1 for the desorption A-factor at the peak maxima gave desorption energies of between 138 and 148 kJ mol–1 and 171 and 181 kJ mol–1. In spite of the high dosages used (ca. 107 Langmuirs), the surface coverages never exceeded 6 × 1012 sites (molecules) cm–2 with the number of high energy sites remaining constant at 3 × 1012 sites cm–2 over the large range of adsorption temperatures; it is inferred that these sites are a defect property of the mixed oxide. The gas adsorption chromatographic peak shapes are also analysed in terms of two adsorption bonds from which the heats of adsorption of 79.9 and 104.2 kJ mol–1 are derived. The adsorption of maleic anhydride on the mixed oxide catalyst is therefore seen to be activated, having adsorption activation energies of 63 and 71 kJ mol–1. These not inconsiderable heats of adsorption and desorption activation energies imply the possibility of product inhibition in the selective oxidation of benzene to maleic anhydride.
TL;DR: In this paper, a new approximate description of adsorption equilibrium of wastewater containing a number of unknown pollutants has been developed by using such a comprehensive index of concentration as TOC, BOD or COD.
Abstract: A new approximate description of adsorption equilibrium of wastewater containing a number of unknown pollutants has been developed by using such a comprehensive index of concentration as TOC, BOD or COD. The description has been constructed on the basis of a new concept, "Characteristic Distribution of Langmuir Coefficient", which is to be identified by the observed differential adsorption equilibrium data. The accuracy of prediction of the integral adsorption equilibrium using this description has been demonstrated by several experiments.
TL;DR: In this article, the catalytic oxidation of CO and O2 to form CO2 has been studied on a polycrystalline palladium foil in a pressure range from 10-4 to 1 Pa.
TL;DR: In this paper, the authors studied the degradation of benzene to maleic anhydride over vanadium pentoxide-molybdenum trioxide catalyst using a combination of transient techniques.
Abstract: The kinetics of the oxidation of benzene to maleic anhydride over a vanadium pentoxide–molybdenum trioxide catalyst have been studied using a combination of transient techniques. Temperature programmed desorption (t.p.d.) has shown (i) the existence of a weakly-bound molecular oxygen species having a desorption activation energy of between 105 and 113 kJ mol–1 and (ii) that the adsorption of benzene is heteroenergetic having three sets of desorption activation energies of between 97.9 and 104.2 kJ mol–1, 107.9 and 119.2 kJ mol–1 and 130.5 and 133.5 kJ mol–1. (As before, these desorption energies are obtained by solution of the Redhead equation for the peak maximum temperature for an assumed 1013 s–1A-factor.) In spite of the high benzene dosages used in these studies (ca. 3 × 1010 Langmuir, 1 Langmuir = 1.33 × 10–4 N m–2 s) the total coverages by these sites never exceeded 4 × 1011 cm–2, suggesting that they are an intrinsic defect property of the catalyst.Temperature programmed reaction spectroscopy (t.p.r.s.) has shown that (i) the overall oxidation of benzene to maleic anhydride is rate limited in the desorption of the product, the desorption activation energies of the reactively produced maleic anhydride (in the ranges 143.5–148.1 kJ mol–1 and 166.1–169.9 kJ mol–1) being identical to those obtained for pre-adsorbed maleic anhydride, (ii) the activation energy for the surface oxidation of the adsorbed benzene to adsorbed maleic anhydride is low, having a value of 31.4 kJ mol–1, (iii) the reactively produced maleic anhydride occupies the site upon which its precursor, benzene, was chemisorbed, inhibiting further benzene adsorption on that site and (iv) from the population distribution of the adsorbed maleic anhydride on the energetically heterogeneous surface, it was formed at the benzene adsorption temperature (50 °C).The immobility of the adsorbed maleic anhydride suggests that the oxygen is transported to the adsorbed benzene, which in combination with the low surface oxidation activation energy appears to preclude the involvement of lattice oxygen in this step, inferring that the oxidant is a mobile chemisorbed species, possibly the weakly bound molecular state seen in the t.p.d. experiments.Gas adsorption chromatography (g.a.c.) shows the heats of adsorption of benzene to be low, 58.6 and 69.5 kJ mol–1, the latter heat being a composite of two heats which cannot be resolved. The maximum number of sites available for benzene adsorption is only 2.7 × 1012 cm–2 of which 97.5% have a heat of adsorption of 58.6 kJ mol–1. Benzene adsorption is therefore weakly activated.
TL;DR: In this article, the experimental data on solitons formed due to self-compression (physical collapse) of nonlinear Langmuir and oblique Langemuir waves in magnetized plasma excited by electron beams are compared with theory.
TL;DR: A study was initiated to explore the nature of surface-active groups of model compounds that might cause chemisorption of comonomers used in the polymerization of dental resins on hydroxyapatite and thus effect a strong and durable bond between the resins and hard tooth tissues.
TL;DR: In this paper, the saturated amount of adsorption was almost constant irrespective of the amount of NaCl added, but the binding constant increased with the amount added NaCl, which is a function of the thermodynamic activity of NaOH.
Abstract: Hydroxyapatite (HAP) in water exhibited a buffer function in the region from weakly acidic through weakly alkaline pH. Equilibrium pH depends on the amount of HAP added, and on the species and concentration of added electrolyte. This function seems to originate from the ability of HAP to adsorb OH-and/or from the protonation-deprotonation equilibrium of surface phosphate ion. Theoretical calculation of the suspension pH was attempted. The isotherm of OH- adsorption from aqueous solutions of NaOH mixed with NaCl was of Langmuir type. The saturated amount of OH- adsorption was almost constant irrespective of the amount of NaCl added, but the binding constant increased with the amount of added NaCl. The adsorption isotherms, however, formed just one curve irrespective of the amount of NaCl added when they were expressed as a function of the thermodynamic activity of NaOH. On the other hand, the amount of adsorbed OH- increased with the amount of Ca2+ added, because Ca2+ is adsorbed on the HAP surface and forms a positively charged adsorption site for OH-. An electrophoresis experiment confirmed that HAP particles have positive charges due to adsorbed Ca2+ even in solutio at high pH.
TL;DR: With magnetic fields that are not too weak, Langmuir collapse times can be prolonged and the packet geometry significantly distorted as mentioned in this paper, and the magnetic field can be too weak to be stable.
Abstract: With magnetic fields that are not too weak, Langmuir collapse times can be prolonged and the packet geometry significantly distorted.
TL;DR: In this paper, the sorption capacity of an activated alumina columnar packed bed was found to be 30 mg PO 4 −3 per gram alumina, up to the breakthrough of 1000 bed volumes.
TL;DR: In this paper, the sublimation and thermal decomposition of HMX were studied by means of Langmuir evaporation and effusion mass spectrometry in the temperature range 175-275°C.
TL;DR: In this article, the adsorption of copper by four alkaline soils of northwest India using 0.05m CaCI2 as supporting electrolyte was investigated, and the results conformed to the competitive Langmuir equation although there was possibility of copper hydroxide or carbonate precipitation at higher concentrations of added copper.
Abstract: Summary
The adsorption of copper by four alkaline soils of northwest India was investigated using 0.05m CaCI2 as supporting electrolyte. The adsorption data conformed to the competitive Langmuir adsorption equation although there was possibliity of copper hydroxide or carbonate precipitation at higher concentrations of added copper. The adsorption capacities of soils were related to CEC, clay content and CaCO3 equivalent of soil. The free energy changes for adsorption and for interaction were negative and positive respectively.
TL;DR: In this article, the adsorption of L-asparagine and L-alanine on α-zirconium phosphate (α-ZrP) was studied at 25°C.
TL;DR: In this paper, the Freundlich isotherm used in place of the Langmuir isotherms to describe the adsorption mode in the dual sorption theory of glassy polymer gas systems was used.