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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 63 (1991), S. 167-202 
    ISSN: 1572-9613
    Keywords: Random sequential addition ; hard-core particles ; distribution functions ; nonequilibrium configurations ; Kirkwood-Salsburg-like equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Random sequential addition (RSA) of hard objects is an irreversible process defined by three rules: objects are introduced on a surface (or ad-dimensional volume) randomly and sequentially, two objects cannot overlap, and, once inserted, an object is clamped in its position. The configurations generated by an RSA can be characterized, in the macroscopic limit, by a unique set of distribution functions and a density. We show that these “nonequilibrium” RSA configurations can be described in a manner which, in many respects, parallels the usual statistical mechanical treatment of equilibrium configurations: Kirkwood-Salsburg-like hierarchies for the distribution functions, zero-separation theorems, diagrammatic expansions, and approximate equations for the pair distribution function. Approximate descriptions valid for low to intermediate densities can be combined with exact results already derived for higher densities close to the jamming limit of the process. Similarities and differences between the equilibrium and the RSAconfigurations are emphasized. Finally, the potential application of RSA processes to the study of glassy phases is discussed.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 92 (1998), S. 891-908 
    ISSN: 1572-9613
    Keywords: Random sequential adsorption ; hard-sphere particles ; gravity ; diffusion ; coverage ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigate the coverage and structure of a layer of particles deposited on a line after diffusion in a gravitational field. The dynamics of the depositing particles is controlled by the gravity number N G(=πd 4 Δρg/6k B T), where d is the diameter of the particles, Δρ is the density difference between the particles and the solution, g is the acceleration due to gravity, k B is Boltzmann's constant, and T is the temperature. The position-dependent flux of particles in a gap formed by two preadsorbed particles is estimated by superposition of solutions of a steady-state convective diffusion equation for the flux in the presence of a single preadsorbed particle. The saturation coverages are found with a recursion relation and are in good agreement with those obtained from Brownian dynamics simulation. The jamming coverage increases rapidly with increasing particle size, particularly for large values of Δρ. An algorithm is presented to generate adsorbed configurations from which the structure of the deposit is determined.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1087-1087 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 1322-1329 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We present a theoretical study of the adsorption kinetics of particles with a continuous distribution of sizes. If the particles interact with short-ranged forces, the diminishing rate of adsorption with increasing surface coverage can be attributed to a geometrical blocking effect of the preadsorbed particles. We exploit the fact that at low coverages the blocking effects result from isolated adsorbed particles to develop an analytic description of the adsorption kinetics using a moment expansion approach. We evaluate the time-dependent surface coverage, density and the average size of the adsorbed particles and compare these quantities with those of the bulk phase. The effect of desorption is studied by introducing a size-independent desorption constant, and the corresponding adsorption equilibria properties, which are valid at low coverages, are derived. Simulation results for irreversible adsorption are obtained and compared with the theoretical predictions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 2471-2478 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The adsorption selectivity, Si, j = (Xi/yi)/(xj/yj), is examined in a 1-D model of a mixture of hard rods adsorbing on a linear substrate. The adsorbed components are characterized by their length, li, and equilibrium constant, ki. We derive an expression for the bulk-phase pressure Po, for which there is no separation of components i and j, S,i, j = 1, in terms of these parameters. The selectivity of the smaller component always increases with the bulk pressure, which results in a selectivity reversal if, as is usually the case, the larger component is more strongly adsorbed at low surface coverages. In a binary mixture, when P 〈 Po, the selectivity of the smaller component decreases with increasing bulk-phase mole fraction, y1, while for P 〉 Po, the reverse is true. The effect of varying the molecular parameters on the selectivity is also studied.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1685-1696 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most existing adsorption models do not properly consider steric hindrance effects of preadsorbed solutes. As a consequence, the models often fail to represent the adsorption kinetics and equilibria accurately. In this work, we extend the random sequential adsorption concept for irreversible adsorption to analyze reversible adsorption on a continuous surface and a random site surface. Based on simulation results of these processes, general kinetic equations for one-component adsorption are developed. The equations are used to correlate chromatography frontal curves of lysozyme and isotherm data of ethane adsorption on activated carbon and ethylene adsorption on a molecular sieve. The significance of the equations, as compared with the Langmuir equation, lies not only in their ability to correlate the experimental data more accurately, but in the physical significance of the adsorption parameters such as the maximum adsorption capacity obtained from the correlation. Our study shows that steric hindrance effects alone result in nonlinear Scatchard and Hill plots with negative cooperativity.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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