https://web.iitd.ac.in/~arunku/files/CEL311_Y13/Adsorption%20Theory%20to%20practice_Dabrowski.pdf

Adsorption — from theory to practice

Mathematical modelling of chemotaxis (the movement of biological cells or organisms in response to chemical gradients) has developed into a large and diverse discipline, whose aspects include its mechanistic basis, the modelling of specific systems and the mathematical behaviour of the underlying equations. The Keller-Segel model of chemotaxis (Keller and Segel in J Theor Biol 26:399–415, 1970; 30:225–234, 1971) has provided a cornerstone for much of this work, its success being a consequence of its intuitive simplicity, analytical tractability and capacity to replicate key behaviour of chemotactic populations. One such property, the ability to display “auto-aggregation”, has led to its prominence as a mechanism for self-organisation of biological systems. This phenomenon has been shown to lead to finite-time blow-up under certain formulations of the model, and a large body of work has been devoted to determining when blow-up occurs or whether globally existing solutions exist. In this paper, we explore in detail a number of variations of the original Keller–Segel model. We review their formulation from a biological perspective, contrast their patterning properties, summarise key results on their analytical properties and classify their solution form. We conclude with a brief discussion and expand on some of the outstanding issues revealed as a result of this work.

/pdf/a-user-s-guide-to-pde-models-for-chemotaxis-4zxd8lr4pw.pdf

A user’s guide to PDE models for chemotaxis

The Maxwell-Stefan approach to mass transfer

Preface. 1. Introductory Remarks. 2. Fundamental Factors for Designing Adsorbent. 3. Sorbent Selection: Equilibrium Isotherms, Diffusion, Cyclic Processes, and Sorbent Selection Criteria. 4. Pore Size Distribution. 5. Activated Carbon. 6. Silica Gel, MCM, and Activated Alumina. 7. Zeolites and Molecular Sieves. 8. &pi -Complexation Sorbents and Applications. 9. Carbon Nanotubes, Pillared Clays, and Polymeric Resins. 10. Sorbents for Applications. Author Index. Subject Index.

/pdf/adsorbents-fundamentals-and-applications-2732spmgdj.pdf

Adsorbents: Fundamentals and Applications

Solar thermochemical production of hydrogen--a review

A pressure swing adsorption cycle comprised of blowdown, purge, pressurization, feed, pressure equalization and rinse steps provided recovery from an atmospheric air feed, essentially dry and free of carbon dioxide, of a high yield of high purity nitrogen gas and a high yield of a product gas rich in oxygen as well as recovery of a residual feed byproduct gas for recycle with the air feed.

Pressure swing adsorption

Pressure swing adsorption: Development of an equilibrium theory for gas separations☆

Adsorption of water vapor on silica gel, at influent humidities from 6 to 80% at 25 and 50°C, yielded breakthrough curves of unusual shapes. Breakthrough patterns varied from the expected sigmoidal shape at low humidity to a curve resembling the tangent function, but symmetric about the stoichiometric breakthrough time. Unusual shapes were found to be due to subtle combination of Type-IV isotherm behavior and heat effects. A mathematical model was developed to simulate the performance. The results show that complex breakthrough behavior need not be ascribed to complicated causes (such as diffusion in bidisperse pores), which require multiparameter fitting of experimental data. In fact, the effects may be predicted from properties measured in simple independent experiments, though some care is required to account for the effects accurately.

Adsorption breakthrough behavior: Unusual effects and possible causes

Pure-component equilibrium data for nitrogen, oxygen, and argon, and multicomponent equilibrium data for air in 20 × 40 mesh 5A molecular sieve were measured at 297.15, 233.15, and 203.15 K and up to pressures of 4 bar. The multicomponent data were analyzed by a statistical thermodynamic model, ideal adsorbed solution theory, an extended Langmuir-Sips equation, and an extended Langmuir equation. The multicomponent system exhibited nonideal behavior at 233.15 and 203.15 K. Isotherm parameters determined in this work may be useful in the design and evaluation of molecular sieve air separation systems.

Equilibria of nitrogen, oxygen, argon, and air in molecular sieve 5A

A pressure swing adsorption (PSA) process for splitting oxygen from a feed gas comprising 95% oxygen and 5% argon to achieve an oxygen purity of at least about 99.7% is provided. A column used in the PSA process includes therein a bed of silver mordenite, an adsorbent determined to be selective to argon. In a preferred embodiment, the feed gas has a pressure of about 10.7 atm and a flow rate of about 8.8-9.2 vol. per cycle/vol of column.

Kent S. Knaebel

Papers

Pressure swing adsorption

Pressure swing adsorption: Development of an equilibrium theory for gas separations☆

Adsorption breakthrough behavior: Unusual effects and possible causes

Equilibria of nitrogen, oxygen, argon, and air in molecular sieve 5A

Pressure swing adsorption system to purify oxygen