This overview of diffusion and separation processes brings unsurpassed, engaging clarity to this complex topic. Diffusion is a key part of the undergraduate chemical engineering curriculum and at the core of understanding chemical purification and reaction engineering. This spontaneous mixing process is also central to our daily lives, with importance in phenomena as diverse as the dispersal of pollutants to digestion in the small intestine. For students, Diffusion goes from the basics of mass transfer and diffusion itself, with strong support through worked examples and a range of student questions. It also takes the reader right through to the cutting edge of our understanding, and the new examples in this third edition will appeal to professional scientists and engineers. Retaining the trademark enthusiastic style, the broad coverage now extends to biology and medicine.

Diffusion: Mass Transfer in Fluid Systems

This review reports the progress on the recent development of micromixers. The review first presents the different micromixer types and designs. Micromixers in this review are categorized as passive micromixers and active micromixers. Due to the simple fabrication technology and the easy implementation in a complex microfluidic system, passive micromixers will be the focus of this review. Next, the review discusses the operation points of the micromixers based on characteristic dimensionless numbers such as Reynolds number Re, Peclet number Pe, and in dynamic cases the Strouhal number St. The fabrication technologies for different mixer types are also analysed. Quantification techniques for evaluation of the performance of micromixers are discussed. Finally, the review addresses typical applications of micromixers.

https://iopscience.iop.org/article/10.1088/0960-1317/15/2/R01/pdf

Micromixers?a review

The Maxwell-Stefan approach to mass transfer

In a controlled release system a drug, pesticide, or other bio-active agent is incorporated into a carrier, generally a polymeric material. The rate of release of the substance is determined by the properties of the polymer itself and is only weakly dependent on environmental factors (such as the pH of bodily fluids). Controlled release systems are capable of delivering substances slowly and continuously for up to several years.

Chemical and Physical Structure of Polymers as Carriers for Controlled Release of Bioactive Agents: A Review

Metal-organic frameworks (MOFs) represent the largest known class of porous crystalline materials ever synthesized Their narrow pore windows and nearly unlimited structural and chemical features have made these materials of significant interest for membrane-based gas separations In this comprehensive review, we discuss opportunities and challenges related to the formation of pure MOF films and mixed-matrix membranes (MMMs) Common and emerging separation applications are identified, and membrane transport theory for MOFs is described and contextualized relative to the governing principles that describe transport in polymers Additionally, cross-cutting research opportunities using advanced metrologies and computational techniques are reviewed To quantify membrane performance, we introduce a simple membrane performance score that has been tabulated for all of the literature data compiled in this review These data are reported on upper bound plots, revealing classes of MOF materials that consistently demonstrate promising separation performance Recommendations are provided with the intent of identifying the most promising materials and directions for the field in terms of fundamental science and eventual deployment of MOF materials for commercial membrane-based gas separations

MOF-Based Membranes for Gas Separations.

1. Phenomenology of Diffusive and Viscous Fluxes.- 2. Elementary Prediction of Transport Coefficients.- 3. Constitutive Equations of Diffusion In Multicomponent Systems without Walls.- 4. Constitutive Equations of Diffusion and Wall Effects.- 5. Analysis of Applications.- 6. History of Diffusion.- References.

R. J. J. Williams

Papers

Diffusion in Gases and Porous Media